Science.gov

Sample records for adjacent sierra nevada

  1. Sierra Nevada

    Atmospheric Science Data Center

    2014-05-15

    ... view of the scene when viewed with red/blue glasses. The red filter should be placed over your left eye. To facilitate the stereo viewing, ... the lower right; a large number of reservoirs that supply water for crop irrigation are apparent in the western foothills of the Sierras. ...

  2. Climatic and hydrologic oscillations in the Owens Lake basin and adjacent Sierra Nevada, California

    SciTech Connect

    Benson, L.V.; Burdett, J.W.; Phillips, F.M.

    1996-11-01

    Oxygen isotope and total organic carbon values of cored sediments from the Owens Lake basin, California, indicate that Owens Lake overflowed most of the time between 52,500 and 12,500 carbon-14 ({sup 14}C) years before present (B.P.). Owens Lake desiccated during or after Heinrich event H1 and was hydrologically closed during Heinrich event H2. The magnetic susceptibility and organic carbon content of cored sediments indicate that about 19 Sierra Nevada glaciations occurred between 52,500 and 23,500 {sup 14}C years B.P. Most of glacial advances were accompanied by decreases in the amount of discharge reaching Owens Lake. Comparison of the timing of glaciation with the lithic record of North Atlantic core V23-81 indicates that the number of mountain glacial cycles and the number of North Atlantic lithic events were about equal between 39,000 and 23,500 {sup 14}C years B.P. 27 refs., 3 figs.

  3. Sierra Nevada's Dream Chaser Model Assembly

    NASA Video Gallery

    This time lapse video shows the assembly of a scale model of Sierra Nevada Space Systems' Dream Chaser vehicle. The Dream Chaser model is undergoing final preparations for buffet tests at the Trans...

  4. CCP: Sierra Nevada Captive-Carry Test

    NASA Video Gallery

    Sierra Nevada Corporation (SNC) Space System's Dream Chaser design passed one of its most complex tests to date with a successful captive-carry test conducted near the Rocky Mountain Metropolitan A...

  5. CCiCap: Sierra Nevada Corporation

    NASA Video Gallery

    NASA announced today its plans to partner with Sierra Nevada Corp. (SNC) for the next phase of the agency's Commercial Crew Program (CCP). Called Commercial Crew integrated Capability (CCiCap), the...

  6. Sierra Nevada snow melt from SMS-2

    NASA Technical Reports Server (NTRS)

    Breaker, L. C.; Mcmillan, M. C.

    1975-01-01

    A film loop from SMS-2 imagery shows snow melt over the Sierra Nevadas from May 10 to July 8, 1975. The sequence indicates a successful application of geostationary satellite data for monitoring dynamic hydrologic conditions.

  7. GPS Imaging of Sierra Nevada Uplift

    NASA Astrophysics Data System (ADS)

    Hammond, W. C.; Blewitt, G.; Kreemer, C.

    2015-12-01

    Recent improvements in the scope and precision of GPS networks across California and Nevada have allowed for uplift of the Sierra Nevada to be observed directly. Much of the signal, in the range of 1 to 2 mm/yr, has been attributed to lithospheric scale rebound following massive groundwater withdrawal in the San Joaquin Valley in southern California, exacerbated by drought since 2011. However, natural tectonic deformation associated with long term uplift of the range may also contribute to the observed signal. We have developed new algorithms that enhance the signal of Sierra Nevada uplift and improve our ability to interpret and separate natural tectonic signals from anthropogenic contributions. We apply our new Median Interannual Difference Adjusted for Skewness (MIDAS) algorithm to the vertical times series and a inverse distance-weighted median spatial filtering and Delaunay-based interpolation to despeckle the rate map. The resulting spatially continuous vertical rate field is insensitive to outliers and steps in the GPS time series, and omits isolated features attributable to unstable stations or unrepresentative rates. The resulting vertical rate field for California and Nevada exhibits regionally coherent signals from the earthquake cycle including interseismic strain accumulation in Cascadia, postseismic relaxation of the mantle from recent large earthquakes in central Nevada and southern California, groundwater loading changes, and tectonic uplift of the Sierra Nevada and Coast Ranges. Uplift of the Sierra Nevada extends from the Garlock Fault in the south to an indefinite boundary in the north near the latitude of Mt. Lassen to the eastern Sierra Nevada range front in Owen's Valley. The rates transition to near zero in the southern Walker Lane. The eastern boundary of uplift coincides with the highest strain rates in the western Great Basin, suggesting higher normal fault slip rates and a component of tectonic uplift of the Sierra Nevada.

  8. MISR Sees the Sierra Nevadas in Stereo

    NASA Technical Reports Server (NTRS)

    2000-01-01

    These MISR images of the Sierra Nevada mountains near the California-Nevada border were acquired on August 12, 2000 during Terra orbit 3472. On the left is an image from the vertical-viewing (nadir) camera. On the right is a stereo 'anaglyph' created using the nadir and 45.6-degree forward-viewing cameras, providing a three-dimensional view of the scene when viewed with red/blue glasses. The red filter should be placed over your left eye. To facilitate the stereo viewing, the images have been oriented with north toward the left.

    Some prominent features are Mono Lake, in the center of the images; Walker Lake, to its left; and Lake Tahoe, near the lower left. This view of the Sierra Nevadas includes Yosemite, Kings Canyon, and Sequoia National Parks. Mount Whitney, the highest peak in the contiguous 48 states (elev. 14,495 feet), is visible near the righthand edge. Above it (to the east), the Owens Valley shows up prominently between the Sierra Nevada and Inyo ranges.

    Precipitation falling as rain or snow on the Sierras feeds numerous rivers flowing southwestward into the San Joaquin Valley. The abundant fields of this productive agricultural area can be seen along the lower right; a large number of reservoirs that supply water for crop irrigation are apparent in the western foothills of the Sierras. Urban areas in the valley appear as gray patches; among the California cities that are visible are Fresno, Merced, and Modesto.

    MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

  9. Groundwater quality in the Sierra Nevada, California

    USGS Publications Warehouse

    Fram, Miranda S.; Belitz, Kenneth

    2014-01-01

    Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project (PBP) of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. The Sierra Nevada Regional study unit constitutes one of the study units being evaluated.

  10. Fuel bed characteristics of Sierra Nevada conifers

    USGS Publications Warehouse

    van Wagtendonk, J.W.; Benedict, J.M.; Sydoriak, W.M.

    1998-01-01

    A study of fuels in Sierra Nevada conifer forests showed that fuel bed depth and fuel bed weight significantly varied by tree species and developmental stage of the overstory. Specific values for depth and weight of woody, litter, and duff fuels are reported. There was a significant positive relationship between fuel bed depth and weight. Estimates of woody fuel weight using the planar intercept method were significantly related to sampled values. These relationships can be used to estimate fuel weights in the field.

  11. DISTRIBUTIONS OF AIRBORNE AGRICULTURAL CONTAMINANTS RELATIVE TO AMPHIBIAN POPULATIONS IN THE SOUTHERN SIERRA NEVADA, CA

    EPA Science Inventory

    The Sierra Nevada mountain range lies adjacent to one of the heaviest pesticide use areas in the USA, the Central Valley of California. Because of this proximity, concern has arisen that agricultural pesticides, in addition to other contaminants, are adversely affecting the natur...

  12. [The Southern Sierra Nevada continental dynamics project]. Final technical report

    SciTech Connect

    Clayton, R.W.; Saleeby, J.B.

    1997-12-16

    The main objective of this study was to determine whether or not the Southern Sierra Nevada Mountain Range is supported by a crustal root. A secondary goal was to evaluate the relationship between the Sierra Nevada Range and the adjoining Death Valley extensional province. As part of the project, two seismic profiles were executed. The first was a north-south profile running from Ridgecrest to Chafant Valley. The second was an east-west profile from Death Valley to Coalinga. An NPE shot was recorded on the east-west receiver line, and the data were analyzed by forward modeling with a staggered-grid finite-difference code. Concurrently, the authors initiated an in-depth study of lower crustal and upper mantle xenoliths hosted by Neogene volcanic rocks of the central and southern Sierra Nevada region. This initial work focused on thermobarometric estimates of representative xenolith samples aimed at understanding the vertical composition of the Sierra Nevada lithosphere.

  13. SNOWS: Sierra Nevada Observatory weather system

    NASA Astrophysics Data System (ADS)

    Costillo, Luis P.; Ibáñez, J. Miguel; Aparicio, Beatriz; García, Antonio J.

    2006-06-01

    The Observatorio de Sierra Nevada (OSN) is located at an altitude of 2800m at the Loma de Dilar in the Sierra Nevada mountain range, in the province of Granada, Spain. It is operated and maintained by the Instituto de Astrofisica de Andalucia (IAA-CSIC) and contains two Nasmyth telescopes with apertures of 1.5 and 0.9m and an Altazimuth telescope with an aperture of 0.6 m. Given that the quality of the images and, indeed, the performance of the instruments are influenced by weather conditions, it would appear that the existence of a weather station capable of producing accurate descriptions is an essential component of any observatory. This is particularly true, however, in our case where, given the altitude, weather conditions at certain times of the year are especially harsh. For this reason, our observatory has required the installation of a robust weather station with easily replaceable sensors which can provide accurate and reliable measures of wind, temperature and humidity. At the same time, in order to avoid a complex topology of unmanageably long wires due to the distribution of a large number of sensors around the buildings, domes telescope mirrors and instruments, it has been necessary to implement a distributed system with several independent nodes connected to a CAN bus. This system is now in operation and running automatically at the OSN and provides all the data from sensors to the observatory control systems and to internet users. This paper gives a detailed description of the SNOWS project, including the development of the weather station, the software and hardware architecture, and the use of distributed nodes with a linear serial bus. The paper also provides some results regarding the wind, temperature and humidity sensors employed at the OSN.

  14. Permian to Triassic I to S-type magmatic switch in the northeast Sierra Nevada de Santa Marta and adjacent regions, Colombian Caribbean: Tectonic setting and implications within Pangea paleogeography

    NASA Astrophysics Data System (ADS)

    Cardona, A.; Valencia, V.; Garzón, A.; Montes, C.; Ojeda, G.; Ruiz, J.; Weber, M.

    2010-10-01

    The Late Paleozoic to Triassic tectonics of northwestern South America have major implications for the understanding of Laurentia-Gondwana interactions that formed Pangea, and the origin of several tectonostratigraphic terranes dispersed by the break-up of this supercontinent during the formation of the Caribbean. Two mylonitic and orthogneissic granitoid suites have been recognized in the northeastern segment of the Sierra Nevada de Santa Marta, the lower Magdalena basin and the Guajira Serranias, within the Caribbean region of Colombia. For the Santa Marta region U/Pb LAM-ICP-MS analysis yielded zircon crystallization ages of 288.1 ± 4.5 Ma, 276.5 ± 5,1 Ma and 264.9 ± 4.0 Ma, related to the magmatic intrusion. Geochemical and modal variations show a compositional spectrum between diorite and granite, whereas LREE enrichment, Ti and Nb anomalies and geochemical discrimination suggest that this granitoid suite was formed within a magmatic arc setting. Inherited zircons suggest that this Early Permian plutonism was formed with the participation of Neoproterozoic and Grenvillian basement proximal to the South American continent. Evidence of a superimposed Early Triassic (ca. 250 Ma) deformational event in Santa Marta, together with a well defined S-type magmatism in the basement rocks from the adjacent lower Magdalena Valley and Guajira Peninsula regions are related to a major shift in the regional tectonic evolution. It's envisioned that this event records either terrane accretion or strong plate coupling during the final stages of Pangea agglutination. Connections with the main Alleghanian-Ouachitan Pangean orogen are precluded due to their timing differences. The plutons temporally and compositionally correlate with an arc found in the northern Andes and Mexican Gondwana terranes, and represent a broader magmatic event formed at the proto-Pacific margin, outside the nucleus of the Laurentia-Gondwana Alleghanian-Oachitan orogens. Evidence of lower temperature

  15. Snowmelt discharge characteristics Sierra Nevada, California

    USGS Publications Warehouse

    Peterson, David; Smith, Richard; Stewart, Iris; Knowles, Noah; Soulard, Chris; Hager, Stephen

    2005-01-01

    Alpine snow is an important water resource in California and the western U.S. Three major features of alpine snowmelt are the spring pulse (the first surge in snowmelt-driven river discharge in spring), maximum snowmelt discharge, and base flow (low river discharge supported by groundwater in fall). A long term data set of hydrologic measurements at 24 gage locations in 20 watersheds in the Sierra Nevada was investigated to relate patterns of snowmelt with stream discharge In wet years, the daily variations in snowmelt discharge at all the gage locations in the Sierra Nevada correlate strongly with the centrally located Merced River at Happy Isles, Yosemite National Park (i.e., in 1983, the mean of the 23 correlations was R= 0.93 + 0.09) ; in dry years, however, this correlation breaks down (i.e., in year 1977, R=0.72 + 0.24). A general trend towards earlier snowmelt was found and modeled using correlations with the timing of the spring pulse and the river discharge center of mass. For the 24 river and creek gage locations in this study, the spring pulse appeared to be a more sensitive measure of early snowmelt than the center of mass. The amplitude of maximum daily snowmelt discharge correlates strongly with initial snow water equivalent. Geologic factors, base rock permeability and soil-to-bedrock ratio, influence snowmelt flow pathways. Although both surface and ground water flows and water levels increase in wet years compared to dry years, the increase was greater for surface water in a watershed with relatively impermeable base rock than for surface water in a watershed with highly permeable base rock The relation was the opposite for base flow (ground water). The increase was greater for groundwater in a watershed with permeable rock compared to ground water in a watershed with impermeable rock. A similar, but weaker, surface/groundwater partitioning was observed in relatively impermeable granitic watersheds with differing soil-to-bedrock ratios. The

  16. Amplitudes of regional seismic phases in relation to crustal structure of the Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Paul, A.; Jongmans, D.; Campillo, M.; Malin, P.; Baumont, D.

    1996-11-01

    We have recorded and modeled the amplitudes of regional seismic waves produced by the Nevada Test Site Non Proliferation Experiment explosion along a 400-km profile across the southern Sierra Nevada of California. Along this profile the amplitudes of the crustal phases Pg and Lg decrease monotonically with distance because of the cumulative effects of geometrical spreading and a frequency-dependent crustal attenuation given by Q ≃ 138 f0.76 (1 ≤ f ≤ 8 Hz). This observation implies that the crust of the Sierras is not more attenuative to P and S waves than the crusts of the adjacent Great Valley and Basin and Range. The only amplitude anomaly related to the crustal structure is a strong attenuation of Lg on the vertical component in the Great Valley due to the refraction of rays in the low-velocity sediments of the basin. In contrast to Pg and Lg, Pn amplitude increases across the Sierra Nevada and the eastern edge of the Great Valley. Then, some 30 km west of the exposed Sierran batholith, the amplitude of Pn suddenly decreases by a factor of 10. On the basis of a new refraction model produced by the Southern Sierra Nevada Continental Dynamics study and on numerical simulations of the Pn/Pg energy ratio, these changes in Pn amplitude are shown to be due to a local increase in crustal thickness, from roughly 35 to 45 km, centered under the western Sierra. The size and location of the amplitude anomaly can be explained with a gently sloping two-layer crust-mantle model with P velocities of 6.0 km/s and 8.0 km/s. The small offset crustal root focuses Pn waves toward the westernmost Sierra Nevada and the easternmost Great Valley, significantly increasing the Pn energy in these regions. The focusing effects diminish rapidly toward the west as the Moho is again horizontal.

  17. Ammonia at Blodgett Forest, Sierra Nevada, USA

    NASA Astrophysics Data System (ADS)

    Fischer, M. L.; Littlejohn, D.

    2007-10-01

    Ammonia is a reactive trace gas that is emitted in large quantities by animal agriculture and other sources in California, which subsequently forms aerosol particulate matter, potentially affecting visibility, climate, and human health. We performed initial measurements of NH3 at the Blodgett Forest Research Station (BFRS) during a two week study in June, 2006. The site is used for ongoing air quality research and is a relatively low-background site in the foothills of the Sierra Nevada. Measured NH3 mixing ratios were quite low (<1 to ~2 ppb), contrasting with typical conditions in many parts of the Central Valley. Eddy covariance measurements showed NH3 fluxes that scaled with measured NH3 mixing ratio and calculated aerodynamic deposition velocity, suggesting dry deposition is a significant loss mechanism for atmospheric NH3 at BFRS. A simple model of NH3 transport to the site supports the hypothesis that NH3 is transported from the Valley to BFRS, but deposits on vegetation during the summer. Further work is necessary to determine whether the results obtained in this study can be generalized to other seasons.

  18. Ammonia at Blodgett Forest, Sierra Nevada, USA

    SciTech Connect

    Fischer, Marc L.; Littlejohn, David

    2007-11-06

    Ammonia is a reactive trace gas that is emitted in large quantities by animal agriculture and other sources in California, which subsequently forms aerosol particulate matter, potentially affecting visibility, climate, and human health. We performed initial measurements of NH{sub 3} at the Blodgett Forest Research Station (BFRS) during a two week study in June, 2006. The site is used for ongoing air quality research and is a relatively low-background site in the foothills of the Sierra Nevada. Measured NH{sub 3} mixing ratios were quite low (< 1 to {approx} 2 ppb), contrasting with typical conditions in many parts of the Central Valley. Eddy covariance measurements showed NH{sub 3} fluxes that scaled with measured NH{sub 3} mixing ratio and calculated aerodynamic deposition velocity, suggesting dry deposition is a significant loss mechanism for atmospheric NH{sub 3} at BFRS. A simple model of NH{sub 3} transport to the site supports the hypothesis that NH{sub 3} is transported from the Valley to BFRS, but deposits on vegetation during the summer. Further work is necessary to determine whether the results obtained in this study can be generalized to other seasons.

  19. Contaminant studies in the Sierra Nevadas

    USGS Publications Warehouse

    Sparling, D.W.; Fellers, G.

    2002-01-01

    full text: Several species of anuran amphibians (frogs and toads) are experiencing severe population declines in even seemingly pristine areas of the Sierra Mountains of California. Among the most severely depressed species are the redlegged frog, the foothill and mountain yellow-legged frogs, the Yosemite toad, and the Cascades frog. Several factors, such as habitat fragmentation, introduced predators (especially fish), and disease, have been linked to these declines. But recent evidence from a USGS-led study shows that contaminants are a primary factor. During the past three years, researchers from the USGS Patuxent Wildlife Research Center, the Western Ecology Research Center, the USDA Beltsville Agriculture Research Center, and the Texas A&M University have teamed up to conduct an extensive study on airborne pesticides and their effects on amphibian populations in the Sierra Nevada Mountains. Previous work on environmental chemistry demonstrated that pesticides from the intensely agricultural Central Valley of California are being blown into the more pristine Sierra Nevada Mountains, especially around Sequoia and Yosemite National Parks. Several pesticides, including diazinon, chlorpyrifos, malathion and endosulfan, can be measured in snow, rainfall, and pond waters in these national parks. With the exception of endosulfan, these pesticides affect and even kill both invertebrates and vertebrate species by inhibiting cholinesterase, an enzyme essential to proper nervous system functioning. In the summer of 2001, we published a paper showing that these same pesticides are now found in adults and the tadpoles of Pacific treefrogs. The results of this landmark study showed that more than 50 percent of the tadpoles and adults sampled in Yosemite and Sequoia National Parks had detectable levels of diazinon or chlorpyrifos and that 86 percent of the Pacific treefrogs sampled in the Lake Tahoe region had detectable levels of endosulfan. In contrast, frogs that were

  20. A Miocene to Pleistocene climate and elevation record of the Sierra Nevada (California)

    PubMed Central

    Mulch, A.; Sarna-Wojcicki, A. M.; Perkins, M. E.; Chamberlain, C. P.

    2008-01-01

    Orographic precipitation of Pacific-sourced moisture creates a rain shadow across the central part of the Sierra Nevada (California) that contrasts with the southern part of the range, where seasonal monsoonal precipitation sourced to the south obscures this rain shadow effect. Orographic rainout systematically lowers the hydrogen isotope composition of precipitation (δDppt) and therefore δDppt reflects a measure of the magnitude of the rain shadow. Hydrogen isotope compositions of volcanic glass (δDglass) hydrated at the earth's surface provide a unique opportunity to track the elevation and precipitation history of the Sierra Nevada and adjacent Basin and Range Province. Analysis of 67 well dated volcanic glass samples from widespread volcanic ash-fall deposits located from the Pacific coast to the Basin and Range Province demonstrates that between 0.6 and 12.1 Ma the hydrogen isotope compositions of meteoric water displayed a large (>40‰) decrease from the windward to the leeward side of the central Sierra Nevada, consistent with the existence of a rain shadow of modern magnitude over that time. Evidence for a Miocene-to-recent rain shadow of constant magnitude and systematic changes in the longitudinal climate and precipitation patterns strongly suggest that the modern first-order topographic elements of the Sierra Nevada characterized the landscape over at least the last 12 million years. PMID:18441101

  1. Observations on the extended tectonic history of the southern Sierra Nevada

    SciTech Connect

    Silver, L.T. )

    1993-04-01

    The crust of the southern Sierra Nevada has been the site of repeated major tectonic dislocations in keeping with its Mesozoic-Cenzoic positions near active plate boundaries. The several Mesozoic magmatic arc which invaded it show evidence of pre- and inter-batholithic juxtapositions of different lithospheres as far back as the Jurassic. This has been noted in mapping strontium, neodymium and lead initial ratios and [delta][sup 18]O variations. The Cretaceous arc carries isotopic zonations consistent with a major lithospheric dislocation extending SE from the Melones-Bear Mountain fault systems through the southern Sierra Nevada into the Mojave desert (restoring the Garlock fault). This is a candidate site for the postulated late Jurassic Mojave-Sonora megashear. During Cretaceous arc evolution major plate changes have taken place at [approximately]104[+-]2 ma and [approximately]80--85 ma. A broad (100( )km) wedge of accreted deepwater sediments and oceanic crust was partly subducted eastward under the Cretaceous arc, producing the Rand, Pelona, Orocopia and Chocolate Mountain schists of southern California. The southern Sierra Nevada saw the northern part of this event. The underlying subduction zone was not disrupted; arc magmatism was quickly renewed in the northern part of the wedge (Rand Mountains). Eastern underthrusting was accompanied and followed by a succession of major westward-vergent low angle faults in the interval 80--60( ) ma with net displacements well in excess of 150 km, and shallow crustal surface rotations in the southern Sierra Nevada and adjacent regions. The southern Sierra Nevada is now clearly detached from its plutonic roots by several generations of low-angle faulting.

  2. Catastrophic rockfalls and rockslides in the Sierra Nevada, USA

    USGS Publications Warehouse

    Wieczorek, Gerald F.; Evans, Stephen G.; DeGraff, Jerome V.

    2002-01-01

    Despite having a low recorded historical incidence of landsliding, the Sierra Nevada has undergone large prehistoric and historical rockfalls and rockslides that could be potentially catastrophic if they occurred today in the more densely populated parts of the region. Several large documented rockfall and rockslides have been triggered either by strong seismic shaking or long periods of unusually wet weather; however, in several instances no obvious triggering event can be identified. The glaciated topography of the higher elevations of the SierraNevada has produced many relatively small falls and slides within relatively hard, massively jointed, granitic rocks; however, where exposed to weathering for long periods after glaciation, the oversteepened rock slopes are prone to uncommonly large falls and slides. At lower elevations on the nonglaciated slopes of the Sierra Nevada, rockslides commonly occur within more weathered granitic rocks, where the strength of the rock mass is typically affected by joint weathering and alteration of the intact rock to saprolite. Historical large rock-falls and rockslides in the Sierra Nevada have created additional secondary natural hazards, including debris flows and floods from the breaching of landslide dams that can be as hazardous as the initial rockfalls and rockslides.

  3. Relative Contributions of Phosphorus in High Elevation Sierra Nevada Lakes

    NASA Astrophysics Data System (ADS)

    Jensen, L. K.; McIntyre, B. M.; Lyons, R. A.

    2015-12-01

    High elevation lakes of the Sierra Nevada mountain range show signs of eutrophication due to increased phosphorus loading. Phosphorus is a major contributing factor to freshwater lake eutrophication when in excess. Three previously researched sources of phosphorus to high-elevation montane lakes include atmospheric deposition, internal loading from sediments, and excretions from non-native stocked fish. The goal of this research was to isolate the estimated phosphorus contributions from residential shoreline developments and stocked non-native fish. A steady-state phosphorus loading rate model was created to quantify relative phosphorus loading into two lakes in the Eastern Sierra Nevada: Convict and Silver Lake. A conglomerate control lake was created from Eastern Brook Lake in the Eastern Sierra Nevada, Pear Lake in the Southern Sierra Nevada, and Snowflake Lake in Canada. Both Convict and Silver Lakes contain stocked non-native trout species and Silver Lake also has ~25 vacation homes on its eastern shore. Seasonal steady-state total phosphorus concentrations were determined using EPA Method 365.2. Loading rate constants were calculated using loading rates from literature and corresponding concentrations. It was determined that as much as 42% of phosphorous to Silver Lake came from shoreline housing developments, and 24% came from stocked fish depending on the season. Previous studies showed much lower contributions from non-native fish.

  4. Lithospheric Control on Spatial Patterns of Active Faulting in the Southeastern Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Amos, C. B.; Unruh, J. R.; Lutz, A.; Fisher, B.; Kelson, K. I.; Rood, D. H.; Jayko, A. S.

    2011-12-01

    Patterns of active faulting in the southeastern Sierra Nevada of California reflect both far-field plate motion as well as localized forces that drive seismogenic deformation. Oblique divergence between the Sierra and the western Cordillera results in an overall pattern of dextral shear and northwest-directed extension in the eastern California shear zone (ECSZ) and southern Walker Lane belt. Within the nominally rigid southern Sierra Nevada block, newly recognized active normal faulting, as well as seismicity, indicate primarily extensional deformation beneath the high topography of the southern range. Investigations of the northern Kern Canyon fault, the Little Lake fault, and the Sierra Nevada range-front faults in Rose Valley combine data from both aerial and ground-based laser scanning, paleoseismic trenching, geologic and geomorphic mapping, and surface exposure dating to define spatial and temporal patterns of fault slip. Taken together, these studies indicate that deformation kinematics along the southeastern Sierran escarpment undergo a pronounced shift at an approximate latitude of 36.5° N. To the north in Owens valley, range-front faults accommodate active extension and normal faulting, while the adjacent Owens Valley fault displays primarily dextral strike-slip motion. South of Lone Pine, however, a component of active normal faulting steps westward into the southern Sierra Nevada block to the Kern Canyon fault, while range-front faults in Rose Valley accommodate a significant component of oblique dextral extension. Focal mechanism inversion of earthquakes in the southern Sierra Nevada reveals a zone of horizontal extension and vertical crustal thinning coincident with this westward shift of normal faulting into the range. The zone of extension is directly east of the "Isabella Anomaly," a zone of anomalous high P-wave mantle velocities thought to reflect convectively downwelling or foundering lower Sierran lithosphere below the Central Valley. As such

  5. Correlation of the Klamath Mountains and Sierra Nevada

    USGS Publications Warehouse

    Irwin, William P.

    2003-01-01

    This report graphically portrays the broadly parallel tectonic development of the Klamath Mountains and Sierra Nevada from early Paleozoic to Early Cretaceous time. It is dedicated to J.S. Diller of the U.S. Geological Survey who, during his pioneer field studies a century ago, recognized significant similarities between these two important provinces. The report is based mainly on the numerous published reports of the field and laboratory studies by various geologists and students during the last century, and to a lesser extent on my own field work which has been substantial in the Klamath Mountains but minimal in the Sierra Nevada. For brevity, required by the format of this report, little of the extensive literature pertaining to these two provinces is referenced. This report is preliminary in nature and was prepared as an aid to further study of the tectonic relations between the Klamath Mountains and Sierra Nevada. This report consists of two sheets: Sheet 1, Map showing accreted terranes and plutons of the Klamath Mountains and Sierra Nevada, and Sheet 2, Successive accretionary episodes of the Klamath mountains and northern part of Sierra Nevada, showing related plutonic, volcanic, and metamorphic events. The map on Sheet 1 was compiled and modified from two Open-File maps (Irwin and Wooden, 1999 and 2001) which had been compiled and modified mainly from Jennings (1977), Harwood (1992), Irwin (1994), Jayko (1988), Graymer and Jones (1994), Edelman and Sharp (1989), Schweickert and others (1999), Saucedo and Wagner(1992), Saleeby and Sharp (1980), Wagner and others (1981), and various other sources. For detailed lists of the sources for the isotopic age data used in Sheets 1 and 2, see Irwin and Wooden (1999 and 2001). On Sheet 2, the accretionary episodes are shown sequentially from left to right in two tiers of figures. Episodes for the Klamath Mountains are in the upper tier; correlative episodes of the Sierra Nevada are directly below in the lower tier

  6. 75 FR 44942 - 2015 Resource Pool-Sierra Nevada Customer Service Region

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-30

    ... Nevada Customer Service Region AGENCY: Western Area Power Administration, DOE. ACTION: Notice of Proposed... the Sierra Nevada Customer Service Region (SNR) in the Federal Register on June 25, 1999. The... Anderson, Power Marketing Manager, Sierra Nevada Customer Service Region, Western Area Power...

  7. Updated paleomagnetic pole from Cretaceous plutonic rocks of the Sierra Nevada, California: Tectonic displacement of the Sierra Nevada block

    USGS Publications Warehouse

    Hillhouse, J.W.; Gromme, S.

    2011-01-01

    We report remanent magnetization measurements from 13 sites in Cretaceous plutonic rocks in the northern Sierra Nevada (38??N-39.5??N). By increasing the number of available paleomagnetic sites, the new data tighten constraints on the displacement history of the Sierra Nevada block and its pre-extensional position relative to interior North America. We collected samples in freshly exposed outcrops along four highway transects. The rocks include diorite, granodiorite, and tonalite with potassium-argon ages (hornblende) ranging from 100 Ma to 83 Ma. By combining our results with previous paleomagnetic determinations from the central and southern Sierra Nevada (excluding sites from the rotated southern tip east of the White Wolf-Kern Canyon fault system), we find a mean paleomagnetic pole of 70.5??N, 188.2??E, A95 = 2.6?? (N = 26, Fisher concentration parameter, K = 118). Thermal demagnetization indicates that the characteristic remanence is generally unblocked in a narrow range within 35 ??C of the Curie temperature of pure magnetite. Small apparent polar wander during the Cretaceous normal-polarity superchron, plus prolonged acquisition of remanence at the site level, may account for the low dispersion of virtual geomagnetic poles and relatively large K value. Tilt estimates based on overlapping sediments, stream gradients, and thermochronology of the Sierra Nevada plutons vary from 0?? to 3?? down to the southwest. Without tilt correction, the mean paleomagnetic pole for the Sierra Nevada is essentially coincident with the North American reference pole during the Cretaceous stillstand (125 Ma to 80 Ma). At 95% confidence, the apparent latitude shift is 1.1?? ?? 3.0?? (positive northward), and the apparent rotation is negligible, 0.0?? ?? 4.7??. Correcting for each degree of tilt, which is limited to 3?? on geologic evidence, increases the rotation anomaly 2.2?? counterclockwise, while the apparent latitude shift remains unchanged. ?? 2011 Geological Society of

  8. Rangewide glaciation in the Sierra Nevada, California

    USGS Publications Warehouse

    Moore, James G.; Moring, Barry C.

    2013-01-01

    The 600-km-long Sierra Nevada underwent extensive Pleistocene glaciation except for its southernmost 100 km. Presently, ∼1700 small glaciers and ice masses near the crest of the range occur above 3250 m in elevation; these covered an area of ∼50 km2 in 1972. Fourteen of the largest glaciers decreased by about one half in area during the period from 1900 to 2004. Rock glaciers, generally glacial ice covered by 1–10 m of rockfall debris, occur in about the same span of the range as ice and permanent snowfields. They are, on average, lower by 200–300 m, apparently because of the insulating layer of rocky rubble that protects their internal ice from the sun’s heat and from wind. The principal Pleistocene glacial stages are the Sherwin (ca. 820 ka), Tahoe (170–130 and ca. 70 ka), Tioga (14–28 ka), and Recess Peak (13 ka). Some 7040 glacial lakes, produced primarily by quarrying from bedrock, were mostly exposed after recession of the Tioga glacial stage. The lakes largely mark the area of primary snow accumulation. Below the lower limit of the lakes, ice flowed downward into river-cut canyons, forming major trunk glaciers within the zone of ablation. The range is in general a westward-tilted block upfaulted on its east side. Therefore, the main late Pleistocene trunk glaciers (Tahoe/Tioga) west of the crest extend 25–60 km, whereas those east of the crest extend only 5–20 km. Because of higher precipitation northward, glacial features such as the toes of existing glaciers and rock glaciers, as well as the late season present-day snowline, all decrease in elevation northward. Likewise, the elevation of the lower limit of glacial lakes, an indication of the zone of snow accumulation during the late Pleistocene, decreases about the same degree. This similarity suggests that the overall climate patterns of the late Pleistocene, though cooler, were similar to those of today. The east slope glaciers show a similar northward depression, but they are ∼500

  9. Correlations and Areal Distribution of the Table Mountain Formation, Stanislaus Group; Central Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Torrez, G.; Carlson, C. W.; Putirka, K. D.; Pluhar, C. J.; Sharma, R. K.

    2011-12-01

    Late Cenozoic evolution of the western Cordillera is a matter of ongoing debate in geologic studies. Volcanic deposits within, and adjacent to the Sierra Nevada have played a significant role in many of these debates. With local faulting coincident with eruption of members of the Stanislaus Group at ca. 38°N, the composition and correlation of these volcanics can greatly aid our understanding of Sierra Nevada tectonics. At the crest of the central Sierra Nevada, 23 trachyandesite lava flows of the Table Mountain Formation, dated at ~10 Ma, cap Sonora Peak. These 23 flows compose the thickest and most complete known stratigraphic section of the Table Mountain Formation in the region. Located ~12 km east of Sonora Peak are 16 flows of trachyandesite at Grouse Meadow. We have collected a detailed set of geochemical and paleomagnetic data for flows of these two sections at Sonora Peak and Grouse Meadows in an attempt to correlate volcanic, paleomagnetic and structural events related to uplift and extension in the Sierra Nevada and the Walker Lane. Correlation of individual flows is possible based on: stratigraphic order, temporal gaps in deposition as determined by paleomagnetic remanence direction and nonconformities, and flow geochemistry. These correlations allow us to infer source localities, flow directions, and temporal changes in flow routes. The large number of flows present at Grouse Meadow provides an additional data set from which to correlate various localities in the region to those units not represented at Sonora Peak. Several flows which occur in the upper portions of the Sonora Peak and Grouse Meadow stratigraphic sections do not correlate between these localities. The causes of stratigraphic discontinuity potentially represent: tectonic isolation across the Sierran Crest, topographic isolation by the emplacement of younger flows, or the combination of the two. Additional to the correlation of individual flows at these localities, this study shows a

  10. Bounds of foundering in the southern Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Gilbert, H.; Yang, Y.; Forsyth, D. W.; Jones, C. H.; Owens, T. J.; Zandt, G.

    2008-12-01

    Previous petrologic and tomographic observations have found that while a thick residual root formed under the southern Sierra Nevada batholith, it has since foundered and descends into the mantle. The recent Sierra Nevada EarthScope Project (SNEP) FlexArray in eastern California sought to improve our understanding of the mechanism, extent, and tectonic consequences of this process. Over fifty broadband seismic stations deployed between 2005 and 2007 comprised the SNEP array. Many of these stations were redeployed once to occupy ~100 sites spanning much of the mountain range. Surrounding stations from the TransportableArray provide a common reference for analyzing SNEP stations that moved. Using fundamental mode Rayleigh waves, generated by teleseismic earthquakes at periods between 20 and 100 s, we examine lithospheric structures beyond the crust into the mantle. By employing an array processing approach, and treating the incoming surface wave field as two interfering plane waves (Forsyth and Li, 2005), we account for multipathing and scattering of the wave field, which is common along continental margins and within mountain ranges. The 25 km station spacing of the SNEP deployment allows for features to be resolved that could not be found using only the TransportableArray. For periods between 20 and 50 s that are sensitive structures in the crust and uppermost mantle, the pattern of phase velocities along the southern Sierra Nevada exhibits a similar asymmetry to that found for crustal structures. Within this period range, low phase velocities characterize regions of thin crust of the southeastern Sierra and extend out to Walker Lane and the western Basin and Range. Conversely, the western foothills possess thicker crust and higher phase velocities. In the central Sierra, at latitudes near Lake Tahoe, the distribution of anomalies changes and the low and the high phase velocities that mark the eastern and western sides of the southern Sierra terminate. These

  11. 77 FR 66607 - Sierra Pacific Power Company, Nevada Power Company; Notice of Petition for Declaratory Order

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-06

    ... From the Federal Register Online via the Government Publishing Office ] DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Sierra Pacific Power Company, Nevada Power Company; Notice of... Pacific Power Company and Nevada Power Company (Applicants) filed a petition for declaratory...

  12. Groundwater quality in the Southern Sierra Nevada, California

    USGS Publications Warehouse

    Fram, Miranda S.; Belitz, Kenneth

    2012-01-01

    Groundwater provides more than 40 percent of California's drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State's groundwater quality and increases public access to groundwater-quality information. The Tehachapi-Cummings Valley and Kern River Valley basins and surrounding watersheds in the Southern Sierra Nevada constitute one of the study units being evaluated.

  13. Foundering lithosphere imaged beneath the southern Sierra Nevada, California, USA.

    PubMed

    Boyd, Oliver S; Jones, Craig H; Sheehan, Anne F

    2004-07-30

    Seismic tomography reveals garnet-rich crust and mantle lithosphere descending into the upper mantle beneath the southeastern Sierra Nevada. The descending lithosphere consists of two layers: an iron-rich eclogite above a magnesium-rich garnet peridotite. These results place descending eclogite above and east of high P wave speed material previously imaged beneath the southern Great Valley, suggesting a previously unsuspected coherence in the lithospheric removal process.

  14. Groundwater quality in the Central Sierra Nevada, California

    USGS Publications Warehouse

    Fram, Miranda S.; Belitz, Kenneth

    2012-01-01

    Groundwater provides more than 40 percent of California's drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State's groundwater quality and increases public access to groundwater-quality information. Two small watersheds of the Fresno and San Joaquin Rivers in the Central Sierra Nevada constitute one of the study units being evaluated.

  15. Inventory of glaciers in the Sierra Nevada, California

    USGS Publications Warehouse

    Raub, William; Brown, C. Suzanne; Post, Austin

    2006-01-01

    All perennial bodies of ice in the Sierra Nevada are listed and classified. The inventory includes 497 glaciers covering a total area of 50 square kilometers and 788 small ice bodies which do not meet the definition of a glacier, covering a total of 13 square kilometers. The listings include each ice body's drainage basin, location, orientation, altitude, area, and length the glaciers are also classified as to form, source, surface condition, and nature and activity of the terminus.

  16. Color and 3D views of the Sierra Nevada mountains

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A stereo 'anaglyph' created using the nadir and 45.6-degree forward-viewing cameras provides a three-dimensional view of the scene when viewed with red/blue glasses. The red filter should be placed over your left eye. To facilitate the stereo viewing, the images have been oriented with north toward the left. Some prominent features are Mono Lake, in the center of the image; Walker Lake, to its left; and Lake Tahoe, near the lower left. This view of the Sierra Nevadas includes Yosemite, Kings Canyon, and Sequoia National Parks. Mount Whitney, the highest peak in the contiguous 48 states (elev. 14,495 feet), is visible near the righthand edge. Above it (to the east), the Owens Valley shows up prominently between the Sierra Nevada and Inyo ranges. Precipitation falling as rain or snow on the Sierras feeds numerous rivers flowing southwestward into the San Joaquin Valley. The abundant fields of this productive agricultural area can be seen along the lower right; a large number of reservoirs that supply water for crop irrigation are apparent in the western foothills of the Sierras. Urban areas in the valley appear as gray patches; among the California cities that are visible are Fresno, Merced, and Modesto.

  17. Tectonic geomorphology of the southern Sierra Nevada Mountains (California): Evidence for uplift and basin formation

    NASA Astrophysics Data System (ADS)

    Figueroa, Andrea M.; Knott, Jeffrey R.

    2010-11-01

    Hypotheses regarding uplift of the Sierra Nevada Mountains (Sierra), California, USA, vary from a single slowly tilting block to rapid Pliocene and/or Quaternary uplift in the south exclusively. To test these hypotheses, we examined geomorphic indices of the western Sierra. We interpret longitudinal profiles of the larger westerly flowing rivers, mountain front sinuosity, valley floor-to-width to height ratio, and relief ratio to show that relative tectonic activity is greater in the southern Sierra near the Kern River Gorge fault. The Sierra range crest profile indicates that the increased tectonism is related to more recent uplift in the southern Sierra. Only westward migration of Basin and range extension is consistent with the locus of uplift in the southern Sierra. We hypothesize that the Sierra topography is the result of Pliocene delamination-related uplift in the central Sierra and post-Pliocene interaction of the San Andreas, Garlock, and Sierra Nevada Frontal fault zones.

  18. GPS Imaging of vertical land motion in California and Nevada: Implications for Sierra Nevada uplift.

    PubMed

    Hammond, William C; Blewitt, Geoffrey; Kreemer, Corné

    2016-10-01

    We introduce Global Positioning System (GPS) Imaging, a new technique for robust estimation of the vertical velocity field of the Earth's surface, and apply it to the Sierra Nevada Mountain range in the western United States. Starting with vertical position time series from Global Positioning System (GPS) stations, we first estimate vertical velocities using the MIDAS robust trend estimator, which is insensitive to undocumented steps, outliers, seasonality, and heteroscedasticity. Using the Delaunay triangulation of station locations, we then apply a weighted median spatial filter to remove velocity outliers and enhance signals common to multiple stations. Finally, we interpolate the data using weighted median estimation on a grid. The resulting velocity field is temporally and spatially robust and edges in the field remain sharp. Results from data spanning 5-20 years show that the Sierra Nevada is the most rapid and extensive uplift feature in the western United States, rising up to 2 mm/yr along most of the range. The uplift is juxtaposed against domains of subsidence attributable to groundwater withdrawal in California's Central Valley. The uplift boundary is consistently stationary, although uplift is faster over the 2011-2016 period of drought. Uplift patterns are consistent with groundwater extraction and concomitant elastic bedrock uplift, plus slower background tectonic uplift. A discontinuity in the velocity field across the southeastern edge of the Sierra Nevada reveals a contrast in lithospheric strength, suggesting a relationship between late Cenozoic uplift of the southern Sierra Nevada and evolution of the southern Walker Lane.

  19. GPS Imaging of vertical land motion in California and Nevada: Implications for Sierra Nevada uplift

    NASA Astrophysics Data System (ADS)

    Hammond, William C.; Blewitt, Geoffrey; Kreemer, Corné

    2016-10-01

    We introduce Global Positioning System (GPS) Imaging, a new technique for robust estimation of the vertical velocity field of the Earth's surface, and apply it to the Sierra Nevada Mountain range in the western United States. Starting with vertical position time series from Global Positioning System (GPS) stations, we first estimate vertical velocities using the MIDAS robust trend estimator, which is insensitive to undocumented steps, outliers, seasonality, and heteroscedasticity. Using the Delaunay triangulation of station locations, we then apply a weighted median spatial filter to remove velocity outliers and enhance signals common to multiple stations. Finally, we interpolate the data using weighted median estimation on a grid. The resulting velocity field is temporally and spatially robust and edges in the field remain sharp. Results from data spanning 5-20 years show that the Sierra Nevada is the most rapid and extensive uplift feature in the western United States, rising up to 2 mm/yr along most of the range. The uplift is juxtaposed against domains of subsidence attributable to groundwater withdrawal in California's Central Valley. The uplift boundary is consistently stationary, although uplift is faster over the 2011-2016 period of drought. Uplift patterns are consistent with groundwater extraction and concomitant elastic bedrock uplift, plus slower background tectonic uplift. A discontinuity in the velocity field across the southeastern edge of the Sierra Nevada reveals a contrast in lithospheric strength, suggesting a relationship between late Cenozoic uplift of the southern Sierra Nevada and evolution of the southern Walker Lane.

  20. Geologic map of the South Sierra Wilderness and South Sierra Roadless area, southern Sierra Nevada, California

    SciTech Connect

    Diggles, M.F. ); Carter, K.E. )

    1993-04-01

    The study area is underlain predominantly by granitoid rocks of the Sierra Nevada batholith. Metamorphic rocks are present in roof pendants mainly in the southwest corner of the study area and consist of quartz-biotite schist, phyllite, quartzite, marble, calc-silicate hornfels, and meta-dacite. Among the seven Triassic and (or) Jurassic plutons are three newly described units that consist of the gabbro of Deer Mountain, the tonalite of Falls Creek, and the quartz diorite of Round Mountain. The map shows one newly described unit that intrudes Triassic rocks: the granodiorite of Monache Creek which is a leucocratic, medium-grained, equi-granular, locally porphyritic biotite hornblende granodiorite. Among the seven Cretaceous plutons are two newly described units. The Cretaceous rocks are generally medium- to coarse-grained, potassium-feldspar porphyritic granite with biotite and minor hornblende; it includes abundant pods of alaskite. The granite of Haiwee Creek is similar but only locally potassium-feldspar porphyritic and with only minor hornblende. Major-element data plotted on Harker diagrams show the older rocks to be higher in iron and magnesium and lower in silica than the younger rocks. There are abundant local pods of alaskite throughout the study area that consist of medium- to coarse-grained, leucocratic granite, alkali-feldspar granite and associated aplite and pegmatite bodies occurring as small pods and highly leucocratic border phases of nearby plutons. Tertiary and Quaternary volcanic rock include the rhyolite of Monache Mountain and Quaternary surficial deposits: fan, stream-channel, colluvium, talus, meadow-filling, rock-glacier, and glacial-moraine deposits. Important structures include the Sierran front fault and a possible extensional feature along which Bacon (1978) suggests Monache Mountain erupted.

  1. Plutonism in the central part of the Sierra Nevada Batholith, California

    USGS Publications Warehouse

    Bateman, Paul C.

    1992-01-01

    The Sierra Nevada batholith comprises the plutonic rocks of Mesozoic age that underlie most of the Sierra Nevada, a magnificent mountain range that originated in the Cenozoic by the westward tilting of a huge block of the Earth's crust. Scattered intrusions west of the batholith in the western metamorphic belt of the Sierra Nevada and east of the Sierra Nevada in the Benton Range and the White and Inyo Mountains are satellitic to but not strictly parts of the Sierra Nevada batholith. Nevertheless, all the plutonic rocks are related in origin. The batholith lies along the west edge of the Paleozoic North American craton, and Paleozoic and early Mesozoic oceanic crust underlies its western margin. It was emplaced in strongly deformed but weakly metamorphosed strata ranging in age from Proterozoic to Cretaceous. Sedimentary rocks of Proterozoic and Paleozoic age crop out east of the batholith in the White and Inyo Mountains, and metamorphosed sedimentary and volcanic rocks of Paleozoic and Mesozoic age crop out west of the batholith in the western metamorphic belt. A few large and many small, generally elongate remnants of metamorphic rocks lie within the batholith. Sparse fossils from metasedimentary rocks and isotopic ages for metavolcanic rocks indicate that the metamorphic rocks in the remnants range in age from Early Cambrian to Early Cretaceous. Within the map area (the Mariposa 1 0 by 2 0 quadrangle), the bedding, cleavage, and axial surfaces of folds generally trend about N. 35 0 W., parallel to the long axis of the Sierra Nevada. The country rocks comprise strongly deformed but generally coherent sequences; however, some units in the western metamorphic belt may partly consist of melanges. Most sequences are in contact with other sequences, at least for short distances, but some sequences within the batholith are bounded on one or more sides by plutonic rocks. Proterozoic and Paleozoic sedimentary strata east of the Sierra Nevada and Paleozoic strata in

  2. Environmental exposures to agrochemicals in the Sierra Nevada mountain range

    USGS Publications Warehouse

    LeNoir, J.; Aston, L.; Data, S.; Fellers, G.; McConnell, L.; Sieber, J.

    2000-01-01

    The release of pesticides into the environment may impact human and environmental health. Despite the need for environmental exposure data, few studies quantify exposures in urban areas and even fewer determine exposures to wildlife in remote areas. Although it is expected that concentrations in remote regions will be low, recent studies suggest that even low concentrations may have deleterious effects on wildlife. Many pesticides are known to interfere with the endocrine systems of humans and wildlife, adversely affecting growth, development, and behavior. This chapter reviews the fate and transport of pesticides applied in the Central Valley of California and quantifies their subsequent deposition into the relatively pristine Sierra Nevada Mountain Range.

  3. Modeling Patterns of Precipitation Phase in the Central Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Strikas, O.; Pavelsky, T.

    2013-12-01

    Snowpack provides 75% of summer hydrologic flow in the western United States. This summer flow is vitally important in California, the country's leading producer of agriculture, with $43.5 billion dollars in cash receipts in 2011. Snowpack in the California Sierra Nevada has declined by approximately half from 1900 to 1990. In this study, we use the Weather Research and Forecasting (WRF) regional climate model at a 3km resolution to understand the critical temperature window at which both snow and rain fall for the Central Sierra Nevada during the 2002 water year. Results suggest that temperature and snow fraction [snowfall / (snowfall + rainfall)] share a logistic relationship with the snow fraction being 1 until approximately 272 K, then the snow fraction decreases by approximately 22%/K leveling at 0 snow fraction at 276.5 K. We further examine the spatial patterns of temperatures, precipitation amounts, and precipitation types in the Sierra Nevada to determine the areas of greatest potential snow to rain transition under a future warmer climate. Preliminary results suggest that the high risk areas are at the low to mid elevations. This research provides evidence that even a minor increase in temperature (+0.5 K) will yield changes in spring and summer hydrographs for the region. The spatial variability of IPCC temperature regime change for 2050 and 2100 will be downscaled for a higher resolution prediction of precipitation. It is currently under investigation how the proposed IPCC (A1 and B2) predictions of climate change for the region by 2050 (+2.7 K; +1.6 K ) and 2100 (+4.4 K; +2.7 K) will alter the corresponding annual river hydrographs. Given the complex topography of the Sierra Nevada, several spatial interpolations using GIS and statistical algorithms will be executed to render this high resolution (3km) output. Other future work with collaborators intends to model the agricultural risk associated with our predicted changes. This plot demonstrates the

  4. 75 FR 7518 - Notice of Public Meeting: Sierra Front Northwestern Basin Resource Advisory Council, Nevada

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-19

    ...: 14X1109] Notice of Public Meeting: Sierra Front Northwestern Basin Resource Advisory Council, Nevada... Great Basin Resource Advisory Council (RAC), will meet in Carson City, Nevada. The meeting is open to... Mill Road, Carson City, Nevada. A field trip to locations in Storey and Washoe counties will occur...

  5. Hand-Hewn Granite Basins at Native American Saltworks, Sierra Nevada, California

    USGS Publications Warehouse

    Moore, James G.; Diggles, Michael F.

    2009-01-01

    This site in the northern Sierra Nevada contains about 369 circular basins carved in fresh, glaciated granodioritic bedrock, with 325 basins crowded together in an area of 2,700 m2 on the main terrace. These terrace basins have a median average diameter of 125 cm (80 percent between 100 and 160 cm) and a median depth of 75-80 cm. They show a strong congruity to similar granitic basins in the southern Sierra Nevada apparently of Native American origin that are generally shallower. The basins are not of natural origin, as indicated by uniformity in size and nonoverlapping character of the basins; their common arrangement in lineaments; details of the shape of the basins; features in common with granite basins in the Southern Sierra Nevada; and, most compelling, the clustering of all the basins adjacent to (within 20 m of) two saline streams fed from a nearby salt spring. Native Americans apparently excavated them for the purpose of collecting saline water to evaporate and make salt for their use, and also as an animal attractant and a trade commodity. The flow of the salty streams delivers about 2.9 metric tons of salt per summer season to the basin area, and evaporation rates and the holding capacity of the basins indicate that about 2.5 tons of salt could be produced per season. This correspondence shows that the Indians made enough basins to exploit the resource. The site is the most impressive prehistoric saltworks yet discovered in North America and represents a unique departure from traditional hunter-gatherer activities to that of manufacturing. The actual grinding of so many basins in granite could not have been done without the labor of a concentrated population. It is believed that the work was accomplished over a long time by many people and with the use of fire to help disaggregate the bedrock.

  6. Interactions among wildland fires in a long-established Sierra Nevada natural fire area

    USGS Publications Warehouse

    Collins, B.M.; Miller, J.D.; Thode, A.E.; Kelly, M.; van Wagtendonk, J.W.; Stephens, S.L.

    2009-01-01

    We investigate interactions between successive naturally occurring fires, and assess to what extent the environments in which fires burn influence these interactions. Using mapped fire perimeters and satellite-based estimates of post-fire effects (referred to hereafter as fire severity) for 19 fires burning relatively freely over a 31-year period, we demonstrate that fire as a landscape process can exhibit self-limiting characteristics in an upper elevation Sierra Nevada mixed conifer forest. We use the term 'self-limiting' to refer to recurring fire as a process over time (that is, fire regime) consuming fuel and ultimately constraining the spatial extent and lessening fire-induced effects of subsequent fires. When the amount of time between successive adjacent fires is under 9 years, and when fire weather is not extreme (burning index <34.9), the probability of the latter fire burning into the previous fire area is extremely low. Analysis of fire severity data by 10-year periods revealed a fair degree of stability in the proportion of area burned among fire severity classes (unchanged, low, moderate, high). This is in contrast to a recent study demonstrating increasing high-severity burning throughout the Sierra Nevada from 1984 to 2006, which suggests freely burning fires over time in upper elevation Sierra Nevada mixed conifer forests can regulate fire-induced effects across the landscape. This information can help managers better anticipate short- and long-term effects of allowing naturally ignited fires to burn, and ultimately, improve their ability to implement Wildland Fire Use programs in similar forest types. ?? 2008 Springer Science+Business Media, LLC.

  7. EXPOSURE OF AMPHIBIANS TO SEMI-VOLATILE ORGANIC COMPOUNDS IN THE SIERRA NEVADA MOUNTAINS AND CALIFORNIA CASCADES: RELATIONSHIP BETWEEN TADPOLE TISSUE AND SEDIMENT CONCENTRATIONS

    EPA Science Inventory

    Pesticides and other semi-volatile organic compounds (SOCs) undergo regional and longrange atmospheric transport. One such example is the transport of current-use pesticides from the intensely cultivated Central Valley of California into the adjacent Sierra Nevada and Cascade Mou...

  8. GPS Imaging of vertical land motion in California and Nevada: Implications for Sierra Nevada uplift

    PubMed Central

    Blewitt, Geoffrey; Kreemer, Corné

    2016-01-01

    Abstract We introduce Global Positioning System (GPS) Imaging, a new technique for robust estimation of the vertical velocity field of the Earth's surface, and apply it to the Sierra Nevada Mountain range in the western United States. Starting with vertical position time series from Global Positioning System (GPS) stations, we first estimate vertical velocities using the MIDAS robust trend estimator, which is insensitive to undocumented steps, outliers, seasonality, and heteroscedasticity. Using the Delaunay triangulation of station locations, we then apply a weighted median spatial filter to remove velocity outliers and enhance signals common to multiple stations. Finally, we interpolate the data using weighted median estimation on a grid. The resulting velocity field is temporally and spatially robust and edges in the field remain sharp. Results from data spanning 5–20 years show that the Sierra Nevada is the most rapid and extensive uplift feature in the western United States, rising up to 2 mm/yr along most of the range. The uplift is juxtaposed against domains of subsidence attributable to groundwater withdrawal in California's Central Valley. The uplift boundary is consistently stationary, although uplift is faster over the 2011–2016 period of drought. Uplift patterns are consistent with groundwater extraction and concomitant elastic bedrock uplift, plus slower background tectonic uplift. A discontinuity in the velocity field across the southeastern edge of the Sierra Nevada reveals a contrast in lithospheric strength, suggesting a relationship between late Cenozoic uplift of the southern Sierra Nevada and evolution of the southern Walker Lane. PMID:27917328

  9. Snow chemistry of the Cascade-Sierra Nevada Mountains

    USGS Publications Warehouse

    Laird, L.B.; Taylor, H.E.; Kennedy, V.C.

    1986-01-01

    This investigation assesses geographic variations in atmospheric deposition in Washington, Oregon, and California using snow cores from the Cascade-Sierra Nevada Mountains, collected from late February to mid-March 1983. A statistical analysis of the analytical and sampling precision was made. The snowpack in the higher Cascades and Sierra Nevada is not strongly influenced by anthropogenic activities at present. The pH of snow samples ranges from 5.11 to 5.88. Sulfate and nitrate correlate with H+ in some segments of the sample traverse. The SO4 data show apparent influence from major source areas in Washington and California; nitrate does not. An apparent decrease in NH4 in snow in Washington and California suggests atmospheric interactions resulting in the removal of NH4. The NH4 reduction raises questions about nutrient supply to the mountain vegetation. Heavy-metal correlations included Cd, Cu, and Fe with Pb, and Mn with K and DOC, among others. No correlation was found between constituents and snow-water content.

  10. Snow chemistry of the Cascade-Sierra Nevada Mountains

    SciTech Connect

    Laird, L.B.; Taylor, H.E.; Kennedy, V.C.

    1986-03-01

    This investigation assesses geographic variations in atmospheric deposition in Washington, Oregon, and California using snow cores from the Cascade-Sierra Nevada Mountains, collected from late February to mid-March 1983. A statistical analysis of the analytical and sampling precision was made. The snowpack in the higher Cascades and Sierra Nevada is not strongly influenced by anthropogenic activities at present. The pH of snow samples ranges from 5.11 to 5.88. Sulfate and nitrate correlate with H/sup +/ in some segments of the sample traverse. The SO/sub 4/ data show apparent influence from major source areas in Washington and California; nitrate does not. An apparent decrease in NH/sub 4/ in snow in Washington and California suggests atmospheric interactions resulting in the removal of NH/sub 4/. The NH/sub 4/ reduction raises questions about nutrient supply in the mountain vegetation. Heavy-metal correlations included Cd, Cu, and Fe with Pb, and Mn with K and DOC, among others. No correlation was found between constituents and snow-water content. 47 references, 11 figures, 7 tables.

  11. Late Pleistocene vegetation of Kings Canyon, Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Cole, Kenneth

    1983-01-01

    Seven packrat midden samples make possible a comparison between the modern and late Pleistocene vegetation in Kings Canyon on the western side of the southern Sierra Nevada. One modern sample contains macrofossils and pollen derived from the present-day oak-chaparral vegetation. Macrofossils from the six late Pleistocene samples record a mixed coniferous forest dominated by the xerophytic conifers Juniperus occidentalis, Pinus cf. ponderosa, and P. monophylla. The pollen spectra of these Pleistocene middens are dominated by Pinus sp., Taxodiaceae-Cupressaceae-Taxaceae (TCT), and Artemisia sp. Mesophytic conifers are represented by low macrofossil concentrations. Sequoiadendron giganteum is represented by a few pollen grains in the full glacial. Edaphic control and snow dispersal are the most likely causes of these mixed assemblages. The dominant macrofossils record a more xeric plant community than those that now occur on similar substrates at higher elevations or latitudes in the Sierra Nevada. These assemblages suggest that late Wisconsin climates were cold with mean annual precipitation not necessarily greater than modern values. This conclusion supports a model of low summer ablation allowing for the persistence of the glaciers at higher elevations during the late Wisconsin. The records in these middens also suggest that S. giganteum grew at lower elevations along the western side of the range and that P. monophylla was more widely distributed in cismontane California during the Pleistocene.

  12. Sierra Nevada Rock Glaciers: Biodiversity Refugia in a Warming World?

    NASA Astrophysics Data System (ADS)

    Millar, C. I.; Westfall, R. D.

    2007-12-01

    Rock glaciers and related periglacial rock-ice features (RIFs) are common landforms in high, dry mountain ranges, and widely distributed throughout canyons of the Sierra Nevada, California, USA (Millar & Westfall, in press). Due to insulating rock carapaces, active rock glaciers (ice-cored) have been documented to maintain ice longer, and thus contribute to more enduring hydrologic output, under past warming climates than typical ice glaciers. This function has been suggested for the coming century. We propose a broader hydrologic and ecologic role for RIFs as temperatures rise in the future. For the Sierra Nevada, we suggest that canyons with either active or relict RIFs (Holocene and Pleistocene) maintain water longer and distribute water more broadly than canyons that were scoured by ice glaciers and are defined by primary river and lake systems. RIFs provide persistent, distributed water for extensive wetland habitat, rare in these otherwise barren, high, and dry locations. We mapped and assessed the area of wetlands surrounding active and relict RIFs from the central eastern Sierra Nevada; from these we delineated wetland vegetation community types and recorded plant species found in RIF-supported wetlands. Mid-elevation RIFs, likely inactive or with transient ice, develop soil patches on their rock matrix. At the Barney Rock Glacier (Duck Pass, Mammoth Crest), we inventoried plant species on all soil patches, and measured cover for each species per patch and total plant cover for the rock glacier. RIF landforms also appear to support high-elevation mammals. We show that American beaver (Castor canadensis) is associated with canyons dominated by active or relict RIFs and propose that the articulating, persistent, and distributed nature of streams makes dam-building easier than other canyons. Beavers further contribute to maintaining water and creating wetland habitat in upper watersheds by engineering ponds and marshes, and contributing to riparian extent. We

  13. Water and carbon cycling along the Sierra Nevada climate gradient

    NASA Astrophysics Data System (ADS)

    Kelly, A. E.; Goulden, M.; Meadows, M. W.; Bales, R. C.; Winston, G.

    2011-12-01

    Conifer forests dominate the western slope of the southern Sierra Nevada above 1000 m elevation. The climate of this region is Mediterranean, with hot dry summers and cool wet winters. The lower elevations of the conifer belt receive most precipitation as rain, while the upper elevations receive nearly all precipitation as snow. We have found that the differences in temperature and precipitation regime along the gradient affect interactions between water and carbon balance at seasonal and annual scales. Timing, degree of drought stress, and cold limitation along the western slope of the Sierra drive critical differences in biomass, productivity, carbon allocation, carbon turnover rates, seasonality of production, and seasonality and rates of evapotranspiration. We measured eddy covariance, weather, sap flux, biomass, productivity, and soil moisture at four sites along an elevation transect from 400 to 2700 m within the Southern Sierra Critical Zone Observatory (SSCZO). At lower elevations, summer drought and mild winters produce low biomass, high turnover, winter-productive forests. At high elevations, cold snowy winters and short mild summers produce low biomass, low turnover, summer-productive forests. At mid elevations, cool winters and warm summers produce high biomass forests, including giant sequoia groves, with a year-round growing season.

  14. Hydrogen isotopes in Eocene river gravels and paleoelevation of the Sierra Nevada.

    PubMed

    Mulch, Andreas; Graham, Stephan A; Chamberlain, C Page

    2006-07-07

    We determine paleoelevation of the Sierra Nevada, California, by tracking the effect of topography on precipitation, as recorded in hydrogen isotopes of kaolinite exposed in gold-bearing river deposits from the Eocene Yuba River. The data, compared with the modern isotopic composition of precipitation, show that about 40 to 50 million years ago the Sierra Nevada stood tall (>/=2200 meters), a result in conflict with proposed young surface uplift by tectonic and climatic forcing but consistent with the Sierra Nevada representing the edge of a pre-Eocene continental plateau.

  15. Quantifying the Restorable Water Volume of California's Sierra Nevada Meadows

    NASA Astrophysics Data System (ADS)

    Emmons, J. D.; Yarnell, S. M.; Fryjoff-Hung, A.; Viers, J.

    2013-12-01

    The Sierra Nevada is estimated to provide over 66% of California's water supply, which is largely derived from snowmelt. Global climate warming is expected to result in a decrease in snow pack and an increase in melting rate, making the attenuation of snowmelt by any means, an important ecosystem service for ensuring water availability. Montane meadows are dispersed throughout the mountain range and can act like natural reservoirs, and also provide wildlife habitat, water filtration, and water storage. Despite the important role of meadows in the Sierra Nevada, a large proportion is degraded from stream incision, which increases volume outflows and reduces overbank flooding, thus reducing infiltration and potential water storage. Restoration of meadow stream channels would therefore improve hydrological functioning, including increased water storage. The potential water holding capacity of restored meadows has yet to be quantified, thus this research seeks to address this knowledge gap by estimating the restorable water volume due to stream incision. More than 17,000 meadows were analyzed by categorizing their erosion potential using channel slope and soil texture, ultimately resulting in six general erodibility types. Field measurements of over 100 meadows, stratified by latitude, elevation, and geologic substrate, were then taken and analyzed for each erodibility type to determine average depth of incision. Restorable water volume was then quantified as a function of water holding capacity of the soil, meadow area and incised depth. Total restorable water volume was found to be 120 x 10^6 m3, or approximately 97,000 acre-feet. Using 95% confidence intervals for incised depth, the upper and lower bounds of the total restorable water volume were found to be 107 - 140 x 10^6 m3. Though this estimate of restorable water volume is small in regards to the storage capacity of typical California reservoirs, restoration of Sierra Nevada meadows remains an important

  16. Sierra Nevada tree-rings and atmospheric circulation

    NASA Astrophysics Data System (ADS)

    Garfin, Gregg Marc

    The primary objective of this research is to investigate relationships between extremes in central Sierra Nevada tree growth, temperature and precipitation and winter and summer atmospheric circulation. Using existing Sierra Nevada chronologies, I developed two mean chronologies for the period of overlap between instrumental and tree- ring records (1900-1987), one for giant sequoia (Sequoiadendron giganteum) and one for treeline pines (Pinus balfouriana, Pinus albicaulis) and selected the highest and lowest quintiles of tree growth as extreme years. For these years, I constructed and analyzed maps of composite anomalies for the following climatic data: tropospheric pressure (SLP, 700 mb, 500 mb), storm track (positive vorticity advection [PVA], a variable not previously used in dendroclimatology), temperature, precipitation, and snow (a variable often assumed have the same effects on growth as winter precipitation). Results suggest that extreme growth in these trees is associated with distinct patterns of winter atmospheric circulation and snow depth that are consistent with instrumental studies for the Western U.S. The storm track and snow analyses, seldom used in dendroclimatology, added substance to inferences based on analyses of tropospheric and surface climate parameters. This study shows the strong potential for reconstruction of these variables using Sierra Nevada trees. Synthesis of these results suggests that sequoia exhibit low growth during years with meridional winter and summer circulation, winter storms primarily occluded in the Gulf of Alaska, and low snow depth; sequoia exhibit high growth during years with low winter pressure in the north Pacific, long duration storms, a SW-NE oriented storm track entering North America at the California-Oregon border, high snow depth and zonal summer flow. Treeline pines exhibit low growth during years with enhanced ridging over the eastern Pacific, cool, short duration winter storms along a northern track, low

  17. Structural lineaments in the southern Sierra Nevada, California

    NASA Technical Reports Server (NTRS)

    Liggett, M. A. (Principal Investigator); Childs, J. F.

    1974-01-01

    The author has identified the following significant results. Several lineaments observed in ERTS-1 MSS imagery over the southern Sierra Nevada of California have been studied in the field in an attempt to explain their geologic origins and significance. The lineaments are expressed topographically as alignments of linear valleys, elongate ridges, breaks in slope or combinations of these. Natural outcrop exposures along them are characteristically poor. Two lineaments were found to align with foliated metamorphic roof pendants and screens within granitic country rocks. Along other lineaments, the most consistant correlations were found to be alignments of diabase dikes of Cretaceous age, and younger cataclastic shear zones and minor faults. The location of several Pliocene and Pleistocene volcanic centers at or near lineament intersections suggests that the lineaments may represent zones of crustal weakness which have provided conduits for rising magma.

  18. Mercury in Stream Sediments in the Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Humphreys, R. D.; Tuffly, M. F.

    2001-12-01

    Mercury lost during California's gold rush is still found in Sierra Nevada rivers and streams. Mercury droplets and gold-mercury amalgam are found in stream bedrock fissures and along stream bedrock in watersheds that were subjected to intense hydraulic gold mining. Recreational gold miners report finding mercury puddles, sometimes containing mercury by the pound, on stream bedrock. The poster depicts where and how mercury was found and its spatial relationship to major hydraulic mines and dredge fields. Additional sampling is planned. Other studies are investigating the biological consequences of legacy mercury on the aquatic food chain. The positions of all confirmed locations were recorded and corrected using Trimble or CMT Global Positioning Systems (GPS). In the few instances were GPS positions could not be recorded, positions were determined by hand plotting from UGSG 7.5 minute topographic map.

  19. 76 FR 13177 - Public Utilities Commission of Nevada and Sierra Pacific Power Company v. Tuscarora Gas...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-10

    ... Energy Regulatory Commission Public Utilities Commission of Nevada and Sierra Pacific Power Company v. Tuscarora Gas Transmission Company; Notice of Complaint Take notice that on February 28, 2011, pursuant to... and Sierra Pacific Power Company (Complainants) filed a formal complaint against Tuscarora...

  20. Human-induced uplift of the Sierra Nevada Mountains and seismicity modulation on the San Andreas Fault

    NASA Astrophysics Data System (ADS)

    Amos, Colin; Audet, Pascal; Hammond, William C.; Burgmann, Roland; Johanson, Ingrid A.; Blewitt, Geoffrey

    2014-05-01

    We investigate the cause of geodetically observed mountain uplift in the Sierra Nevada, western US. In the process, we reveal a possible human-induced mechanism that may be driving Sierra Nevada uplift, and may also be pushing the San Andreas Fault closer to failure. An initial study of the Sierra Nevada [Hammond et al., Geology, 40, 2012] exploited the complementary strengths of point positions from GPS and blanket coverage measurements from InSAR, to show that contemporary vertical motion of the Sierra Nevada is between 1 - 2 mm/yr relative to the comparatively stable Great Basin to the east. One possible interpretation of this is that the most modern episode of tectonic uplift is still active in the Sierra Nevada. However, we now discover that GPS stations surrounding the southern San Joaquin Valley in California show a pattern of uplift concentrated not only in the Sierra Nevada to the east, but more broadly along the basin margins, including the adjacent central Coast Range to the west. Peak vertical velocities reach values up to 1 - 3 mm/yr. This suggests the San Joaquin Valley plays a key role in the uplift of the Sierra Nevada to the east, with possible implications for the San Andreas Fault to the west. Anthropogenic groundwater depletion in the southern San Joaquin Valley has been massive and sustained, therefore hydrological loading variation might explain contemporary uplift. To test this, we apply a simple elastic model that uses a line load centered along the valley axis, a range of elastic parameters, and published estimates of the integrated rate of mass loss due to groundwater removal over the last decade. Predicted uplift centered along the valley axis matches well with patterns of GPS motion, with the upward vertical rates decaying away from the valley margins. Observed seasonal variability in the vertical GPS positions lends support for this model, showing peak uplift for stations surrounding the valley during the dry summer and fall months. On

  1. Biogeochemistry of a soil catena in the eastern Sierra Nevada Range, NV

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As a field/lab project, students in the Soil Biogeochemistry class of the University of Nevada, Reno described and characterized five pedons at Little Valley, NV, at the eastern edge of the Sierra Nevada. Developed largely from granite, the catena encompassed five pedons, which from high to low elev...

  2. Influence of the Pacific decadal oscillation on the climate of the Sierra Nevada, California and Nevada

    USGS Publications Warehouse

    Benson, L.; Linsley, B.; Smoot, J.; Mensing, S.; Lund, S.; Stine, S.; Sarna-Wojcicki, A.

    2003-01-01

    Mono Lake sediments have recorded five major oscillations in the hydrologic balance between A.D. 1700 and 1941. These oscillations can be correlated with tree-ring-based oscillations in Sierra Nevada snowpack. Comparison of a tree-ring-based reconstruction of the Pacific Decadal Oscillation (PDO) index (D' Arrigo et al., 2001) with a coral-based reconstruction of Subtropical South Pacific sea-surface temperature (Linsley et al., 2000) indicates a high degree of correlation between the two records during the past 300 yr. This suggests that the PDO has been a pan-Pacific phenomena for at least the past few hundred years. Major oscillations in the hydrologic balance of the Sierra Nevada correspond to changes in the sign of the PDO with extreme droughts occuring during PDO maxima. Four droughts centered on A.D. 1710, 1770, 1850, and 1930 indicate PDO-related drought reoccurrence intervals ranging from 60 to 80 yr. ?? 2003 Elsevier Science (USA). All rights reserved.

  3. Debris-Covered Glaciers in the Sierra Nevada, California, and Their Implications for Snowline Reconstructions

    USGS Publications Warehouse

    Clark, D.H.; Clark, M.M.; Gillespie, A.R.

    1994-01-01

    Ice-walled melt ponds on the surfaces of active valley-floor rock glaciers and Matthes (Little Ice Age) moraines in the southern Sierra Nevada indicate that most of these landforms consist of glacier ice under thin (ca. 1 - 10 m) but continuous covers of rock-fall-generated debris. These debris blankets effectively insulate the underlying ice and greatly reduce rates of ablation relative to that of uncovered ice. Such insulation explains the observations that ice-cored rock glaciers in the Sierra, actually debris-covered glaciers, are apparently less sensitive to climatic warming and commonly advance to lower altitudes than do adjacent bare-ice glaciers. Accumulation-area ratios and toe-to-headwall-altitude ratios used to estimate equilibrium-line altitudes (ELAs) of former glaciers may therefore yield incorrect results for cirque glaciers subject to abundant rockfall. Inadvertent lumping of deposits from former debris-covered and bare-ice glaciers partially explains an apparently anomalous regional ELA gradient reported for the pre-Matthes Recess Peak Neoglacial advance. Distinguishing such deposits may be important to studies that rely on paleo-ELA estimates. Moreover, Matthes and Recess Peak ELA gradients along the crest evidently depend strongly on local orographic effects rather than latitudinal climatic trends, indicating that simple linear projections and regional climatic interpretations of ELA gradients of small glaciers may be unreliable.

  4. Geologic Map of the Tower Peak Quadrangle, Central Sierra Nevada, California

    USGS Publications Warehouse

    Wahrhaftig, Clyde

    2000-01-01

    Introduction The Tower Peak quadrangle, which includes northernmost Yosemite National Park, is located astride the glaciated crest of the central Sierra Nevada and covers an exceptionally well-exposed part of the Sierra Nevada batholith. Granitic plutonic rocks of the batholith dominate the geology of the Tower Peak quadrangle, and at least 18 separate pre-Tertiary intrusive events have been identified. Pre-Cretaceous metamorphic rocks crop out in the quadrangle in isolated roof pendants and septa. Tertiary volcanic rocks cover granitic rocks in the northern part of the quadrangle, but are not considered in this brief summary. Potassium-argon (K-Ar) age determinations for plutonic rocks in the quadrangle range from 83 to 96 million years (Ma), including one of 86 Ma for the granodiorite of Lake Harriet (Robinson and Kistler, 1986). However, a rubidium-strontium whole-rock isochron age of 129 Ma has been obtained for the Lake Harriet pluton (Robinson and Kistler, 1986), which field evidence indicates is the oldest plutonic body within the quadrangle. This suggests that some of the K-Ar ages record an episode of resetting during later thermal events and are too young. The evidence indicates that all the plutonic rocks are of Cretaceous age, with the youngest being the Cathedral Peak Granodiorite at about 83 Ma. The pre-Tertiary rocks of the Tower Peak quadrangle fall into two groups: (1) an L-shaped area of older plutonic and metamorphic rocks, 3 to 10 km wide, that extends diagonally both northeast and southeast from near the center of the quadrangle; and (2) a younger group of large, probably composite intrusions that cover large areas in adjacent quadrangles and extend into the Tower Peak quadrangle from the east, north, and southwest.

  5. Sinfonevada: Dataset of Floristic diversity in Sierra Nevada forests (SE Spain).

    PubMed

    Pérez-Luque, Antonio Jesús; Bonet, Francisco Javier; Pérez-Pérez, Ramón; Rut Aspizua; Lorite, Juan; Zamora, Regino

    2014-01-01

    The Sinfonevada database is a forest inventory that contains information on the forest ecosystem in the Sierra Nevada mountains (SE Spain). The Sinfonevada dataset contains more than 7,500 occurrence records belonging to 270 taxa (24 of these threatened) from floristic inventories of the Sinfonevada Forest inventory. Expert field workers collected the information. The whole dataset underwent a quality control by botanists with broad expertise in Sierra Nevada flora. This floristic inventory was created to gather useful information for the proper management of Pinus plantations in Sierra Nevada. This is the only dataset that shows a comprehensive view of the forest flora in Sierra Nevada. This is the reason why it is being used to assess the biodiversity in the very dense pine plantations on this massif. With this dataset, managers have improved their ability to decide where to apply forest treatments in order to avoid biodiversity loss. The dataset forms part of the Sierra Nevada Global Change Observatory (OBSNEV), a long-term research project designed to compile socio-ecological information on the major ecosystem types in order to identify the impacts of global change in this area.

  6. Sinfonevada: Dataset of Floristic diversity in Sierra Nevada forests (SE Spain)

    PubMed Central

    Pérez-Luque, Antonio Jesús; Bonet, Francisco Javier; Pérez-Pérez, Ramón; Rut Aspizua; Lorite, Juan; Zamora, Regino

    2014-01-01

    Abstract The Sinfonevada database is a forest inventory that contains information on the forest ecosystem in the Sierra Nevada mountains (SE Spain). The Sinfonevada dataset contains more than 7,500 occurrence records belonging to 270 taxa (24 of these threatened) from floristic inventories of the Sinfonevada Forest inventory. Expert field workers collected the information. The whole dataset underwent a quality control by botanists with broad expertise in Sierra Nevada flora. This floristic inventory was created to gather useful information for the proper management of Pinus plantations in Sierra Nevada. This is the only dataset that shows a comprehensive view of the forest flora in Sierra Nevada. This is the reason why it is being used to assess the biodiversity in the very dense pine plantations on this massif. With this dataset, managers have improved their ability to decide where to apply forest treatments in order to avoid biodiversity loss. The dataset forms part of the Sierra Nevada Global Change Observatory (OBSNEV), a long-term research project designed to compile socio-ecological information on the major ecosystem types in order to identify the impacts of global change in this area. PMID:24843285

  7. Hot springs of the central Sierra Nevada, California

    USGS Publications Warehouse

    Mariner, R.H.; Presser, T.S.; Evans, William C.

    1977-01-01

    Thermal springs of the central Sierra Nevada issue dilute to slightly saline sodium chloride, sodium bicarbonate, or sodium mixed-anion waters ranging in pH from 6.4 to 9.3. The solubility of chalcedony appears to control the silica concentration in most of the spring waters. Fales Hot Springs may be associated with a higher temperature aquifer, 150 degrees Celsius or more, in which quartz is controlling the silica concentration. Carbon dioxide is the predominant gas escaping from Fales Hot Springs, the unnamed hot spring on the south side of Mono Lake, and the two thermal springs near Bridgeport. Most of the other thermal springs issue small amounts of gas consisting principally of nitrogen. Methane is the major component of the gas escaping from the unnamed spring on Paoha Island in Mono Lake. The deuterium and oxygen isotopic composition of most of the thermal waters are those expected for local meteoric water which has undergone minor water-rock reaction. The only exceptions are the hot spring on Paoha Island in Mono Lake and perhaps the unnamed warm spring (south side of Mono Lake) which issues mixtures of thermal water and saline lake water. (Woodard-USGS)

  8. Sierra Nevada Batholith: The batholith was generated within a synclinorium.

    PubMed

    Bateman, P C; Eaton, J P

    1967-12-15

    The Sierra Nevada batholith is localized in the axial region of a complex faulted synclinorium that coincides with a downfold in the Mohorovicic discontinuity and in P-wave velocity boundaries within the crust. Observed P-wave velocities are compatible with downward increase in the proportion of diorite, quartz diorite, and calcic granodiorite relative to quartz monzonite and granite in the upper crust, with amphibolite or gabbro-basalt in the lower crust, and with periodotite in the upper mantle. The synclinorium was formed in Paleozoic and Mesozoic strata during early and middle Mesozoic time in a geosyncline marginal to the continent. Granitic magmas are believed to have formed in the lower half of the crust at depths of 25 to 45 kilometers or more, primarily as a result of high radiogenic heat production in the thickened prism of crustal rocks. Magma was generated at different times in different places as the locus of down-folding shifted. It rose into the upper crust because it was less dense than rock of the same composition or residual refractory rocks. Refractory rocks and crystals that were not melted and early crystallized mafic minerals that settled from the rising magma thickened the lower crust. Wall and roof rocks settled around, and perhaps through, the rising magma and provided space for its continued rise. Erosion followed each magmatic episode, and 10 to 12 kilometers of rock may have been eroded away since the Jurassic and 7 to 10 kilometers since the early Late Cretaceous.

  9. The deglaciation of the Sierra Nevada (Southern Spain)

    NASA Astrophysics Data System (ADS)

    Gómez-Ortiz, Antonio; Palacios, David; Palade, Bogdan; Vázquez-Selem, Lorenzo; Salvador-Franch, Ferran

    2012-07-01

    Cosmogenic 36Cl surface exposure dating was carried out on 19 samples from glacially polished bedrock, rock glaciers and moraines of four glaciated valleys with different orientations in the Sierra Nevada (Spain) around Pico del Veleta (37° 3'N 3° 21'W, 3398 m asl). Remains of moraines older than the global Last Glacial Maximum exist, but their poor preservation makes them an unreliable subject for surface exposure dating. Results show that the last local glacial maximum advance took place earlier than the global Last Glacial Maximum, but within the MIS 2, although additional dating is needed to confirm this. Exposure ages from bedrock steps show a general glacier retreat in progress by 15-14 ka. Shortly afterwards an extensive system of rock glaciers formed at the base of the valley headwalls, with the most recent rock glacier lasting until 7 ka ago. From their location, morphology and analysis of other proxies, we interpret their origin as related to the deglaciation process and marked instability of cirque headwalls, rather than to extreme periglacial conditions. A recent similar occurrence was the transformation of the Little Ice Age glacier on the north face of the Pico del Veleta into a rock glacier under temperate high mountain climatic conditions.

  10. California spotted owls: Chapter 5 in Managing Sierra Nevada forests

    USGS Publications Warehouse

    Roberts, Suzanne C.; Brooks, Matthew L.

    2012-01-01

    California spotted owls (Strix occidentalis occidentalis) are habitat specialists that are strongly associated with late-successional forests. For nesting and roosting, they require large trees and snags embedded in a stand with a complex forest structure (Blakesley et al. 2005, Gutiérrez et al. 1992, Verner et al. 1992b). In mixedconifer forests of the Sierra Nevada, California spotted owls typically nest and roost in stands with high canopy closure (≥75 percent) [Note: when citing studies, we use terminology consistent with Jennings et al. (1999), however, not all studies properly distinguish between canopy cover and closure and often use the terms interchangeably (see chapter 14 for clarification)] and an abundance of large trees (>24 in (60 cm) diameter at breast height [d.b.h.]) (Bias and Gutiérrez 1992, Gutiérrez et al. 1992, LaHaye et al. 1997, Moen and Gutiérrez 1997, Verner et al. 1992a). The California spotted owl guidelines (Verner et al. 1992b) effectively summarized much of the information about nesting and roosting habitat. Since that report, research on the California spotted owl has continued with much of the new information concentrated in five areas: population trends, barred owl (Strix varia) invasion, climate effects, foraging habitat, and owl response to fire.

  11. Seed germination of Sierra Nevada postfire chaparral species

    USGS Publications Warehouse

    Keeley, Jon E.; McGinnis, Thomas W.; Bollens, Kim A.

    2005-01-01

    The California chaparral community has a rich flora of species with different mechanisms for cuing germination to postfire conditions. Here we report further germination experiments that elucidate the response of several widespread shrub species whose germination response was not clear and include other species from the Sierra Nevada, which have not previously been included in germination studies. The shrubs Adenostoma fasciculatum and Eriodictyon crassifolium and the postfire annualMentzelia dispersa exhibited highly significant germination in response to smoke treatments, with some enhanced germination in response to heating as well. The shrubs Fremontodendron californicum and Malacothamnus fremontii were stimulated only by heat-shock treatments. Seeds buried in the soil for one year exhibited substantially higher germination for controls and most treatments. In the case of two postfire annuals, Mimulus bolanderi and M. gracilipes, germination of fresh seed was significantly greater with smoke or heating but after soil storage, over two-thirds of the control seeds germinated and treatment effects were not significant. These two annuals are generally restricted to postfire conditions and it is suggested that control germination of soil-stored seed may be a light-response (which was not tested here) as previously reported for another chaparral species in that genus.

  12. LANDSAT-D investigations in snow hydrology. [Sierra Nevada Mountains

    NASA Technical Reports Server (NTRS)

    Dozier, J.

    1983-01-01

    Thematic mapper data for the southern Sierra Nevada area were registered to digital topographic data and compared to LANDSAT MSS and NOAA-7 AVHRR data of snow covered areas in order to determine the errors associated with using coarser resolution and to qualify the information lost when high resolution data are not available. Both the zenith and the azimuth variations in the radiative field are considered in an atmospheric radiative transfer model which deals with a plane parallel structured atmosphere composed of different layers, each assumed to be homogeneous in composition and to have a linear in tau temperature profile. Astronomical parameters for each layer are Earth-Sun distance and solar flux at the top of the atmosphere. Atmospheric parameters include pressure temperature, chemical composition of the air molecules, and the composition and size of the aerosol, water droplets, and ice crystals. Outputs of the model are the monochromatic radiance and irradiance at each level. The use of the model in atmospheric correction of remotely sensed data is discussed.

  13. Three-dimensional crustal structure of the southern Sierra Nevada from seismic fan profiles and gravity modeling

    USGS Publications Warehouse

    Fliedner, M.M.; Ruppert, S.; Malin, P.E.; Park, S.K.; Jiracek, G.; Phinney, R.A.; Saleeby, J.B.; Wernicke, B.; Clayton, R.; Keller, Rebecca Hylton; Miller, K.; Jones, C.; Luetgert, J.H.; Mooney, W.D.; Oliver, H.; Klemperer, S.L.; Thompson, G.A.

    1996-01-01

    Traveltime data from the 1993 Southern Sierra Nevada Continental Dynamics seismic refraction experiment reveal low crustal velocities in the southern Sierra Nevada and Basin and Range province of California (6.0 to 6.6 km/s), as well as low upper mantle velocities (7.6 to 7.8 km/s). The crust thickens from southeast to northwest along the axis of the Sierra Nevada from 27 km in the Mojave Desert to 43 km near Fresno, California. A crustal welt is present beneath the Sierra Nevada, but the deepest Moho is found under the western slopes, not beneath the highest topography. A density model directly derived from the crustal velocity model but with constant mantle density satisfies the pronounced negative Bouguer anomaly associated with the Sierra Nevada, but shows large discrepancies of >50 mgal in the Great Valley and in the Basin and Range province. Matching the observed gravity with anomalies in the crust alone is not possible with geologically reasonable densities; we require a contribution from the upper mantle, either by lateral density variations or by a thinning of the lithosphere under the Sierra Nevada and the Basin and Range province. Such a model is consistent with the interpretation that the uplift of the present Sierra Nevada is caused and dynamically supported by asthenospheric upwelling or lithospheric thinning under the Basin and Range province and eastern Sierra Nevada.

  14. Three-dimensional crustal structure of the southern Sierra Nevada from seismic fan profiles and gravity modeling

    SciTech Connect

    Fliedner, M.M.; Ruppert, S.; Park, S.K.; and others.

    1996-04-01

    Traveltime data from the 1993 Southern Sierra Nevada Continental Dynamics seismic refraction experiment reveal low velocities in the southern Sierra Nevada and Basin and Range province of California (6.0 to 6.6 km/s), as well as low upper mantle velocities (7.6 to 7.8 km/s). The crust thickens from southeast to northwest along the axis of the Sierra Nevada from 27 km in the Mojave Desert to 43 km near Fresno, California. A crustal welt is present beneath the Sierra Nevada, but the deepest Moho is found under the western slopes, not beneath the highest topography. A density model directly derived from the crustal velocity model but with constant mantle density satisfies the pronounced negative Bouguer anomaly associated with the Sierra Nevada, but shows large discrepancies of >50 mgal in the Great Valley and in the Basin and Range province. Matching the observed gravity with anomalies in the crust alone is not possible with geologically reasonable densities; we require a contribution from the upper mantle, either by lateral density variations or by a thinning of the lithosphere under the Sierra Nevada and the Basin and Range province. Such a model is consistent with the interpretation that the uplift of the present Sierra Nevada is caused and dynamically supported by asthenospheric upwelling or lithospheric thinning under the Basin and Range province and eastern Sierra Nevada. 20 refs., 4 figs.

  15. Dataset of Passerine bird communities in a Mediterranean high mountain (Sierra Nevada, Spain)

    PubMed Central

    Pérez-Luque, Antonio Jesús; Barea-Azcón, José Miguel; Álvarez-Ruiz, Lola; Bonet-García, Francisco Javier; Zamora, Regino

    2016-01-01

    Abstract In this data paper, a dataset of passerine bird communities is described in Sierra Nevada, a Mediterranean high mountain located in southern Spain. The dataset includes occurrence data from bird surveys conducted in four representative ecosystem types of Sierra Nevada from 2008 to 2015. For each visit, bird species numbers as well as distance to the transect line were recorded. A total of 27847 occurrence records were compiled with accompanying measurements on distance to the transect and animal counts. All records are of species in the order Passeriformes. Records of 16 different families and 44 genera were collected. Some of the taxa in the dataset are included in the European Red List. This dataset belongs to the Sierra Nevada Global-Change Observatory (OBSNEV), a long-term research project designed to compile socio-ecological information on the major ecosystem types in order to identify the impacts of global change in this area. PMID:26865820

  16. Dataset of Passerine bird communities in a Mediterranean high mountain (Sierra Nevada, Spain).

    PubMed

    Pérez-Luque, Antonio Jesús; Barea-Azcón, José Miguel; Álvarez-Ruiz, Lola; Bonet-García, Francisco Javier; Zamora, Regino

    2016-01-01

    In this data paper, a dataset of passerine bird communities is described in Sierra Nevada, a Mediterranean high mountain located in southern Spain. The dataset includes occurrence data from bird surveys conducted in four representative ecosystem types of Sierra Nevada from 2008 to 2015. For each visit, bird species numbers as well as distance to the transect line were recorded. A total of 27847 occurrence records were compiled with accompanying measurements on distance to the transect and animal counts. All records are of species in the order Passeriformes. Records of 16 different families and 44 genera were collected. Some of the taxa in the dataset are included in the European Red List. This dataset belongs to the Sierra Nevada Global-Change Observatory (OBSNEV), a long-term research project designed to compile socio-ecological information on the major ecosystem types in order to identify the impacts of global change in this area.

  17. Chronology for fluctuations in late pleistocene Sierra Nevada glaciers and lakes

    SciTech Connect

    Phillips, F.M.; Zreda, M.G.; Plummer, M.A.

    1996-11-01

    Mountain glaciers, because of their small size, are usually close to equilibrium with the local climate and thus should provide a test of whether temperature oscillations in Greenland late in the last glacial period are part of global-scale climate variability or are restricted to the North Atlantic region. Correlation of cosmogenic chlorine-36 dates on Sierra Nevada moraines with a continuous radiocarbon-dated sediment record from nearby Owens Lake shows that Sierra Nevada glacial advances were associated with Heinrich events 5, 3, and 1. 27 refs., 2 figs., 1 tab.

  18. Improved Present Day Euler Vector for the Sierra Nevada Block Using GPS

    NASA Astrophysics Data System (ADS)

    Psencik, K. O.; Dixon, T. H.; Schmalzle, G.; McQuarrie, N.; McCaffery, R.

    2006-12-01

    We present a new surface velocity field for California and Nevada (UM-CANVAS) and use it to solve for a new angular velocity for the rigid Sierra Nevada-Great Valley block. We use all publicly available GPS data for this region, from both continuous (CGPS) and episodic campaign (EGPS) sites. All data were re-processed to create a consistent velocity field. Site velocities are referenced to both stable North America and the central Basin and Range. The Sierra Nevada block is a relatively long, narrow block, bounded on the west by the San Andreas Fault, on the east by a complex fault system comprising the Eastern California Shear Zone and the Walker Lane Belt, and on the south by the Garlock fault. The northern extent of the block is not well defined. The new data along with a strain accumulation algorithm may help to define this boundary. Published estimates for the motion of Sierra Nevada block include clockwise, counter-clockwise, and no rotation relative to stable North America; the new velocity data may also help to resolve this discrepancy. To better understand the motion of the Sierra Nevada block over time, we compare our model of present day motion to a geologic model of block motion over the last 2-3 Ma (McQuarrie and Wernicke, 2005). McQuarrie, N. and B. Wernicke, An Animated tectonic reconstruction of southwestern North America since 36 Ma. Geosphere, V.1; no.3; 147-172; 2005.

  19. Dynamics of magma ascent through the Sierra Nevada, California

    SciTech Connect

    Kovach, L.A.

    1984-01-01

    A 9 m.y. old alkali basalt intrudes the Red Lake pluton, approx.90 m.y. old granodiorite of the Huntington Lake quadrangle in the Sierra Nevada, California. The basaltic neck, standing 5 meters above the floor of the Big Creek drainage (approx. 25 meters in diameter), appears to have been the feeder for the flows that cap Chinese Peak (approx. 1 km to the south). The surrounding Red Lake granodiorite was partially fused during the intrusive process. Ten meters of the fused rock is now exposed surrounding the basaltic neck. Thermal models indicate that magma must have flowed through the pipe for approx. 1000 years to produce the extensive melting of the country rock. The basalt was probably intruded at a temperature of 900/sup 0/C, ultramafic nodules indicate its mantle origin. Surrounding the inner basaltic core is a region of basalt interlayered with granitic melt and xenoliths, which formed due to interaction of the basalt and partially molten wall rock during magma ascent. The partially fused granodiorite wall rock contains 40-45% melt at the contact, decreasing to 20% melt 10 meters from the contact. The glass composition (approx.73%-approx.75% SiO/sub 2/, 5% K/sub 2/O) suggests invariant melting. Data on Rb, Sr, and Sr isotopic composition of the glass, residual crystals, and whole rocks are used to model chemical and isotopic equilibration of silicic liquids with their residual crystals. In comparison to the granodiorite, the glass is enriched in Rb (approx.250 ppm), depleted in Sr (approx.135 ppm), permitting the construction of an apparent isochron 11.0 +/- 2.7 m.y.

  20. Quantifying the Effects of Wildfire Severity on Snow Water Equivalent in the Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Nguyen, A.; Cunningham, S.; Sodergren, C.; Anzelc, J.; Cate, N.; Arya, V.

    2015-12-01

    Snowpack in the Sierra Nevada is a crucial component of the California water supply. Climate change effects on forest ecosystems in this region have reduced snowpack and resulted in earlier snowmelt. Wildfire frequency and severity in the Sierra Nevada have also increased, due to higher temperatures, drought, and a legacy of fire suppression policies leading to fuel loads augmented beyond the historic range of variability. These combined factors have the potential to severely impact California water supply. Using 2014 California Basin Characterization Model (BCM) climate data and automated classification of various Landsat imagery, this study geospatially quantified the effects of low, moderate, and high- severity wildfire on snowpack and snow water equivalent (SWE) in the Sierra Nevada. An assessment of modeled SWE data were also conducted to examine its usefulness in better understanding areas effected by wildfire. Results indicate little to no significant change in post-fire SWE for high and moderate severity wildfire, however, delineated a significant decrease in post-fire SWE in the low severity wildfire. Additionally, tests show little no significant change in fractional snow cover post-fire. This use of remote sensing and modeled data will assist in decision and policy making related to management of forest ecosystems and water resources within the Sierra Nevada.

  1. Multimillennial records of climatic variation in the Sierra Nevada inferred from tree rings

    SciTech Connect

    Graumlich, L.J.; Lloyd, A.H.; Hughes, M.K.

    1995-06-01

    Temporally precise, regional reconstructions of climatic variation provide a context in which to interpret population dynamics of long-lived (> 1000 yr) species. We use tree-ring data from living trees and subfossil material in the Sierra Nevada and White Mountains to infer climatic variations over the last 3000 years. Tree growth of foxtail pine (Pinus balfouriana; upper treeline, Sierra Nevada) is influenced by summer temperature and winter precipitation. Tree growth of giant sequoia (Sequoiadendron giganteum; west slope, Sierra Nevada) is influenced by short-term fluctuations in precipitation, especially extremely dry years, while growth of bristlecone pine (Pinus longaeva; lower forest border, White Mountains) reflects both short- and long-term variation in precipitation. Summer temperatures anomalies include an extended warm period from A.D. 1100 to 1375 and a cold period from A.D. 1450 to 1850. The precipitation reconstruction indicates severe drought from A.D. 1021 to 1070 and A.D. 1249 to 1365. These results are corroborated by radiocarbon dates of submerged and re-exposed tree stump at Mono Lake indicating severe drought from A.D. 900 to 1100 and A.D. 1200 to 1350. Our ongoing work seeks to understand the influence of long-term climatic variation on population dynamics in the subalpine zone of the Sierra Nevada.

  2. From Typology to Topography in Clarence King's "Mountaineering in the Sierra Nevada."

    ERIC Educational Resources Information Center

    Hoekzema, Loren

    The book "Mountaineering in the Sierra Nevada" by Clarence King, a late-ninteenth-century American geologist, writer, art critic, and romantic, is discussed in this paper. In the writing and revision of this book, King was attempting a metamorphosis of landscape description into popular reading as he moved from being a symbolic writer to…

  3. Glaciation about 3,000,000 Years Ago in the Sierra Nevada.

    PubMed

    Curry, R R

    1966-11-11

    Abstract. Major glaciation in the Sierra Nevada of California resulted in the deposition of till which underlies latite 2.7 x 10(6) years old and overlies andesite 3.1 x 10(6) years old. This till, herein called the Deadman Pass till, is the oldest Pleistocene glacial deposit that has been found in temperate latitudes.

  4. Mercury in Tadpoles Collected from Remote Alpine Sites in the Southern Sierra Nevada Mountains, California, USA

    EPA Science Inventory

    Amphibians in alpine wetlands of the Sierra Nevada mountains comprise key components of an aquatic-terrestrial food chain, and mercury contamination is a concern because concentrations in fish from this regin exceed thresholds of risk to piscivorous wildlife. Total mercury conc...

  5. Remotely-Sensed Glacial Velocities: Mt. Shasta Advance vs. Sierra Nevada Retreat

    NASA Astrophysics Data System (ADS)

    Thompson, J. A.; Bookhagen, B.; Burbank, D. W.

    2008-12-01

    Monitoring changes in alpine glaciers is crucial to understanding the impacts of global climate change because alpine glacier systems respond quickly to changes in the earth´s climate. The glaciers of the Sierra Nevada and southern Cascades are of particular interest because they provide a major water reservoir to the state of California. Oddly, while most glaciers worldwide (including in the Sierra Nevada) are retreating, glaciers in northern California are advancing, and examining differences between these two locations will help resolve this paradox. Whereas previous studies have mapped the spatial extents of glaciers from aerial and satellite imagery, this study utilizes glacial velocities as a monitoring tool to examine the differences of the glaciers in the Sierra Nevada and on Mount Shasta. Using the program COSI-Corr in ENVI, horizontal surface ice flow velocities are calculated at the subpixel level from a time-series of co-registered, orthorectified, and correlated, late-summer satellite imagery. Through a combination of 15-meter Advanced Spaceborne Thermal Emission Radiometer (ASTER) and 5-meter SPOT imagery, orthorectified using a 15-meter resampled Shuttle Radar Topographic Mission (SRTM) digital elevation model (DEM), glacial velocities are derived on major glaciers on Mount Shasta and in the Palisades of the Sierra Nevada for 2000-2008. This study demonstrates the utility of combining various types of remote sensing imagery to create a complete time record, and from this record derive glacial velocities for use in monitoring climate change effectively.

  6. PARTITIONING OF WATER FLUX IN A SIERRA NEVADA PONDEROSA PINE PLANTATION. (R826601)

    EPA Science Inventory

    The weather patterns of the west side of the Sierra Nevada Mountains (cold, wet winters and hot, dry summers) strongly influence how water is partitioned between transpiration and evaporation and result in a specific strategy of water use by ponderosa pine trees (Pinus pond...

  7. 33 CFR 162.215 - Lake Tahoe, Nev.; restricted area adjacent to Nevada Beach.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Lake Tahoe, Nev.; restricted area adjacent to Nevada Beach. 162.215 Section 162.215 Navigation and Navigable Waters COAST GUARD, DEPARTMENT... § 162.215 Lake Tahoe, Nev.; restricted area adjacent to Nevada Beach. (a) The restricted area....

  8. 33 CFR 162.215 - Lake Tahoe, Nev.; restricted area adjacent to Nevada Beach.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Lake Tahoe, Nev.; restricted area adjacent to Nevada Beach. 162.215 Section 162.215 Navigation and Navigable Waters COAST GUARD, DEPARTMENT... § 162.215 Lake Tahoe, Nev.; restricted area adjacent to Nevada Beach. (a) The restricted area....

  9. 33 CFR 162.215 - Lake Tahoe, Nev.; restricted area adjacent to Nevada Beach.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Lake Tahoe, Nev.; restricted area adjacent to Nevada Beach. 162.215 Section 162.215 Navigation and Navigable Waters COAST GUARD, DEPARTMENT... § 162.215 Lake Tahoe, Nev.; restricted area adjacent to Nevada Beach. (a) The restricted area....

  10. 33 CFR 162.215 - Lake Tahoe, Nev.; restricted area adjacent to Nevada Beach.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Lake Tahoe, Nev.; restricted area adjacent to Nevada Beach. 162.215 Section 162.215 Navigation and Navigable Waters COAST GUARD, DEPARTMENT... § 162.215 Lake Tahoe, Nev.; restricted area adjacent to Nevada Beach. (a) The restricted area....

  11. 33 CFR 162.215 - Lake Tahoe, Nev.; restricted area adjacent to Nevada Beach.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Lake Tahoe, Nev.; restricted area adjacent to Nevada Beach. 162.215 Section 162.215 Navigation and Navigable Waters COAST GUARD, DEPARTMENT... § 162.215 Lake Tahoe, Nev.; restricted area adjacent to Nevada Beach. (a) The restricted area....

  12. Multi-century Evaluation of Sierra Nevada Snowpack

    NASA Astrophysics Data System (ADS)

    Belmecheri, S.; Trouet, V.; Babst, F.; Wahl, E. R.; Stahle, D. W.

    2015-12-01

    California (CA) is currently experiencing a record-setting drought that started in 2012. Snowpack conditions in the Sierra Nevada (SN) mountains present an ominous sign of the severity of this drought: the April 1, 2015 snow water equivalent (SWE) was at only 5% of its historical average. However, no long-term historical context is available for the recent SN snowpack decline. We present an annually-resolved reconstruction of SN-wide April 1 SWE conditions for the past 500 years (Fig. 1). We combined an extensive compilation of blue oak tree-ring series that reflects large-scale CA winter precipitation anomalies with a CA February-March temperature reconstruction in a reconstruction that explains 63% of the SN SWE variance over the instrumental period. Our reconstruction reveals that the 2015 low is unprecedented in the context of the last 500 years. Our error estimation indicates that there is a possibility that a few - primarily16thcentury - years exceeded the 2015 low, but the estimated return interval for the 2015 SWE value - as calculated based on a generalized extreme value (GEV) distribution - is 3,100 years and confirms the exceptional character of the 2015 SWE low. We further find that the 2015 SWE value is strongly exceptional - exceeding the 95 % CI for a 1000-yr return period - at low elevation SN sites where winter temperature has a strong control on SWE, but less so at high elevation sites, where it exceeds the 95 % CI for only a 95-yr return period. The 2015 record low snowpack coincides with record high CA January-March temperatures and highlights the modulating role of temperature extremes in CA drought severity. Snowpack lows - amongst other drought metrics- are driven by the co-occurrence of precipitation deficits and high temperature extremes and we find that the exacerbating effect of warm winter temperatures is stronger at low than at high SN elevations. Anthropogenic warming is projected to further increase the probability of severe drought

  13. Paleozoic and Mesozoic deformations in the central Sierra Nevada, California

    USGS Publications Warehouse

    Nokleberg, Warren J.; Kistler, Ronald Wayne

    1980-01-01

    Analysis of structural and stratigraphic data indicates that several periods of regional deformation, consisting of combined folding, faulting, cataclasis, and regional metamorphism, occurred throughout the central Sierra Nevada during Paleozoic and Mesozoic time. The oldest regional deformation occurred alono northward trends during the Devonian and Mississippian periods in most roof pendants containing lower Paleozoic metasedimentary rocks at the center and along the crest of the range. This deformation is expressed in some roof pendants by an angular unconformity separating older thrice-deformed from younger twice-deformed Paleozoic metasedimentary rocks. The first Mesozoic deformation, which consisted of uplift and erosion and was accompanied by the onset of Andean-type volcanism during the Permian and Triassic, is expressed by an angular unconformity in several roof pendants from the Saddlebag Lake to the Mount Morrison areas. This unconformity is defined by Permian and Triassic andesitic to rhyolitic metavolcanic rocks unconformably overlying more intensely deformed Pennsylvanian, Permian(?), and older metasedimentary rocks. A later regional deformation occurred during the Triassic along N. 20?_30? W. trends in Permian and Triassic metavolcanic rocks of the Saddlebag Lake and Mount Dana roof pendants, in upper Paleozoic rocks of the Pine Creek roof pendant, and in the Calaveras Formation of the western metamorphic belt; the roof pendants are crosscut by Upper Triassic granitic rocks of the Lee Vining intrusive epoch. A still later period of Early and Middle Jurassic regional deformation occurred along N. 30?-60? E. trends in upper Paleozoic rocks of the Calaveras Formation of the western metamorphic belt. A further period of deformation was the Late Jurassic Nevadan orogeny, which occurred along N. 20?_40? W. trends in Upper Jurassic rocks of the western metamorphic belt that are crosscut by Upper Jurassic granitic rocks of the Yosemite intrusive epoch

  14. Dense Root Removal by Asymmetric Delamination in Sierra Nevada, California: Insights from Numerical Modeling

    NASA Astrophysics Data System (ADS)

    Valera, J.; Negredo, A. M.; Billen, M.

    2008-12-01

    Recent studies provide compelling evidence for an event of removal of lithospheric mantle in southern -and possibly central- Sierra Nevada (SN) mountains, California (Zandt et al., Nature, 431, 2004). A sequential history of foundering of the ultramafic root of the Sierra Nevada batholith, with a pronounced asymmetric flow, is proposed to explain a number of geophysical and geological observations, including a fast seismic velocity in the mantle located to the west of the SN crest, a gap in the Moho, recent subsidence and tilting of the Sierra Nevada, and a change in mineralogy of the xenolith population recorded at the surface. In the present study we focus on the quantitative evaluation of this conceptual model. We apply new thermo- mechanical algorithms, developed in MATLAB code, suitable to study the temporal evolution of laterally migrating lithospheric delamination. The motion equation, formulated in terms of the stream function, and the coupled thermal equation are solved applying finite difference techniques. Our physical modeling is shown to properly reproduce the first order features of the conceptual model for lithospheric delamination in the Sierra Nevada. We investigate the evolution of a dense ultramafic root, which brings about a Rayleigh-Taylor gravitational instability. Following our preliminary results, the presence of a fluid-weakened lithosphere, located just east of Sierra Nevada, is required to reproduce the asymmetric development of this instability, as previously proposed by Zandt et al. (2004). This weak rheology zone, which is modeled by means of a reduced viscosity, is shown to enable the ascent of asthenospheric material and westward propagation of delamination. Our predictions are also consistent with the previous inference of the V-shaped cone of crust being dragged down into the downwelling mantle (i.e., the Moho gap). Present results highlight that viscous drag is also likely responsible for present-day surface subsidence.

  15. Late Cenzoic rhyolites from the Kern Plateau, southern Sierra Nevada, California.

    USGS Publications Warehouse

    Bacon, C.R.; Duffield, W.A.

    1981-01-01

    Four late Cenozoic rhyolite domes lie atop the Kern Plateau, 30 to 40km S-SE of Mount Whitney. K-Ar and 40Ar/39Ar dating shows that Monache, Templeton, and Little Templeton Mountains are all about 2.4Ma old; a small dome nearby is approx 0.2Ma old. The three older rhyolites have SiO2 = 73-74% and have steep, fractionated rare earth element (REE) patterns; the youngest has SiO2 = 76% and a concave-upward REE pattern with a large negative Eu anomaly, Monache rhyolite contains the unusual phenocryst assemblage almandine + fayalite + biotite + oligoclase. The 2.4Ma old rocks may be nearly unmodified partial melts of crustal sources, whereas the 0.2Ma old rhyolite may be a product of relatively shallow differentiation. The rhyolites and nearby basalts are coeval with mafic and silicic volcanic rocks in the Coso Range about 40km to the SE. Their generation and eruption may reflect intense tectonic extension at the margin of the Basin and Range province and concomitant relaxation of compressive stress in a W- NW direction, allowing melts to reach the surface in the adjacent Sierra Nevada.-Authors

  16. Can footwall unloading explain late Cenozoic uplift of the Sierra Nevada crest?

    USGS Publications Warehouse

    Thompson, G.A.; Parsons, T.

    2009-01-01

    Globally, normal-fault displacement bends and warps rift flanks upwards, as adjoining basins drop downwards. Perhaps the most evident manifestations are the flanks of the East African Rift, which cuts across the otherwise minimally deformed continent. Flank uplift was explained by Vening Meinesz (1950, Institut Royal Colonial Belge, Bulletin des Seances, v. 21, p. 539-552), who recognized that isostasy should cause uplift of a normal-faulted footwall and subsidence of its hanging wall. Uplift occurs because slip on a dipping normal fault creates a broader root of less-dense material beneath the footwall, and a narrowed one beneath the hanging wall. In this paper, we investigate the potential influence of this process on the latest stages of Sierra Nevada uplift. Through theoretical calculations and 3D finite element modelling, we find that cumulative slip of about 4km on range-front faults would have produced about 1.3km peak isostatic uplift at the ridge crest. Numerical models suggest that the zone of uplift is narrow, with the width controlled by bending resistance of the seismogenic crust. We conclude that footwall unloading cannot account for the entire elevation of the Sierran crest above sea level, but if range-front faulting initiated in an already elevated plateau like the adjacent Basin and Range Province, then a hybrid model of pre-existing regional uplift and localized footwall unloading can account for the older and newer uplift phases suggested by the geologic record.

  17. Effects of bedrock nutrient density on vegetation and topography in the Sierra Nevada Batholith, California

    NASA Astrophysics Data System (ADS)

    Hahm, W.; Riebe, C. S.; Araki, S.

    2012-12-01

    against erosion. If nutrient availability is insufficient, such that it limits vegetation, physical erosion can overcome soil production and strip the landscape bare, ultimately slowing the rate of surface lowering. Our measurements of cosmogenic nuclides indicate that exposed surfaces in the western Sierra Nevada are eroding three to ten times slower than adjacent soil-mantled terrain. This implies that linkages between intrinsic bedrock nutrient density and vegetation could regulate relief at the pluton scale. The observation that nutrient density varies sharply among plutons cautions against unqualified use of granitoids as a uniform state factor in studies of weathering and pedogenesis.

  18. Stratigraphy and structure of the Strawberry Mine roof pendant, central Sierra Nevada, California

    USGS Publications Warehouse

    Nokleberg, W.J.

    1981-01-01

    regional metamorphism along N. 25? W. trends. Crosscutting of these structures by the contemporaneous granodiorite of Jackass Lakes indicates that this deformation occurred simultaneously with volcanism and plutonism during the middle Cretaceous. The third deformation involved both the roof pendant and adjacent plutonic rocks and consists of folds, faults, schistosities, and regional metamorphism along N. 65? -900 W. trends. Crosscutting of similar structures in other middle Cretaceous plutonic rocks of the Merced Peak quadrangle by undeformed late Cretaceous plutonic rocks indicates a regional deformation of middle to late Cretaceous age. Structures of similar style, orientation, and age occur elsewhere in metavolcanic and plutonic rocks throughout the central Sierra Nevada.

  19. Groundwater-surface water interactions in montane meadows of the Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Lucas, R. G.; Conklin, M. H.

    2012-12-01

    Meadows often lie in low gradient, groundwater fed terrain of the Sierra Nevada. These settings result in near saturated conditions for much of the year, shallow groundwater tables, and groundwater discharge to surface flow. Our hypothesis is that groundwater fluctuations integrate watershed processes rather than meadow specific processes. Meadow characteristics are in contrast to the adjacent forested landscapes, where soils go dry in the summer, groundwater tables are much deeper, and some fraction of soil water is lost to deeper percolation. We utilize a series water column data from monitoring wells and piezometers in two meadows, soil moisture and snow depth data from nodes in the associated catchment, located within the Southern Sierra Critical Zone Observatory, from water years 2008-2012. Water samples from wells and associated streams were analyzed for major ions and stable water isotopes. Results from the monitoring wells and piezometers show groundwater tables and pressure heads that are highest during snowmelt and decrease over the summer growing season; inter-annual variation is correlated to total accumulated precipitation for the given water year. Groundwater elevations exhibit diurnal fluctuations influenced by snowmelt and evapotranspiration (ET) processes in the spring, transitioning to an ET dominated signal during the summer growing season. These fluctuations are of greatest magnitude near the meadow-forest boundary and least near the center of the meadow. ET signals continue after the meadow vegetation senesces, suggesting influences from the adjacent forested landscape. Deep piezometers (>2.5 m depth) do not exhibit fluctuation at the daily time scale while shallower piezometers (<1 m depth) tend to show some fluctuation at this time interval. Further analysis of the piezometer data shows seasonal variation in the direction and magnitude of groundwater flux. Both near the meadow edge and meadow center, groundwater discharge is strongest during

  20. Spatial Patterns of Atmospherically Deposited Organic Contaminants at High Elevation in the Southern Sierra Nevada Mountains, California

    EPA Science Inventory

    Atmospherically deposited contaminants in the Sierra Nevada mountains of California have been implicated as adversely affecting amphibians and fish, yet the distributions of contaminants within the mountains are poorly known, particularly at high elevation. We tested the hypothe...

  1. Spatial Patterns of Atmospherically Deposited Organic Contaminants at High Elevation in the Southern Sierra Nevada Mountains, California

    EPA Science Inventory

    Atmospherically deposited contaminants in the Sierra Nevada mountains of California have been implicated as a factor adversely affecting biological resources such as amphibians and fish, yet the distributions of contaminants within the mountains are poorly known, particularly at...

  2. Temporal Slip Variation of the Sierra Nevada Frontal Fault System and Effects on Landscape Evolution

    NASA Astrophysics Data System (ADS)

    Kemp, C. D.; Wakabayashi, J.

    2008-12-01

    Temporal variability of vertical separation- and slip-rates determined by new geochronologic and geomorphic studies provides data to better understand the tectonic and geomorphic evolution of the Sierra Nevada. The Quincy and Lake Almanor region of the northern Sierra Nevada hosts ideal field relations to examine both long- and short-term slip- and vertical-separation rates of the Eastern Sierra Frontal Fault system (Frontal Fault system) and their relation to landscape evolution. We report initial results of the study. Geochronology provides key data to determine 1) the rate of uplift-related stream incision 2) the rate of vertical separation of the Frontal Fault system 3) the northern Sierra Nevada landscape response to temporal rate variations. Forty-one Late Cenozoic volcanic deposits yield K-Ar conventional and Ar-Ar incremental heating ages between .15 Ma and 3.3 Ma; another ten Ar-Ar ages of rocks from the Mehrten and Yana Formations are pending and the expected age range for these samples is ~2.8 Ma to ~5 Ma respectively. The present northern Sierra Nevada landscape is characterized by high plateau-like ridges capped by Yana or Mehrten volcanics above deeply incised canyons. Field and geomorphic relations reveal a reverse stratigraphic sequence of terrace-like remnants of basaltic or andesitic composition in the North Fork Feather River canyon. Ar-Ar ages of the inset volcanics indicate rapid incision since 2.8 Ma with rates of incision increasing into the present. Similarly, field and geomorphic relations of older rocks reveal incipience and evolution of relief generation. Rocks of the ~5 Ma Mehrten Formation are occasionally underlain by Eocene to Miocene "auriferous" gravels deposited by trans-Sierran paleochannels; field relations of the Mehrten Fm. and gravels indicate low-relief paleotopography at Miocene-Pliocene time. Likewise, the Yana Fm. indicates similar paleotopography at 2.8 Ma thus constraining timing of relief production to post

  3. Population dynamics of spotted owls in the Sierra Nevada, California

    USGS Publications Warehouse

    Blakesley, J.A.; Seamans, M.E.; Conner, M.M.; Franklin, A.B.; White, Gary C.; Gutierrez, R.J.; Hines, J.E.; Nichols, J.D.; Munton, T.E.; Shaw, D.W.H.; Keane, J.J.; Steger, G.N.; McDonald, T.L.

    2010-01-01

    The California spotted owl (Strix occidentalis occidentalis) is the only spotted owl subspecies not listed as threatened or endangered under the United States Endangered Species Act despite petitions to list it as threatened. We conducted a meta-analysis of population data for 4 populations in the southern Cascades and Sierra Nevada, California, USA, from 1990 to 2005 to assist a listing evaluation by the United States Fish and Wildlife Service. Our study areas (from N to S) were on the Lassen National Forest (LAS), Eldorado National Forest (ELD), Sierra National Forest (SIE), and Sequoia and Kings Canyon National Parks (SKC). These study areas represented a broad spectrum of habitat and management conditions in these mountain ranges. We estimated apparent survival probability, reproductive output, and rate of population change for spotted owls on individual study areas and for all study areas combined (meta-analysis) using model selection or model-averaging based on maximum-likelihood estimation. We followed a formal protocol to conduct this analysis that was similar to other spotted owl meta-analyses. Consistency of field and analytical methods among our studies reduced confounding methodological effects when evaluating results. We used 991 marked spotted owls in the analysis of apparent survival. Apparent survival probability was higher for adult than for subadult owls. There was little difference in apparent survival between male and female owls. Model-averaged mean estimates of apparent survival probability of adult owls varied from 0.811 ?? 0.021 for females at LAS to 0.890 ?? 0.016 for males at SKC. Apparent survival increased over time for owls of all age classes at LAS and SIE, for adults at ELD, and for second-year subadults and adults at SKC. The meta-analysis of apparent survival, which included only adult owls, confirmed an increasing trend in survival over time. Survival rates were higher for owls on SKC than on the other study areas. We analyzed data

  4. Airborne Pesticides as an Unlikely Cause for Population Declines of Alpine Frogs in the Sierra Nevada, California

    EPA Science Inventory

    Airborne pesticides from the Central Valley of California have been implicated as a cause for population declines of several amphibian species, with the strongest evidence for the mountain yellow-legged frog complex (Rana muscosa and R. sierrae) in the Sierra Nevada. We measured...

  5. A new genus and species of larval mite (Acari: Prostigmata: Microtrombidiidae) parasitising Orthoptera (Tettigoniidae) from the Sierra Nevada, Spain.

    PubMed

    Mayoral, Jaime G; Barranco, Pablo

    2012-09-01

    Nevada capileirarum n. g., n. sp. (Acari: Microtrombidiidae: Microtrombidiinae) is described from ectoparasitic larvae parasitising two endemic species of Orthoptera (Tettigoniidae), Baetica ustulata (Rambur) and Pycnogaster inermis (Rambur) from the Sierra Nevada mountain range, Granada, Spain. A key to the larvae of microtrombidiine genera with three dorsal scuta and a coxal setal formula of 2-1-1 is presented.

  6. Estimating aboveground biomass for broadleaf woody plants and young conifers in Sierra Nevada, California forests.

    USGS Publications Warehouse

    McGinnis, Thomas W.; Shook, Christine D.; Keeley, Jon E.

    2010-01-01

    Quantification of biomass is fundamental to a wide range of research and natural resource management goals. An accurate estimation of plant biomass is essential to predict potential fire behavior, calculate carbon sequestration for global climate change research, assess critical wildlife habitat, and so forth. Reliable allometric equations from simple field measurements are necessary for efficient evaluation of plant biomass. However, allometric equations are not available for many common woody plant taxa in the Sierra Nevada. In this report, we present more than 200 regression equations for the Sierra Nevada western slope that relate crown diameter, plant height, crown volume, stem diameter, and both crown diameter and height to the dry weight of foliage, branches, and entire aboveground biomass. Destructive sampling methods resulted in regression equations that accurately predict biomass from one or two simple, nondestructive field measurements. The tables presented here will allow researchers and natural resource managers to easily choose the best equations to fit their biomass assessment needs.

  7. Estimating aboveground biomass for broadleaf woody plants and young conifers in Sierra Nevada, California, forests

    USGS Publications Warehouse

    McGinnis, T.W.; Shook, C.D.; Keeley, J.E.

    2010-01-01

    Quantification of biomass is fundamental to a wide range of research and natural resource management goals. An accurate estimation of plant biomass is essential to predict potential fire behavior, calculate carbon sequestration for global climate change research, assess critical wildlife habitat, and so forth. Reliable allometric equations from simple field measurements are necessary for efficient evaluation of plant biomass. However, allometric equations are not available for many common woody plant taxa in the Sierra Nevada. In this report, we present more than 200 regression equations for the Sierra Nevada western slope that relate crown diameter, plant height, crown volume, stem diameter, and both crown diameter and height to the dry weight of foliage, branches, and entire aboveground biomass. Destructive sampling methods resulted in regression equations that accurately predict biomass from one or two simple, nondestructive field measurements. The tables presented here will allow researchers and natural resource managers to easily choose the best equations to fit their biomass assessment needs.

  8. Ten Years of Forest Cover Change in the Sierra Nevada Detected Using Landsat Satellite Image Analysis

    NASA Technical Reports Server (NTRS)

    Potter, Christopher S.

    2014-01-01

    A detailed geographic record of recent vegetation regrowth and disturbance patterns in forests of the Sierra Nevada remains a gap that can be filled with remote sensing data. Landsat (TM) imagery was analyzed to detect 10 years of recent changes (between 2000 and 2009) in forest vegetation cover for areas burned by wildfires between years of 1995 to 1999 in the region. Results confirmed the prevalence of regrowing forest vegetation during the period 2000 and 2009 over 17% of the combined burned areas.

  9. Hydrologic Response and Watershed Sensitivity to Climate Warming in California's Sierra Nevada

    PubMed Central

    Null, Sarah E.; Viers, Joshua H.; Mount, Jeffrey F.

    2010-01-01

    This study focuses on the differential hydrologic response of individual watersheds to climate warming within the Sierra Nevada mountain region of California. We describe climate warming models for 15 west-slope Sierra Nevada watersheds in California under unimpaired conditions using WEAP21, a weekly one-dimensional rainfall-runoff model. Incremental climate warming alternatives increase air temperature uniformly by 2°, 4°, and 6°C, but leave other climatic variables unchanged from observed values. Results are analyzed for changes in mean annual flow, peak runoff timing, and duration of low flow conditions to highlight which watersheds are most resilient to climate warming within a region, and how individual watersheds may be affected by changes to runoff quantity and timing. Results are compared with current water resources development and ecosystem services in each watershed to gain insight into how regional climate warming may affect water supply, hydropower generation, and montane ecosystems. Overall, watersheds in the northern Sierra Nevada are most vulnerable to decreased mean annual flow, southern-central watersheds are most susceptible to runoff timing changes, and the central portion of the range is most affected by longer periods with low flow conditions. Modeling results suggest the American and Mokelumne Rivers are most vulnerable to all three metrics, and the Kern River is the most resilient, in part from the high elevations of the watershed. Our research seeks to bridge information gaps between climate change modeling and regional management planning, helping to incorporate climate change into the development of regional adaptation strategies for Sierra Nevada watersheds. PMID:20368984

  10. Spatial characterization of glacial and periglacial landforms in the highlands of Sierra Nevada (Spain).

    PubMed

    Palma, P; Oliva, M; García-Hernández, C; Gómez Ortiz, A; Ruiz-Fernández, J; Salvador-Franch, F; Catarineu, M

    2017-04-15

    Sierra Nevada constitutes the southernmost and highest massif in the Iberian Peninsula, with elevations exceeding 3000m. Two large glacial advances were recorded during the Last Glaciation and several minor advances occurred until the Early Holocene. Since then, periglacial activity has prevailed above 2500m. Here, we present a new and more accurate geomorphological map of the highlands of Sierra Nevada, integrating in a GIS environment i) high resolution satellite imagery, ii) topographic data, and iii) field observations. This approach has allowed a better characterization of the spatial extent of cold-climate morphogenic processes and associated landforms formed during the Last Glaciation and subsequent deglaciation. Despite its extension and high altitude, the steep relief of Sierra Nevada and its southern location conditioned a significantly lower glaciated surface (104.6km(2)) with respect to other Iberian massifs. We have also inferred the paleoclimatic conditions of the study area through the calculation of Equilibrium Line Altitudes (ELAs). The distribution of the lowest moraines suggests an ELA for the maximum glacial extent at 2525m in the northern slope and 2650m in the southern side, increasing towards the east. Local ELA differences are related to: (i) the influence of the warmer Mediterranean Sea in contrast to the cooler Atlantic Ocean, (ii) the climate with more continental characteristics on the northern slope, and (iii) the microscale control of the local topography. Mean annual air temperatures in the ice-free summit plateaus were between -4/-6°C during the maximum local glacial extent, determining permafrost conditions with intense periglacial dynamics. Rock glaciers and protalus lobes developed until 2500m, the lowest boundary for permafrost regime. The distribution of other glacial and periglacial landforms within the limits of the maximum ice extent provides evidence to better understand the extent of subsequent glacial stages and post

  11. Resilience Through Disturbance: Effects of Wildfire on Vegetation and Water Balance in the Sierra Nevadas

    NASA Astrophysics Data System (ADS)

    Boisrame, G. F. S.; Thompson, S. E.; Stephens, S.; Collins, B.; Tague, N.

    2015-12-01

    A century of fire suppression in the Western United States has drastically altered the historically fire-adapated ecology in California's Sierra Nevada Mountains. Fire suppression is understood to have increased the forest cover, as well as the stem density, canopy cover and water demand of montane forests, reducing resilience of the forests to drought, and increasing the risk of catastrophic fire by drying the landscape and increasing fuel loads. The potential to reverse these trends by re-introducing fire into the Sierra Nevada is highly promising, but the likely effects on vegetation structure and water balance are poorly quantified. The Illilouette Creek Basin in Yosemite National Park represents a unique experiment in the Sierra Nevada, in which managers have moved from fire suppression to allowing a near-natural fire regime to prevail since 1972. Changes in vegetation structure in the Illilouette since the restoration of natural burning provides a unique opportunity to examine how frequent, mixed severity fires can reshape the Sierra Nevada landscape. We characterize these changes from 1969 to the present using a combination of Landsat products and high-resolution aerial imagery. We describe how the landscape structure has changed in terms of vegetation composition and its spatial organization, and explore the drivers of different post-fire vegetation type transitions (e.g. forest to shrubland vs. forest to meadow). By upscaling field data using vegetation maps and Landsat wetness indices, we explore how these vegetation transitions have impacted the water balance of the Illilouette Creek Basin, potentially increasing its resilience in the face of drought, climate change, and catastrophic fire. In a region that is adapted to frequent disturbance from fire, this work helps us understand how allowing such natural disturbances to take place can increase the sustainability of diverse landscapes in the long term.

  12. Cretaceous plutonic rocks in the Donner Lake-Cisco Grove area, northern Sierra Nevada, California

    USGS Publications Warehouse

    Kulow, Matthew J.; Hanson, Richard E.; Girty, Gary H.; Girty, Melissa S.; Harwood, David S.

    1998-01-01

    The northernmost occurrences of extensive, glaciated exposures of the Sierra Nevada batholith occur in the Donner Lake-Cisco Grove area of the northern Sierra Nevada. The plutonic rocks in this area, which are termed here the Castle Valley plutonic assemblage, crop out over an area of 225 km2 and for the most part are shown as a single undifferentiated mass on previously published geological maps. In the present work, the plutonic assemblage is divided into eight separate intrusive units or lithodemes, two of which each consist of two separate plutons. Compositions are dominantly granodiorite and tonalite, but diorite and granite form small plutons in places. Spectacular examples of comb layering and orbicular texture occur in the diorites. U-Pb zircon ages have been obtained for all but one of the main units and range from ~120 to 114 Ma, indicating that the entire assemblage was emplaced in a narrow time frame in the Early Cretaceous. This is consistent with abundant field evidence that many of the individual phases were intruded penecontemporaneously. The timing of emplacement correlates with onset of major Cretaceous plutonism in the main part of the Sierra Nevada batholith farther south. The emplacement ages also are similar to isotopic ages for gold-quartz mineralization in the Sierran foothills west of the study area, suggesting a direct genetic relationship between the voluminous Early Cretaceous plutonism and hydrothermal gold mineralization.

  13. Winter orographic precipitation ratios in the Sierra Nevada - Large-scale atmospheric circulations and hydrologic consequences

    USGS Publications Warehouse

    Dettinger, M.; Redmond, K.; Cayan, D.

    2004-01-01

    The extent to which winter precipitation is orographically enhanced within the Sierra Nevada of California varies from storm to storm, and season to season, from occasions when precipitation rates at low and high altitudes are almost the same to instances when precipitation rates at middle elevations (considered here) can be as much as 30 times more than at the base of the range. Analyses of large-scale conditions associated with orographic precipitation variations during storms and seasons from 1954 to 1999 show that strongly orographic storms most commonly have winds that transport water vapor across the range from a more nearly westerly direction than during less orographic storms and than during the largest overall storms, and generally the strongly orographic storms are less convectively stable. Strongly orographic conditions often follow heavy precipitation events because both of these wind conditions are present in midlatitude cyclones that form the cores of many Sierra Nevada storms. Storms during La Nin??a winters tend to yield larger orographic ratios (ORs) than do those during El Nin?? os. A simple experiment with a model of streamflows from a river basin draining the central Sierra Nevada indicates that, for a fixed overall basin-precipitation amount, a decrease in OR contributes to larger winter flood peaks and smaller springtime flows, and thus to an overall hastening of the runoff season. ?? 2004 American Meteorological Society.

  14. Airborne SAR determination of relative ages of Walker Valley moraines, eastern Sierra Nevada

    NASA Technical Reports Server (NTRS)

    Fox, A.; Isacks, B.; Bloom, A.; Fielding, E.; Mcmurry, D.

    1991-01-01

    A regional study of the distribution and elevations of Pleistocene moraines in the Andes requires a method of determining relative age from space. One of our primary objectives is to establish the relative chronology of major climatic events responsible for glaciation in the Andes and other regions that are difficult to access on the ground and where suitable material for absolute age determination is lacking. The sensitivity of radar to surface roughness makes it possible to develop a remotely-based relative dating technique for landforms for which surface age and roughness can be correlated. We are developing such a technique with Airborne Synthetic Aperture Radar (AIRSAR) imagery of the eastern Sierra Nevada where independent evidence is available for the ages and physical characteristics of moraines. The Sierra Nevada moraines are similar in form and environmental setting to Andean moraines that we have targeted for study during the pending Shuttle Imaging Radar-C (SIR-C) mission. SAR imagery is used to differentiate the ages of five moraine sequences of Walker Valley in the eastern Sierra Nevada. Other aspects of this investigation are briefly discussed.

  15. Evidence for nutrient enrichment of high-elevation lakes in the Sierra Nevada, California

    USGS Publications Warehouse

    Sickman, James O.; Melack, John M.; Clow, David W.

    2003-01-01

    Long-term measurements (1983-2001) of nutrients and seston in Emerald Lake (Sierra Nevada, California) have revealed ecologically significant patterns. Nitrate, both during spring runoff and during growing seasons, declined from 1983 through 1995. Declining snowmelt nitrate was caused primarily by changes in snow regime induced by the 1987-1992 drought: years with shallow, early melting snowpacks had lower snowmelt nitrate concentrations owing to less labile N production in catchment soils and longer plant growing seasons. However, nitrate declines during growing seasons carried through the wetter years of 1993-2000 and are likely the result of increased P loading to the lake and the release of phytoplankton from P limitation. Contemporaneous with these changes was an increase in algal biomass and a shift from P limitation toward more frequent N limitation of phytoplankton abundance. Particulate carbon concentrations in the late 1990s were two- to threefold greater than in the early 1980s. These trends were reflected in a larger set of Sierra Nevada lakes sampled as part of synoptic surveys (n = 28). Between 1985 and 1999, nitrate decreased and total P increased in >70% of the lakes sampled. Our data suggest that lakes throughout the Sierra Nevada are experiencing measurable eutrophication in response to the atmospheric deposition of nutrients.

  16. Landslide susceptibility in the Sierra Nevada National Park (SE Spain) using a multivariate statistics method.

    NASA Astrophysics Data System (ADS)

    Azañón, J. M.; Pérez-Peña, V.; Yesares, J. M.; Roldán, F. J.; Mateos, R. M.; Rodríguez-Fernández, J.; Rodríguez-Peces, M. J.; Ureña, C.

    2012-04-01

    In this work we have evaluated the landslide susceptibility of the Sierra Nevada National Park area. In order to assess the landslide susceptibility, as well as the traditional factors extracted from the Digital Elevation Model and the lithology, we analyzed many important variables that had not been taken into account in previous studies such as; normalized vegetation index (NDVI), distance to active tectonic structures (folds and faults), snow melting cycles, snow duration, and runoff coefficient (P0). We have differentiated three types of slope instabilities; rotational landslides, fluxes, and rocks failures. For each landslide type we carried out a field inventory using aerial photographs and field work. We used a multivariate statistic approach to obtain those factors that better explain the variance of the landslide distribution through a Principal Component Analysis (PCA). In order to produce the different susceptibility maps for each landslide type, we performed a discrimination analysis to weigh the different factors. The three resulting susceptibility maps have been combined to obtain a general susceptibility map for slope movements in the Sierra Nevada National Park area. This study indicates that some of the new analyzed factors as NVDI index, tectonic activity, and runoff coefficient have a strong influence in the landslide susceptibility in the Sierra Nevada National Park.

  17. Cocorp Deep Seismic Reflection Profiling in the Northern Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Nelson, K. D.; Zhu, T. F.; Gibbs, A.; Harris, R.; Oliver, J. E.; Kaufman, S.; Brown, L.; Schweickert, R. A.

    1986-04-01

    A COCORP seismic reflection profile across the northern Sierra Nevada in California shows several east-dipping zones of discontinuous reflections. Correlation with surface geology suggests that these zones probably originate from faults of the Foothills fault system. In particular, the Melones fault, which coincides with the "Mother Lode" of the central and southern Sierra foothills, appears to be marked by prominent reflections in the midcrust. Migration of the COCORP data suggests that these faults are approximately planar, have moderately steep east dips (35°-47°), and penetrate at least to midcrustal depths (>20 km). At present it is unclear whether these faults are primary Nevadan thrusts, "late" Nevadan backthrusts (retrocharriage), or younger Cretaceous or Cenozoic faults, also known to occur in the region. Other more problematic features imaged on the profile include a prominent west-dipping zone of reflections in the midcrust beneath the Eastern belt, and subhorizontal reflections at 22- to 26-km depth beneath the Tahoe graben. The former might represent a west-dipping thrust analogous to the Taylorsville thrust cropping out to the north of the survey route. The latter might represent the base of the Sierra Nevada batholith, the westward extension of any one of several thrust systems cropping out in Nevada, a low-angle extensional detachment, or Moho.

  18. Observations of Aerosol Conditions Associated with Precipitation Events in the Remote Sierra Nevada Foothills

    NASA Astrophysics Data System (ADS)

    Collins, D. B.; Kingsmill, D.; Roberts, G. C.; Noblitt, S.; Prather, K. A.

    2011-12-01

    Recent investigations of atmospheric aerosols have suggested their importance in affecting clouds and precipitation patterns, especially in regions where anthropogenic contributions to aerosol loadings are large. Aerosols entrained into precipitating clouds have been shown to either enhance or suppress precipitation based on the characteristics of the cloud condensation nuclei (CCN) or ice nuclei (IN) introduced. Due to the inherent chemical dependence of CCN activity, the chemical composition of aerosols introduced into precipitating clouds will determine their effect on precipitation. This presentation will utilize ground-based chemical and physical measurements of aerosols and precipitation from multiple winter seasons gathered at Sugar Pine Dam (Foresthill, CA) as part of the CalWater experiment. The coupled behavior of landfalling frontal systems, regional terrain-parallel flow along the windward slopes of the Sierra Nevada (i.e., the Sierra Barrier Jet), and observed aerosol conditions in the Sierra Nevada foothills will be demonstrated and related issues explored. Temporally correlated changes in aerosol chemical composition with approaching winter storms may provide key insights into the evolution of the Sierra Barrier Jet, a dynamic feature that can have a major influence on orographically-forced precipitation in this region, and could provide clues to the coupling of Central Valley pollution with winter-time orographic precipitation episodes (or lack thereof). Gaining an overall understanding of the frequency and magnitude of the entrainment of Central Valley pollutants on winter storm systems will ultimately provide an estimate of how much aerosols affect precipitation in California.

  19. SR-71A - in Flight over Southern Sierra Nevada Mountains

    NASA Technical Reports Server (NTRS)

    1997-01-01

    NASA Dryden Flight Research Center's SR-71A, tail number 844, banks away over the Sierra Nevada mountains after air refueling from a USAF tanker during a 1997 flight. Two SR-71 aircraft have been used by NASA as testbeds for high-speed and high-altitude aeronautical research. The aircraft, an SR-71A and an SR-71B pilot trainer aircraft, have been based here at NASA's Dryden Flight Research Center, Edwards, California. They were transferred to NASA after the U.S. Air Force program was cancelled. As research platforms, the aircraft can cruise at Mach 3 for more than one hour. For thermal experiments, this can produce heat soak temperatures of over 600 degrees Fahrenheit (F). This operating environment makes these aircraft excellent platforms to carry out research and experiments in a variety of areas -- aerodynamics, propulsion, structures, thermal protection materials, high-speed and high-temperature instrumentation, atmospheric studies, and sonic boom characterization. The SR-71 was used in a program to study ways of reducing sonic booms or over pressures that are heard on the ground, much like sharp thunderclaps, when an aircraft exceeds the speed of sound. Data from this Sonic Boom Mitigation Study could eventually lead to aircraft designs that would reduce the 'peak' overpressures of sonic booms and minimize the startling affect they produce on the ground. One of the first major experiments to be flown in the NASA SR-71 program was a laser air data collection system. It used laser light instead of air pressure to produce airspeed and attitude reference data, such as angle of attack and sideslip, which are normally obtained with small tubes and vanes extending into the airstream. One of Dryden's SR-71s was used for the Linear Aerospike Rocket Engine, or LASRE Experiment. Another earlier project consisted of a series of flights using the SR-71 as a science camera platform for NASA's Jet Propulsion Laboratory in Pasadena, California. An upward-looking ultraviolet

  20. Sierra Nevada Ecoregion: Chapter 15 in Status and trends of land change in the Western United States--1973 to 2000

    USGS Publications Warehouse

    Raumann, Christian G.; Soulard, Christopher E.

    2012-01-01

    This chapter has been modified from original material published in Raumann and Soulard (2007), entitled “Land-cover trends of the Sierra Nevada Ecoregion, 1973–2000” (U.S. Geological Survey Scientific Investigations Report 2007–5011). The Sierra Nevada Ecoregion covers approximately 53,413 km² (20,623 mi²) with the majority of the area (98 percent) in California and the remainder in Nevada (fig. 1) (Omernik, 1987; U.S. Environmental Protection Agency, 1997). The Sierra Nevada Ecoregion is generally oriented north-south and is essentially defined by the Sierra Nevada physiographic province, which separates California’s Central Valley to the west from the Great Basin to the east. It is bounded by seven other ecoregions: Southern and Central California Chaparral and Oak Woodlands Ecoregion on the west; Klamath Mountains and Eastern Cascades Slopes and Foothills Ecoregions on the north; Southern California Mountains Ecoregion on the south; and Northern Basin and Range, Central Basin and Range, and Mojave Basin and Range Ecoregions on the east (fig. 1). The Sierra Nevada range is a granitic batholith, much of which is exposed at higher elevations, with a gradual western slope and a generally steep eastern escarpment.

  1. Geochemical Composition and Correlation of Oligocene Ash-flow Tuffs in the Northern Sierra Nevada of California

    NASA Astrophysics Data System (ADS)

    Cassel, E. J.; Graham, S. A.

    2008-12-01

    Along the western slopes of the northern Sierra Nevada, a sequence of Oligocene rhyolitic ash-flow tuffs is interbedded with tuffaceous paleosol horizons and volcaniclastic fluvial sand (Valley Springs and Delleker Formations; Wagner et al., 2000). These tuffs are preserved across the modern crest of the Sierra Nevada and into the foothills of the range, and have been correlated to ash-flow tuffs identified and isotopically dated in the Walker Lane fault zone and central Nevada (Faulds et al., 2005; Henry et al., 2004), using trace and rare earth element geochemical analyses. Ash-flow tuffs were sampled within the northern Sierra Nevada and western Nevada, from 30-160 km from the eastern edge from the Great Valley. Unaltered volcanic glass was isolated from the tuffs for trace and rare earth element analyses, and three distinct geochemical compositions were identified. Ash-flow tuffs sampled from within the northern Sierra Nevada correlate with geochemically similar tuffs sampled in western Nevada, which have previously been identified and isotopically dated in that region: the Axehandle Canyon, Dogskin Mountain, and Campbell Creek tuffs. These tuffs were sourced from calderas in central Nevada, with 40Ar/39Ar ages of 31.2 ± 0.1, 29.2 ± 0.1, and 28.8 ± 0.1 Ma, respectively (Henry et al., 2004). New single-grain 40Ar/39Ar age dating of sanidine crystals from the Sierra Nevada tuff samples is underway to corroborate and refine correlations. These results show that Oligocene ash-flow tuffs traveled over 200 km from their source calderas across what is now the crest of the Sierra Nevada (assuming extension of 10-25% in western Nevada and 15-100% in central Nevada), and that the Oligocene drainage divide must have been much farther east than it is today. Placed in the context of other recent studies, a steep western gradient in the Oligocene Sierra Nevada and source calderas likely located in a region of high topography to the east of the range allowed for the large

  2. Hillslope Erosion and Water Quality from the Rim Fire, Sierra Nevada, CA

    NASA Astrophysics Data System (ADS)

    Kuhn, T. J.; Austin, L. J.; Forrester, H.; DeLong, S. B.; Lever, R.; Roche, J. W.

    2014-12-01

    The Rim Fire in 2013 burned approximately 1036 km2 in the Sierra Nevada (including 312 km2 within Yosemite National Park), generating considerable public concern regarding potential impacts to the Tuolumne River watershed, in terms of water quality and water supply infrastructure serving the City of San Francisco. Land management responses included a multi-million dollar watershed treatment project on USFS lands near Cherry Creek, with similar actions suggested for areas in the Hetch Hetchy and Lake Eleanor watersheds. In response to the concern that the post-burn landscape will negatively impact water quality, we are investigating hydrologic effects and hillslope erosion in two small burned basins (2.2 and 5.2 km2) within the Tuolumne River basin in Yosemite National Park. Within a month after fire containment, sites were equipped with instrumentation to record stream stage, turbidity, and total suspended sediment. We also installed 21 sediment fences that trap all sediment silt sized and larger on moderate (20%) to steep (50%) hillslopes from 100 m2 plots within moderate and high severity burn areas. Accumulated sediment is collected, weighed, and sub-sampled after each storm event, and, analyzed for dry weight, particle size, gravimetric water content, bulk density, pH, color, carbon and nitrogen content from % fine organics, and % coarse organics. As of July 31, 2014, four discrete storm events had been sampled. Data are used to calculate annual sediment yield, and to investigate organic carbon storage, deposition, and transport. We are also collecting repeat terrestrial laser scans to assess topographic change and identify the hillslope processes that contribute to erosion and deposition at plot- and hillslope-scale. These findings provide analogs for possible changes in adjacent burned areas and to inform management decisions in response to future fires and potential impacts to water quality in areas valued by the park, the City of San Francisco and other

  3. Spatiotemporal patterns of fault slip rates across the Central Sierra Nevada frontal fault zone

    NASA Astrophysics Data System (ADS)

    Rood, Dylan H.; Burbank, Douglas W.; Finkel, Robert C.

    2011-01-01

    Patterns in fault slip rates through time and space are examined across the transition from the Sierra Nevada to the Eastern California Shear Zone-Walker Lane belt. At each of four sites along the eastern Sierra Nevada frontal fault zone between 38 and 39° N latitude, geomorphic markers, such as glacial moraines and outwash terraces, are displaced by a suite of range-front normal faults. Using geomorphic mapping, surveying, and 10Be surface exposure dating, mean fault slip rates are defined, and by utilizing markers of different ages (generally, ~ 20 ka and ~ 150 ka), rates through time and interactions among multiple faults are examined over 10 4-10 5 year timescales. At each site for which data are available for the last ~ 150 ky, mean slip rates across the Sierra Nevada frontal fault zone have probably not varied by more than a factor of two over time spans equal to half of the total time interval (~ 20 ky and ~ 150 ky timescales): 0.3 ± 0.1 mm year - 1 (mode and 95% CI) at both Buckeye Creek in the Bridgeport basin and Sonora Junction; and 0.4 + 0.3/-0.1 mm year - 1 along the West Fork of the Carson River at Woodfords. Data permit rates that are relatively constant over the time scales examined. In contrast, slip rates are highly variable in space over the last ~ 20 ky. Slip rates decrease by a factor of 3-5 northward over a distance of ~ 20 km between the northern Mono Basin (1.3 + 0.6/-0.3 mm year - 1 at Lundy Canyon site) to the Bridgeport Basin (0.3 ± 0.1 mm year - 1 ). The 3-fold decrease in the slip rate on the Sierra Nevada frontal fault zone northward from Mono Basin is indicative of a change in the character of faulting north of the Mina Deflection as extension is transferred eastward onto normal faults between the Sierra Nevada and Walker Lane belt. A compilation of regional deformation rates reveals that the spatial pattern of extension rates changes along strike of the Eastern California Shear Zone-Walker Lane belt. South of the Mina Deflection

  4. Spatiotemporal Patterns of Fault Slip Rates Across the Central Sierra Nevada Frontal Fault Zone

    NASA Astrophysics Data System (ADS)

    Rood, D. H.; Burbank, D.; Finkel, R. C.

    2010-12-01

    We examine patterns in fault slip rates through time and space across the transition from the Sierra Nevada to the Eastern California Shear Zone-Walker Lane belt. At each of four sites along the eastern Sierra Nevada frontal fault zone between 38-39° N latitude, geomorphic markers, such as glacial moraines and outwash terraces, are displaced by a suite of range-front normal faults. Using geomorphic mapping, surveying, and Be-10 surface exposure dating, we define mean fault slip rates, and by utilizing markers of different ages (generally, ~20 ka and ~150 ka), we examine rates through time and interactions among multiple faults over 10-100 ky timescales. At each site for which data are available for the last ~150 ky, mean slip rates across the Sierra Nevada frontal fault zone have probably not varied by more than a factor of two over time spans equal to half of the total time interval (~20 ky and ~150 ky timescales): 0.3 ± 0.1 mm/yr (mode and 95% CI) at both Buckeye Creek in the Bridgeport basin and Sonora Junction; and 0.4 +0.3/-0.1 mm/yr along the West Fork of the Carson River at Woodfords. Our data permit that rates are relatively constant over the time scales examined. In contrast, slip rates are highly variable in space over the last ~20 ky. Slip rates decrease by a factor of 3-5 northward over a distance of ~20 km between the northern Mono Basin (1.3 +0.6/-0.3 mm/yr at Lundy Canyon site) and the Bridgeport Basin (0.3 ± 0.1 mm/yr). The 3-fold decrease in the slip rate on the Sierra Nevada frontal fault zone northward from Mono Basin reflects a change in the character of faulting north of the Mina Deflection as extension is transferred eastward onto normal faults between the Sierra Nevada and Walker Lane belt. A compilation of regional deformation rates reveal that the spatial pattern of extension rates changes along strike of the Eastern California Shear Zone-Walker Lane belt. South of the Mina Deflection, extension is accommodated within a diffuse zone of

  5. Potential increase in floods in California's Sierra Nevada under future climate projections

    USGS Publications Warehouse

    Das, T.; Dettinger, M.D.; Cayan, D.R.; Hidalgo, H.G.

    2011-01-01

    California's mountainous topography, exposure to occasional heavily moisture-laden storm systems, and varied communities and infrastructures in low lying areas make it highly vulnerable to floods. An important question facing the state-in terms of protecting the public and formulating water management responses to climate change-is "how might future climate changes affect flood characteristics in California?" To help address this, we simulate floods on the western slopes of the Sierra Nevada Mountains, the state's primary catchment, based on downscaled daily precipitation and temperature projections from three General Circulation Models (GCMs). These climate projections are fed into the Variable Infiltration Capacity (VIC) hydrologic model, and the VIC-simulated streamflows and hydrologic conditions, from historical and from projected climate change runs, allow us to evaluate possible changes in annual maximum 3-day flood magnitudes and frequencies of floods. By the end of the 21st Century, all projections yield larger-than-historical floods, for both the Northern Sierra Nevada (NSN) and for the Southern Sierra Nevada (SSN). The increases in flood magnitude are statistically significant (at p <= 0. 01) for all the three GCMs in the period 2051-2099. The frequency of flood events above selected historical thresholds also increases under projections from CNRM CM3 and NCAR PCM1 climate models, while under the third scenario, GFDL CM2. 1, frequencies remain constant or decline slightly, owing to an overall drying trend. These increases appear to derive jointly from increases in heavy precipitation amount, storm frequencies, and days with more precipitation falling as rain and less as snow. Increases in antecedent winter soil moisture also play a role in some areas. Thus, a complex, as-yet unpredictable interplay of several different climatic influences threatens to cause increased flood hazards in California's complex western Sierra landscapes. ?? 2011 Springer Science

  6. Hillslope and stream connections to water tables in montane meadows of the southern Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Conklin, M. H.; Lucas, R. G.

    2011-12-01

    Montane meadows are often areas of groundwater discharge. In this study we characterized the groundwater - surface water interactions of two meadow systems and their connectivity to the surrounding catchment . We analyzed groundwater elevation data in 24 wells in two meadows located in the southern Sierra Nevada. Well transects extended from the meadow centers near the stream, to the meadow edged, and into the adjacent forest-where wells were drilled into the weathered granite saprock layer. Water samples were collected from the monitoring wells and from streams associated with the meadow systems and analyzed for major ions and stable water isotopes. Ground water elevations in the monitoring wells were used to calculate daily evapotranspiration (ET) values. These values show that locations on the meadow slopes and near the meadow edges are losing water to the atmosphere at near potential evapotranspiration rates during the height of the growing season. ET signals from wells near the meadow streams are muted, likely due to the vegetation utilizing the available surface water at these locations. Wells installed in the saprock layer, outside of the meadow boundaries, show diurnal fluctuations in sync with fluctuations observed at the meadow edge. This trend persists after the meadow vegetation senesces, indicating that groundwater elevations in the meadow, especially near the meadow edge, are significantly influenced by the adjacent hillslope saprock layer and forest ET. Geochemical sampling results indicate that the meadow streams are predominantly fed by snowmelt in the spring and early summer, moving toward more influence from base flow in the late summer and early fall. Results from the geochemical analysis established the connections of the hillslope to the meadow water tables and of the meadow subsurface waters to the down-gradient streams. Our results indicate that the these meadows are directly connected to the shallow sub-surface processes in the up gradient

  7. Road Sediment Production and Delivery in the Southern Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Korte, A.; MacDonald, L. H.

    2005-12-01

    Unpaved roads are a major source of sediment in many forested watersheds, but there are relatively few data on road sediment production rates and even fewer data on the delivery of road-related sediment to the stream network. The primary goals of this study are to: (1) quantify sediment production rates from different road surfaces; (2) determine the key controls on road sediment production rates; and (3) quantify the extent to which roads are connected to the stream channel network. The study is part of the Kings River Experimental Watershed study (KREW) in the southern Sierra Nevada Mountains in east-central California. Elevations range from 1485 m to 2420 m, and most of the precipitation falls as snow. Sediment production was measured with sediment fences from 36 road segments and 9 undisturbed swales over the 2003-2004 wet season, and from 41 road segments and 18 undisturbed swales over the 2004-2005 wet season. The road segments are stratified into native-surface roads, ditches adjacent to paved roads, gravel roads, and mixed-surface roads. A detailed survey on 13 km of roads has identified and characterized individual road segments, and the connectivity of each segment to the stream network. Precipitation for the 2003-2004 wet season was 700 mm or 70% of the long-term mean. Native surface roads had the highest mean sediment production rate at 0.44 kg m-2, while the mixed-surface roads averaged 0.10 kg m-2 and the gravel roads generated only 0.06 kg m-2. No sediment was produced from the ditches adjacent to the paved roads or the undisturbed hillslopes. In the second wet season precipitation was well above average and the initial results indicate that sediment production rates were 2-4 times higher than in the first wet season. The preliminary analysis of the road survey data indicate that 54% of the road segments had either no sediment plume or a plume less than 20 m in length. Thirty-three percent of the road segments had sediment plumes longer than 20 m but

  8. Latest extension of the Laujar fault in a convergence setting (Sierra Nevada, Betic Cordillera)

    NASA Astrophysics Data System (ADS)

    Martínez-Martos, Manuel; Galindo-Zaldívar, Jesus; Sanz de Galdeano, Carlos; García-Tortosa, Francisco Juan; Martínez-Moreno, Francisco José; Ruano, Patricia; González-Castillo, Lourdes; Azañón, José Miguel

    2017-02-01

    The present-day relief of the Betic Cordillera formed since the Late Miocene through the regional N-S to NW-SE Africa-Eurasia convergence that developed large folds. The Laujar Fault Zone is a south-dipping E-W oriented structure located at the northern boundary of the Alpujarran Corridor Neogene intramontane basin, which separates Sierra Nevada and Sierra de Gador antiforms, in the Internal Zones of the Betic Cordillera. The fault zone acted in a first stage as a dextral strike-slip fault. Currently it moves as a normal fault evidenced by striated calcretes, also in agreement with regional continuous GPS (CGPS) data that support the hypothesis of an active N-S extension in the fault area. In order to analyse the deep geometry of the Laujar Fault Zone, we combined several geophysical techniques (gravity, magnetic, electric resistivity tomography and audio-magnetotelluric data) with field geological observations. Fault surfaces seem to join at a southward-dipping shallow detachment level, including faults covered by the sedimentary infill. The fault zone was developed in a previously weakened area by wrench faults parallel to the Alpujarran Corridor. The recent normal activity of this fault zone may be a consequence of a change in the Africa-Eurasia convergence orientation, which implies a decrease in the N-S compression component. This structure along the southern limb of Sierra Nevada antiform evidences the gravitational collapse of previously thickened crust in a regional compressional context simultaneous to metamorphic core uplift.

  9. Changes in precipitating snow chemistry with location and elevation in the California Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Creamean, Jessie M.; Axson, Jessica L.; Bondy, Amy L.; Craig, Rebecca L.; May, Nathaniel W.; Shen, Hongru; Weber, Michael H.; Pratt, Kerri A.; Ault, Andrew P.

    2016-06-01

    Orographic snowfall in the Sierra Nevada Mountains is an important source of water for California and can vary significantly on an annual basis. The microphysical properties of orographic clouds and subsequent formation of precipitation are impacted, in part, by aerosols of varying size, number, and chemical composition, which are incorporated into clouds formed along the Sierra barrier. Herein, the physicochemical properties and sources of insoluble residues and soluble ions found in precipitation samples were explored for three sites of variable elevation in the Sierra Nevada during the 2012-2013 winter season. Residues were characterized using a suite of physicochemical techniques to determine the size-resolved number concentrations and associated chemical composition. A transition in the aerosol sources that served as cloud seeds or were scavenged in-cloud and below-cloud was observed as a function of location and elevation. Anthropogenic influence from the Central Valley was dominant at the two lowest elevation sites (1900 and 2200 m above mean sea level (AMSL)), whereas long-range transported mineral dust was a larger contributor at the highest elevation site where cleaner conditions were observed (2600 m AMSL). The residues and soluble ions observed provide insight into how multiple aerosol sources can impact cloud and precipitation formation processes, even over relatively small spatial scales. The transition with increasing elevation to aerosols that serve as ice nucleating particles may impact the properties and extent of snowfall in remote mountain regions where snowpack provides a vital supply of water.

  10. Isotasy and its implications for the structure of the Sierra, Nevada

    SciTech Connect

    Jones, C.H. . Center for Neotectonic Studies)

    1993-04-01

    Much of the understanding of the structure of the Sierra Nevada has evolved from the assumption of a thick crustal root; gravity models of the Sierra have generally started from such a root and then calculated density anomalies in the upper crust necessary to completely fit gravity measurements. Recent challenges to the seismic basis as this assumption suggest that alternate models of isostasy for the Sierra be explored. Direct observation of crustal structure at great depth is only possible in the Tehachapi Mtns., where paleodepths of 25--30 km have been reported, densities still range over [approximately]0.2 g/cm[sup 3], and the west-to-east difference in the Bouguer gravity anomaly is only [approximately]50 mgal (compared to > 150 mgal farther north). If these variations accurately reflect conditions present today at [approximately]15--30 km under the central Sierra, then surface density differences between foothills and Sierran crest could extend to 30--40 km depth. Published seismic refraction profiles support a bulk difference of [approximately]0.1 g/cm[sup 3] through the crust. Thus variations of bulk properties in the surface exposures of the Sierran batholith and countryrock might represent variations throughout the upper crust and possibly the entire crust. Because these variations are virtually unquestionably Mesozoic in age, such a structure has profound implications for the Cenozoic history of the range. For example, placing these crustal densities over a thick root in mid-Cenozoic history of the range. For example, structure has profound implications for the Cenozoic history of the range. For example, placing these crustal densities over a thick root in mid-Cenozoic time when the Sierra was only [approximately]1 km high, would make the mid-Cz Sierra tremendously overcompensated.

  11. Pesticides are involved with population declines of amphibians in the California Sierra Nevadas

    USGS Publications Warehouse

    Sparling, D.W.; Fellers, G.; McConnell, L.

    2001-01-01

    Several species of frogs and toads are in serious decline in the Sierra Nevada Mountains of California. These species include the threatened red-legged frog ( Rana aurora ), foothill yellow-legged frog ( R. boylii ), mountain yellow-legged frog ( R. muscosa ), Cascades frog ( Rana cascadae ), western toad ( Bufo boreas ) and Yosemite toad ( B. canorus ). For many of these species current distributions are down to 10% of historical ranges. Several factors including introduced predators, habitat loss, and ultraviolet radiation have been suggested as causes of these declines. Another probable cause is air-borne pesticides from the Central Valley of California. The Central Valley, especially the San Joaquin Valley, is a major agricultural region where millions of pounds of active ingredient pesticides are applied each year (http://www.cdpr.ca.gov/dprdatabase.htm). Prevailing westerly winds from the Pacific Coast transport these pesticides into the into the Sierras.

  12. Origin of high mountains in the continents: The Southern Sierra Nevada

    USGS Publications Warehouse

    Wernicke, B.; Clayton, R.; Ducea, M.; Jones, C.H.; Park, S.; Ruppert, S.; Saleeby, J.; Snow, J.K.; Squires, L.; Fliedner, M.; Jiracek, G.; Keller, Rebecca Hylton; Klemperer, S.; Luetgert, J.; Malin, P.; Miller, K.; Mooney, W.; Oliver, H.; Phinney, R.

    1996-01-01

    Active and passive seismic experiments show that the southern Sierra, despite standing 1.8 to 2.8 kilometers above its surroundings, is underlain by crust of similar seismic thickness, about 30 to 40 kilometers. Thermobarometry of xenolith suites and magnetotelluric profiles indicate that the upper mantle is eclogitic to depths of 60 kilometers beneath the western and central parts of the range, but little subcrustal lithosphere is present beneath the eastern High Sierra and adjacent Basin and Range. These and other data imply the crust of both the High Sierra and Basin and Range thinned by a factor of 2 since 20 million years ago, at odds with purported late Cenozoic regional uplift of some 2 kilometers.

  13. Thermal evolution and exhumation of deep-level batholithic exposures, southernmost Sierra Nevada, California

    USGS Publications Warehouse

    Saleeby, J.; Farley, K.A.; Kistler, R.W.; Fleck, R.J.

    2007-01-01

    The Tehachapi complex lies at the southern end of the Sierra Nevada batholith adjacent to the Neogene-Quaternary Garlock fault. The complex is composed principally of high-pressure (8-10 kbar) Cretaceous batholithic rocks, and it represents the deepest exposed levels of a continuous oblique crustal section through the southern Sierra Nevada batholith. Over the southern ???100 km of this section, structural/petrologic continuity and geochronological data indicate that ???35 km of felsic to intermediate-composition crust was generated by copious arc magmatism primarily between 105 and 99 Ma. In the Tehachapi complex, these batholithic rocks intrude and are bounded to the west by similar-composition gneissic-textured high-pressure batholithic rocks emplaced at ca. 115-110 Ma. This lower crustal complex is bounded below by a regional thrust system, which in Late Cretaceous time tectonically eroded the underlying mantle lithosphere, and in series displaced and underplated the Rand Schist subduction assemblage by low-angle slip from the outboard Franciscan trench. Geophysical and mantle xenolith studies indicate that the remnants of this shallow subduction thrust descend northward through the crust and into the mantle, leaving the mantle lithosphere intact beneath the greater Sierra Nevada batholith. This north-dipping regional structure records an inflection in the Farallon plate, which was segmented into a shallow subduc-tion trajectory to the south and a normal steeper trajectory to the north. We combine new and published data from a broad spectrum of thermochronom-eters that together form a coherent data array constraining the thermal evolution of the complex. Integration of these data with published thermobarometric and petro-genetic data also constrains the tectonically driven decompression and exhumation history of the complex. The timing of arc magmatic construction of the complex, as denoted above, is resolved by a large body of U/Pb zircon ages. High

  14. Potential environmental effects of pack stock on meadow ecosystems of the Sierra Nevada, USA

    USGS Publications Warehouse

    Ostoja, Steven M.; Brooks, Matthew L.; Moore, Peggy E.; Berlow, Eric L.; Robert Blank,; Roche, Jim; Chase, Jennifer T.; Sylvia Haultain,

    2014-01-01

    Pack and saddle stock, including, but not limited to domesticated horses, mules, and burros, are used to support commercial, private and administrative activities in the Sierra Nevada. The use of pack stock has become a contentious and litigious issue for land management agencies in the region inter alia due to concerns over effects on the environment. The potential environmental effects of pack stock on Sierra Nevada meadow ecosystems are reviewed and it is concluded that the use of pack stock has the potential to influence the following: (1) water nutrient dynamics, sedimentation, temperature, and microbial pathogen content; (2) soil chemistry, nutrient cycling, soil compaction and hydrology; (3) plant individuals, populations and community dynamics, non-native invasive species, and encroachment of woody species; and (4) wildlife individuals, populations and communities. It is considered from currently available information that management objectives of pack stock should include the following: minimise bare ground, maximise plant cover, maintain species composition of native plants, minimise trampling, especially on wet soils and stream banks, and minimise direct urination and defecation by pack stock into water. However, incomplete documentation of patterns of pack stock use and limited past research limits current understanding of the effects of pack stock, especially their effects on water, soils and wildlife. To improve management of pack stock in this region, research is needed on linking measurable monitoring variables (e.g. plant cover) with environmental relevancy (e.g. soil erosion processes, wildlife habitat use), and identifying specific environmental thresholds of degradation along gradients of pack stock use in Sierra Nevada meadows.

  15. The Sierra Nevada-San Joaquin Hydrologic Observatory (SNSJHO): A WATERS Network Test Bed

    NASA Astrophysics Data System (ADS)

    Fisher, J.; Meng, X.; Rice, R.; Butler, C.; Molotch, N.; Harmon, T. C.; Bales, R.

    2007-12-01

    A mountain-to-valley virtual hydrologic observatory in Central California provides a focus for data and information in support of hydrologic research, a testbed for prototype measurement systems, and guidance for development of measurement and cyber infrastructure in an actual observatory. The multiple rivers and watersheds making up the 60,000 km2 greater San Joaquin drainage are physically disconnected by mountain-front dams that provide flood control, hydropower, seasonal water delivery and recreation. However, the mountain and valley portions are institutionally connected in multiple ways. For example, each year the winter snowpack and watershed conditions determine the magnitude of annual runoff. Errors in snowpack measurements and runoff forecasts have huge economic implications for valley water users. Second, valley flood control, water quality, irrigation demand and hydropower operations have a very strong interest in influencing mountain watershed management. The broader aim of the Sierra Nevada-San Joaquin Hydrologic Observatory is to build research infrastructure and promote research for improving the knowledge base for sound hydrologic management in the Sierra Nevada, San Joaquin Valley and across the Western U.S. In the Sierra Nevada the current focus is on developing spatially distributed instrument clusters that, when blended with remotely sensed data, will improve water balance closure from hillslope to watershed scales. Five instrument clusters at or just above the rain-snow transition are in place and under development. In the San Joaquin Valley, the focus is on sensor systems for observing fertilizer application rates in agriculture, groundwater-surface water exchanges in rivers, and flow and mixing in the confluence zones between the main stem San Joaquin and tributary Merced Rivers. A common digital library and analysis framework further links the mountain and valley portions of the virtual observatory (see https://eng.ucmerced.edu/dev00/snsjno).

  16. The Influence of Antecedent Soil Moisture on Springtime Runoff in the Sierra Nevada Mountains

    NASA Astrophysics Data System (ADS)

    Flint, A. L.; Flint, L. E.; Dettinger, M. D.

    2009-12-01

    As the changing climate influences precipitation, air temperature, and snowmelt, measurements in the Sierra Nevada are illustrating the contribution of antecedent soil moisture on the timing and volume of springtime runoff. Delays in runoff correspond to low antecedent soil moisture from the preceding fall when snow fell on dry soil. In the Tuolumne River streamgage at the Little Grand Canyon just above Hetch Hetchy reservoir, no delay occurred between runoff and snowmelt in 2007 when the soil was wetter due to a cooler summer and fall rains. However, a 26-day delay in runoff was observed after the onset of snowmelt in 2008 when the soil was drier than the preceding fall at the time of the first snowfall due to a hotter and drier summer. If soils are dry prior to snowfall then the soil moisture is first replenished by springtime snowmelt, which not only delays runoff, but also reduces runoff volume to less than that estimated from snow pack. Typical runoff forecasts rely heavily on snow survey data and snowpack conditions, and the exclusion of soil moisture data could lead to an overestimate of the amount of runoff and compromise reservoir operations. In an average snowfall year, for example, the Kaweah Basin in the southern Sierra Nevada could lose as much as 20 percent of its snow water equivalent and the Merced Basin could lose 12 percent of its snow water equivalent simply to recharge soil moisture. Analyses of measured soil moisture in the Sierra Nevada, corresponding high elevation streamflow records, regional hydrologic modeling, and analysis of future climate projections to define the nature of summer and fall temperature and precipitation, will be used to illustrate the important role antecedent soil moisture plays in the timing and volume of springtime runoff in a changing climate.

  17. The surface of crystalline basement, Great Valley and Sierra Nevada, California: A digital map database

    USGS Publications Warehouse

    Wentworth, Carl M.; Fisher, G. Reid; Levine, Paia; Jachens, Robert C.

    1995-01-01

    Crystalline basement in central California extends westward from the exposed Sierra Nevada beneath the sedimentary fill of the Great Valley and under the eastern edge of the Coast Ranges at mid-crustal depth. The surface of this basement is defined from three types of control: in the Sierra Nevada from the topography itself, beneath the eastern two thirds of the Great Valley in considerable detail from numerous wells drilled for oil and gas, and beneath the western San Joaquin Valley in less detail from seismic reflection and refraction profiles. Together, these data demonstrate that the surface of crystalline rock is continuous from the exposed rock in the mountains to the top of high-velocity rock buried deep beneath the eastern front of the southern Coast Ranges. This report presents a compilation of data through 1985 that define the surface of this crystalline basement, a contour map of the surface, and the lithology of the basement rock sampled by many of the wells. The compilation was begun as part of the investigation of the 1983 Coalinga earthquake, and was subsequently converted to digital form and extended to the whole of the Great Valley and Sierra Nevada. The main purpose was to explore and document the shape and continuity of the basement surface and to determine the relation of the surface to the tectonic wedge hypothesis (Wentworth and others, 1984; Wentworth and Zoback, 1989). Available basement samples from wells - principally the thin-section collection of May and Hewitt (1948) preserved by the California Academy of Sciences - were also reexamined by cooperating petrologists in an effort to distinguish wells that bottomed in ophiolitic rocks.

  18. Aquatic Empididae (Diptera: Hemerodromiinae and Clinocerinae) of the Sierra Nevada, Spain, with the description of five new species .

    PubMed

    Ivković, Marija; Zamora-Muñoz, Carmen; Sainz-Bariaín, Marta; Sinclair, Bradley J

    2014-04-14

    In total 24 species of aquatic Empididae (Clinocerinae and Hemerodromiinae) are known from the Sierra Nevada Mountains of Spain, including five new species (Hemerodromia planti Ivković & Sinclair sp. nov., Kowarzia nevadensis Sinclair & Ivković sp. nov., Wiedemannia darioi Sinclair & Ivković sp. nov., W. horvati Ivković & Sinclair sp. nov. and W. vedranae Ivković & Sinclair sp. nov.). The new species are described, illustrated and distribution of all species listed. Wiedemannia (Philolutra) angelieri Vaillant and W. (Roederella) ouedorum Vaillant are newly recorded in Sierra Nevada and nine species are endemic to this region. A key to all 24 species of aquatic empidids is presented.

  19. Data on snow chemistry of the Cascade-Sierra Nevada Mountains

    USGS Publications Warehouse

    Laird, L.B.; Taylor, H.E.; Lombard, R.E.

    1986-01-01

    Snow chemistry data were measured for solutes found in snow core samples collected from the Cascade-Sierra Nevada Mountains from late February to mid-March 1983. The data are part of a study to assess geographic variations in atmospheric deposition in Washington, Oregon, and California. The constituents and properties include pH and concentrations of hydrogen ion, calcium, magnesium, sodium, potassium, chloride, sulfate, nitrate, fluoride, phosphate, ammonium, iron, aluminum, manganese, copper, cadmium, lead, and dissolved organic carbon. Concentrations of arsenic and bromide were below the detection limit. (USGS)

  20. LANDSAT-D investigations in snow hydrology. [Sierra Nevada Mountains, California

    NASA Technical Reports Server (NTRS)

    Dozier, J.

    1983-01-01

    Two tapes of the southern Sierra Nevada study area were received and the TM data are being registered to digital data. The spectral, spatial, temporal, and economic characteristics of data from LANDSAT 4 TM and MSS were compared with those of NOAA-r AVHRR data for snow cover mapping. An atmospheric radiative transfer model which accounts for both the zenith and aximuth variation in the radiative field is presented and its advantages are discussed. A Monte Carlo method for solving the atmospheric correction problem for an inhomogeneous surface is also considered.

  1. Isotopic age constraints on middle Paleozoic deformation in the northern Sierra Nevada, California

    SciTech Connect

    Saleeby, J.; Hannah, J.L.; Varga, R.J.

    1987-08-01

    Allochthons of the lower Paleozoic Shoo Fly Complex in the northern Sierra Nevada were assembled and internally deformed prior to formation of a Devonian-Permian island-arc sequence. U/Pb data on zircons indicate ages of 423 +5/-15 Ma for a submarine tuff within the uppermost thrust slice of the Shoo Fly Complex and 378 +5/-10 Ma for a granitic intrusion that may be cogenetic with the lower part of the arc sequence. These data indicate late Early Silurian Shoo Fly deposition and proximity to active volcanism, as well as late Middle Devonian initiation of arc-related magmatism.

  2. Monitoring of wet deposition in alpine areas in the Sierra Nevada. Final report

    SciTech Connect

    Melack, J.M.; Sickman, J.O.

    1997-01-16

    The quantity and chemical composition of precipitation in the Sierra Nevada was monitored at high elevation stations during the period of 1990 through 1995. From 1990 through 1993, eleven sites were included in the network. For 1994 the number was seven and during the spring of 1995, the snowpack was sampled at six stations. During the course of the study a total of 1546 snow samples were collected from 225 snowpits and an additional 514 non-winter precipitation events were sampled. All major solutes in wet deposition were measured and a rigorous quality assurance-quality control protocol was followed.

  3. A new species of salamander (Caudata: Plethodontidae, Bolitoglossa) from Sierra Nevada de Mérida, Venezuela.

    PubMed

    García-Gutiérrez, Javier; Escalona, Moisés; Mora, Andrés; Díaz De Pascual, Amelia; Fermin, Gustavo

    2013-01-01

    In this article, a new species of salamander of the genus Bolitoglossa (Eladinea) from the cloud forest near La Mucuy in Sierra Nevada de Mérida, Venezuelan Andes, is described. Bolitoglossa mucuyensis sp. nov. differs from all Venezuelan salamanders, except B. orestes, by a larger SVL/TL ratio, and from La Culata salamander B. orestes by a reduced webbing extension of the front and hind limbs. Additionally, B. mucuyensis sp. nov. and B. orestes diverge 3.12% in terms of the nucleotide sequence of the 16S rRNA gene, as previously reported, and in 8.1% for the cytb gene as shown in this study.

  4. A New View of Cenozoic Lithosphere Degradation ("Delamination") Beneath the Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Putirka, K. D.

    2011-12-01

    There presently exists a conflict in our understanding of basaltic volcanism in the Sierra Nevada. Some geophysical studies (Fliedner and Ruppert, 1996; Savage et al., 2004; Jones et al., 2004) indicate that the continental crust beneath the southern Sierra lies directly upon asthenosphere. In contrast, volcanic rock and mantle xenolith compositions show that enriched mantle lithosphere currently exists beneath the eastern Sierra range front (Leeman, 1974; Beard and Glazner, 1995; Cousens, 1996; Lee, 2005; Putirka and Busby, 2007; Cousens et al., 2008; Blondes et al., 2008). For example, volcanic rocks have 87Sr/86Sr ratios (at MgO>8%) >0.705, and 143Nd/144Nd <0.5127, which are unlike asthenosphere (at the EPR, 87Sr/86Sr <0.7027; 143Nd/144Nd > 0.5129), but very much like Cordilleran mantle lithosphere. Sierran volcanic rocks also have continental mantle lithosphere-like trace element ratios, with La/Nb>3 and Th/Nb>1 (asthenosphere-derived melts have La/Nb<1.5, Th/Nb<0.08). Finally, spinel-bearing mantle xeonoliths from the eastern Sierra have 87Sr/86Sr and ɛNd ratios that range to 0.7065 and -3.4 respectively. To test where such enriched mantle may exist, we calculate melt extraction depths using Si activity barometers (Putirka, 2008; Lee et al. 2009); these models show that such enriched mantle occurs at 40-75 km, and so extends to the base of the crust, and occupies precisely the depth range where Savage et al. (2004) indicate that continental mantle lithosphere is absent. Melt extraction depths estimated from mineralogy-sensitive trace element ratios (Sm/Yb, Lu/Hf) are consistent with the Si-activity results, and require partial melting depths for high K2O Pliocene volcanics to extend to 110 km, i.e., into the garnet-peridotite stability field. These results show that garnet-bearing lithologies could not have been dislodged from beneath the Sierra during or before the eruption of Pliocene-age magmas; they do allow for removal of garnet-bearing mantle

  5. Montane meadows and hydrologic connections between forests and streams in the Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Lucas, R. G.; Conklin, M. H.

    2013-12-01

    Montane meadows of the Sierra Nevada often serve as the interface between up-gradient forested area and down-gradient streamflow. We investigated the roles that meadow groundwater and evapotranspiration play in the greater catchment water cycle using a water-column data from monitoring wells and piezometers in two meadows for water years 2008-2012. Analyses include mass balance and modeling using 1-D HYDRUS. Though spatially heterogeneous, groundwater fluxes contribute to evapotranspiration (ETg) across the meadows, and are constrained by surface-water discharge. Near the meadow center groundwater discharges occur for the duration of the snow-free season, ET¬g is relatively low. At the meadow edge the groundwater flux changes from discharge to recharge when the growing season begins; also ETg increases, and major-ion concentrations in groundwater are more dilute than those near the meadow center. When groundwater is discharged throughout the meadow during snowmelt, the stream-water ion content more closely resembles water sampled from wells at the meadow edge. These trends change as the summer season progresses--groundwater is no longer discharged at the meadow edge and the stream water ion concentration matches the groundwater sampled from the center of the meadow. Slug tests performed in the monitoring wells indicate a saturated hydraulic conductivity (Kh) of meadow substrates between 10-5 and 10-6 m s-1. The upper end of this range reflects substrate with large sand fractions, while lower values reflect finer-grained or higher-organic-content substrate. Applying the higher Kh values to groundwater gradients during snowmelt results in groundwater discharge rates greater than streamflow measured at the meadow outlet. This suggests that the peat layer at the meadow surface, with significantly lower Kh values, retards groundwater discharge from the meadow during snowmelt. ETg signals in wells at the meadow edge and in wells installed just outside of the meadow

  6. Constraints on the history and topography of the Northeastern Sierra Nevada from a Neogene sedimentary basin in the Reno-Verdi area, Western Nevada

    USGS Publications Warehouse

    Trexler, James; Cashman, Patricia; Cosca, Michael

    2012-01-01

    Neogene (Miocene–Pliocene) sedimentary rocks of the northeastern Sierra Nevada were deposited in small basins that formed in response to volcanic and tectonic activity along the eastern margin of the Sierra. These strata record an early phase (ca. 11–10 Ma) of extension and rapid sedimentation of boulder conglomerates and debrites deposited on alluvial fans, followed by fluvio-lacustrine sedimentation and nearby volcanic arc activity but tectonic quiescence, until ~ 2.6 Ma. The fossil record in these rocks documents a warmer, wetter climate featuring large mammals and lacking the Sierran orographic rain shadow that dominates climate today on the eastern edge of the Sierra. This record of a general lack of paleo-relief across the eastern margin of the Sierra Nevada is consistent with evidence presented elsewhere that there was not a significant topographic barrier between the Pacific Ocean and the interior of the continent east of the Sierra before ~ 2.6 Ma. However, these sediments do not record an integrated drainage system either to the east into the Great Basin like the modern Truckee River, or to the west across the Sierra like the ancestral Feather and Yuba rivers. The Neogene Reno-Verdi basin was one of several, scattered endorheic (i.e., internally drained) basins occupying this part of the Cascade intra-arc and back-arc area.

  7. Radiometric Observations of Supercooled Liquid Water within a Split Front over the Sierra Nevada.

    NASA Astrophysics Data System (ADS)

    Heggli, Mark F.; Reynolds, David W.

    1985-11-01

    A storm bearing close structural resemblance to a katafront was observed from the ground with microwave radiometry and a vertically pointing Ka-band radar over the Sierra Nevada of California. The onset and duration of supercooled liquid water was determined and matched to a split front model used to describe the synoptic features of a katafront. Results indicate that prior to the passage of the upper front no supercooled liquid water was observed. This portion of the storm provided the deepest cloud and coldest cloud tops. Supercooled liquid water was most prevalent after the upper front passage, and persisted until the suspected surface front passage. The duration of measured supercooled water was 16 hours.This information broadens the knowledge regarding the presence of supercooled liquid water, and thus possible seeding potential, within winter storms so that treatment can be confined to the period of storms amenable to cloud seeding. Future studies may well confirm the ease with which these periods can be predicted on an operational basis in the Sierra Nevada.

  8. Late Cretaceous age of fractures in the Sierra Nevada batholith, California

    SciTech Connect

    Segall, P. Stanford Univ., CA ); McKee, E.H.; Turrin, B.D. ); Martel, S.J. )

    1990-12-01

    Regional sets of steeply dipping joints and faults are common throughout the Sierra Nevada batholith, yet relatively little is known about how or when they formed. Within some east-northeast-striking, left-lateral fault zones in the Mount Abbot quadrangle of the central Sierra Nevada, the host granodiorite is hydrothermally altered to a lower greenschist assemblage that contains muscovite. The muscovite yields a mean K-Ar and {sup 40}Ar/{sup 39}Ar age of 79 Ma, which provides a minimum age for the faulting. Field relations show that these faults developed from earlier formed, mineralized joints, so these ages also provide a minimum age for the jointing. Published ages of biotite, hornblende, and zircon from the host granodiorite of Lake Edison are 80 Ma (K-Ar), 85 Ma (K-Ar), and 90 Ma (U-Pb), respectively. The geochronology, field relations, and hydrothermal mineral assemblages together suggest that the mineralized joints and faults all formed between 85 and 79 Ma, soon after the host pluton was emplaced.

  9. Increasing elevation of fire in the Sierra Nevada and implications for forest change

    USGS Publications Warehouse

    Schwartz, Mark W.; Butt, Nathalie; Dolanc, Christopher R.; Holguin, Andrew; Moritz, Max A.; North, Malcolm P.; Safford, Hugh D.; Stephenson, Nathan L.; Thorne, James H.; van Mantgem, Phillip J.

    2015-01-01

    Fire in high-elevation forest ecosystems can have severe impacts on forest structure, function and biodiversity. Using a 105-year data set, we found increasing elevation extent of fires in the Sierra Nevada, and pose five hypotheses to explain this pattern. Beyond the recognized pattern of increasing fire frequency in the Sierra Nevada since the late 20th century, we find that the upper elevation extent of those fires has also been increasing. Factors such as fire season climate and fuel build up are recognized potential drivers of changes in fire regimes. Patterns of warming climate and increasing stand density are consistent with both the direction and magnitude of increasing elevation of wildfire. Reduction in high elevation wildfire suppression and increasing ignition frequencies may also contribute to the observed pattern. Historical biases in fire reporting are recognized, but not likely to explain the observed patterns. The four plausible mechanistic hypotheses (changes in fire management, climate, fuels, ignitions) are not mutually exclusive, and likely have synergistic interactions that may explain the observed changes. Irrespective of mechanism, the observed pattern of increasing occurrence of fire in these subalpine forests may have significant impacts on their resilience to changing climatic conditions.

  10. Dataset of Phenology of Mediterranean high-mountain meadows flora (Sierra Nevada, Spain).

    PubMed

    Pérez-Luque, Antonio Jesús; Sánchez-Rojas, Cristina Patricia; Zamora, Regino; Pérez-Pérez, Ramón; Bonet, Francisco Javier

    2015-01-01

    Sierra Nevada mountain range (southern Spain) hosts a high number of endemic plant species, being one of the most important biodiversity hotspots in the Mediterranean basin. The high-mountain meadow ecosystems (borreguiles) harbour a large number of endemic and threatened plant species. In this data paper, we describe a dataset of the flora inhabiting this threatened ecosystem in this Mediterranean mountain. The dataset includes occurrence data for flora collected in those ecosystems in two periods: 1988-1990 and 2009-2013. A total of 11002 records of occurrences belonging to 19 orders, 28 families 52 genera were collected. 73 taxa were recorded with 29 threatened taxa. We also included data of cover-abundance and phenology attributes for the records. The dataset is included in the Sierra Nevada Global-Change Observatory (OBSNEV), a long-term research project designed to compile socio-ecological information on the major ecosystem types in order to identify the impacts of global change in this area.

  11. Wavelet analysis of Snow course data within the Sierra Nevada Mountains

    NASA Astrophysics Data System (ADS)

    Rios, T.; Dracup, J. A.

    2003-12-01

    In recent years, an analytical method known as wavelet analysis has received increasing applications in geophysical fields (Foufoula-Georgiou and Kumar 1994). Wavelet analysis can be used to identify the time and frequency regime in data while still maintaining the time coordinate. By applying the wavelet analysis method to the Mount Shasta snow course for the time period from 1937-1997 using the continuous 1-D wavelet toolbox in MATLAB, we found that several frequency regimes are present within the signal. The inter-annual noise dominates the frequency regime below the seven-year scale, but there is a relatively consistent 9-13 year oscillation that is present within the snow data. This frequency regime is also observed to shift to lower scales as the time series progresses, possibly indicating a shift in the climate variability due to climate change. In addition, analyses of the depth and the water content data exhibit nearly identical wavelet images. We are currently in the process of identifying other climate variables that may exhibit similar periodicity with the continuous 1-D wavelet analysis, such as the PDO and ENSO. Preliminary results show that by analyzing the hydrologic variables of the Sierra Nevada snowpack depth and/or water content using the wavelet method, we may be able to provide useful insights into the synergy and expression of climate change and variability within the California Sierra Nevadas.

  12. Fumio Matsumura--accomplishments at the University of California, Davis, and in the Sierra Nevada Mountains.

    PubMed

    Seiber, James N

    2015-05-01

    Fumio Matsumura joined the University of California, Davis, faculty in 1987 where he served as founding director of the Center for Environmental Health Sciences, associate director of the U.C. Toxic Substances Research and Teaching Program, and chair of the Department of Environmental Toxicology. He was an active affiliate with the NIEHS-funded Superfund Basic Research Program and the NIH Comprehensive Cancer Center. He was in many instances a primary driver or otherwise involved in most activities related to environmental toxicology at Davis, including the education of students in environmental biochemistry and ecotoxicology. A significant part of his broad research program was focused on the long range transport of chemicals such as toxaphene, PCBs and related contaminants used or released in California to the Sierra Nevada mountains, downwind of the urban and agricultural regions of the state. He hypothesized that these chemical residues adversely affected fish and wildlife, and particularly the declining populations of amphibians in Sierra Nevada streams and lakes. Fumio and his students and colleagues found residues of toxaphene and PCBs at higher elevations, an apparent result of atmospheric drift and deposition in the mountains. Fumio and his wife Teruko had personal interests in, and a love of the mountains, as avid skiers, hikers, and outdoor enthusiasts.

  13. Late Cretaceous age of fractures in the Sierra Nevada batholith, California

    USGS Publications Warehouse

    Segall, P.; McKee, E.H.; Martel, S.J.; Turrin, B.D.

    1990-01-01

    Regional sets of steeply dipping joints and faults are common throughout the Sierra Nevada batholith, yet relatively little is known about how or when they formed. Within some east-northeast-striking, left-lateral fault zones in the Mount Abbot quadrangle of the central Sierra Nevada, the host granodiorite is hydrothermally altered to a lower greenschist assemblage that contains muscovite. The muscovite yields a mean K-Ar and 40Ar/39Ar age of 79 Ma, which provides a minimum age for the faulting. Field relations show that these faults developed from earlier formed, mineralized joints, so these ages also provide a minimum age for the jointing. Published ages of biotite, hornblende, and zircon from the host granodiorite of Lake Edison are 80 Ma (K-Ar), 85 Ma (K-Ar), and 90 Ma (U-Pb), respectively. The geochronology, field relations, and hydrothermal mineral assemblages together suggest that the mineralized joints and faults all formed between 85 and 79 Ma, soon after the host pluton was emplaced. -Authors

  14. Associations of stream health to altered flow and water temperature in the Sierra Nevada, California

    USGS Publications Warehouse

    Carlisle, Daren M.; S. Mark Nelson,; May, Jason

    2016-01-01

    Alteration of streamflow and thermal conditions may adversely affect lotic invertebrate communities, but few studies have assessed these phenomena using indicators that control for the potentially confounding influence of natural variability. We designed a study to assess how flow and thermal alteration influence stream health – as indicated by the condition of invertebrate communities. We studied thirty streams in the Sierra Nevada, California, that span a wide range of hydrologic modification due to storage reservoirs and hydroelectric diversions. Daily water temperature and streamflows were monitored, and basic chemistry and habitat conditions were characterized when invertebrate communities were sampled. Streamflow alteration, thermal alteration, and invertebrate condition were quantified by predicting site-specific natural expectations using statistical models developed using data from regional reference sites. Monthly flows were typically depleted (relative to natural expectations) during fall, winter, and spring. Most hydrologically altered sites experienced cooled thermal conditions in summer, with mean daily temperatures as much 12 °C below natural expectations. The most influential predictor of invertebrate community condition was the degree of alteration of March flows, which suggests that there are key interactions between hydrological and biological processes during this month in Sierra Nevada streams. Thermal alteration was also an important predictor – particularly at sites with the most severe hydrological alteration.

  15. In Situ Aerosol Properties Measured over the California Central Valley and the Sierra Nevada Mountain Range

    NASA Astrophysics Data System (ADS)

    Tomlinson, J. M.; Comstock, J. M.; Hubbe, J.; Kluzek, C.; Schmid, B.; Jonsson, H.; Woods, R.

    2011-12-01

    Anthropogenic aerosols are hypothesized to influence the formation of clouds and precipitation amounts within the Sierra Nevada Mountains. This could have a profound effect on the California water supply. To study this phenomena, an Ultra High Sensitivity Aerosol Spectrometer (UHSAS), Passive Cavity Aerosol Spectrometer (PCASP), and Cloud Aerosol Spectrometer (CAS) were operated aboard the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Aerial Facility (AAF) Gulfstream-1 aircraft from February 2 to March 6, 2011 during the CalWater field campaign. The combined aerosol size distribution from the three instruments characterizes the size-resolved concentration of the submicron and supermicron aerosol over the California Central Valley and Sierra Nevada Mountain Range. The measured aerosol size distributions from CalWater are compared with the size distributions measured during the DOE Carbonaceous Aerosol and Radiative Effects Study (CARES) in June 2010 to determine the changes in the aerosol size distributions during different seasons, atmospheric river events, and long-range transport events from Asia. These changes are used to estimate the resulting aerosol effect on cloud condensation nuclei concentrations and the potential impact on cloud formation and precipitation.

  16. Dataset of Phenology of Mediterranean high-mountain meadows flora (Sierra Nevada, Spain)

    PubMed Central

    Pérez-Luque, Antonio Jesús; Sánchez-Rojas, Cristina Patricia; Zamora, Regino; Pérez-Pérez, Ramón; Bonet, Francisco Javier

    2015-01-01

    Abstract Sierra Nevada mountain range (southern Spain) hosts a high number of endemic plant species, being one of the most important biodiversity hotspots in the Mediterranean basin. The high-mountain meadow ecosystems (borreguiles) harbour a large number of endemic and threatened plant species. In this data paper, we describe a dataset of the flora inhabiting this threatened ecosystem in this Mediterranean mountain. The dataset includes occurrence data for flora collected in those ecosystems in two periods: 1988–1990 and 2009–2013. A total of 11002 records of occurrences belonging to 19 orders, 28 families 52 genera were collected. 73 taxa were recorded with 29 threatened taxa. We also included data of cover-abundance and phenology attributes for the records. The dataset is included in the Sierra Nevada Global-Change Observatory (OBSNEV), a long-term research project designed to compile socio-ecological information on the major ecosystem types in order to identify the impacts of global change in this area. PMID:25878552

  17. Potential for acid precipitation damage to lakes of the Sierra Nevada, California

    SciTech Connect

    Harte, J.; Holdren, J.; Tonnesson, K.

    1983-04-01

    One of the areas of California potentially sensitive to acidic deposition is the Sierra Nevada, located along the eastern boundary. A report on sensitive areas in North America identifies the Sierra as a region characterized by poorly buffered soils and granite based lakes. The subalpine and alpine lakes in this region share many of the characteristics of lakes adversely affected by acid deposition in other parts of the US and the world. For this investigation selected subalpine lakes of the western slope of the Sierra were chosen for study, to establish baseline water quality which would allow for the identification of chemical and biological changes due to acidic deposition. It was then attempted to simulate the ecosystem stress of increased acidic deposition, particularly in the form of snowmelt, on these systems by performing microcosm experiments in the laboratory. These experiments were particularly concerned with recording changes in concentrations of micronutrients which might be leached from lake sediments with increasing acidification. This phenomenon is particularly important to study in the light of finds on the importance of aluminum leaching in the northeast which was led to toxic effects of biota in Adirondack lakes. 10 references, 3 figures, 1 table.

  18. Coherent Cloudiness Variability from Sierra Nevada to the Sea in California

    NASA Astrophysics Data System (ADS)

    Sumargo, E.; Cayan, D. R.

    2015-12-01

    Cloud variability serves as the principal modulator of incoming solar radiation. These cloud effects are particularly important in mountain settings such as the Sierra Nevada in California, because the solar irradiance is a primary input to the snowpack energy balance. An important, unanswered question is whether the mountain clouds over the Sierra Nevada are only one part of a larger-scale system or whether they vary distinctly from cloud patterns upstream over the Central Valley and coastal areas. To address this question we investigate cloud variability over California using 19 years (1996-2014) of GOES visible albedo product with 4-km spatial and 30-minute temporal resolutions. Two domains are considered: high elevations in which only higher (>800m) elevations are included, thus excluding the coast and valley clouds, and all elevations which includes all elevations from the offshore North Pacific to Nevada. Our focus is on the spring and early summer period, which is crucial because it includes much of the snowmelt runoff from the Sierra Nevada. Inter-annual variation of cloudiness, represented by the coefficient of variation of cloud albedo, reveals the highest relative variability from California coasts and lowlands in the winter and spring to highlands and mountains in the summer and autumn. This pattern also occurs across shorter to longer time-scales, with coefficient of variation ranging from 30-180% on daily scale to 5-40% on seasonal scale. Considering the spatial structure of anomalous cloudiness, rotated EOF (REOF) analyses of de-seasonalized daily cloud albedo in the high elevation domain yields patterns and temporal variations that are well correlated with those from the all elevation domain. This indicates that, to a large degree, the mountain clouds co-vary with those over the Central Valley and the California coast, even though the valley and coastal clouds include low stratus clouds. The monthly standard deviations of the amplitudes of the time

  19. Evaluation of Sierra Nevada seeding effects on snowfall processes and distribution. Final report, 1 July 1988-30 June 1989

    SciTech Connect

    Warburton, J.A.

    1990-10-01

    Studies were conducted in regions of the central Sierra Nevada to determine the distribution of seeding aerosols in seeded target areas. These studies involved field operations of seeding and snow sampling equipment and cloud chamber investigations of ice crystal morphology. Secondary ice formation and chemical reactions including aerosol removal processes.

  20. 77 FR 28619 - Notice of Public Meetings: Sierra Front-Northwestern Great Basin Resource Advisory Council, Nevada

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-15

    ...-Northwestern Great Basin Resource Advisory Council (RAC), will hold two meetings in Nevada in fiscal year 2012... raise other topics at the meetings. Final agendas will be posted on-line at the BLM Sierra Front... accommodations, or who wish to receive a copy of each agenda, may contact Lisa Ross no later than 10 days...

  1. Spatial patterns of atmospherically deposited organic contaminants at high elevation in the southern Sierra Nevada mountains, California, USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Airborne contaminants in the Sierra Nevada mountains of California have been implicated as a factor adversely affecting biological resources like amphibians and fish, yet the distributions of contaminants within the mountains are poorly known, particularly at high elevation. we evaluated contaminan...

  2. REGIONAL ANALYSIS OF INORGANIC NITROGEN YIELD AND RETENTION IN HIGH-ELEVATION ECOSYSTEMS OF THE SIERRA NEVADA AND ROCKY MOUNTAINS

    EPA Science Inventory

    Yields and retention of inorganic nitrogen (DIN) and nitrate concentrations in surface runoff are summarized for 28 high elevation watersheds in the Sierra Nevada, California and Rocky Mountains of Wyoming and Colorado. Catchments ranged in elevation from 2475 to 3603 m and from...

  3. Improving stable isotope-based reconstructions of Sierra Nevada paleotopography using insights from regional air parcel trajectories

    NASA Astrophysics Data System (ADS)

    Lechler, A.; Galewsky, J.

    2012-12-01

    The geodynamic evolution of the Sierra Nevada Mountains of the western US remains subject to debate due to the lack of consensus on the Cenozoic paleoelevation history of the range. The majority of recent studies attempting to quantify the surface uplift history of the Sierra Nevada rely on stable isotope paleoaltimetry methods that often implicitly assume that atmospheric flow interactions with topography can be simply modeled as a Rayleigh distillation process in which air mass trajectories ascend and rainout heavy isotopologues of water (18O and D) across topographic barriers relatively unimpeded. Accordingly, stable isotope paleoaltimetry studies commonly target leeward side paleo-meteoric water proxies to constrain paleotopography of the windward barrier. We present a modern (1979 - 2010) air parcel trajectory analysis using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model that shows that the fundamental assumptions of stable isotope paleoaltimetry are often violated in the Sierra Nevada region. Trajectory analysis indicates that westerly air masses are frequently orographically blocked by and redirected around the higher elevations (> 2.5 km) of the Sierra Nevada. As a result, trajectories reaching the Sierran lee commonly travel around, rather than over, the highest range elevations. These blocking and redirection effects are particularly pronounced for leeward sites that are distal (> 150 km) from the Sierran crest but are also evident in trajectory patterns for both windward and proximal leeward locations in the northern Sierra Nevada. In addition, trajectory patterns indicate that much of the Sierran lee receives a non-negligible proportion of annual precipitation from summer storm systems sourced in the subtropical Pacific Ocean and Gulf of California that have little to no interaction with Sierran topography. This trajectory analysis highlights the complexity of orographic precipitation patterns and processes in the Sierra

  4. The northern Walker Lane refraction experiment: Pn arrivals and the northern Sierra Nevada root

    NASA Astrophysics Data System (ADS)

    Louie, John N.; Thelen, Weston; Smith, Shane B.; Scott, James B.; Clark, Matthew; Pullammanappallil, Satish

    2004-09-01

    In May 2002, we collected a new crustal refraction profile from Battle Mountain, Nevada across western Nevada, the Reno area, Lake Tahoe, and the northern Sierra Nevada Mountains to Auburn, CA. Mine blasts and earthquakes were recorded by 199 Texan instruments extending across this more than 450-km-long transect. The use of large mine blasts and the ultra-portable Texan recorders kept the field costs of this profile to less than US$10,000. The seismic sources at the eastern end were mining blasts at Barrick's GoldStrike mine. The GoldStrike mine produced several ripple-fired blasts using 8000-44,000 kg of ANFO each, a daily occurrence. First arrivals from the larger GoldStrike blasts are obvious to distances of 300 km in the raw records. First arrivals from a quarry blast west of the survey near Watsonville, CA, located by the Northern California Seismic Network with a magnitude of 2.2, can be picked across the recording array to distances of 600 km. The Watsonville blast provides a western source, nearly reversing the GoldStrike blasts. A small earthquake near Bridgeport, CA. also produced pickable P-wave arrivals across the transect, providing fan-shot data. Arrivals from M5 events in the Mariana and Kuril Islands also appear in the records. This refraction survey observes an unexpectedly deep crustal root under the northern Sierra Nevada range, over 50 km in thickness and possibly centered west of the topographic crest. Pn delays of 4-6 s support this interpretation. At Battle Mountain, Nevada, we observe anomalously thin crust over a limited region perhaps only 150 km wide, with a Moho depth of 19-23 km. Pn crossover distances of less than 80 km support this anomaly, which is surrounded by observations of more normal, 30-km-thick crust. A 10-km-thick and high-velocity lower-crustal "pillow" is an alternative hypothesis, but unlikely due to the lack of volcanics west of Battle Mountain. Large mine and quarry blasts prove very effective crustal refraction sources

  5. Ecological impacts of wheat seeding after a Sierra Nevada wildfire

    USGS Publications Warehouse

    Keeley, Jon E.

    2004-01-01

    The Highway Fire burned 1680 ha of mixed ponderosa pine–oak–chaparral in the newly created Giant Sequoia National Monument and the adjacent Sequoia National Forest of Fresno County, California in August 2001. The USDA Forest Service Burned Area Emergency Rehabilitation (BAER) program recommended that portions of the burned forest be seeded with a non-persistent variety of wheat at a density of 157 kg ha–1 (140 lb/ac). The present study compared the vascular plant diversity and cover in seeded and unseeded parts of this burn to evaluate the ecological impact of seeding an alien grass. In the first post-fire growing season, the natural regeneration of unseeded control sites averaged ~55% ground surface covered. Wheat seeding enhanced the ground cover, averaging 95% ground surface cover. Wheat was the dominant species on the seeded sites, comprising 67% of the total cover. Dominance–diversity curves were markedly affected by the seeding and indicated a disruption in the natural ecological structure of these communities. On seeded sites, wheat dominated and all other species were poorly represented whereas, on unseeded control sites, there was a more equitable distribution of species. Correlated with the wheat cover was a significant decrease in species richness at all scales examined. Total species richness was reduced from 152 species across all unseeded sites to 104 species on all seeded sites. Average species richness, at scales from 1 to 1000 m2, was 30–40% lower on seeded sites. Species most strongly inhibited were post-fire endemics whose lifecycle is restricted to immediate post-fire environments. Seeded sites had fewer alien species than unseeded sites; however, this may not have any lasting effect since other studies show the primary alien threat is not in the first post-fire year. Seeding was also associated with an order of magnitude drop in Pinus ponderosa seedling recruitment and, coupled with the massive thatch still remaining on the site, it

  6. Spatiotemporal Variation in Chemical Fluxes across the Last Undammed Watershed Draining the Sierra Nevada, California: a Paired Basin Study

    NASA Astrophysics Data System (ADS)

    Ahearn, D. S.; Sheibley, R. W.; Santoriello, P.; Dahlgren, R. A.

    2002-12-01

    The Cosumnes River is the last remaining river draining the Sierra Nevada without a major dam impounding its course. In order to determine the baseline biogeochemical characteristics of this free flowing river we have established an array of 28 sampling sites over the 2745 sq km of the watershed. Additionally 6 sampling sites have been located on the adjacent Mokelumne River both above and below the Pardee-Camanche Reservoir system. The Cosumnes has revealed seasonal chemical fluctuations that can be explained by variations in hydrologic flow paths and storm intensity/timing. Spatial variation in water quality within this system can be explained by changes in rock type, vegetation, and land use. The Mokelumne is a more hydrologically complex system with numerous dams and powerhouses. Consequently, seasonal and spatial variations in water quality can not be explained in the same manner as they are in the Cosumnes. The contrast in chemical dynamics between the two basins has given us the opportunity to study the influence that large dams have on water chemistry at the watershed scale. Our data show that the Pardee and Camanche Reservoirs act to buffer stream temperature, reduce total dissolved salts during storm events, and significantly alter the timing of nutrient discharge to the lowlands. Major dams, similar to those found on the Mokelumne, exist on 19 of the 20 rivers that drain into the Central Valley of California. Our data suggest that this ubiquity of large impoundments has drastically altered the spatiotemporal chemical dynamics of California's waterways.

  7. Clustering of velocities in a GPS network spanning the Sierra Nevada Block, the northern Walker Lane Belt, and the Central Nevada Seismic Belt, California-Nevada

    USGS Publications Warehouse

    Savage, James C.; Simpson, Robert W.

    2013-01-01

    The deformation across the Sierra Nevada Block, the Walker Lane Belt, and the Central Nevada Seismic Belt (CNSB) between 38.5°N and 40.5°N has been analyzed by clustering GPS velocities to identify coherent blocks. Cluster analysis determines the number of clusters required and assigns the GPS stations to the proper clusters. The clusters are shown on a fault map by symbols located at the positions of the GPS stations, each symbol representing the cluster to which the velocity of that GPS station belongs. Fault systems that separate the clusters are readily identified on such a map. Four significant clusters are identified. Those clusters are strips separated by (from west to east) the Mohawk Valley-Genoa fault system, the Pyramid Lake-Wassuk fault system, and the Central Nevada Seismic Belt. The strain rates within the westernmost three clusters approximate simple right-lateral shear (~13 nstrain/a) across vertical planes roughly parallel to the cluster boundaries. Clustering does not recognize the longitudinal segmentation of the Walker Lane Belt into domains dominated by either northwesterly trending, right-lateral faults or northeasterly trending, left-lateral faults.

  8. A Stable Isotope Study of Fluid-Rock Interactions in the Saddlebag Lake Roof Pendant, Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Lojasiewicz, I.; Hartman, S. M.; Holk, G. J.; Paterson, S. R.

    2015-12-01

    The Saddlebag Lake Pendant (SLP) is a ~ 100 km2 zone of Ordovician-Cretaceous metasedimentary and metavolcanic rocks just east of the 95-85 Ma Tuolumne Intrusive Complex (TIC) in the Sierra Nevada of central California. Western SLP and adjacent parts of TIC are affected by the Steelhead Lake Shear Zone (SLSZ), with leucogranitic dikes, abundant qz-tm veins, ductile epidote-chlorite alteration, and massive qz veins. While TIC shows uniform stable isotope values, isotope studies of other Sierra Nevada pendants evidence diversity of fluid sources: Jurassic seawater, Cretaceous magmatic fluids, metamorphic fluids, and meteoric-hydrothermal fluids. We conducted a stable isotope study of 49 samples from units across the SLSZ, focusing on the shear zone. Unlike other pendants, both δ18 O and δD values from SLSZ showed great variability, and most samples were not in isotopic equilibrium. Overall, δ18 O mineral values ranged from -1.5‰(plag) to +15.8‰(bt); mineral δD values ranged from -140‰(tm) to -67‰(bt). TIC δ18 O was +7.8 to +10.0 (plag) and +4.8 to +9.2 (tm), normal magmatic values, and δD were -105 to -75. Paleozoic and Triassic metasedimentary units had most qz δ18 O from +11.3 to +15.8, so within metamorphic range, and δD from -100 to -72 (ep and tm). Jurassic metasedimentary units (Sawmill) and Triassic metavolcanics (Koip) had largest isotopic variability: δ18 O qz from +8.1 to +14.8, plag from -1.1 to +11.8, but ep and tm between +1.3 and +9.3 and δD between -108 and -81. All lower (submagmatic) isotopic values were from a wider, possibly transtensional, part of the SLSZ, transected by Sawmill Canyon. Although TIC and many of the Paleozoic units do not show isotopic evidence for alteration, the Koip and Sawmill units were likely infiltrated by later magmatic waters, and then subjected to very localized meteoric water infiltration in the area surrounding Sawmill Canyon.

  9. Mineralogy and geochemistry of two metamorphosed sedimentary manganese deposits, Sierra Nevada, California, USA

    USGS Publications Warehouse

    Flohr, M.J.K.; Huebner, J.S.

    1992-01-01

    Laminated to massive rhodochrosite, hausmannite, and Mn-silicates from the Smith prospect and Manga-Chrome mine, Sierra Nevada, California were deposited as ocean floor sediments associated with chert and shale. The principal lithologies at Smith are chert, argillite, rhodochrosite-, hausmannite- and chlorite-rich layers, and relatively uncommon layers of jacobsite. The Manga-Chrome mine also contains layers rich in manganoan calcite and caryopilite. Tephroite, rhodonite, spessartine, and accessory alleghanyite and sonolite formed during metamorphism. Volcaniclastic components are present at Manga-Chrome as metavolcanic clasts and as Mn-poor, red, garnet- and hematite-rich layers. There is no evidence, such as relict lithologies, that Mn was introduced into Mn-poor lithologies such as chert, limestone or mudstone. Replacement of Mn-poor phases by Mn-rich phases is observed only in the groundmass of volcanic clasts that appear to have fallen into soft Mn-rich mud. Manganiferous samples from the Smith prospect and Manga-Chrome mine have high Mn Fe and low concentrations of Ni, Cu, Zn, Co, U, Th and the rare-earth elements that are similar to concentrations reported from other ancient Mn deposits found in chert-greenstone complexes and from manganiferous sediments and crusts that are forming near modern sea floor vents. The Sierra Nevada deposits formed as precipitates of Mn-rich sediments on the sea floor, probably from mixtures of circulating hydrothermal fluids and seawater. The composition of a metabasalt from the Smith prospect is consistent with those of island-arc tholeiites. Metavolcanic clasts from the Manga-Chrome mine are compositionally distinct from the Smith metabasalt and have alkaline to calc-alkaline affinities. A back-arc basin is considered to be the most likely paleoenvironment for the formation of the Mn-rich lenses at the Manga-Chrome mine and, by association, the Smith prospect. Layers of rhodochrosite, hausmannite and chert preserve the

  10. Seasonal frost conditions and permafrost regime distribution in the high lands of Sierra Nevada (Spain)

    NASA Astrophysics Data System (ADS)

    Oliva, Marc; Gómez-Ortiz, Antonio; Salvador-Franch, Ferran; Salvà-Catarineu, Montserrat; Palacios, David; Tanarro, Luis Miguel; Ramos, Miguel

    2016-04-01

    Sierra Nevada, Southern Spain (37°S, 3°W), is the massif including the southernmost permafrost remnants in Europe. Over the last decades the distribution of permafrost in this massif has been examined through a combined approach including geomorphological, geophysical and monitoring studies. The purpose of this communication is to summarize all the studies relating to soil thermal regime in the high lands of Sierra Nevada. A 114.5 m deep borehole was drilled in 2000 in the Veleta summit (3380 m) in order to monitor soil temperatures in the summits of the massif. No permafrost regime was detected, with average temperatures stabilizing at 20 m depth at 2 °C. Seasonal frost conditions were also detected in periglacial landforms such as solifluction lobes and sorted-circles. In the Rio Seco cirque the mean annual temperatures in a solifluction lobe located in a southern glacial cirque of the massif (3005 m) were 3.9 °C at 1 m depth between 2006 and 2012; in the north-exposed San Juan valley, soil temperatures in another solifluction landform (2864 m) were 3.9 °C at 1 m depth between 2003 and 2012. In a sorted-circle located in the high plateau of Cerro de los Machos (3297 m) soil temperatures recorded an average of 1.7 °C at 50 cm depth between 2003 and 2011. The only place where temperatures were permanently negative was inside of the only active rock glacier distributed in the Veleta cirque, on the northern slope of the Veleta peak. Here, the remnants of a small glacier that existed during the Little Ice Age (LIA) are still present in the form of buried ice and permafrost buried under the boulders of this rock glacier. Temperatures averaged 0.2 °C at 1 m depth between 2006 and 2013, with permanently negative temperatures below this level until, at least, 10 m depth. Consequently, seasonal frost is widespread nowadays in most of the Sierra Nevada, with permafrost conditions strongly conditioned by the geomorphological setting and the recent environmental

  11. Sierra Nevada serpentinites. An important element in the architectonic heritage of Granada (Spain).

    NASA Astrophysics Data System (ADS)

    Navarro, Rafael; Pereira, Dolores; Rodríguez-Navarro, Carlos; Sebastián-Pardo, Eduardo

    2013-04-01

    Serpentinites are widely used in historic buildings in the whole world, from Ancient Greek or Egypt to more recent colonial buildings in the USA. Serpentinites from Sierra Nevada (S of Spain) have been traditionally used as ornamental elements in historic buildings of Granada city, both indoors and outdoors. The Cathedral, Carlos V Palace, Royal Chancery and some others are good examples of their use. Some other important cases can be found outside Granada, like El Escorial monastery, Las Salesas Reales convent, etc… all of them part of Madrid architectonic heritage. There are two quarries located in Sierra Nevada that supplied all the material to make the different elements in the cited buildings. In this work, a thorough characterization of the main serpentinites from Sierra Nevada, their uses, and their state of conservation in selected buildings from Granada has been performed. Samples from the main original quarry and from one historical building (Real Chancillería) have been analysed, determining the mineralogical and geochemical composition, texture, water parameters (absorption, porosity, density) and possible alteration by salt formation. It has been observed that the mineralogical and geochemical compositions are similar in both sets of samples, although the ones coming from the historical building show a highly advanced state of alteration. Regarding physical and mechanical parameters, samples from the quarry have very low water absorption values, while the porosity of serpentinites sampled from the Real Chancillería is comparatively much higher. We explain this difference as due to the weathering of the emplaced serpentinites by salt crystallization processes (mainly gypsum or epsomite), that generate strong internal pressures causing the disintegration of the whole natural stone. In addition, the increase of the porosity can be caused by dissolution processes related to the presence of acid solutions related to oxidation and hydrolysis of iron

  12. A ~31 ka Plinian-subplinian eruption at Tláloc Volcano, Sierra Nevada, Mexico

    NASA Astrophysics Data System (ADS)

    Rueda, H.; Arce, J.; Macias, J.; Garcia-Palomo, A.

    2006-12-01

    Tláloc volcano (19°24`40"N; 98°42`48"W; 4,120 m.a.s.l.) is a Pliocene-Pleistocene stratovolcano located NE of México City, Mexico. It represents the northernmost volcano of the N-S Sierra Nevada Range, which consists of Tláloc-Telapón, Téyotl, Iztaccíhuatl, and Popocatépetl volcanoes. Tláloc has always been considered the oldest (and extinct) volcano of the Sierra Nevada Range, although no detailed studies had been carried out. Recent field data has revealed important new information about its eruptive history, including a large magnitude Plinian-subplinian eruption, here referred to as the Multilayered White Pumice (MWP). This eruption started with a continuous yet unstable eruptive column that reached the stratosphere, which deposited several pumice-rich horizons that total 1 m at a distance of 12 km from the volcano. A preliminary isopach map of the deposit indicates that these fall layers were distributed mainly to the north-northeast, and encompass a minimum area of 120 km2 around the volcano. The event ended with total collapse of the eruptive column, which produced four, pumice-rich pyroclastic flows dispersed on the N and E slopes of the volcano. Those flow deposits fill gullies up to 25 m in thickness, at a distance of 12 km from the vent. The deposits are massive matrix-supported layers consisting of block-size fibrous rhyolitic pumice set in an ashy matrix rich in quartz and biotite crystals. Pumice clasts contain phenocrysts of K- feldspar, quartz, biotite, and Fe-Ti oxides. Charred logs are common, and charcoal from those logs yield an age of 31,490 +1995/-1595 years BP. So far, the MWP is the youngest dated deposit of Tláloc Volcano. Our results call into question the widespread idea of a N-S migration of the volcanism in the Sierra Nevada, beginning with the formation of Tláloc volcano and ending with the active Popocatépetl volcano.

  13. Recent crustal movements in the Sierra Nevada-Walker lane region of California-Nevada: Part i, rate and style of deformation

    USGS Publications Warehouse

    Slemmons, D.B.; Wormer, D.V.; Bell, E.J.; Silberman, M.L.

    1979-01-01

    This review of geological, seismological, geochronological and paleobotanical data is made to compare historic and geologic rates and styles of deformation of the Sierra Nevada and western Basin and Range Provinces. The main uplift of this region began about 17 m.y. ago, with slow uplift of the central Sierra Nevada summit region at rates estimated at about 0.012 mm/yr and of western Basin and Range Province at about 0.01 mm/yr. Many Mesozoic faults of the Foothills fault system were reactivated with normal slip in mid-Tertiary time and have continued to be active with slow slip rates. Sparse data indicate acceleration of rates of uplift and faulting during the Late Cenozoic. The Basin and Range faulting appears to have extended westward during this period with a reduction in width of the Sierra Nevada. The eastern boundary zone of the Sierra Nevada has an irregular en-echelon pattern of normal and right-oblique faults. The area between the Sierra Nevada and the Walker Lane is a complex zone of irregular patterns of ho??rst and graben blocks and conjugate normal-to right- and left-slip faults of NW and NE trend, respectively. The Walker Lane has at least five main strands near Walker Lake, with total right-slip separation estimated at 48 km. The NE-trending left-slip faults are much shorter than the Walker Lane fault zone and have maximum separations of no more than a few kilometers. Examples include the 1948 and 1966 fault zone northeast of Truckee, California, the Olinghouse fault (Part III) and possibly the almost 200-km-long Carson Lineament. Historic geologic evidence of faulting, seismologic evidence for focal mechanisms, geodetic measurements and strain measurements confirm continued regional uplift and tilting of the Sierra Nevada, with minor internal local faulting and deformation, smaller uplift of the western Basin and Range Province, conjugate focal mechanisms for faults of diverse orientations and types, and a NS to NE-SW compression axis (??1) and an

  14. Lead and cadmium in wild boar (Sus scrofa) in the Sierra Nevada Natural Space (southern Spain).

    PubMed

    Mulero, Rocío; Cano-Manuel, Javier; Ráez-Bravo, Arián; Pérez, Jesús M; Espinosa, José; Soriguer, Ramón; Fandos, Paulino; Granados, José E; Romero, Diego

    2016-08-01

    The aims of the present study were to investigate Pb and Cd levels in tissues of wild boar (Sus scrofa) from the Sierra Nevada Natural Space (SNNS) (southern Spain). Heavy metal concentrations in livers, kidneys and bones from 111 animals were determined by inductively coupled plasma optical emission spectrometry (ICP-OES). Bones and kidneys were the most Pb- and Cd-contaminated tissues, respectively; Cd concentrations were 5.6 times higher in kidneys than in livers. This is the first biomonitoring study of these pollutants in wild boar tissues in the SNNS, and findings indicate that this population is chronically exposed to these heavy metals. The detected Pb and Cd concentrations were lower than those found in many studies performed in Europe on the same species.

  15. DC-8 Airborne Laboratory in flight over snow-capped Sierra Nevada mountain range

    NASA Technical Reports Server (NTRS)

    1998-01-01

    NASA's DC-8 Airborne Laboratory during a flight over the snow-covered Sierra Nevada Mountains. Over the past several years the DC-8 has conducted research missions in such diverse places as the Pacific in spring and Sweden in winter. NASA is using a DC-8 aircraft as a flying science laboratory. The platform aircraft, based at NASA's Dryden Flight Research Center, Edwards, Calif., collects data for many experiments in support of scientific projects serving the world scientific community. Included in this community are NASA, federal, state, academic and foreign investigators. Data gathered by the DC-8 at flight altitude and by remote sensing have been used for scientific studies in archeology, ecology, geography, hydrology, meteorology, oceanography, volcanology, atmospheric chemistry, soil science and biology.

  16. Chemical composition of snow in the northern Sierra Nevada and other areas

    USGS Publications Warehouse

    Feth, John Henry Frederick; Rogers, S.M.; Roberson, Charles Elmer

    1964-01-01

    Melting snow provides a large part of the water used throughout the western conterminous United States for agriculture, industry, and domestic supply. It is an active agent in chemical weathering, supplies moisture for forest growth, and sustains fish and wildlife. Despite its importance, virtually nothing has been known of the chemical character of snow in the western mountains until the present study. Analysis of more than 100 samples, most from the northern Sierra Nevada, but some from Utah, Denver, Colo., and scattered points, shows that melted snow is a dilute solution containing measurable amounts of some or all of the inorganic constituents commonly found in natural water. There are significant regional differences in chemical composition; the progressive increase in calcium content with increasing distance eastward from the west slope of the Sierra Nevada is the most pronounced. The chemical character of individual snowfalls is variable. Some show predominant influence of oceanic salt; others show strong effects of mineralization from continental sources, probably largely dust. Silica and boron were found in about half the samples analyzed for these constituents; precipitation is seldom analyzed for these substances. Results of the chemical analyses for major constituents in snow samples are summarized in the following table. The median and mean values for individual constituents are derived from 41-78 samples of Sierra Nevada snow, 6-18 samples of Utah snow, and 6-17 samples of Denver, Colo., snow. [Table] The sodium, chloride, and perhaps boron found in snow are probably incorporated in moisture-laden air masses as they move over the Pacific Ocean. Silica, although abundant in the silicate-mineral nuclei found in some snowflakes, may be derived in soluble form largely from dust. Calcium, magnesium, and some bicarbonate are probably added by dust of continental origin. The sources of the other constituents remain unknown. When snowmelt comes in contact

  17. Osmium isotopic evidence for mesozoic removal of lithospheric mantle beneath the sierra nevada, california

    PubMed

    Lee; Yin; Rudnick; Chesley; Jacobsen

    2000-09-15

    Thermobarometric and Os isotopic data for peridotite xenoliths from late Miocene and younger lavas in the Sierra Nevada reveal that the lithospheric mantle is vertically stratified: the shallowest portions (<45 to 60 kilometers) are cold (670 degrees to 740 degrees C) and show evidence for heating and yield Proterozoic Os model ages, whereas the deeper portions (45 to 100 kilometers) yield Phanerozoic Os model ages and show evidence for extensive cooling from temperatures >1100 degrees C to 750 degrees C. Because a variety of isotopic evidence suggests that the Sierran batholith formed on preexisting Proterozoic lithosphere, most of the original lithospheric mantle appears to have been removed before the late Miocene, leaving only a sliver of ancient mantle beneath the crust.

  18. Individual acoustic variation in Belding's ground squirrel alarm chirps in the High Sierra Nevada

    NASA Astrophysics Data System (ADS)

    McCowan, Brenda; Hooper, Stacie L.

    2002-03-01

    The acoustic structure of calls within call types can vary as function of individual identity, sex, and social group membership and is important in kin and social group recognition. Belding's ground squirrels (Spermophilus beldingi) produce alarm chirps that function in predator avoidance but little is known about the acoustic variability of these alarm chirps. The purpose of this preliminary study was to analyze the acoustic structure of alarm chirps with respect to individual differences (e.g., signature information) from eight Belding's ground squirrels from four different lakes in the High Sierra Nevada. Results demonstrate that alarm chirps are individually distinctive, and that acoustic similarity among individuals may correspond to genetic similarity and thus dispersal patterns in this species. These data suggest, on a preliminary basis, that the acoustic structure of calls might be used as a bioacoustic tool for tracking individuals, dispersal, and other population dynamics in Belding's ground squirrels, and perhaps other vocal species.

  19. Some additional observations on inclusions in the granitic rocks of the Sierra Nevada

    USGS Publications Warehouse

    Dodge, F.C.W.; Kistler, R.W.

    1990-01-01

    Microgranular quartz diorite and diorite inclusions are widespread in central Sierra Nevada granitoid rocks and are almost exclusively restricted to hornblende-bearing rocks, most commonly felsic tonalites and mafic granodiorites. The Nd-Sm and Rb-Sr systematics indicate that most inclusions were in isotopic equilibrium with enclosing materials at the time of formation. Silica contents of inclusions and granitoids are contiguous, but inclusions generally contain less than, and granitoids more than, 60% SiO2. Ferric oxide and H2O+ trends relative to SiO2 suggests many inclusions formed as concentrations of hydrous mafic minerals. Variation of other major element oxides and trace elements support this inference. Most inclusions represent fragmented crystal accumulations of early-formed, near-liquidus minerals generated from these previously mixed magmas. -from Authors

  20. The relationship between snowpack and seasonal low flows in the Sierra Nevada: climate change and water availability in California

    NASA Astrophysics Data System (ADS)

    Godsey, S. E.; Kirchner, J. W.

    2004-12-01

    Seasonal low flows are important for sustaining aquatic ecosystems, and for supplying human needs during mid-summer. When the timing of water supply and demand do not coincide, humans rely on both natural and artificial storage. In California, the gap in timing between supply and demand is bridged primarily by the Sierra Nevada snowpack, which slowly melts throughout the spring and summer. However, most future climate scenarios suggest a decreased snowpack in the Sierra. Previous studies have investigated changes in snowmelt timing and spring snowmelt flood events. Here, by contrast, we explore how changes in the Sierra Nevada snowpack will affect annual low flows. We have identified all of the gauged catchments in the Sierra Nevada with unimpaired streamflow records and with at least ten years of overlapping snowpack and streamflow data. In each of these catchments, we have analyzed up to 40 years of historical snow and streamflow records. We find that annual minimum, mean, and maximum flows in these catchments all increase and decrease proportionally, or more-than-proportionally, as the annual peak snowpack water content changes from year to year. For every 10% decrease in snowpack, there is a 9-17% decrease in annual minimum flow. Minimum flows also occur earlier in years with smaller snowpacks; for every 10% decrease in snowpack, minimum flows occur 3-7 days earlier in the year. Finally, we find that in some catchments, annual low flows are significantly correlated not only with that year's snowpack, but with the previous year's snowpack as well. That is, seasonal low flows in some Sierra Nevada catchments exhibit a multi-year "memory" of snowmelt water inputs. We evaluate possible mechanisms that might underlie this observed memory effect. If these observed relationships between snow and flow hold in the future climate regime, the projected decrease in snowpack is likely to have a severe effect on seasonal low flows.

  1. Reconstruction of 20th Century Atmospheric Deposition Rates in the Sierra Nevada (California) using Spheroidal Carbonaceous Particles

    NASA Astrophysics Data System (ADS)

    Heard, A.; Sickman, J. O.; Rose, N.

    2012-12-01

    Atmospheric nitrogen deposition is altering biogeochemical cycles and ecological processes in high-elevation aquatic ecosystems. A need for stricter standards based on measurable ecological effects has been identified as an important step towards their long-term protection. One of the challenges with identifying ecological thresholds is a lack of knowledge of background conditions (pre- industrial) and changes that may have occurred prior to extensive monitoring programs. However, this information can be obtained using paleolimnological approaches. We are investigating historic atmospheric deposition in the Sierra Nevada using spheroidal carbonaceous particles (SCPs) in lake sediments. SCPs are strong geochemical indicators of anthropogenic atmospheric deposition because they are only produced by industrial combustion of fossil fuels---there are no natural sources. We detected SCPs as early as 1870 at Moat Lake in the eastern Sierra Nevada. SCP concentrations increased over time, peaking in the mid-1980's (2,399 gDM-1) while SCP accumulation rates peaked in the early 1920's (105 no, cm-2 yr-1) (Figure 1). Lakes along the western slope of the Sierra (Pear and Emerald) show similar patterns although differences vary by site and are likely explained by watershed characteristics and proximity to emission sources. SCP concentrations at Pear and Emerald lakes peak 10-15 years earlier than Moat. A consistent decrease was observed at Pear and Moat following the peak concentrations until present. Present day concentrations are 556 gDM-1 at Moat and 473 gDM-1 at Pear. At Emerald lake SCPs also initially decreased starting in 1964, but an increasing trend is observed from 1995 through present. These data improve our understanding of historic atmospheric deposition patterns and are being used to inform additional palaeolimnological research, including diatom analyses, with the broader objective of reconstructing historic nitrogen deposition and estimating critical loads for

  2. A Quantitative Evaluation of the Conservation Umbrella of Spotted Owl Management Areas in the Sierra Nevada

    PubMed Central

    Burnett, Ryan D.; Roberts, L. Jay

    2015-01-01

    Whether by design or default, single species management often serves as an umbrella for species with similar habitat requirements. In recent decades the focus of National Forest management in the Sierra Nevada of California has shifted towards increasing closed canopy mature forest conditions through the protection of areas occupied by the California Spotted Owl (Strix occidentalis occidentalis). To evaluate the implications of these habitat changes and the potential umbrella resulting from a system of owl reserves on the broader avian community, we estimated occupancy of birds inside and outside of Spotted Owl Home Range Core Areas in northeastern California. We used point count data in a multi-species hierarchical Bayesian model incorporating the detection history of 81 species over a two-year time period (2005-2006). A small set of vegetation cover and topography covariates were included in the model to account for broad differences in habitat conditions, as well as a term identifying whether or not a site was within a Core Area. Seventeen species had a negative Core Area effect, seven had a positive effect, and the rest were not significant. Estimated species richness was significantly different with 23.1 species per 100 m radius circle outside Core Areas and 21.7 inside Core Areas. The majority of the species negatively associated with Core Areas are tied to early successional and other disturbance-dependent habitats. Conservation and climate vulnerability rankings were mixed. On average we found higher scores (greater risk) for the species positively associated with Core Areas, but a larger number of species with the highest scores were negatively associated with Core Areas. We discuss the implications for managing the Sierra Nevada ecosystem and illustrate the role of monitoring broader suites of species in guiding management of large complex ecosystems. PMID:25905920

  3. Atmospheric transport of organophosphate pesticides from California's Central Valley to the Sierra Nevada Mountains

    USGS Publications Warehouse

    Zabik, John M.; Seiber, James N.

    1993-01-01

    Atmospheric transport of organophosphate pesticides from California's Central Valley to the Sierra Nevada mountains was assessed by collecting air- and wet-deposition samples during December, January, February, and March, 1990 to 1991. Large-scale spraying of these pesticides occurs during December and January to control insect infestations in valley orchards. Sampling sites were placed at 114- (base of the foothills), 533-, and 1920-m elevations. Samples acquired at these sites contained chlorpyrifos [phosphorothioic acid; 0,0-diethyl 0-(3,5,6-trichloro-2-pyridinyl) ester], parathion [phosphorothioic acid, 0-0-diethylo-(4-nitrophenyl) ester], diazinon {phosphorothioic acid, 0,0-diethyl 0-[6-methyl-2-(1-methylethyl)-4-pyrimidinyl] ester} diazinonoxon {phosphoric acid, 0,0-diethyl 0-[6-methyl-2-(1-methylethyl)-4-pyrimidinyl] ester}, and paraoxon [phosphoric acid, 0,0-diethyl 0-(4-nitrophenyl) ester] in both air and wet deposition samples. Air concentrations of chloropyrifos, diazinon and parathion ranged from 13 to 13 000 pg/m3 at the base of the foothills. At 533-m air concentrations were below the limit of quantification (1.4 pg/m3) to 83 pg/m3 and at 1920 m concentrations were below the limit of quantification. Concentrations in wet deposition varied with distance and elevation from the Central Valley. Rainwater concentrations at the base of the foot hills ranged from 16 to 7600 pg/mL. At 533-m rain and snow water concentrations ranged from below the limit of quantification (1.3 pg/mL) to 140 pg/mL and at 1920 m concentrations ranged from below the limit of quantification to 48 pg/mL. These findings indicate that atmospheric transport of pesticides applied in the valley to the Sierra Nevada mountains is occurring, but the levels decrease as distance and elevation increase from the valley floor.

  4. The mineral resources of the Sierra Nevada de Santa Marta, Columbia (Zone I)

    USGS Publications Warehouse

    Tschanz, Charles McFarland; Jimeno V., Andres; Cruz, Jaime B.

    1970-01-01

    The Sierra Nevada de Santa Maria on the north coast of Colombia is an isolated triangular mountain area that reaches altitudes of almost 19,000 feet. The exceedingly complex geology is shown on the 1:200,000 geologic map. Despite five major periods of granitic intrusion, three major periods of metamorphism, and extensive volcanic eruptions, metallic deposits are small and widely scattered. Sulfide deposits of significant economic value appear to be absent. Many small copper deposits, of chalcocite, cuprite, malachite, and azurite are found in epidotized rock in Mesozoic redbeds and intercalated volcanic rocks, but their economic potential is very small. Deposits of other common base metals appear to be absent. The most important metallic deposits may prove to be unusual bimineralic apatite-ilmenite deposits associated with gneissic anorthosite. The known magnetite deposits are too small to be exploited commercially. Primary gold deposits have not been identified and the placer deposits are uneconomic and very small. The largest and most important deposits are nonmetallic. Enormous reserves of limestone are suitable for cement manufacture and some high-purity limestone is suitable for the most exacting chemical uses. Small deposits of talc-tremolite could be exploited locally for ceramic use. The important noncoking bituminous coal deposits in the Cerrej6n area are excluded from this study. Other nonmetallic resources include igneous dimension stone in a variety of colors and textures, and agricultural dolomite. There probably are important undeveloped ground water resources on the slopes of the wide Rancheria and Cesar valleys, which separate the Sierra Nevada from the Serrania de Persia.

  5. Thermal alteration of water extractable organic matter in climosequence soils from the Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Santos, Fernanda; Russell, David; Berhe, Asmeret Asefaw

    2016-11-01

    In the next decades, the influence of wildfires in controlling the cycling and composition of soil organic matter (SOM) globally and in the western U.S. is expected to grow. While the impact of fires on bulk SOM has been extensively studied, the extent at which heating of soil affects the soluble component of SOM remains unclear. Here we investigated the thermal transformations of water-extractable organic matter (WEOM) by examining the changes in the distribution of carbon (C) functional groups in WEOM from soils heated at low and intermediate temperatures. WEOM (<0.7 µm particle size) was extracted from topsoils (0-5 cm depth) of five soil series formed from a nonglaciated granitic bedrock and sampled along a Sierra Nevada climosequence. Soils were heated in a muffle furnace at 150°C, 250°C, and 350°C for 1 h. The extracted solution was analyzed for WEOM aromaticity, mean molecular weight, organic C (OC) concentration, and major structural components by employing optical spectrophotometry and liquid-state 1H-NMR spectroscopy. At 150°C and 250°C, OC concentrations increased relative to the thermally unaltered samples, with losses of oxygenated functional C groups and enrichment of aliphatic C structures observed at 250°C. Conversely, OC concentration and mean molecular weight decreased as heating increased from 250°C to 350°C, whereas WEOC became more enriched in aromatic C structures. Our results suggest that low and intermediate fire intensities significantly alter the nature of dissolved organic matter exported from soils to rivers in the Sierra Nevada and beyond.

  6. A quantitative evaluation of the conservation umbrella of spotted owl management areas in the Sierra Nevada.

    PubMed

    Burnett, Ryan D; Roberts, L Jay

    2015-01-01

    Whether by design or default, single species management often serves as an umbrella for species with similar habitat requirements. In recent decades the focus of National Forest management in the Sierra Nevada of California has shifted towards increasing closed canopy mature forest conditions through the protection of areas occupied by the California Spotted Owl (Strix occidentalis occidentalis). To evaluate the implications of these habitat changes and the potential umbrella resulting from a system of owl reserves on the broader avian community, we estimated occupancy of birds inside and outside of Spotted Owl Home Range Core Areas in northeastern California. We used point count data in a multi-species hierarchical Bayesian model incorporating the detection history of 81 species over a two-year time period (2005-2006). A small set of vegetation cover and topography covariates were included in the model to account for broad differences in habitat conditions, as well as a term identifying whether or not a site was within a Core Area. Seventeen species had a negative Core Area effect, seven had a positive effect, and the rest were not significant. Estimated species richness was significantly different with 23.1 species per 100 m radius circle outside Core Areas and 21.7 inside Core Areas. The majority of the species negatively associated with Core Areas are tied to early successional and other disturbance-dependent habitats. Conservation and climate vulnerability rankings were mixed. On average we found higher scores (greater risk) for the species positively associated with Core Areas, but a larger number of species with the highest scores were negatively associated with Core Areas. We discuss the implications for managing the Sierra Nevada ecosystem and illustrate the role of monitoring broader suites of species in guiding management of large complex ecosystems.

  7. Forest management effects on snow, runoff and evapotranspiration in Sierra Nevada mixed-conifer headwater catchments

    NASA Astrophysics Data System (ADS)

    Ray, R. L.; Saksa, P. C.; Bales, R. C.; Conklin, M. H.

    2012-12-01

    We used intensive field measurements and data-intensive hydro-ecological modeling to investigate the impact of forest vegetation management on the sensitivity of snow accumulation, evapotranspiration and discharge at seven headwater catchments in the Sierra Nevada. Catchments are located in dense mixed-conifer forest, at elevations of 1500 - 2100 m, and receive a mix of rain and snow precipitation. Management scenarios for reducing forest density by uniform thinning and forest clearings were implemented in the Regional Hydro-ecological Simulation System (RHESSys). Results obtained using inherent model equations to separate total precipitation into snow and rain underestimated snow water content in some of the catchments, requiring manual input of snow and rain for accurate simulations. Modeling precipitation phase accurately was critical for the current forest condition, as the change in vegetation has differing effects on rain, snow and snowmelt. Results using RHESSys show that light, uniform thinning alone (<20% canopy) may not be enough to change water yield significantly, but this threshold of canopy reduction is lowered by creating gaps in the forest alone or in combination with uniform thinning, and has potential to measurably increase water yield beyond background variation. Clarifying these specific impacts of forest vegetation on snow processes and water yield is essential for simulating forest management in the Sierra Nevada and it shows the forest structure has significant influence on the catchment water balance. However, modifying forest canopy density and canopy cover to calculate average levels of snow water equivalent at a basin-scale may not be detailed enough to incorporate all the complex forest structure effects on snow processes in mountain watersheds.

  8. The Central Sierra Nevada Volcanic Field: A Geochemical Study of a Transitional Arc

    NASA Astrophysics Data System (ADS)

    Jean, M. M.; Putirka, K.; Busby, C.; Hagan, J.

    2006-12-01

    The Central Sierra Nevada (CSN) offers evidence about the effects of an arc/post-arc transition, which occurred in the middle to late Miocene. With passage of the Mendocino Triple Junction (MTJ), there should be a reflection of this new tectonic regime in the geochemistry of the resulting volcanic rocks. We conducted a search for systematic changes in magma chemistry, with regard to time and/or geography that may yield clues regarding tectonic origin, post 6 M.a. Major oxide and trace element analysis of 42 volcanic rock samples from the Sierra Nevada have been collected to assess the characteristics of ancestral Cascade volcanism. Major oxide element variation of 35 samples displayed high total alkalis (Na2O + K2O), medium to high K calc-alkaline compositions, and lavas that range from 50-75 wt% SiO2; all key signatures for Cascade volcanism. The remaining 7 samples displayed tholeiitic affinities. We looked for distinct chemical signatures to examine whether CSN volcanism was indicative of arcs. Spider-diagrams assisted in illustrating that the CSN suite is enriched in large ion lithophile elements (LILE) and depleted in high field strength elements (HFSE). Arcs contain Ba/Nb between 52 and 151 (Lange et. al., 1996), low Zr/Ba ratios, Y + Nb from 10 to 100 ppm, and high Sr/P2O5 ratios. The CSN volcanic field has geochemical characteristics that agree with each of these criteria that define subduction-related lavas. Two models were tested to explain the evolution of the CSN suite: fractional crystallization (FC) and combined assimilation-fractional crystallization (AFC). FC better explains both major oxide and trace element variations, compared to AFC. Our initial magma crystallized along the following liquid line of descent: ol+cpx, ol+cpx+plag, ol+cpx+plag+opx+hbl, ol+cpx+plag+opx+hbl+mag+ap.

  9. Sources and evolution of cloud-active aerosol in California's Sierra Nevada Mountains

    NASA Astrophysics Data System (ADS)

    Roberts, G. C.; Corrigan, C.; Noblitt, S.; Creamean, J.; Collins, D. B.; Cahill, J. F.; Prather, K. A.; Collett, J. L.; Henry, C.

    2011-12-01

    To assess the sources of cloud-active aerosol and their influence on the hydrological cycle in California, the CalWater Experiment took place in winter 2011 in the foothills of the Sierra Nevada Mountains. During this experiment, we coupled the capabilities of demonstrated miniaturized instrumentation - cloud condensation nuclei (CCN), water condensation nuclei (WCN) and microchip capillary electrophoresis (MCE) - to provide direct chemical measurements of cloud active aerosols. Ion concentrations of CCN droplets attribute the anthropogenic, marine and secondary organic contributions to cloud-active aerosols. Detailed spectra from an Aerosol-Time-of-Flight Mass Spectrometer provide additional information on the sources of aerosol. Storm fronts and changes in atmospheric boundary layer brought aerosol and anions associated with Central Valley pollution to the field site with CCN concentrations reaching several thousand cm-3. Hygroscopicity parameters indicate aging of the organic fraction during aerosol transport from the Central Valley to the mountains. Otherwise, CCN concentrations were low when high pressure systems prevented boundary layer development and intrusion of the Central Valley pollution to the site. MCE results show that nitrates and sulfates comprise most of the fraction of the aerosol anion mass (PM1). During the passage of storm fronts, which transported pollution from the Central Valley upslope, nitrate concentrations peaked at several μ g m-3. Low supersaturation CCN concentrations coincide with increases in aerosol nitrate, which suggests that nitrate has a role in cloud formation of giant CCN and, furthermore, in precipitation processes in the Sierra Nevada. CCN spectra show large variations depending on the aerosol sources and sometimes exhibit bi-modal distributions with minima at 0.3% Sc -- similar to the so-called 'Hoppel minima' associated to number size distributions. During these bi-modal events, sulfate also increases supporting the

  10. Patterns of cosmogenic nuclide acquisition in the Sierra Nevada, Southern Spain

    NASA Astrophysics Data System (ADS)

    Reinhardt, L.; Bishop, P.; Dempster, T.; Hoey, T.; Fifield, K.; Barrows, T.

    2003-04-01

    Tectonically active mountain ranges are expected to respond rapidly to changes in base level. Sediment derived from such areas are expected to be rapidly delivered to sedimentary basins. A comprehensive terrestrial cosmogenic nuclide-based study aims to test these assumptions in an actively uplifting mountain block and to investigate particle transport paths prior to final deposition. The Sierra Nevada of western Spain is a tectonically active mountain range on the southern margin of the Eurasian plate. Thermochronological data indicate that the present day topography (maximum elevation 3480m) has developed within the past 10 Ma Our study focuses on the Rio Torrente catchment, a small (9km × 3km) east-west trending, 2000m relief catchment in the western Sierra Nevada. The Torrente has a denudationally stable headwater region of thick regolith cover and low slope angles, which passes abruptly downstream across a major knickpoint into the very steep topography of a drainage net that is currently experiencing a rejuvenation event. Frequent shallow bedrock landslides, promoted by a strong northward dipping bedrock schistosity, dominate rejuvenated areas. The distribution of Be-10 concentrations in sediment and bedrock corresponds very well with observed geomorphic processes within the Rio Torrente Catchment. Be-10 concentrations as low as 10 000 atoms/gram in bedrock and sediment, corresponding to apparent erosion rates in excess of 2mm per annum, characterise the steep landslide-dominated lower catchment. Areas of the catchment as yet unaffected by rejuvenation are readily identifiable through their relatively high Be-10 contents. GIS based data analysis, involving a simple tracking of particles across the landscape to estimate elevation histories during particle exhumation and transport, enables identification of the pattern of nuclide acquisition as sediment is generated and transported through the Rio Torrente Catchment.

  11. Partitioning of water flux in a Sierra Nevada ponderosa pine plantation

    USGS Publications Warehouse

    Kurpius, M.R.; Panek, J.A.; Nikolov, N.T.; McKay, M.; Goldstein, Allen H.

    2003-01-01

    The weather patterns of the west side of the Sierra Nevada Mountains (cold, wet winters and hot, dry summers) strongly influence how water is partitioned between transpiration and evaporation and result in a specific strategy of water use by ponderosa pine trees (Pinus ponderosa) in this region. To investigate how year-round water fluxes were partitioned in a young ponderosa pine ecosystem in the Sierra Nevada Mountains, water fluxes were continually measured from June 2000 to May 2001 using a combination of sap flow and eddy covariance techniques (above- and below-canopy). Water fluxes were modeled at our study site using a biophysical model, FORFLUX. During summer and fall water fluxes were equally partitioned between transpiration and soil evaporation while transpiration dominated the water fluxes in winter and spring. The trees had high rates of canopy conductance and transpiration in the early morning and mid-late afternoon and a mid-day depression during the dry season. We used a diurnal centroid analysis to show that the timing of high canopy conductance and transpiration relative to high vapor pressure deficit (D) shifted with soil moisture: during periods of low soil moisture canopy conductance and transpiration peaked early in the day when D was low. Conversely, during periods of high soil moisture canopy conductance and transpiration peaked at the same time or later in the day than D. Our observations suggest a general strategy by the pine trees in which they maximize stomatal conductance, and therefore carbon fixation, throughout the day on warm sunny days with high soil moisture (i.e. warm periods in winter and late spring) and maximize stomatal conductance and carbon fixation in the morning through the dry periods. FORFLUX model estimates of evaporation and transpiration were close to measured/calculated values during the dry period, including the drought, but underestimated transpiration and overestimated evaporation during the wet period. ?? 2003

  12. Cattle grazing and conservation of a meadow-dependent amphibian species in the Sierra Nevada.

    PubMed

    Roche, Leslie M; Latimer, Andrew M; Eastburn, Danny J; Tate, Kenneth W

    2012-01-01

    World-wide population declines have sharpened concern for amphibian conservation on working landscapes. Across the Sierra Nevada's national forest lands, where almost half of native amphibian species are considered at risk, permitted livestock grazing is a notably controversial agricultural activity. Cattle (Bos taurus) grazing is thought to degrade the quality, and thus reduce occupancy, of meadow breeding habitat for amphibian species of concern such as the endemic Yosemite toad (Anaxyrus [ = Bufo] canorus). However, there is currently little quantitative information correlating cattle grazing intensity, meadow breeding habitat quality, and toad use of meadow habitat. We surveyed biotic and abiotic factors influencing cattle utilization and toad occupancy across 24 Sierra Nevada meadows to establish these correlations and inform conservation planning efforts. We utilized both traditional regression models and Bayesian structural equation modeling to investigate potential drivers of meadow habitat use by cattle and Yosemite toads. Cattle use was negatively related to meadow wetness, while toad occupancy was positively related. In mid and late season (mid July-mid September) grazing periods, cattle selected for higher forage quality diets associated with vegetation in relatively drier meadows, whereas toads were more prevalent in wetter meadows. Because cattle and toads largely occupied divergent zones along the moisture gradient, the potential for indirect or direct negative effects is likely minimized via a partitioning of the meadow habitat. During the early season, when habitat use overlap was highest, overall low grazing levels resulted in no detectable impacts on toad occupancy. Bayesian structural equation analyses supported the hypothesis that meadow hydrology influenced toad meadow occupancy, while cattle grazing intensity did not. These findings suggest cattle production and amphibian conservation can be compatible goals within this working landscape.

  13. Potential effects of climate change on streamflow, eastern and western slopes of the Sierra Nevada, California and Nevada

    USGS Publications Warehouse

    Jeton, A.E.; Dettinger, M.D.; Smith, Jody L.

    1996-01-01

    Precipitation-runoff models of the East Fork Carson and North Fork American Rivers were developed and calibrated for use in evaluating the sensitivity of streamflow in the north-central Sierra Nevada to climate change. The East Fork Carson River drains part of the rain-shadowed, eastern slope of the Sierra Nevada and is generally higher than the North Fork American River, which drains the wetter, western slope. First, a geographic information system was developed to describe the spatial variability of basin characteristics and to help estimate model parameters. The result was a partitioning of each basin into noncontiguous, but hydrologically uniform, land units. Hydrologic descriptions of these units were developed and the Precipitation- Runoff Modeling System (PRMS) was used to simulate water and energy balances for each unit in response to daily weather conditions. The models were calibrated and verified using historical streamflows over 22-year (Carson River) and 42-year (American River) periods. Simulated annual streamflow errors average plus 10 percent of the observed flow for the East Fork Carson River basin and plus 15 percent for the North Fork American River basin. Interannual variability is well simulated overall, but, at daily scales, wet periods are simulated more accurately than drier periods. The simulated water budgets for the two basins are significantly different in seasonality of streamflow, sublimation, evapotranspiration, and snowmelt. The simulations indicate that differences in snowpack and snowmelt timing can play pervasive roles in determining the sensitivity of water resources to climate change, in terms of both resource availability and amount. The calibrated models were driven by more than 25 hypothetical climate-change scenarios, each 100 years long. The scenarios were synthesized and spatially disaggregated by methods designed to preserve realistic daily, monthly, annual, and spatial statistics. Simulated streamflow timing was not very

  14. Late Miocene to Quaternary Transition in Magmatism and Tectonics, Sierra Nevada - Basin and Range Boundary, Northern California-Western Nevada

    NASA Astrophysics Data System (ADS)

    Prytulak, J.; Cousens, B. L.; Henry, C. D.

    2001-12-01

    During the late Miocene and early Pliocene, the Ancestral Cascades Arc (ARC) in northern CA and western NV shut off as the Mendocino triple junction migrated northward. At the same time, Basin and Range extension migrated westward into the Sierra Nevada block, with major episodes at 12 and 3 Ma. These tectonic events are reflected in a complex transition in magmatic composition and style. We are using geochemical, isotopic, and 40Ar/39Ar data to evaluate magma petrogenesis, the timing of volcanism, and the relationship between volcanism and tectonism in this poorly understood region of Mio-Pliocene arc volcanism. The ARC erupted highly porphyritic, pyroxene- or hornblende-plagioclase andesites to dacites, termed the Kate Peak Formation, from numerous stratovolcano complexes over basement rocks of the Sierra Nevada Batholith. Our new and published dating indicate activity from \\sim16 to 4 Ma. Immediately west of Reno, sequences dominated by poorly-phyric, olivine- and pyroxene-basaltic andesite, commonly termed Lousetown Formation, began to erupt as early as 10 Ma and continued to \\sim1 Ma. Early episodes, at 10.3 and 4 Ma, were contemporaneous with continued arc magmatism. Further, post-arc mafic volcanism continued in the area north of Lake Tahoe between 2.9 and 1.2 Ma. Although the change from hydrous intermediate rocks to \\sim anhydrous mafic rocks suggests a fundamental change in magmatic sources and tectonic setting, the mafic rocks have normalized incompatible element patterns and radiogenic isotope compositions that include a strong subduction component that is virtually indistinguishable from that in ARC intermediate lavas. Thus mafic and intermediate magmas, including post-arc magmas, share a common, fluid-modified, mantle wedge source. Additionally, the timing of mafic magmatism coincides only imprecisely with extension. No mafic magmas erupted before the beginning of extension at any location, but the earliest activity followed extension by \\sim2Ma

  15. Effects of Climate and Fuels Management on Wildfire Occurrence, Size, Severity and Emissions in the Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Westerling, A. L.; Fites, J. A.; Keyser, A.

    2015-12-01

    Annual wildfire burned area in federally managed Sierra Nevada forests has increased by more than 10,000 ha per decade since the early 1970s. At the same time, recent years have seen some extremely large fires compared to the historical record, with significant areas of moderate to high severity fire (e.g., McNally 2002, Rim 2013, King 2014 fires). Changes to fuels and fire regimes due to fire suppression and land use, as well as warming temperatures and the occurrence of drought, are thought to be significant factors contributing to increased risks of large, severe fires in Sierra Nevada forests. Over 70% of the vegetated area in federally managed forests in the Sierra Nevada is classified as having altered fuels and fire regimes, while average annual temperature in the Sierra Nevada has been above the long term mean for all but four years in the past two decades. As climate is expected to continue warming for decades to come, we explored fuels management scenarios as the primary tools available to modify risks of large, severe wildfires. We developed experimental statistical models of fire occurrence, fire size, and high severity burned area, to explore the interaction between climate and altered fuels conditions. These models were applied to historical climate conditions, a sample of future climate projections, and to both current fuels conditions and a range of scenarios for fuels treatments. Emissions from wildfires were estimated using the Fire Inventory from the National Center for Atmospheric Research. Our models project that average annual burned area in the Sierra Nevada will more than double by mid-century. Similarly, particulate and other pollution emissions from Sierra Nevada wildfires are projected to more than double, even if future fire severity does not change. Fuels treatment scenarios significantly reduced simulated future burned area and emissions below untreated projections. High severity burned area responded to both climate and fuels

  16. Modeling Multi-Reservoir Hydropower Systems in the Sierra Nevada with Environmental Requirements and Climate Warming

    NASA Astrophysics Data System (ADS)

    Rheinheimer, David Emmanuel

    Hydropower systems and other river regulation often harm instream ecosystems, partly by altering the natural flow and temperature regimes that ecosystems have historically depended on. These effects are compounded at regional scales. As hydropower and ecosystems are increasingly valued globally due to growing values for clean energy and native species as well as and new threats from climate warming, it is important to understand how climate warming might affect these systems, to identify tradeoffs between different water uses for different climate conditions, and to identify promising water management solutions. This research uses traditional simulation and optimization to explore these issues in California's upper west slope Sierra Nevada mountains. The Sierra Nevada provides most of the water for California's vast water supply system, supporting high-elevation hydropower generation, ecosystems, recreation, and some local municipal and agricultural water supply along the way. However, regional climate warming is expected to reduce snowmelt and shift runoff to earlier in the year, affecting all water uses. This dissertation begins by reviewing important literature related to the broader motivations of this study, including river regulation, freshwater conservation, and climate change. It then describes three substantial studies. First, a weekly time step water resources management model spanning the Feather River watershed in the north to the Kern River watershed in the south is developed. The model, which uses the Water Evaluation And Planning System (WEAP), includes reservoirs, run-of-river hydropower, variable head hydropower, water supply demand, and instream flow requirements. The model is applied with a runoff dataset that considers regional air temperature increases of 0, 2, 4 and 6 °C to represent historical, near-term, mid-term and far-term (end-of-century) warming. Most major hydropower turbine flows are simulated well. Reservoir storage is also

  17. Measured Black Carbon Deposition on the Sierra Nevada Snow Pack and Implication for Snow Pack Retreat

    SciTech Connect

    Hadley, O.L.; Corrigan, C.E.; Kirchstetter, T.W.; Cliff, S.S.; Ramanathan, V.

    2010-01-12

    Modeling studies show that the darkening of snow and ice by black carbon deposition is a major factor for the rapid disappearance of arctic sea ice, mountain glaciers and snow packs. This study provides one of the first direct measurements for the efficient removal of black carbon from the atmosphere by snow and its subsequent deposition to the snow packs of California. The early melting of the snow packs in the Sierras is one of the contributing factors to the severe water problems in California. BC concentrations in falling snow were measured at two mountain locations and in rain at a coastal site. All three stations reveal large BC concentrations in precipitation, ranging from 1.7 ng/g to 12.9 ng/g. The BC concentrations in the air after the snow fall were negligible suggesting an extremely efficient removal of BC by snow. The data suggest that below cloud scavenging, rather than ice nuclei, was the dominant source of BC in the snow. A five-year comparison of BC, dust, and total fine aerosol mass concentrations at multiple sites reveals that the measurements made at the sampling sites were representative of large scale deposition in the Sierra Nevada. The relative concentration of iron and calcium in the mountain aerosol indicates that one-quarter to one-third of the BC may have been transported from Asia.

  18. Snowmelt infiltration and evapotranspiration in Red Fir forest ecosystems of the Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Kirchner, P. B.; Bales, R. C.; North, M. P.; Small, E. E.

    2008-12-01

    Measurements from two forested catchments in the mixed conifer, Red Fir zone of the southern Sierra Nevada (2,200-2,600 m elevation) demonstrate the controls that topography and canopy cover exert over snow cover. Snow-depth, soil-moisture, stream-stage and sap-flow measurements from the Wolverton basin in Sequoia National Park and Teakettle Experimental Area in the Sierra National Forest exhibit distinct and rapid responses to spring snowmelt. Spatial heterogeneity in snow water equivalent is influenced by tree clusters and individual canopies. Snowmelt and soil moisture timing are controlled by proximity to stem of tree and canopy clustering. Aspect and slope position affect soil moisture, with drier conditions predominating on the steeper slopes. Synchronous fluctuations in soil moisture, stream flow and sap flow were observed. Continuous instrumental and synoptic survey data show snow water equivalent is approximately 15% less 1 m from the tree stem than in open areas at peak accumulation, with snowmelt occurring in shaded open areas 1 to 4 weeks later than under canopy. Soil moisture tracks the snowmelt pattern closely, with diel fluctuations in soil moisture under saturated conditions followed by an exponential dry-down to field capacity after snowmelt. This is followed by a prolonged summer drought punctuated by rain events of <5% of total precipitation. Synoptic surveys of steeper slopes and multiple aspects show consistent patterns of drier conditions on steeper terrain.

  19. Evolution of the northern Sierra Nevada metamorphic belt: Petrological, structural, and Ar/Ar constraints

    SciTech Connect

    Hacker, B.R.

    1993-05-01

    The Sierra Nevada metamorphic belt constitutes an important record of the growth of continental crust from essentially oceanic materials. In the northern Sierra, the central part of the belt is made up of volcanoplutonic arcs and sediment-dominated units inferred to be accretionary wedges or closed ocean basins. The latter are broken formation and melange composed of radiolarian chert, lava, and volcanogenic and continental turbidites. Sedimentary detritus in the largest of these units can be plausibly linked to sources farther east in the Sierra, suggesting that deposition occurred near the eastern Sierran arc. Isoclinal folds, steeply dipping foliations, and steeply plunging down-dip lineations are characteristics structures. The westernmost unit is only feebly recrystallized, and deformation was accomplished principally by stress solution and local redeposition in veins. More easterly, inboard units are compositionally similar, but they recrystallized at pumpellyite-actinolite-and blueschist-facies conditions and deformed via solution-transfer and dislocation creep. Phengite silica contents, the degree of quartz veining, and the locations of pseudo-isograds support an eastward increase in metamorphic pressure and temperature. Metamorphic conditions during the growth of pumpellyite and actinolite ranged from {approximately}150-350 {degrees}C and 200-400 MPa, compatible with recrystallization and deformation in subduction zones or the deeper levels of magmatic arcs. Ar/Ar ages of volcanisclastic rocks and crosscutting plutons constrain the age of deformation and metamorphism in the western part of the region to 174-165 Ma. Deformation and recrystallization in more easterly units may have been coeval or begun as early as Triassic time. 58 refs., 14 figs., 4 tabs.

  20. Spatial and temporal variation of Cenozoic surface elevation in the Great Basin and Sierra Nevada

    USGS Publications Warehouse

    Horton, T.W.; Sjostrom, D.J.; Abruzzese, M.J.; Poage, M.A.; Waldbauer, J.R.; Hren, M.; Wooden, J.; Chamberlain, C.P.

    2004-01-01

    The surface uplift of mountain belts caused by tectonism plays an important role in determining the long-term climate evolution of the Earth. However, the general lack of information on the paleotopography of mountain belts limits our ability to identify the links and feedbacks between topography, tectonics, and climate change on geologic time-scales. Here, we present a ??18O and ??D record of authigenic minerals for the northern Great Basin that captures the timing and magnitude of regional surface uplift and subsidence events in the western United States during the Cenozoic. Authigenic calcite, smectite, and chert ??18O values suggest the northern Great Basin region experienced ???2km of surface uplift between the middle Eocene and early Oligocene followed by ???1 to 2km of surface subsidence in the southern Great Basin and/or Sierra Nevada since the middle Miocene. These data when combined with previously published work show that the surface uplift history varied in both space and time. Surface uplift migrated from north to south with high elevations in southern British Columbia and northeastern Washington in the middle Eocene and development of surface uplift in north and central Nevada in the Oligocene. This pattern of north to south surface uplift is similar to the timing of magmatism in the western Cordillera, a result that supports tectonic models linking magamtism with removal of mantle lithosphere and/or a subducting slab.

  1. Exposure of a late cretaceous layered mafic-felsic magma system in the central Sierra Nevada batholith, California

    USGS Publications Warehouse

    Coleman, D.S.; Glazner, A.F.; Miller, J.S.; Bradford, K.J.; Frost, T.P.; Joye, J.L.; Bachl, C.A.

    1995-01-01

    New U-Pb zircon ages for the Lamarck Granodiorite, associated synplutonic gabbro and diorite plutons, and two large mafic intrusive complexes that underlie them in the Sierra Nevada batholith are 92??1 Ma. These ages establish the Late Cretaceous as a period of extensive mafic-felsic magmatism in the central part of the batholith, and confirm the significance of mafic magmatism in the evolution of the voluminous silicic plutions in the Sierran arc. The lack of significant zircon inheritance in any of the units analyzed supports isotopic evidence that the Lamarck and other Late Cretaceous Sierran plutons were derived predominantly from young crust. Recognition of an extensive mafic-felsic magma system in the Sierra Nevada batholith emphasizes the importance of basaltic liquids in the evolution of continental crust in arc settings. ?? 1995 Springer-Verlag.

  2. Petrographic (thin section) notes on selected samples from hornblende-rich metamorphic terranes in the southernmost Sierra Nevada, California

    USGS Publications Warehouse

    Ross, Donald Clarence

    1983-01-01

    Medium- to high-grade metamorphic rocks that are commonly hornblende-rich, and probably largely of 'oceanic' affinity, are widespread in the southernmost Sierra Nevada, California. These metamorphic rocks are largely amphibolite, mafic and felsic gneiss, granofels, and hypersthene granulite The mineral assemblages suggest that these rocks are at least in part of granulite grade, represent relatively deep crustal levels, and may be exposed parts of the root zone of the Sierra Nevada batholith. Access to the largest area of these rocks is relatively limited and for this reason petrographic data (textures and mineral content based on thin section study) are summarized here. Directions to readily accessible localities are presented, however, where the major metamorphic rock types can be examined and sampled.

  3. Implementing a Web-Based Decision Support System to Spatially and Statistically Analyze Ecological Conditions of the Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Nguyen, A.; Mueller, C.; Brooks, A. N.; Kislik, E. A.; Baney, O. N.; Ramirez, C.; Schmidt, C.; Torres-Perez, J. L.

    2014-12-01

    The Sierra Nevada is experiencing changes in hydrologic regimes, such as decreases in snowmelt and peak runoff, which affect forest health and the availability of water resources. Currently, the USDA Forest Service Region 5 is undergoing Forest Plan revisions to include climate change impacts into mitigation and adaptation strategies. However, there are few processes in place to conduct quantitative assessments of forest conditions in relation to mountain hydrology, while easily and effectively delivering that information to forest managers. To assist the USDA Forest Service, this study is the final phase of a three-term project to create a Decision Support System (DSS) to allow ease of access to historical and forecasted hydrologic, climatic, and terrestrial conditions for the entire Sierra Nevada. This data is featured within three components of the DSS: the Mapping Viewer, Statistical Analysis Portal, and Geospatial Data Gateway. Utilizing ArcGIS Online, the Sierra DSS Mapping Viewer enables users to visually analyze and locate areas of interest. Once the areas of interest are targeted, the Statistical Analysis Portal provides subbasin level statistics for each variable over time by utilizing a recently developed web-based data analysis and visualization tool called Plotly. This tool allows users to generate graphs and conduct statistical analyses for the Sierra Nevada without the need to download the dataset of interest. For more comprehensive analysis, users are also able to download datasets via the Geospatial Data Gateway. The third phase of this project focused on Python-based data processing, the adaptation of the multiple capabilities of ArcGIS Online and Plotly, and the integration of the three Sierra DSS components within a website designed specifically for the USDA Forest Service.

  4. Evaluating the Spatial Distribution of Toxic Air Contaminants in Multiple Ecosystem Indicators in the Sierra Nevada-Southern Cascades

    NASA Astrophysics Data System (ADS)

    Nanus, L.; Simonich, S. L.; Rocchio, J.; Flanagan, C.

    2013-12-01

    Toxic air contaminants originating from agricultural areas of the Central Valley in California threaten vulnerable sensitive receptors including surface water, vegetation, snow, sediments, fish, and amphibians in the Sierra Nevada-Southern Cascades region. The spatial distribution of toxic air contaminants in different ecosystem indicators depends on variation in atmospheric concentrations and deposition, and variation in air toxics accumulation in ecosystems. The spatial distribution of organic air toxics and mercury at over 330 unique sampling locations and sample types over two decades (1990-2009) in the Sierra Nevada-Southern Cascades region were compiled and maps were developed to further understand spatial patterns and linkages between air toxics deposition and ecological effects. Potential ecosystem impacts in the Sierra Nevada-Southern Cascades region include bioaccumulation of air toxics in both aquatic and terrestrial ecosystems, reproductive disruption, and immune suppression. The most sensitive ecological end points in the region that are affected by bioaccumulation of toxic air contaminants are fish. Mercury was detected in all fish and approximately 6% exceeded human consumption thresholds. Organic air toxics were also detected in fish yielding variable spatial patterns. For amphibians, which are sensitive to pesticide exposure and potential immune suppression, increasing trends in current and historic use pesticides are observed from north to south across the region. In other indicators, such as vegetation, pesticide concentrations in lichen increase with increasing elevation. Current and historic use pesticides and mercury were also observed in snowpack at high elevations in the study area. This study shows spatial patterns in toxic air contaminants, evaluates associated risks to sensitive receptors, and identifies data gaps. Future research on atmospheric modeling and information on sources is needed in order to predict which ecosystems are the

  5. Polychlorinated biphenyls and toxaphene in Pacific tree frog tadpoles (Hyla regilla) from the California Sierra Nevada, USA.

    PubMed

    Angermann, Jeffrey E; Fellers, Gary M; Matsumura, Fumio

    2002-10-01

    Pacific tree frog (Hyla regilla) tadpoles were collected throughout the Sierra Nevada mountain range, California, USA, in 1996 and 1997 and analyzed for the presence of polychlorinated biphenyls (PCBs) and toxaphene. Whole-tadpole sigma PCB levels ranged from 244 ng/g (wet wt) at lower elevations on the western slope to 1.6 ng/g high on the eastern slope, whereas sigma toxaphene levels ranged from 15.6 to 1.5 ng/g. Linear regression of PCB and toxaphene residue levels versus elevation indicated a significant relationship, with an r2 value of 0.33 for PCB and 0.45 for toxaphene indicating a significant elevation effect on PCB and toxaphene bioaccumulation in Sierra Nevada H. regilla. Tadpole samples from sites in east-facing versus west-facing drainage basins showed significant differences in PCB and toxaphene residue levels, suggesting the possibility of a rain-shadow effect in the long-range atmospheric transport of these contaminants to the Sierra Nevada Mountains.

  6. Polychlorinated biphenyls and toxaphene in Pacific tree frog tadpoles (Hyla regilla) from the California Sierra Nevada, USA

    USGS Publications Warehouse

    Angermann, Jeffrey E.; Fellers, Gary M.; Matsumura, Fumio

    2002-01-01

    Pacific tree frog (Hyla regilla) tadpoles were collected throughout the Sierra Nevada mountain range, California, USA, in 1996 and 1997 and analyzed for the presence of polychlorinated biphenyls (PCBs) and toxaphene. Whole-tadpole Σ PCB levels ranged from 244 ng/g (wet wt) at lower elevations on the western slope to 1.6 ng/g high on the eastern slope, whereas Σ toxaphene levels ranged from 15.6 to 1.5 ng/g. Linear regression of PCB and toxaphene residue levels versus elevation indicated a significant relationship, with an r2 value of 0.33 for PCB and 0.45 for toxaphene indicating a significant elevation effect on PCB and toxaphene bioaccumulation in Sierra Nevada H. regilla. Tadpole samples from sites in east-facing versus west-facing drainage basins showed significant differences in PCB and toxaphene residue levels, suggesting the possibility of a rain-shadow effect in the long-range atmospheric transport of these contaminants to the Sierra Nevada Mountains.

  7. Water resources and rural growth: a policy analysis of water resource management in the Sierra Nevada foothills

    SciTech Connect

    Birch, D.N.

    1986-01-01

    Reverse migration has caused a phenomenal increase in population growth in the Sierra-Nevada region of California. The highest rate of growth is occurring in the unincorporated areas of rural counties where local government is least capable of providing public services. County government is the primary water-management entity in these areas, with land-use planning and the implementation of federal water-quality mandates the principal means of preventing water-resource exploitation and degradation from unrestricted growth and development. El Dorado, Placer, Sierra and Nevada counties constitute the study area of the report. The counties of Placer and Sierra were more successful in the resolution of water-management problems than either Nevada or El Dorado. In providing an analysis of water management policy in each of the four counties, the variables pertaining to success or failure in water management are identified and discussed. The research constituted a case study of decision making with respect to water availability, usage, and quality control. The principal competition for the limited water supply is between agriculture and residential land development - the latter the most prevalent form of land use activity in the study area. This competition has resulted in the overdrafting of ground water, threatening contamination.

  8. Moho-Depth Dike Swarms and Rifting of the Sierra Nevada Microplate, Northeast California

    NASA Astrophysics Data System (ADS)

    Smith, K. D.; Kent, G.; von Seggern, D. H.; Eissis, A.; Driscoll, N. W.

    2012-12-01

    Moho-depth earthquake swarms below N. Lake Tahoe (LT) in late 2003 and, beneath southern Sierra Valley (SV), California in late 2011/early 2012, ~50 km to the north, define nearly identical dike injection events along the same Moho-depth structure. Each swarm lasts ~6 months, outlines an ~7x7 km fault area, initiates at its deepest extent, shows dominantly reverse slip mechanisms, and aligns along an ~N45W striking, ~50 degree east dipping Moho-depth structure. About 1600 events were located in the LT swarm (maximum M 2.2; b-value 2.0) and nearly 2200 have been located under SV (maximum M 1.9; b-value 1.7); an NSF-Earthscope supported deployment in SV includes five broadband instruments that are currently operating within one focal depth - three directly above the sequence. A Long-Period earthquake (LP), located at a depth of 30 km along the dipping structure (9/29/2011) was located midway between the two sequences. This is the first LP identified outside of the Long Valley volcanic center along the northeastern Sierra. These diking events define a northward propagating rift boundary along the northeastern boundary of the Sierran Microplate. Extension driven decompression melting of upper mantle magmas and weakening of a stronger (~5 km thick) upper-Moho lid drives dike injection and faulting of the rift structure. Following failure of the strong upper mantle layer, footwall unloading and flexural response help bring the Sierran block elevations into equilibrium with the upper-mantle and crustal profile. Forces driving plate boundary processes, slab roll back, westward escape of the southern Cascadia upper plate, and northward evolution of the Mendocino Triple Junction (MTJ) result in northwestward motion of the Sierra block (e.g., Atwater and Stock, 1988) and extension east of the Sierra, driving northwestward rift propagation. These overall processes are reflected in the historical earthquake record in northeast California and western Nevada. Shear dominated San

  9. Annually resolved late Holocene paleohydrology of the southern Sierra Nevada and Tulare Lake, California

    NASA Astrophysics Data System (ADS)

    Adams, Kenneth D.; Negrini, Robert M.; Cook, Edward R.; Rajagopal, Seshadri

    2015-12-01

    Here we present 2000 year long, annually resolved records of streamflow for the Kings, Kaweah, Tule, and Kern Rivers in the southwestern Sierra Nevada of California and consequent lake-level fluctuations at Tulare Lake in the southern San Joaquin Valley. The integrated approach of using moisture-sensitive tree ring records from the Living Blended Drought Atlas to reconstruct annual discharge and then routing this discharge to an annual Tulare Lake water balance model highlights the differences between these two types of paleoclimate records, even when subject to the same forcing factors. The reconstructed streamflow in the southern Sierra responded to yearly changes in precipitation and expressed a strong periodicity in the 2-8 year range over most of the reconstruction. The storage capacity of Tulare Lake caused it to fluctuate more slowly, masking the 2-8 year streamflow periodicity and instead expressing a strong periodicity in the 32-64 year range over much of the record. Although there have been longer droughts, the 2015 water year represents the driest in the last 2015 years and the 2012-2015 drought represents the driest 4 year period in the record. Under natural conditions, simulated Tulare Lake levels would now be at about 60 m, which is not as low as what occurred multiple times over the last 2000 years. This long-term perspective of fluctuations in climate and water supply suggests that different drought scenarios that vary in terms of severity and duration can produce similar lake-level responses in closed lake basins.

  10. Response of Sierra Nevada forests to projected climate-wildfire interactions.

    PubMed

    Liang, Shuang; Hurteau, Matthew D; Westerling, Anthony LeRoy

    2016-11-01

    Climate influences forests directly and indirectly through disturbance. The interaction of climate change and increasing area burned has the potential to alter forest composition and community assembly. However, the overall forest response is likely to be influenced by species-specific responses to environmental change and the scale of change in overstory species cover. In this study, we sought to quantify how projected changes in climate and large wildfire size would alter forest communities and carbon (C) dynamics, irrespective of competition from nontree species and potential changes in other fire regimes, across the Sierra Nevada, USA. We used a species-specific, spatially explicit forest landscape model (LANDIS-II) to evaluate forest response to climate-wildfire interactions under historical (baseline) climate and climate projections from three climate models (GFDL, CCSM3, and CNRM) forced by a medium-high emission scenario (A2) in combination with corresponding climate-specific large wildfire projections. By late century, we found modest changes in the spatial distribution of dominant species by biomass relative to baseline, but extensive changes in recruitment distribution. Although forest recruitment declined across much of the Sierra, we found that projected climate and wildfire favored the recruitment of more drought-tolerant species over less drought-tolerant species relative to baseline, and this change was greatest at mid-elevations. We also found that projected climate and wildfire decreased tree species richness across a large proportion of the study area and transitioned more area to a C source, which reduced landscape-level C sequestration potential. Our study, although a conservative estimate, suggests that by late century, forest community distributions may not change as intact units as predicted by biome-based modeling, but are likely to trend toward simplified community composition as communities gradually disaggregate and the least tolerant

  11. Assessing modern climatic controls on southern Sierra Nevada precipitation and speleothem δ18O

    NASA Astrophysics Data System (ADS)

    McCabe-Glynn, S. E.; Johnson, K. R.; Berkelhammer, M. B.

    2012-12-01

    Precipitation in the southwestern United States (SW US) is highly seasonal and exhibits inter-annual to inter-decadal variability. A 1154-year δ18O time series obtained from a southwestern Sierra Nevada Mountain stalagmite from Crystal Cave, CRC-3, (36.58°N; 118.56°W; 1540 m) reveals substantial decadal to multi-decadal variability closely linked to the Pacific Decadal Oscillation (PDO), and more specifically, to sea surface temperatures (SSTs) in the Kuroshio Extension region, which impact the atmospheric trajectory and isotopic composition of moisture reaching the study site. The instrumental portion of the CRC-3 δ18O time series suggests that more negative precipitation δ18O values are delivered from higher latitudes during positive phases of the PDO and/or when SSTs in the Kuroshio Extension region are anomalously cool, such as during La Niña events. In order to improve our understanding of the controls on speleothem δ18O in this region, we have conducted a detailed modern study of the climate, hydrology, and stable isotopic composition of meteoric waters (precipitation and drip water) at the cave. Here we present Crystal Cave drip logger results from 2010 to 2012, the isotopic composition of North American Deposition Program precipitation samples collected from 2001 to 2012 from several locations near our site including Ash Mountain (ASM), Sequoia National Park-Giant Forest (Ca75), and Yosemite National Park (Ca99), and isotopic composition of cave drip water and glass plate calcite. We also compare the δ18O values in the precipitation to satellite imagery, NCAR/NCEP data, and NOAA Hysplit Model backward trajectories between the sites. Results indicate that this site is particularly sensitive to "Pineapple Express" type storms, a persistent flow of atmospheric moisture and heavy rainfall extending from near the Hawaiian Islands to the coast of North America, which average about twice as much precipitation as other storms in the Sierra Nevada during

  12. Igneous phenocrystic origin of K-feldspar megacrysts in granitic rocks from the Sierra Nevada batholith

    USGS Publications Warehouse

    Moore, J.G.; Sisson, T.W.

    2008-01-01

    Study of four K-feldspar megacrystic granitic plutons and related dikes in the Sierra Nevada composite batholith indicates that the megacrysts are phenocrysts that grew in contact with granitic melt. Growth to megacrystic sizes was due to repeated replenishment of the magma bodies by fresh granitic melt that maintained temperatures above the solidus for extended time periods and that provided components necessary for K-feldspar growth. These intrusions cooled 89-83 Ma, are the youngest in the range, and represent the culminating magmatic phase of the Sierra Nevada batholith. They are the granodiorite of Topaz Lake, the Cathedral Peak Granodiorite, the Mono Creek Granite, the Whitney Granodiorite, the Johnson Granite Porphyry, and the Golden Bear Dike. Megacrysts in these igneous bodies attain 4-10 cm in length. All have sawtooth oscillatory zoning marked by varying concentration of BaO ranging generally from 3.5 to 0.5 wt%. Some of the more pronounced zones begin with resorption and channeling of the underlying zone. Layers of mineral inclusions, principally plagioclase, but also biotite, quartz, hornblende, titanite, and accessory minerals, are parallel to the BaO-delineated zones, are sorted by size along the boundaries, and have their long axes preferentially aligned parallel to the boundaries. These features indicate that the K-feldspar megacrysts grew while surrounded by melt, allowing the inclusion minerals to periodically attach themselves to the faces of the growing crystals. The temperature of growth of titanite included within the K-feldspar megacrysts is estimated by use of a Zr-in-titanite geothermometer. Megacryst-hosted titanite grains all yield temperatures typical of felsic magmas, mainly 735-760 ??C. Titanite grains in the granodiorite hosts marginal to the megacrysts range to lower growth temperatures, in some instances into the subsolidus. The limited range and igneous values of growth temperatures for megacryst-hosted titanite grains support the

  13. Snowmelt sensitivity to warmer temperatures: a field-validated model analysis, southern Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Musselman, K. N.; Molotch, N. P.; Margulis, S. A.

    2014-12-01

    We present model simulations of climate change impacts on snowmelt processes over a 1600 km2 area in the southern Sierra Nevada, including western Sequoia National Park. The domain spans a 3600 m elevation gradient and ecosystems ranging from semi-arid grasslands to giant sequoia groves to alpine tundra. Three reference years were evaluated: a moderately dry snow season (23% below average SWE), an average snow season (7% above average SWE), and a moderately wet snow season (54% above average SWE). The Alpine3D model was run for the reference years and results were evaluated against data from a multi-scale measurement campaign that included repeated manual snow courses and basin-scale snow surveys, dozens of automated snow depth sensors, and automated SWE stations. Compared to automated measurements, the model represented the date of snow disappearance within two days. Compared to manual measurements, model SWE RMSE values for the average and wet snow seasons were highly correlated (R2=0.89 and R2=0.73) with the distance of SWE measurements from the nearest precipitation gauge used to force the model; no significant correlation was found with elevation. The results suggest that Alpine3D is highly accurate during the melt season and that precipitation uncertainty may critically limit snow model accuracy. The air temperature measured at 19 regional stations for the three reference years was modified by +1°C to +6°C to simulate the impact of warmer temperatures on snowmelt dynamics over the 3600 m elevation gradient. For all years, progressively warmer temperatures caused the seasonal SWE centroid to shift earlier and higher in elevation. At forested middle elevations, 70 - 80% of the present-day snowpack volume is lost in a +2°C scenario; 30 - 40% of that change is a result of precipitation phase shift and the remainder is due to enhanced melt. At all elevations, spring and fall snowpack was most sensitive to warmer temperatures; mid-winter sensitivity was least

  14. Exploration of long-term reanalysis of Sierra Nevada snowpack inferred from snow covered area information

    NASA Astrophysics Data System (ADS)

    Girotto, M.; Margulis, S. A.; Durand, M.

    2012-04-01

    The spatial heterogeneity of the mountain snowpack and a continuously changing climate affects a variety of processes including surface water discharge. An apparent shift in ablation time and loss of snow water equivalent (SWE) in the Sierra Nevada range in California (CA), U.S.A. has been reported from several past studies based on downstream flow and/or point scale in-situ observations records. Understanding the geophysical controls and interannual variability of the spatial patterns of snow accumulation and ablation are critical for predicting the effects of climate variability on the snowpack water storage. Therefore, a continuous space-time characterization of snow distribution that uses spatially and temporally extensive remotely sensed information is necessary to improve our ability to predict and monitor this vital resource in complex mountainous terrain. Toward this end, this research generates spatial and temporal SWE estimates over a snow-dominated watershed located in the Southern Sierra Nevada, CA. We use a reanalysis data assimilation approach that is capable of merging remotely sensed Snow Covered Area (SCA) data into snow prediction models, while at the same time accounting for the limitations of each. SCA information derived from the long-term record of Landsat-5 Thematic Mapper measurements are used. The assimilation of SCA into the land surface model, coupled together with a snow depletion model, predicts continuous (in space and time) SWE at a high spatial resolution. The resulting SWE dataset from the reanalysis framework, and its relation to physiographic properties, is studied to explore specific information related to how snow accumulation and snow melt has evolved and been effected by climate variability and change. In particular, the analysis focuses on highlighting how patterns related to different physiographic components respond to observed climate signals (e.g. Pacific Decadal Oscillation (PDO) and the Oceanic El Niño Index (ONI)) and

  15. Spatial interpolation of precipitation indexes in Sierra Nevada (Spain): comparing the performance of some interpolation methods

    NASA Astrophysics Data System (ADS)

    Pereira, Paulo; Oliva, Marc; Misiune, Ieva

    2016-11-01

    The objective of this paper is to examine the spatial distribution of several precipitation indexes in Sierra Nevada, Spain: mean annual number of wet days ( R ≥ 1 mm), mean annual number of heavy rainy days ( R ≥ 10 mm) and mean annual number of very heavy precipitation days ( R ≥ 20 mm) and test the performance of several interpolation methods using these variables. In total, 17 univariate and multivariate methods were tested. A set of 36 metereological stations distributed in Sierra Nevada and neighbouring areas was analysed in this study. The original data did not followed the normal distribution; thus, a logarithm was applied to data meet normality purposes. Interpolator's performance was assessed using the root mean square error generated from cross-validation. The results showed that the mean annual R ≥ 10 mm and R ≥ 20 mm have a higher variability than R ≥ 1 mm. While the elevation and longitude did not show a significant correlation with the studied indexes, the latitude (i.e. distance to the sea) showed a significant negative correlation. The regressions carried out confirmed that elevation was the covariate with higher capacity to explain the variability of the indexes. The incorporation of elevation and longitude slightly increased the explanation capacity of the models. The data of LogR ≥ 1 mm, LogR ≥ 10 mm and LogR ≥ 20 mm displayed a clustered pattern, especially the last two indexes that also showed a strong spatial dependency attributed to the effects of local topography, slope, aspect and valley orientation. The best fitted variogram model to LogR ≥ 1 mm was the linear one while for the LogR ≥ 10 mm and LogR ≥ 20 mm, the Gaussian was the most appropriate. The best interpolator for LogR ≥ 1 mm was the local polinomyal with the power of 1, whereas for LogR ≥ 10 mm and LogR ≥ 20 mm, regression kriging (ROK) using as auxiliary variables the elevation, latitude and longitude was the most accurate. ROK methods significantly

  16. Fuel deposition rates of montane and subalpine conifers in the central Sierra Nevada, California, USA

    USGS Publications Warehouse

    van Wagtendonk, J.W.; Moore, P.E.

    2010-01-01

    Fire managers and researchers need information on fuel deposition rates to estimate future changes in fuel bed characteristics, determine when forests transition to another fire behavior fuel model, estimate future changes in fuel bed characteristics, and parameterize and validate ecosystem process models. This information is lacking for many ecosystems including the Sierra Nevada in California, USA. We investigated fuel deposition rates and stand characteristics of seven montane and four subalpine conifers in the Sierra Nevada. We collected foliage, miscellaneous bark and crown fragments, cones, and woody fuel classes from four replicate plots each in four stem diameter size classes for each species, for a total of 176 sampling sites. We used these data to develop predictive equations for each fuel class and diameter size class of each species based on stem and crown characteristics. There were consistent species and diameter class differences in the annual amount of foliage and fragments deposited. Foliage deposition rates ranged from just over 50 g m-2 year-1 in small diameter mountain hemlock stands to ???300 g m-2 year-1 for the three largest diameter classes of giant sequoia. The deposition rate for most woody fuel classes increased from the smallest diameter class stands to the largest diameter class stands. Woody fuel deposition rates varied among species as well. The rates for the smallest woody fuels ranged from 0.8 g m-2 year-1 for small diameter stands of Jeffrey pine to 126.9 g m-2 year-1 for very large diameter stands of mountain hemlock. Crown height and live crown ratio were the best predictors of fuel deposition rates for most fuel classes and species. Both characteristics reflect the amount of crown biomass including foliage and woody fuels. Relationships established in this study allow predictions of fuel loads to be made on a stand basis for each of these species under current and possible future conditions. These predictions can be used to

  17. Impacts of the 2014 Drought on Vegetation Processes in the Sierra Nevada of California

    NASA Astrophysics Data System (ADS)

    Loik, M. E.; Wade, C. E.; Reed, C. C.

    2014-12-01

    Sierra Nevada snowpack provides over 60 percent of California's freshwater supplies. The drought of 2014 has been unprecedented in the state's history, and followed below-average precipitation for the hydrologic years 2012 and 2013. Record-low precipitation has resulted in minimal Sierra Nevada snow pack and runoff, and massive reductions in reservoir storage, which has triggered widespread drought adaptation measures for one of the world's largest economies. We assessed the impacts of the 2014 drought on vegetation processes in the headwaters of the Owens River, which is one of the main watersheds for the city of Los Angeles. We monitored water relations, photosynthesis, growth and Leaf Area Index of tree, shrub, herb, and grass species. In order to better understand the effects of drought, we examined responses to watering manipulations, long-term snow fences, elevation gradient analysis, and comparisons to previous wetter years. 1 April 2014 snow pack depth was 330 mm (average for 1928 - 2012 = 1344 mm, CV = 49%). Despite widespread mortality of Pinus jeffreyi saplings (mean 1.5 m tall) at 2300 m, older trees as well as saplings of Pinus contorta showed new growth. There were no significant differences in water potential (Ψ) for the two conifer species in a wet year (2006, 1 April snow depth = 2240 mm) vs. 2014. Water potential for P. contorta in 2014 was higher at 2900 m than at 2300 m but photosynthetic CO2 assimilation (A) and stomatal conductance (gs), were not different. By contrast, Ψ, A, gs, Vcmax and Jmax for the widespread shrub Artemisia tridentata increased along a gradient from 2100 m to 2900 m in 2014. Watering only significantly increased these photosynthetic parameters at the lowest, driest elevation. At the middle elevation, Leaf Area Index in 2014 was about 20% of the 2006 value for the N-fixing shrub Purshia tridentata. Results show reductions in photosynthesis and growth for some species but not others in response to the severe drought

  18. Timber harvest effect on soil moisture in the southern Sierra Nevada: Is there a measurable impact?

    NASA Astrophysics Data System (ADS)

    Meadows, M. W.; Bales, R. C.; Conklin, M. H.; Goulden, M.; Hartsough, P. C.; Hopmans, J. W.; Hunsaker, C. T.; Lucas, R. G.; Malazian, A. I.

    2013-12-01

    We monitored soil-moisture storage, evapotranspiration and streamflow in a Sierra Nevada mixed-conifer forest for three post-snowmelt spring/summer seasons during water years 2010-2013. We measured volumetric water content using a COsmic-ray Soil Moisture Observing Systems (COSMOS) to estimate shallow soil-moisture storage and an eddy-covariance flux tower to measure evapotranspiration, covering an area of about 20 ha. Soil-moisture sensors were also strategically placed at depths of 10, 30, 60 and 90 cm at 30 locations in and around the COSMOS and tower footprints. Timber harvest occurred during the summer of 2012, involving uneven-age thinning limited to trees less than 76.2 cm diameter at breast height (DBH). Timber harvest intensity varied by tree size class: approximately 39% of the trees 0 to 25.5 cm DBH, 21% of the trees 25.5 to 50.8 cm DBH, and 4% of trees 50.8-76.2 cm DBH. Merchantable timber removed from the site was about 81-100 cubic m per ha. Annual evapotranspiration was similar for all four years, averaging about 80 cm each year, despite large variability in annual precipitation amounts. Annual evapotranspiration was about 10% lower following harvest. However, 2012 and 2013 were both dry years. Water year 2011 was one of the wettest years on record - approximately 200 cm of precipitation - while 2012 was one of the driest with 70 cm of precipitation. Each year soil desiccation immediately followed snow-cover depletion, dropping from field capacity by about 20% volumetric water content over a 3-month period. The rate of soil-water loss was about the same for all years. In 2012 and 2013 the dates of snow disappearance were 2-3 months earlier than in 2011. About half of the annual total evapotranspiration for 2010-2012 occurred during the 3-month period following snowmelt. Each year, total summer precipitation was only 4-6 cm. Thus soil-water storage derived from snowmelt and rainfall provides much of the moisture for evapotranspiration in the mixed

  19. Inorganic and suspended/dissolved-organic nitrogen in Sierra Nevada soil core leachates

    SciTech Connect

    Marcus, J.A.; Miller, W.W.; Blank, R.R.

    1998-07-01

    Watershed disturbance has been suggested as a possible mechanism for accelerated nutrient input into Lake Tahoe, California/Nevada. However, little is known regarding how nutrient discharge is coupled to physicochemical watershed processes. Recent investigations in the Lake Tahoe Basin have suggested that suspended/dissolved-organic nutrient transport may play an important role in lake and tributary water quality. The mobility of inorganic and suspended/dissolved-organic N in soils of a Lake Tahoe watershed was assessed using constant head permeameter leaching experiments with intact soil cores. The authors evaluated the interaction of plot condition on magnitude and form of N discharge. Incremental leachate discharge was analyzed for concentrations of inorganic (NH{sub 4}-N and NO{sub 3}-N) and suspended/dissolved-organic N. Leachate from the riparian soil cores had significantly higher concentrations and total discharge NO{sub 3}-N than that from the nonforested or forested areas. Loading of NH{sub 4}-N was more consistent among vegetative cover types, but the riparian leachate again contributed a significantly greater amount. Suspended/dissolved-organic N was mobile and the most dominant form of N for nonforested and forested soil cores with discharge loading ratios of 17:1 and 7:1, respectively. Although the loading ratio was approximately 1:1 for the riparian soil cores, the amount of suspended/dissolved-organic N discharged was greatest. The mobility and presence of significant amounts of suspended/dissolved-organic N indicate that this once unrecognized nutrient form is an important component in at least one Sierra Nevada watershed, and should be more fully investigated elsewhere.

  20. Composition of modern sand and Cretaceous sandstone derived from the Sierra Nevada, California, USA, with implications for Cenozoic and Mesozoic uplift and dissection

    NASA Astrophysics Data System (ADS)

    Ingersoll, Raymond V.

    2012-12-01

    The California Sierra Nevada represents the roots of a primarily Cretaceous magmatic arc that is presently being dissected extensively in the south and to a lesser degree in the north, where it is covered by Cenozoic volcanic rocks. The Cenozoic magmatic arc built on top of the Cretaceous arc has been dissected concurrently with northward migration of the Mendocino triple junction, south of which the magmatic arc is inactive. A north-to-south transect from the modern Cascade arc along the Sierra Nevada, therefore, acts as a proxy for evolution from an active undissected magmatic arc to a transitional arc to a dissected arc to intensely uplifted basement. Discriminant analysis of Cascade and Sierra Nevada modern alluvial sand defines four compositional groups and clearly distinguishes volcaniclastic undissected-arc and plutoniclastic uplifted-basement end members. Two intermediate compositional groups are primarily volcaniplutoniclastic and metamorphiplutoniclastic. The former group represents Dickinson's (1985) "transitional arc;" the latter represents "dissected arc." Sand composition in the southern Sierra Nevada reflects significant uplift, resulting from a combination of latest Cretaceous-Paleogene uplift and late Cenozoic Basin and Range extension (footwall uplift of the western rift shoulder), possibly enhanced by mantle-lithosphere delamination. High concentrations of quartz and feldspar, and near absence of aphanitic lithic fragments are typical of the southern Sierra Nevada and are characteristic of Dickinson's "basement uplift." Cretaceous sandstone petrofacies of the Great Valley Group (GVG) of western California document dissection of the Cretaceous magmatic arc, as well as erosion of residual orogenic highlands (analogous to modern Taiwan) formed during latest Jurassic arc-continent collision (Nevadan orogeny). When Cretaceous petrofacies data are entered into the modern-sand discriminant analysis as unknowns, they are classified into the modern

  1. Hornblende-rich, high grade metamorphic terranes in the southernmost Sierra Nevada, California, and implications for crustal depths and batholith roots

    USGS Publications Warehouse

    Ross, Donald Clarence

    1983-01-01

    The southernmost Sierra Nevaaa widely exposes hornblende-rich, gneissic to granoblastic, amphibolite- to granulite-grade, metamorphic rocks and associated magmatic rocks, all of mid-Cretaceous age. Locally, red garnet, in part in euhedral crystals as large as 10 cm, as well as strongly pleochroic hyperstnene, characterize these rocks. These hornblende-rich rocks dominate the north slopes of the southern tail of the Sierra Nevada, but are also present as inclusion masses of various sizes in the dominantly granitic terrane to She northeast. The mafic, hornblende-rich rocks reflect a deeper crustal level than the dominantly granitic terrane to the northeast based on: 1) 'index' minerals (presence of hypersthene, coarse garnet, and brown hornblende; 2) textures (considerable ambivalence of whether individual samples are metamorphic or magmatic, 3) metamorphic grade (at least local granulite facies); and 4) the presence of migmatite, and the eviaence of local melting and mobilization. These rocks may be exposures of the upper part of the root zone and metamorphic substrate of the Sierra Nevada batholith. Xenoliths of gneiss, amphibolite, and granulite from sub-batholithic levels, that have been transported upward and preserved in volcanic rocks in the central Sierra Nevada, are similar to some exposed rocks of the southernmost Sierra Nevada. Hypersthene-bearing granulite and tonalite, as well as distinctive granofels of mid-Cretaceous age, are exposed in the western part of the Santa Lucia Range (some 300 km to the northwest across the San Andreas fault). These rocks have much in common with some of the metamorphic and magmatic rocks in the southernmost Sierra Nevada, suggesting that the two areas record similar metamorphic conditions and crustal depth. Mid-Cretaceous hypersthene granulite is rare, which makes correlation of the Santa Lucia Range and the southernmost Sierra Nevada seem attractive. Nevertheless, possibly significant petrographic anm rock distribution

  2. Long Valley caldera and the UCERF depiction of Sierra Nevada range-front faults

    USGS Publications Warehouse

    Hill, David P.; Montgomery-Brown, Emily K.

    2015-01-01

    Long Valley caldera lies within a left-stepping offset in the north-northwest-striking Sierra Nevada range-front normal faults with the Hilton Creek fault to the south and Hartley Springs fault to the north. Both Uniform California Earthquake Rupture Forecast (UCERF) 2 and its update, UCERF3, depict slip on these major range-front normal faults as extending well into the caldera, with significant normal slip on overlapping, subparallel segments separated by ∼10  km. This depiction is countered by (1) geologic evidence that normal faulting within the caldera consists of a series of graben structures associated with postcaldera magmatism (intrusion and tumescence) and not systematic down-to-the-east displacements consistent with distributed range-front faulting and (2) the lack of kinematic evidence for an evolving, postcaldera relay ramp structure between overlapping strands of the two range-front normal faults. The modifications to the UCERF depiction described here reduce the predicted shaking intensity within the caldera, and they are in accord with the tectonic influence that underlapped offset range-front faults have on seismicity patterns within the caldera associated with ongoing volcanic unrest.

  3. Climate controls on anomalously high productivity in the mixed conifer forests of the Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Kelly, A. E.; Goulden, M. L.

    2009-12-01

    The Mediterranean climate of California’s Sierra Nevada Mountains supports a dense conifer forest that contains some of the largest trees in the world. Well-established ecological relationships, such as the Miami Model, predict relatively low NPPs for these forests (~250 g/m2/yr to 1300 g/m2/yr) due to winter cold limitation and summer drought. However, the observed rates of NPPs are quite high (up to 2000 g/m2/yr), raising the question of what environmental conditions and plant adaptations promote such a high NPP. We hypothesize that the trees in these forests are neither as cold-limited nor water-limited as surface weather station data suggest. Eddy covariance observations at the top of a 55 m tall micrometeorological tower located at 2050 m elevation indicate daytime CO2 uptake continues year round, and is not limited by winter cold or summer drought. Comparisons of temperature measurements on the tower with operational balloon soundings indicate that tree canopies are often in the free troposphere, which buffers the temperatures they experience and moderates winter cold limitation and summer evapotranspiration.

  4. Paleozoic-Mesozoic boundary in the Berry Creek Quadrangle, northwestern Sierra Nevada, California

    USGS Publications Warehouse

    Hietanen, Anna Martta

    1977-01-01

    Structural and petrologic studies in the Berry Creek quadrangle at the north end of the western metamorphic belt of the Sierra Nevada have yielded new information that helps in distinguishing between the chemically similar Paleozoic and Mesozoic rocks. The distinguishing features are structural and textural and result from different degrees of deformation. Most Paleozoic rocks are strongly deformed and thoroughly recrystallized. Phenocrysts in meta volcanic rocks are granulated and drawn out into lenses that have sutured outlines. In contrast, the phenocrysts in the Mesozoic metavolcanic rocks show well-preserved straight crystal faces, are only slightly or not at all granulated, and contain fewer mineral inclusions than do those in the Paleozoic rocks. The groundmass in the Paleozoic rocks is recrystallized to a fairly coarse grained albite-epidote-amphibole-chlorite rock, whereas in the Mesozoic rocks the groundmass is a very fine grained feltlike mesh with only spotty occurrence of well-recrystallized finegrained albite-epidote-chlorite-actinolite rock. Primary minerals, such as augite, are locally preserved in the Mesozoic rocks but are altered to a mixture of amphibole, chlorite, and epidote in the Paleozoic rocks. In the contact aureoles of the plutons, and within the Big Bend fault zone, which crosses the area parallel to the structural trends, all rocks are thoroughly recrystallized and strongly deformed. Identification of the Paleozoic and Mesozoic rocks in these parts of the area was based on the continuity of the rock units in the field and on gradual changes in microscopic textures toward the plutons.

  5. Characterizing the Networks of Digital Information that Support Collaborative Adaptive Forest Management in Sierra Nevada Forests

    NASA Astrophysics Data System (ADS)

    Lei, Shufei; Iles, Alastair; Kelly, Maggi

    2015-07-01

    Some of the factors that can contribute to the success of collaborative adaptive management—such as social learning, open communication, and trust—are built upon a foundation of the open exchange of information about science and management between participants and the public. Despite the importance of information transparency, the use and flow of information in collaborative adaptive management has not been characterized in detail in the literature, and currently there exist opportunities to develop strategies for increasing the exchange of information, as well as to track information flow in such contexts. As digital information channels and networks have been increased over the last decade, powerful new information monitoring tools have also been evolved allowing for the complete characterization of information products through their production, transport, use, and monitoring. This study uses these tools to investigate the use of various science and management information products in a case study—the Sierra Nevada Adaptive Management Project—using a mixed method (citation analysis, web analytics, and content analysis) research approach borrowed from the information processing and management field. The results from our case study show that information technologies greatly facilitate the flow and use of digital information, leading to multiparty collaborations such as knowledge transfer and public participation in science research. We conclude with recommendations for expanding information exchange in collaborative adaptive management by taking advantage of available information technologies and networks.

  6. Vegetation and climate history from Laguna de Río Seco, Sierra Nevada, southern Spain

    NASA Astrophysics Data System (ADS)

    Anderson, R. S.; Jimenez-Moreno, G.

    2010-12-01

    The largest mountain range in southern Spain - the Sierra Nevada - is an immense landscape with a rich biological and cultural heritage. Rising to 3,479 m at the summit of Mulhacén, the range was extensively glaciated during the late Pleistocene. Subsequent melting of cirque glaciers allowed formation of numerous small lakes and wetlands. One south-facing basin contains Laguna de Río Seco, a small lake at ca. 3020 m elevation, presently above potential treeline. Pollen analysis of sediment cores documents over 11,000 calendar years of vegetation change there. The early record, to ca. 5,700 cal yr BP, is dominated by pine pollen, with birch, deciduous oak, and grass, with an understory of shrubs types. Pine trees probably never grew at the elevation of the lake, but aquatic microfossils indicate lake levels were highest prior to ca. 7,800 cal yr BP, perhaps as a result of heavy winter precipitation, and early Holocene expansion of the ITCZ. Drier conditions commenced by 5,700 cal yr BP, shown by declines in wetland pollen, and increases in high elevation steppe shrubs more common today (juniper, sage, and others). The local and regional impact of humans increased substantially after ca. 2700 years ago, with the regional loss of pine forest or woodland, increases in pollen and spore types associated with pasturing, and olive cultivation at lower elevations.

  7. Evidence of multiple zoonotic agents in a wild rodent community in the eastern Sierra Nevada.

    PubMed

    Adjemian, Jennifer Zipser; Adjemian, Michael K; Foley, Patrick; Chomel, Bruno B; Kasten, Rickie W; Foley, Janet E

    2008-07-01

    This study aimed to describe the occurrence of Yersinia pestis, Rickettsia rickettsii, Anaplasma phagocytophilum, and ectoparasites in a wild rodent community in the eastern Sierra Nevada. From May to September 2006, rodents were live-trapped, examined for ectoparasites, and blood was collected. All rodents were serologically tested for antibodies to Y. pestis, R. rickettsii, and A. phagocytophilum; in addition, blood samples and ectoparasites were tested by PCR to detect the presence of these zoonotic agents. Overall, 89 rodents, 46 fleas, and four ticks were collected. Antibody prevalence rates observed for rodents were 14% for R. rickettsii or antigenically related spotted-fever group rickettsiae, and 8% for A. phagocytophilum. No samples were positive for antibodies to Y. pestis. Positive PCR results included one yellow-pine chipmunk for Y. pestis (CT=32.8), one golden-mantled ground squirrel for R. rickettsii (CT=33), and one flea found to be co-infected with both R. rickettsii (CT=17) and A. phagocytophilum (CT=36). The results of this study provide evidence of multiple zoonoses overlapping within a single, located rodent community.

  8. Origin of Meter-Size Granite Basins in the Southern Sierra Nevada, California

    USGS Publications Warehouse

    Moore, James G.; Gorden, Mary A.; Robinson, Joel E.; Moring, Barry C.

    2008-01-01

    Meter-size granite basins are found in a 180-km belt extending south from the South Fork of the Kings River to Lake Isabella on the west slope of the southern Sierra Nevada, California. Their origin has long been debated. A total of 1,033 basins have been inventoried at 221 sites. The basins occur on bedrock granitic outcrops at a median elevation of 1,950 m. Median basin diameter among 30 of the basin sites varies from 89 to 170 cm, median depth is 12 to 63 cm. Eighty percent of the basin sites also contain smaller bedrock mortars (~1-2 liters in capacity) of the type used by Native Americans (American Indians) to grind acorns. Features that suggest a manmade origin for the basins are: restricted size, shape, and elevation range; common association with Indian middens and grinding mortars; a south- and west-facing aspect; presence of differing shapes in distinct localities; and location in a food-rich belt with pleasant summer weather. Volcanic ash (erupted A.D. 1240+-60) in the bottom of several of the basins indicates that they were used shortly before ~760 years ago but not thereafter. Experiments suggest that campfires built on the granite will weaken the bedrock and expedite excavation of the basins. The primary use of the basins was apparently in preparing food, including acorns and pine nuts. The basins are among the largest and most permanent artifacts remaining from the California Indian civilization.

  9. Isolation of Jamestown Canyon virus from boreal Aedes mosquitoes from the Sierra Nevada of California.

    PubMed

    Campbell, G L; Eldridge, B F; Reeves, W C; Hardy, J L

    1991-03-01

    More than 28,000 mosquitoes in four genera were collected from high elevation (greater than or equal to 1,000 m) areas of California during 1988-89 and tested for virus by plaque assay in Vero cells. Viruses were serogrouped by enzyme immunoassay and serotyped by cross-neutralization. Six strains of Jamestown Canyon virus in the California serogroup were isolated from three species of boreal Aedes in the Aedes communis group of the subgenus Ochlerotatus. All isolates were from mosquitoes collected in Alpine County at approximately 2,300 m elevation in the Sierra Nevada. These included one virus from a pool of male Aedes cataphylla collected in immature stages, which is evidence for vertical transmission; four viruses from adult female Ae. communis (sens. lat.); and one virus from adult female Aedes hexodontus. These are the first isolations of viruses from boreal Aedes mosquitoes in California and the first reported isolations of Jamestown Canyon virus from Ae. cataphylla or Ae. hexodontus.

  10. Plant community influence on soil microbial response after a wildfire in Sierra Nevada National Park (Spain).

    PubMed

    Bárcenas-Moreno, Gema; García-Orenes, Fuensanta; Mataix-Solera, Jorge; Mataix-Beneyto, Jorge

    2016-12-15

    Plant community influence on microbial response after fire has been studied in a Sierra Nevada National Park area affected by a wildfire in 2005. Two different plant communities adapted to different altitudes were selected to analyse possible differences on soil microbial recolonisation process after fire, in oak forest and high mountain shrub communities. Microbial abundance, activity and community composition were monitored to evaluate medium-term changes. Microbial abundance was studied by mean of microbial biomass carbon and plate count methods; microbial activity was analysed by microbial respiration and bacterial growth while microbial community composition was determined by analysing phospholipid fatty acid pattern. Under unburnt conditions oak forest showed higher nutrient content, pH and microbial abundance and activity values than the high mountain shrubs community. Different parameters studied showed different trends with time, highlighting important changes in microbial community composition in high mountain shrubs from first sampling to the second one. Post-fire recolonisation process was different depending on plant community studied. Highlighting fungal response and microbial activity were stimulated in burnt high mountain shrubs community whilst it was negatively affected in oak forest. Fire induced changes in oak forest were almost neutralized 20months after the fire, while high mountain shrubs community still showed fire-induced changes at the end of the study.

  11. Jurassic tectonic wedging and crustal block rotation, northern Sierra Nevada California

    SciTech Connect

    Harwood, D.S.; Griscom, A. )

    1993-04-01

    Rocks in the northern Sierra Nevada east of the Feather River peridotite belt (FRPB) and south of 39[degree]45 minutes N. strike NNW, dip steeply E and form an east-facing homoclinal section as much as 35km thick. The lower Paleozoic Shoo Fly Complex (SFC), the oldest and western-most unit in the homoclinal section, is faulted against the FRPB. Middle Jurassic volcanic rocks (Jv) at the top of the homoclinal section are down-faulted against Paleozoic rocks to the east along the Talbot fault (TF). A positive aeromagnetic anomaly and east-sloping gradient south of 39[degree]45 minutes N. indicate that the east contact of the FRPB dips about 45[degree]E. beneath the homoclinal section and extends to a depth of at least 10km. The contact between the buried FRPB and the homoclinal section is interpreted to be the roof thrust of an east-tapering wedge of serpentinized oceanic crust and upper mantle, probably emplaced in the Early and Middle Jurassic. Normal, west-down displacement on the Talbot fault, contemporaneous with east-vergent edging, resulted in eastward block rotation of the rocks above the wedge, syndepositional thickening of the Early and Middle Jurassic Sailor Canyon Formation (Jsc) relative to the coeval rocks east of the Talbot fault, and structural control for Middle Jurassic magmatism.

  12. [Dung beetles (Coleoptera: Scarabaeinae) of the northwestern slope of the Sierra Nevada of Santa Marta, Colombia].

    PubMed

    Martínez, Neis J; García, Héctor; Pulido, Luz A; Ospino, Deibi; Harváez, Juan C

    2009-01-01

    The community structure of dung beetles in the middle and lower river basin of the Gaira river, Sierra Nevada de Santa Marta, Colombia, is described. Four sites were selected along an altitudinal gradient of 50-940 m for sampling from June to October, 2004. Dung beetles were captured using modified pitfall traps and manual recollections. We captured 7,872 individuals belonging to 29 species, distributed in 15 genera and five tribes of Scarabaeinae. Canthon and Onthophagus were the most diverse genera, each represented by six species. The sampled sites shared the following species: Onthophagus acuminatus Harold, O. clypeatus Blanchard, O. marginicollis Harold. Bocatoma was the most diverse site with 23 species; whereas Port Mosquito presented the highest abundance, with 3,262 individuals. Seven species represented 89% of all captures: Canthidium sp., Dichotomius sp., Uroxys sp. 1, Uroxys sp. 2, O. marginicollis, O. clypeatus and O. acuminatus. Of the 29 captured species, 17 belonged to the functional group of diggers and 10 were ball-rollers. We did not observe significant among-site differences in community structure. Abiotic factors such as altitude, temperature and humidity cannot explain observed variation in community structure across sites, indicating other variables such as vegetation cover, density of the vegetation and soil type may play a role in the community structure of these insects.

  13. Morphology of small, discontinuous montane meadow streams in the Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Slocombe, Michelle L.; Davis, Jerry D.

    2014-08-01

    Various fluvial geomorphic models have been developed to characterize the relationships between planform and bedform features of large alluvial channels; however, little information exists for meadow channel morphology. Field investigation of seven narrow, low-energy meadow stream reaches in the northern Sierra Nevada range of California revealed similarities and differences to larger alluvial channels. The average radius of curvature to channel width ratio (5.54) of the meadow streams was almost double that of larger alluvial streams (3.1), with a standard deviation of 4.66. Average meander wavelength to channel width ratio (22.43) was almost triple that of typical alluvial streams (8.5), with a standard deviation of 16.80. Bedform features occurred at an average of 6.72 channel widths, similar to typical pool-riffle spacing of 5-7 channel widths. Grass sod connected a series of scour pools, providing the same energy drop function as riffles or steps. Results suggest that bedform regularity is similar to typical pool-riffle systems, especially as we move to larger watersheds and higher precipitation and runoff, but planform features are less developed and highly influenced by vegetation. Restoration efforts can benefit from considering how planform and bedform channel patterns develop in these meadows.

  14. Calibrating Late Quaternary terrestrial climate signals: radiometrically dated pollen evidence from the southern Sierra Nevada, USA

    USGS Publications Warehouse

    Litwin, Ronald J.; Smoot, Joseph P.; Durika, Nancy J.; Smith, George I.

    1999-01-01

    We constructed a radiometrically calibrated proxy record of Late Pleistocene and Holocene climate change exceeding 230,000 yr duration, using pollen profiles from two cores taken through age-equivalent dry lakes - one core having greater age control (via 230Th alpha mass-spectrometry) and the other having greater stratigraphic completeness. The better dated of these two serial pollen records (Searles Lake) served as a reference section for improving the effective radiometric age control in a nearby and more complete pollen record (Owens Lake) because they: (1) are situated ~90 km apart in the same drainage system (on, and immediately leeward of, the eastern flank of the Sierra Nevada), and (2) preserved strikingly similar pollen profiles and concordant sequences of sedimentological changes. Pollen assemblages from both lakes are well preserved and diverse, and document serial changes in Late Pleistocene and Holocene plant zone distribution and composition in the westernmost Great Basin; they consist of taxa now inhabiting montane forest, woodland, steppe, and desert-scrub environments. The studied core intervals are interpreted here to be the terrestrial equivalent of marine δ18O stages 1 through 9; these pollen profiles now appear to be among the best radiometrically dated Late Pleistocene records of terrestrial climate change known.

  15. [Presence, abundance and reproductive strategies of ferns in disturbed areas of Sierra Nevada, México].

    PubMed

    Rodríguez Romero, Ma Lucía; Zavala Hurtado, José Alejandro; Pacheco, Leticia

    2011-03-01

    Diverse reproductive strategies shown by ferns and lycophytes allow them to colonize a variety of habitats, particularly after the incidence of natural or anthropogenic disturbances. This study assessed the presence, abundance and reproductive strategies of ferns growing in soils of temperate forests with different levels of disturbance at the Sierra Nevada mountain range in the State of Mexico. Vegetation, soil and environmental variables were recorded in 200 m2 permanent plots located in four forest stands. One-Way ANOVA and Canonical Correspondence Analysis resulted in the recognition of three landscape types defined by the degree of environmental alteration: low, moderate and severe. Also, from five soil samples collected in each stand, germination of ferns and lycophytes was induced. A positive relationship was found between the alteration degree and Cheilanthes abundance. Under a low landscape alteration regime, species richness is restricted to Cheilanthes bonariensis, C. marginata and Pellaea ternifolia subsp. ternifolia. The soil is a reservoir of spores of Cheilanthes and Pellaea ternifolia subsp. ternifolia because their spores can remain viable for different time intervals. Apogamy is the usual reproductive strategy of Cheilanthes species in disturbed ecosystems, although these species also show sexual reproduction in natural ecosystems with adequate water availability. Apogamy may be related to a shorter generation time in comparison with a low disturbed ecosystem. On the other hand, Pellaea ternifolia subsp. ternifolia only has sexual reproduction. Apogamy might be related to a faster generation in comparison with a low disturbed ecosystem.

  16. Characterizing the Networks of Digital Information that Support Collaborative Adaptive Forest Management in Sierra Nevada Forests.

    PubMed

    Lei, Shufei; Iles, Alastair; Kelly, Maggi

    2015-07-01

    Some of the factors that can contribute to the success of collaborative adaptive management--such as social learning, open communication, and trust--are built upon a foundation of the open exchange of information about science and management between participants and the public. Despite the importance of information transparency, the use and flow of information in collaborative adaptive management has not been characterized in detail in the literature, and currently there exist opportunities to develop strategies for increasing the exchange of information, as well as to track information flow in such contexts. As digital information channels and networks have been increased over the last decade, powerful new information monitoring tools have also been evolved allowing for the complete characterization of information products through their production, transport, use, and monitoring. This study uses these tools to investigate the use of various science and management information products in a case study--the Sierra Nevada Adaptive Management Project--using a mixed method (citation analysis, web analytics, and content analysis) research approach borrowed from the information processing and management field. The results from our case study show that information technologies greatly facilitate the flow and use of digital information, leading to multiparty collaborations such as knowledge transfer and public participation in science research. We conclude with recommendations for expanding information exchange in collaborative adaptive management by taking advantage of available information technologies and networks.

  17. Bronchopulmonary nematode infection of Capra pyrenaica in the Sierra Nevada massif, Spain.

    PubMed

    Alasaad, S; Morrondo, P; Dacal-Rivas, V; Soriguer, R C; Granados, J E; Serrano, E; Zhu, X Q; Rossi, L; Pérez, J M

    2009-10-14

    The present investigation examined the prevalence and abundance of bronchopulmonary nematodes in 213 randomly hunted Iberian ibexes (Capra pyrenaica) (87 females and 126 males) in the Sierra Nevada mountain range in Spain between 2003 and 2006. Post mortem examination revealed an overall prevalence of 72% for adult nematodes (Cystocaulus ocreatus 44%, Muellerius capillaris 44%, Protostrongylus sp. 40%, and Dictyocaulus filaria 4%). The abundances were 13.45+/-3.97, 5.18+/-2.49, 6.36+/-2.16, and 2.27+/-0.46, respectively. Protostrongylid adults showed similar infection rates, which were statistically different from that of D. filaria. 20% of the examined Iberian ibexes were infected by three protostrongylid nematodes species, 24% of C. pyrenaica were affected by two protostrongylid species, while infestations with only one protostrongylid species were detected in 20% of the examined animals. The overall prevalence of larvae nematodes in the examined animals was 100%, and the overall abundance (number of the first stage larvae per gram) was 86.45+/-20.63. There was a high correlation between the two sets of data (adults and larvae). Results of the present investigation provided foundation for the effective control of bronchopulmonary nematode infection in Iberian ibex.

  18. Precipitation chemistry in and ionic loading to an alpine basin, Sierra Nevada

    SciTech Connect

    Williams, M.W.; Melack, J.M. )

    1991-07-01

    Wet deposition of solutes to an alpine catchment in the southern Sierra Nevada was measured from October 1984 through March 1988. Rainfall had a volume-weighted pH of 4.9, and snowfall had a volume-weighted pH of 5.3. Acetic and formic acids were important components of all wet deposition, contributing 25-30% of the measured anions in snowfall and, through analysis of charge balance deficits, the same percentage in rainfall. The NO{sub 3}{sup {minus}} to SO{sub 4}{sup 2{minus}} equivalent ratio for all wet deposition was 1.16. Ammonium concentration was tenfold greater than H{sup +} in rainfall: ammonium nitrate and ammonium sulfate appear to be the principal nitrate and sulfate containing aerosols in wet deposition. Snowmelt runoff (1985 and 1986) or snowpack runoff plus rainfall during the period of snowpack runoff (1987) supplied 90% of the annual solute flux from wet deposition to the catchment. Data show that dry deposition was not an important contributor of H{sup +}, NO{sub 3}{sup {minus}}, and SO{sub 4}{sup 2{minus}} to the winter snowpack. The source of the ions in snowfall was air masses that originated over the Pacific Ocean, while low Cl{sup {minus}} and Na{sup +} relative to NO{sub 3}{sup {minus}} and NH{sub 4}{sup +} in rainfall indicate that local urban and agricultural areas were the major source of the ions in rainfall.

  19. Remote sensing aided procedure for conifer growth modeling in the northeastern Sierra Nevada

    NASA Technical Reports Server (NTRS)

    Smith, H. G.; Khorram, S.

    1981-01-01

    The objective of this study was to use remotely-sensed data with ground-acquired data for preparing inputs to a mathematical model for generation of a potential conifer growth map of a wildland area. The study area, jointly selected by the resource managers of the U.S. Forest Service at the Plumas National Forest and researchers, covers approximately 500 sq km in the northeastern scrapment of Sierra Nevada. The approach involved a computerized databank based on both remotely-sensed and ground-acquired data. The remotely-sensed data included Landsat Multispectral Scanner (MSS) data, NOAA-5 Very High Resolution Radiometer (VHRR) data and U-2 Color infrared photography. The ground data included U.S. Geological Survey (USGS) topographic maps, Defense Mapping Agency (DMA)/USGS digital terrain data, soil maps, and vegetation data. The results included a series of maps for the final product as well as the intermediate products. The intermediate products were potential evapotranspiration, aspect, and soil plant available water.

  20. Timing and new geomorphologic evidence of the last deglaciation stages in Sierra Nevada (southern Spain)

    NASA Astrophysics Data System (ADS)

    Palacios, David; Gómez-Ortiz, Antonio; Andrés, Nuria; Salvador, Ferrán; Oliva, Marc

    2016-10-01

    The main objective of this research is to improve knowledge of the deglaciation stages in Sierra Nevada (southern Spain) by applying 36Cl cosmogenic exposure dating to 28 samples from moraine and fossil rock glacier boulders and glacial polished surfaces, in 5 glaciated valleys around Veleta Peak (3396 m asl; 37°03‧02″N 3°20‧54″W). The results show that shortly before the Last Glacial Maximum (LGM) and during the LGM, the heads of the glacial valleys were occupied by ice tongues, with possible glacial transfluence between the valleys. After 19 ka, a major glacial regression started, but glaciers during the Oldest Dryas (OD) expanded again and refilled the valley bottoms. The glacial advances of the pre-LGM, LGM and OD formed polygenic moraine systems. During the Bølling-Allerød the glaciers receded and probably disappeared. Thereafter, the valley bottoms remained ice-free. During the Younger Dryas (YD) small glaciers developed again, but only in cirques shaped on east-facing slopes. Subsequently, these glaciers started retreating towards their valley heads and finally disappeared completely. With the onset of the Holocene, rock glaciers developed inside the deglaciated cirques on the eastern slopes of some valleys, but only under the most active and protected headwalls did large complex rock glaciers develop and remained active until the mid-Holocene.

  1. Spring onset in the Sierra Nevada: When is snowmelt independent of elevation?

    USGS Publications Warehouse

    Lundquist, J.D.; Cayan, D.R.; Dettinger, M.D.

    2004-01-01

    Short-term climate and weather systems can have a strong influence on mountain snowmelt, sometimes overwhelming the effects of elevation and aspect. Although most years exhibit a spring onset that starts first at lowest and moves to highest elevations, in spring 2002, flow in a variety of streams within the Tuolumne and Merced River basins of the southern Sierra Nevada all rose synchronously on 29 March. Flow in streams draining small high-altitude glacial subcatchments rose at the same time as that draining much larger basins gauged at lower altitudes, and streams from north- and south-facing cirques rose and fell together. Historical analysis demonstrates that 2002 was one among only 8 yr with such synchronous flow onsets during the past 87 yr, recognized by having simultaneous onsets of snowmelt at over 70% of snow pillow sites, having discharge in over 70% of monitored streams increase simultaneously, and having temperatures increase over 12??C within a 5-day period. Synchronous springs tend to begin with a low pressure trough over California during late winter, followed by the onset of a strong ridge and unusually warm temperatures. Synchronous springs are characterized by warmer than average winters and cooler than average March temperatures in California. In the most elevation-dependent, nonsynchronous years, periods of little or no storm activity, with warmer than average March temperatures, precede the onset of spring snowmelt, allowing elevation and aspect to influence snowmelt as spring arrives gradually. ?? 2004 American Meteorological Society.

  2. Forest reproduction along a climatic gradient in the Sierra Nevada, California

    USGS Publications Warehouse

    van Mantgem, P.J.; Stephenson, N.L.; Keeley, J.E.

    2006-01-01

    To elucidate broad-scale environmental controls of coniferous forest reproduction in the Sierra Nevada, California, we monitored reproduction for 5 years in 47 plots arrayed across a steep elevational (climatic) gradient. We found that both absolute seedling densities (stems < 1.37 m) and seedling densities relative to overstory parent tree basal area declined sharply with elevation. Rates of seedling turnover (the average of birth and death rates) also declined with elevation. In contrast, seed production was not predicted by elevation and was highly variable from year to year. During a mast year of seed production, the intensity of masting was uneven among plots. Seedling densities were elevated only during the single year immediately following the mast year, suggesting reproduction in our forests may be primarily limited by abiotic factors such as the availability of suitable sites and weather. Disturbance also clearly affected reproduction; plots that had recently burned had significantly higher seedling to parent tree ratios for Abies species, suggesting that even though established Abies concolor may be relatively susceptible to fire, the species can recover rapidly through prolific reproduction. Since reproductive failures may be our earliest signal of changing forest conditions, seedling dynamics could provide a sensitive, if variable, indicator of environmental changes. ?? 2006 Elsevier B.V. All rights reserved.

  3. Relationships between winter atmospheric circulation patterns and extreme tree growth anomalies in the Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Garfin, Gregg M.

    1998-06-01

    Tree-ring data from mid-elevation (2000 m) giant sequoia (Sequoiadendron giganteum) and high elevation (3500 m) pines (Pinus balfouriana, Pinus albicaulis) were used to select extreme growth years from which temperature, precipitation and large-scale winter (November-March, NM) 500 mb circulation patterns associated with the extreme tree growth anomalies were examined.Winters preceding extreme high growth in both giant sequoia and pines are warm and wet and are characterized by anomalous low pressure in the northeastern Pacific Ocean and a tendency for southwesterly flow and advection of warm maritime air into California. For the pines, such winters exhibit a pattern of anomalous low pressure in the northern Pacific, anomalous high pressure over northwestern Canada and anomalous low pressure across the southern US. NM 500 mb heights suggest more meridional circulation during the warm and dry winters preceding extreme low growth in giant sequoia. Atmospheric circulation during these winters exhibits a persistent trough/ridge pattern between the central Pacific and the western US. Storms are deflected away from California during these winters. NM atmospheric circulation patterns associated with extreme low growth in the pines exhibit maximum westerlies north of their mean position and the tendency for enhanced ridging in the northeast Pacific, which advects cool dry air into the Sierra Nevada. As dendroclimatic reconstructions are more frequently employed in order to better understand past variability of temperature and precipitation, synoptic dendroclimatological studies such as this one provide useful insights about atmospheric circulation.

  4. Ten Years of Forest Cover Change in the Sierra Nevada Detected Using Landsat Satellite Image Analysis

    NASA Technical Reports Server (NTRS)

    Potter, Christopher S.

    2014-01-01

    The Landsat Ecosystem Disturbance Adaptive Processing System (LEDAPS) methodology was applied to detected changes in forest vegetation cover for areas burned by wildfires in the Sierra Nevada Mountains of California between the periods of 1975- 79 and 1995-1999. Results for areas burned by wildfire between 1995 and 1999 confirmed the importance of regrowing forest vegetation over 17% of the combined burned areas. A notable fraction (12%) of the entire 5-km (unburned) buffer area outside the 1995-199 fires perimeters showed decline in forest cover, and not nearly as many regrowing forest areas, covering only 3% of all the 1995-1999 buffer areas combined. Areas burned by wildfire between 1975 and 1979 confirmed the importance of disturbed (or declining evergreen) vegetation covering 13% of the combined 1975- 1979 burned areas. Based on comparison of these results to ground-based survey data, the LEDAPS methodology should be capable of fulfilling much of the need for consistent, low-cost monitoring of changes due to climate and biological factors in western forest regrowth following stand-replacing disturbances.

  5. Age, geochemical composition, and distribution of Oligocene ignimbrites in the northern Sierra Nevada, California: Implications for landscape morphology, elevation, and drainage divide geography of the Nevadaplano

    USGS Publications Warehouse

    Cassel, E.J.; Calvert, A.T.; Graham, S.A.

    2009-01-01

    To gain a better understanding of the topographic and landscape evolution of the Cenozoic Sierra Nevada and Basin and Range, we combine geochemical and isotopic age correlations with palaeoaltimetry data from widely distributed ignimbrites in the northern Sierra Nevada, California. A sequence of Oligocene rhyolitic ignimbrites is preserved across the modern crest of the range and into the western foothills. Using trace and rare earth element geochemical analyses of volcanic glass, these deposits have been correlated to ignimbrites described and isotopically dated in the Walker Lane fault zone and in central Nevada (Henry et al., 2004, Geologic map of the Dogskin mountain quadrangle; Washoe County, Nevada; Faulds et al., 2005, Geology, v. 33, p. 505-508). Ignimbrite deposits were sampled within the northern Sierra Nevada and western Nevada, and four distinct geochemical compositions were identified. The majority of samples from within the northern Sierra Nevada have compositions similar to the tuffs of Axehandle Canyon or Rattlesnake Canyon, both likely sourced from the same caldera complex in either the Clan Alpine Mountains or the Stillwater Range, or to the tuff of Campbell Creek, sourced from the Desatoya Mountains caldera. New 40Ar/39Ar age determinations from these samples of 31.2, 30.9, and 28.7Ma, respectively, support these correlations. Based on an Oligocene palinspastic reconstruction of the region, our results show that ignimbrites travelled over 200km from their source calderas across what is now the crest of the Sierra Nevada, and that during that time, no drainage divide existed between the ignimbrite source calderas in central Nevada and sample locations 200km to the west. Palaeoaltimetry data from Sierra Nevada ignimbrites, based on the hydrogen isotopic composition of hydration water in glass, reflect the effect of a steep western slope on precipitation and indicate that the area had elevations similar to the present-day range. These combined

  6. Eocene Topography of the Northern Sierra Nevada: Direct Paleoelevation Evidence from Hydrogen Isotopes in Kaolinite of Paleostream Channels

    NASA Astrophysics Data System (ADS)

    Mulch, A.; Graham, S. A.; Chamberlain, C. P.

    2005-12-01

    The links and feedbacks among topography, tectonics, and climate remain a poorly understood yet important problem in Earth Sciences. Large mountains and high-elevation plateaux exert a strong control on global climate and it is, therefore, critical to understand their topographic history. Despite its importance to global climate change relatively little is known of the Cenozoic topographic development of the western North America. For example, there is considerable debate as to when the Sierra Nevada developed as a mountain range, with one view that the bulk of elevation gain took place in the last 3-5 Ma and the other that it already existed as a major topographic feature throughout much of the Cenozoic. To address this debate we examined the hydrogen isotope composition of kaolinite from weathered Eocene fluvial sediments. These sediments, well known because of past gold mining, occur within Eocene river channels cut into the western flank of the northern Sierra Nevada and are found from paleo-sea level upstream into the modern range. Our results show that the deltaD of kaolinite along paleoslopes decreases systematically by up to 25 per mil within different paleodrainage systems from a high of -80 per mil in sediments deposited at the current base of the Sierra to -106 per mil about 60 km eastward on the flank of the Sierra Nevada. The observed isotopic difference between downstream and upstream samples suggests that the highest altitude samples, collected at ca. 1600 m current elevation, were deposited at Eocene elevations of 1100 m to 1300 m. Thus, Eocene topographic gradients may have been lower than todays, but still reflect mountainous topography, consistent with pebble- to cobble-sized clasts that dominate the Eocene fluvial deposits. Viewed in context of other isotopic and geomorphic studies, we therefore suggest that mountainous topography characterized the Eocene northern Sierra Nevada whose western flank was occupied by high discharge river systems

  7. The Impacts of California's San Francisco Bay Area Gap on Precipitation Observed in the Sierra Nevada during Hmt and Calwater

    NASA Astrophysics Data System (ADS)

    White, A. B.; Neiman, P. J.; Creamean, J.; Coleman, T.; Ralph, F. M.; Prather, K. A.

    2014-12-01

    The National Oceanic and Atmospheric Administration (NOAA)'s Hydrometeorology Testbed (HMT; hmt.noaa.gov) conducts research on the meteorological and microphysical processes contributing to orographically enhanced precipitation. Some of HMT's precipitation research has been focused on a shallow rainfall process driven by collision-coalescence that often is undetected by the National Weather Service's operational scanning radar network, especially in the Western U.S., but that can produce rain rates that are capable of creating floods. Originally it was believed that this shallow rainfall process would occur more prevalently over the coastal mountain ranges than over the Sierra Nevada, since the higher mountains of the Sierra would force deeper atmospheric ascent and produce deeper precipitating cloud systems that extend well above the melting level. This notion was disproved when it was recently discovered that a site in the northern Sierra had nearly as large of a contribution to seasonal rainfall from this shallow rainfall process, on average, as did a habitually wet site in the coast range of Sonoma County north of San Francisco. This work examines this apparent paradox using observations collected during HMT and CalWater field campaigns. In particular, a case study from CalWater is used to highlight the interaction between a landfalling atmospheric river (AR) and the Sierra Barrier Jet (SBJ). The gap in coastal terrain associated with the San Francisco Bay area is shown to allow unprocessed, moisture-enhanced flow in the AR to reach the northern Sierra site, where the SBJ provides a lifting mechanism to create enhanced orographic precipitation as compared to a site in the southern Sierra, where AR-associated dynamics are weaker and AR flow is modified by upstream coastal terrain.

  8. Physical and biogeochemical controls on polymictic behavior in Sierra Nevada stream pools

    NASA Astrophysics Data System (ADS)

    Lucas, R. G.; Conklin, M. H.; Tyler, S. W.; Suarez, F. I.; Moran, J. E.; Esser, B. K.

    2011-12-01

    We observed polymictic behavior in stream pools in a low gradient montane meadow in the southern Sierra Nevada mountains, California. Thermal stratification in stream pools has been observed in various environments; stratification generally persists where the buoyancy forces created by a variation in water density, as a function of water temperature, are able to overcome turbulent forces resulting from stream flow. Because the density gradient creates a relatively weak buoyancy force, low flow conditions are generally required in order to overcome the turbulent forces. In some studies, a cold water source in to the pool bottoms can help to increase the density gradient and perpetuate thermal stratification. Our study took place in Long Meadow, Sequoia National Park, California. Long Meadow lies in the Wolverton Creek watershed and is part of the Southern Sierra Critical Zone Observatory. The 1-4 m diameter and 1-2 m deep pools in our study stratified thermally during the day and mixed completely at night. The low gradient of the meadow provided low stream flows. Piezometers in the meadow indicated groundwater discharge into the meadow in the months during which stratification was observed. Radon 222 activity measured in the pools also indicated groundwater influx to the pool bottoms. We used Fluent, a computational fluid dynamics equation solver, to construct a model of one of the observed pools. Initially we attempted to model the physical mechanisms controlling thermal stratification in the pool including stream flow, groundwater discharge, solar radiation, wind speed, and air, stream and ground water temperatures. Ultimately we found the model best agreed with our observed pool temperatures when we considered the light attenuation coefficients as a function of the dissolve organic carbon (DOC) concentration. Elevated DOC concentrations are expected in low stream flow regimes associated with highly organic soils such as a montane meadow. DOC concentrations

  9. Effect of Tree-to-Shrub Type Conversion in Lower Montane Forests of the Sierra Nevada (USA) on Streamflow

    PubMed Central

    Tague, Christina L.; Moritz, Max A.

    2016-01-01

    Higher global temperatures and increased levels of disturbance are contributing to greater tree mortality in many forest ecosystems. These same drivers can also limit forest regeneration, leading to vegetation type conversion. For the Sierra Nevada of California, little is known about how type conversion may affect streamflow, a critical source of water supply for urban, agriculture and environmental purposes. In this paper, we examined the effects of tree-to-shrub type conversion, in combination with climate change, on streamflow in two lower montane forest watersheds in the Sierra Nevada. A spatially distributed ecohydrologic model was used to simulate changes in streamflow, evaporation, and transpiration following type conversion, with an explicit focus on the role of vegetation size and aspect. Model results indicated that streamflow may show negligible change or small decreases following type conversion when the difference between tree and shrub leaf areas is small, partly due to the higher stomatal conductivity and the deep rooting depth of shrubs. In contrast, streamflow may increase when post-conversion shrubs have a small leaf area relative to trees. Model estimates also suggested that vegetation change could have a greater impact on streamflow magnitude than the direct hydrologic impacts of increased temperatures. Temperature increases, however, may have a greater impact on streamflow timing. Tree-to-shrub type conversion increased streamflow only marginally during dry years (annual precipitation < 800 mm), with most streamflow change observed during wetter years. These modeling results underscore the importance of accounting for changes in vegetation communities to accurately characterize future hydrologic regimes for the Sierra Nevada. PMID:27575592

  10. Assessing the combined effect of dams and climate warming on streamflow in California's Sierra Nevada for regional-scale adaptation

    NASA Astrophysics Data System (ADS)

    Rheinheimer, D. E.; Viers, J. H.

    2012-12-01

    Dams and their operations harm river ecosystems, in part by altering the natural flow regimes that those ecosystems depend on. In the multi-reservoir water management systems of California's Sierra Nevada, greater emphasis is being placed on re-operating existing reservoir systems to recover downstream ecosystems. However, climate change is changing inflow patterns, affecting both ecosystems and traditional water system benefits across the region. As new reservoir operation schemes will be needed to manage for natural resources management objectives at the regional scale, characterizing historical and future environmental impacts of current operations across the region can aid in prioritizing planning efforts. We used a coarse-scale water resources simulation model developed for the western Sierra Nevada to explore the independent and combined effects of dams and climate warming on the flow regime directly below reservoirs, the focal point for instream flow requirements in operations licenses. We quantified changes to mean annual flow, annual low flow duration, annual runoff centroid timing, and weekly rate of decrease under binary combinations of management (unregulated/regulated) and climate (historical/future) conditions. We demonstrate that although rivers in the Sierra Nevada are currently managed in ways that are harmful to instream ecosystems, and that streamflow effects of operations are typically much worse than climate change effects, there are signals that reservoirs can potentially be used to help adapt to some of climate changes harmful effects with little additional effort in some cases. This study is the first step toward a better understanding of the environmental costs from and opportunities afforded by the current stock of reservoirs in a large hydroregion under changing social and environmental conditions.

  11. Effect of Tree-to-Shrub Type Conversion in Lower Montane Forests of the Sierra Nevada (USA) on Streamflow.

    PubMed

    Bart, Ryan R; Tague, Christina L; Moritz, Max A

    2016-01-01

    Higher global temperatures and increased levels of disturbance are contributing to greater tree mortality in many forest ecosystems. These same drivers can also limit forest regeneration, leading to vegetation type conversion. For the Sierra Nevada of California, little is known about how type conversion may affect streamflow, a critical source of water supply for urban, agriculture and environmental purposes. In this paper, we examined the effects of tree-to-shrub type conversion, in combination with climate change, on streamflow in two lower montane forest watersheds in the Sierra Nevada. A spatially distributed ecohydrologic model was used to simulate changes in streamflow, evaporation, and transpiration following type conversion, with an explicit focus on the role of vegetation size and aspect. Model results indicated that streamflow may show negligible change or small decreases following type conversion when the difference between tree and shrub leaf areas is small, partly due to the higher stomatal conductivity and the deep rooting depth of shrubs. In contrast, streamflow may increase when post-conversion shrubs have a small leaf area relative to trees. Model estimates also suggested that vegetation change could have a greater impact on streamflow magnitude than the direct hydrologic impacts of increased temperatures. Temperature increases, however, may have a greater impact on streamflow timing. Tree-to-shrub type conversion increased streamflow only marginally during dry years (annual precipitation < 800 mm), with most streamflow change observed during wetter years. These modeling results underscore the importance of accounting for changes in vegetation communities to accurately characterize future hydrologic regimes for the Sierra Nevada.

  12. Distrubution of the Endocrine Disruptor Nonylphenol and the Effects of Topographical Sheilding in an Eastern Sierra Nevada Mountain Drainage

    NASA Astrophysics Data System (ADS)

    Lyons, R. A.; Van de Bittner, K.; Morgan Jones, S.

    2013-12-01

    Nonylphenol is a biodegradation product of nonylphenol polyethoxylates, a pervasive compound used in many industrial processes and notably in pesticides as a surfactant. Nonylphenol has been shown to act as an endocrine disruptor at low concentrations. It causes hermaphrodism, birth defects, and high mortality in fish, frogs and other amphibians. The Sierra Nevada Mountains separate the Central Valley in the west from the high desert of Mono Country on the east side of the state of California. The Central Valley represents some of the most heavily cultivated agricultural land in the United States. San Joaquin County alone had an annual pesticide use of over 8 million pounds in 2009 according to the Pesticide Action Network, compared with 4800 pounds in Mono County the same year. Fragile alpine ecosystems in the Sierra Nevadas may be highly susceptible to the effects of endocrine disruptors like nonylphenol. The distribution of nonylphenol is affected by localized topography in a steep walled montane canyon in the Eastern Sierra Nevada Mountains, Convict Creek canyon. The concentration of nonylphenol in snow and surface water increases as the elevation in Convict Creek canyon decreases in an easterly direction from not detectable at the highest elevations to as much as .01mg/L in water and 1.8 mg/L in snow at the lowest elevations. The steep head wall of Convict Creek canyon, facing southeast, provides shielding to the higher elevation lakes from deposition of compounds and particulate matter. As a canyon becomes less steep and broader, more nonylphenol is deposited. Identifying these deposition patterns may assist in determining amphibian and fish populations that are at higher risk of negative impact from these compounds.

  13. Research design for hydrologic response to watershed treatments in the mixed conifer zone of California's Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Battles, J.; Bales, R.; Conklin, M.; Saksa, P.; Martin, S.

    2008-12-01

    Water quantity response to forest management is of great interest in California's Sierra Nevada, owing to shifts in the rain-snow transition elevation associated with climate change, increasing value of hydropower from high-elevation dams, and the re-examination of adaptive management strategies for wildfire mitigation. In 2006 we initiated a multi-disciplinary research program to inform adaptive management for Forest Service lands in the Sierra Nevada. The forest treatment approach is based on disconnected, overlapping fuel treatment patches (forest thinning) to reduce the rate and intensity of fire. As little as 30% of the area in a given catchment will be treated. Controlling for confounding influences is particularly challenging when the experimental unit is a whole landscape and the inferential reference is an entire region. To isolate water and ecosystem impacts related to forest thinning, we are using a Before After Control Impact (BACI) design in conjunction with mechanistic modeling. BACI compensates for the sparse replication (2 sites) and the non- random assignment of the treatments by providing robust longitudinal controls. BACI design defines two treatments, a control and an impact. For modeling fire and wildlife response we chose subdivided the region into two 40-km2 sub-firesheds; within each is a 1-km2 hydrologic study catchment. The control site in this a measure of natural variation rather than a true control. Meta-replication using parallel studies in the Sierra Nevada with different approaches is also an important component and involves a creative combination of data from multiple sources. Rather than statistical comparisons or traditional hypothesis testing, we will measure the support in the data for our a priori expectations using mechanistic models. We are currently evaluating how to extend this research design to private forest lands with a wider range of management options.

  14. Do High-elevation Lakes Record Variations in Snowfall and Atmospheric Rivers in the Sierra Nevada of California?

    NASA Astrophysics Data System (ADS)

    Ashford, J.; Sickman, J. O.; Lucero, D. M.

    2014-12-01

    Understanding the underlying causes of interannual variation in snowfall and extreme hydrologic events in the Sierra Nevada is hampered by short instrumental records and the difficulties in reconstructing climate using a traditional paleo-record such as tree-rings. New paleo proxies are needed to provide a record of snowpack water content and extreme precipitation events over millennial timescales which can be used to test hypotheses regarding teleconnections between Pacific climate variability and water supply and flood risk in California. In October 2013 we collected sediment cores from Pear Lake (z = 27 m), an alpine lake in Sequoia National Park. The cores were split and characterized by P-wave velocity, magnetic susceptibility and density scanning. Radiocarbon dates indicate that the Pear Lake cores contain a 13.5K yr record of lake sediment. In contrast to other Sierra Nevada lakes previously cored by our group, high-resolution scanning revealed alternating light-dark bands (~1 mm to 5 mm thick) for most of the Pear Lake core length. This pattern was interrupted at intervals by homogenous clasts (up to 75 mm thick) ranging in grain size from sand to gravel up to 1 cm diameter. We hypothesize that the light-dark banding results from the breakdown of persistent hypolimnetic anoxia during spring snowmelt and autumn overturn. We speculate that the thicknesses of the dark bands are controlled by the duration of anoxia which in turn is controlled by the volume and duration of snowmelt. The sand to gravel sized clasts are most likely associated with extreme precipitation events resulting from atmospheric rivers intersecting the southern Sierra Nevada. We hypothesize that centimeter-sized clasts are deposited in large avalanches and that the sands are deposited in large rain events outside of the snow-cover period.

  15. Evidence for Discrete and Distributed Deformation Accommodated by Bookshelf Faulting From the Central Sierra Nevada, California.

    NASA Astrophysics Data System (ADS)

    Clemons, K. M.; Bartley, J.

    2008-12-01

    Evidence for right-lateral strike-slip faulting along the eastern Sierran Nevada has been identified by a number of workers and these offsets at least partially occurred during late Cretaceous arc plutonism. This evidence includes large magnitude dextral offsets across subvertical ~ north striking faults of the Sr - 0.706 line, Paleozoic metasedimentary rocks, and the Independence dike swarm. A portion of this offset occurred across a 110 m thick cataclastic fault zone in the West Pinnacle Creek drainage in the east-central Sierra Nevada (approximately 3 km of dextral offset). The zone of discrete cataclastic faulting is bordered by a region of distributed deformation (i.e., penetrative at map scale) characterized by small-scale cataclastic to protomylonitic sinistral and dextral shear planes within the Turret Peak, Lake Edison, and Lamarck plutons of the Cretaceous John Muir Intrusive Suite. The distributed damage zone east of the West Pinnacle Creek fault (WPCF) was accommodated primarily by antithetic south-southwest striking left-lateral shear planes. Distributed deformation to the west of the discrete zone was accommodated primarily by synthetic north- northeast-striking right-lateral shear planes. Deformation in the distributed region is characterized by a relatively simple architecture of low displacement strike-slip shear fractures. Average shear strain in the antithetic distributed zone was calculated by measuring centimeter to meter-scale offsets of planar markers (e.g., dikes, enclaves, and modal layers) across macroscopic shear planes (n= 71) along a 0.25 km traverse in the Lake Edison pluton (es = 0.052). The distributed zone deformation is manifested strongly within 3 kilometers of the master fault but dies out quickly beyond this distance. Total displacement within the distributed damage zone (0.194 km) is equal to ~6% of the displacement along the WPCF (~3 km). The strain within the damage zone was focused onto pre-existing joints within the

  16. Dominant modes of variation in the annual progression of snow accumulation and melt in the Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Montoya, E.; Meiring, W.; Dozier, J.

    2014-12-01

    Snow in the Sierra Nevada is an important source of water for California. Due to advances in technology, the environmental sciences are more commonly taking measurements from continuous processes, and sample measurements of snow water equivalent (SWE) from snow pillows are one such example. Snow pillows provide daily samples from the continuous SWE yearly profile if SWE measurements are viewed as a continuous function of time. We examine the dominant modes of variation in the timing of snowpack events using functional principal component analysis. Additionally, we examine the associations between the dominant modes of variation with large-scale climate indices and spatial location.

  17. A fan dam for Tulare Lake, California, and implications for the Wisconsin glacial history of the Sierra Nevada.

    USGS Publications Warehouse

    Atwater, B.F.

    1986-01-01

    Four stratigraphically consistent 14C dates on peat and wood give an age of 26 000 yr BP for the start of Tulare Lake's late Wisconsin transgression. An earlier enlargement of Tulare Lake probably resulted from a fan dam produced by the penultimate major (Tahoe) glaciation of the Sierra Nevada. Average sedimentation rates inferred from depths to a 600 000-yr-old clay and from radiocarbon dates indicate that this earlier lake originated no later than 100 000 yr BP. The Tahoe glaciation therefore is probably pre- Wisconsin. -from Authors

  18. Under-canopy snow accumulation and ablation measured with airborne scanning LiDAR altimetry and in-situ instrumental measurements, southern Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Kirchner, P. B.; Bales, R. C.; Musselman, K. N.; Molotch, N. P.

    2012-12-01

    We investigated the influence of canopy on snow accumulation and melt in a mountain forest using paired snow on and snow off scanning LiDAR altimetry, synoptic measurement campaigns and in-situ time series data of snow depth, SWE, and radiation collected from the Kaweah River watershed, Sierra Nevada, California. Our analysis of forest cover classified by dominant species and 1 m2 grided mean under canopy snow accumulation calculated from airborne scanning LiDAR, demonstrate distinct relationships between forest class and under-canopy snow depth. The five forest types were selected from carefully prepared 1 m vegetation classifications and named for their dominant tree species, Giant Sequoia, Jeffrey Pine, White Fir, Red Fir, Sierra Lodgepole, Western White Pine, and Foxtail Pine. Sufficient LiDAR returns for calculating mean snow depth per m2 were available for 31 - 44% of the canopy covered area and demonstrate a reduction in snow depth of 12 - 24% from adjacent open areas. The coefficient of variation in snow depth under canopies ranged from 0.2 - 0.42 and generally decreased as elevation increased. Our analysis of snow density snows no statistical significance between snow under canopies and in the open at higher elevations with a weak significance for snow under canopies at lower elevations. Incident radiation measurements made at 15 minute intervals under forest canopies show an input of up to 150 w/m2 of thermal radiation from vegetation to the snow surface on forest plots. Snow accumulated on the mid to high elevation forested slopes of the Sierra Nevada represents the majority of winter snow storage. However snow estimates in forested environments demonstrate a high level of uncertainty due to the limited number of in-situ observations and the inability of most remote sensing platforms to retrieve reflectance under dense vegetation. Snow under forest canopies is strongly mediated by forest cover and decoupled from the processes that dictate accumulation

  19. Challenges to Sierra Nevada forests and their local communities: An observational and modeling perspective

    NASA Astrophysics Data System (ADS)

    Schmidt, Cynthia L.

    Global forests are experiencing dramatic changes due to changes in climate as well as anthropogenic activities. Increased warming is causing the advancement of some species upslope and northward, while it is also causing widespread mortality due to increased drought conditions. In addition, increasing human population in mountain regions is resulting in elevated risk of human life and property loss due to larger and more severe wildfires. My research focuses on assessing the current vulnerability of forests and their communities in the Sierra Nevada, and how forests are projected to change in the future based on different climate change scenarios. In the first chapter I use Landsat satellite imagery to identify and attribute cause of forest disturbance between 1985 and 2011, primarily focusing on disturbances due to insect, diseases and drought. The change-detection algorithm, Landtrendr, was successfully used to identify forest disturbance, but identifying cause of disturbance was challenging due to the spectral similarities between disturbance types. Landtrendr was most successful in identifying disturbance due to insect, disease and drought in the San Bernardino National Forest, where there is little forest management activity. In the second chapter, I assess whether state or local land use policies in high-fire prone regions exist to reduce the vulnerability of residential developments to wildfire. Three specific land-use tools associated with reducing wildfire vulnerability are identified: (1) buffers around developments; (2) clustered developments; (3) restricting construction on slopes greater than 25%. The study also determines whether demographic and physical characteristics of selected California counties were related to implementing land use policies related to reducing wildfire vulnerability. Results indicate that land use policies related to preventing wildfire-related losses focus on building materials, road access, water availability and vegetation

  20. CONTROLS OF EXTENSION ON MIOCENE ARC MAGMATISM IN THE CENTRAL SIERRA NEVADA (CA)

    NASA Astrophysics Data System (ADS)

    Busby, C.; Putirka, K. D.; Hagan, J. C.; Koerner, A.; Melosh, B. L.

    2009-12-01

    Ancestral Cascades arc volcanism in the central Sierra Nevada occurred in three Miocene pulses, at about 16-13 Ma, 11-9 Ma, and 7-6 Ma. Our work in the Carson Pass to Sonora Pass areas shows that range-front faults clearly controlled the positions of volcanic centers during the second and third magmatic pulses. Voluminous high-K volcanic rocks of the 11-9 Ma Stanislaus Group record the onset of transtensional calving of the Sierra Nevada microplate off the western edge of the Nevadaplano. The Little Walker Caldera or Center formed at a releasing stepover in range-front faults at Sonora Pass, and erupted widesperad trachydacite ignimbrite in three distinct phases (Eureka Valley Tuff). Interstratified with these ignimbrites are widespread trachyandesite (latite), basaltic-trachyandesite (shoshonite) and trachydacite lava flows, in sections up to 500 m thick, whose vents have never been discovered (e.g. Table Mountain Latite). Although some of these lavas may have erupted from vents buried beneath the Little Walker Center, we recognize intrusions and vent facies for them along Sierran range-front and range-crest faults that emanate northwestward from the Little Walker Center between Sonora Pass and Ebbetts Pass. The biggest volcanic centers of the third magmatic pulse also include silicic volcanic rocks, and are sited along normal faults; they include the Markleeville Center southeast of Carson Pass, and the Ebbetts Pass Center. The 8 km diameter Markleeville Center consists of andesites and dacites that formed within the Hope Valley graben. The next fault to the east of the Hope Valley graben, which we name the Grover Hot Springs fault, extends southward to Ebbetts Pass, where it forms an overlapping right (releasing) step with the Noble Canyon fault to the west. The Ebbetts Pass Center lies above this releasing step along the Sierran crest. The base of the Ebbetts Pass Center is 10 km in diameter and is formed of radially-dipping basaltic andesite lava flows and

  1. Onset and Multiple Fluctuations of Holocene Glaciation in the Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Bowerman, N. D.; Clark, D. H.

    2004-12-01

    Multiple sediment cores from two paternoster tarns (First and Second lakes) in North Fork Big Pine Creek, Sierra Nevada, preserve the most detailed and complete record of Holocene glaciation yet recovered in the range; they indicate that the glacier was absent during the early Holocene, reformed in the late Holocene, and experienced several expansions and contractions, culminating with the Matthes maximum during the last ˜200 years. The lakes are fed by outwash from the Palisade Glacier, the largest ( ˜1.3 km2) and presumably longest-lived glacier in the Sierra Nevada, and capture essentially all of the rock flour produced by the glacier. Distinct late-Holocene (Matthes) and late-Pleistocene (Recess Peak) moraines lie between the modern glacier and the lakes. Thus, the lakes have received continuous sedimentation since the retreat of the Tioga glacier ( ˜15,000 yr B.P.), and therefore capture rock flour related to all subsequent advances. First and Second lakes occupy relatively deep bedrock basins at 3036 m and 3066 m asl., respectively. Third Lake, a shallow (<3 m deep), moraine-dammed lake that lies directly above Second Lake, is the only lake between the Palisade Glacier and the lower lakes. As such, it captures the coarsest (sand/gravel bedload) outwash, but abundant suspended sediment (silt/clay) continues to the lower lakes. We cored the lakes using both Reasoner and Livingston corers, to sediment depths of up to ˜5 m. The deepest cores bottomed in coarse, inorganic sand and silt that we interpret as outwash or slopewash related to Tioga deglaciation. Magnetic susceptibility (MS) analyses of the sediment cores indicate that both lakes record multiple late-Holocene peaks in MS, with the most recent peak being the largest. They also retain outwash near the base related to the more extensive Recess Peak advance. MS peaks in Sierran lakes typically indicate greater abundances of clastic (vs. organic) sediment. The peaks in our cores thus imply 4-5 periods of

  2. Geochronology and Geochemistry of a Late Cretaceous Granitoid Suite, Santa Rosa Range, Nevada: Linking Arc Magmatism in Northwestern Nevada to the Sierra Nevada Batholith

    NASA Astrophysics Data System (ADS)

    Brown, K.; Stuck, R.; Hart, W. K.

    2010-12-01

    Throughout the Mesozoic, an arc-trench system dominated the western margin of North America. One of the principal records of this system’s evolution is a discontinuous alignment of deeply eroded batholiths, which represent the once-active roots of ancient volcanic systems. Although these batholiths extend from Alaska to Mexico, there is a prominent (~500 km) gap located in present-day Nevada that contains scattered plutons that are hypothesized to be similar in age and origin to the larger batholiths. The current understanding of these isolated plutons, however, remains limited to regional isotopic studies aimed at identifying major crustal boundaries and structural studies focused on emplacement mechanisms. Therefore, detailed petrogenetic studies of the plutons exposed within the Santa Rosa Range (SRR) of NW Nevada will better characterize magmatism in this region, placing them within a regional context that explores the hypothesized links between the intrusions of NW Nevada to the Sierra Nevada batholith (SNB). A compilation of published geochronology from this region shows that plutons in the SRR are broadly coeval with the Cathedral Range Intrusive Epoch (~95-83 Ma) and the Shaver Sequence (~118-105 Ma) of the SNB. Preliminary Rb-Sr geochronology from the Granite Peak stock reveals a previously unrecognized period of magmatism (ca. 85.0 Ma) in this region. Therefore, ongoing work will more completely characterize the timing of magmatic pulses in this region and their relationships to the SNB. Preliminary petrographic, geochemical, and isotopic observations suggest that two distinct compositional/textural groups exist: the Santa Rosa/ Andorno group (SRA) and Granite Peak/ Sawtooth group (GPS). The chemical and isotopic variations between the two groups suggest that they were not consanguineous. Whereas the SRA group is generally more mafic (64-72 wt% SiO2) and metaluminous, the GPS group is more felsic (72- 76 wt% SiO2) and peraluminous. This observation is

  3. Conservation of avian diversity in the Sierra Nevada: moving beyond a single-species management focus

    USGS Publications Warehouse

    White, Angela M.; Zipkin, Elise F.; Manley, Patricia N.; Schlesinger, Matthew D.

    2013-01-01

    Background: As a result of past practices, many of the dry coniferous forests of the western United States contain dense, even-aged stands with uncharacteristically high levels of litter and downed woody debris. These changes to the forest have received considerable attention as they elevate concerns regarding the outcome of wildland fire. However, attempts to reduce biomass through fuel reduction (i.e., thinning of trees) are often opposed by public interest groups whose objectives include maintaining habitat for species of concern such as the spotted owl, Strix occidentalis, the northern goshawk, Accipiter gentilis, and the Pacific fisher, Martes pennanti. Whether protection of these upper-trophic level species confers adequate conservation of avian forest diversity is unknown. Methodology and Principal Findings: We use a multi-species occurrence model to estimate the habitat associations of 47 avian species detected at 742 sampling locations within an 880-km2 area in the Sierra Nevada. Our approach, which accounts for variations in detectability of species, estimates occurrence probabilities of all species in a community by linking species occurrence models into one hierarchical community model, thus improving inferences on all species, especially those that are rare or observed infrequently. We address how the avian community is influenced by covariates related to canopy cover, tree size and shrub cover while accounting for the impacts of abiotic variables known to affect species distributions. Conclusions and Significance: Environmental parameters estimated through our approach emphasize the importance of within and between stand-level heterogeneity in meeting biodiversity objectives and suggests that many avian species would increase under more open canopy habitat conditions than those favored by umbrella species of high conservation concern. Our results suggest that a more integrated approach that emphasizes maintaining a diversity of habitats across

  4. Fungal role in post-fire ecosystem recovery in Sierra Nevada National Park (Spain)

    NASA Astrophysics Data System (ADS)

    Bárcenas-Moreno, Gema; Jiménez-Morillo, Nicasio T.; Mataix-Beneyto, Jorge; Martín Sánchez, Ines

    2016-04-01

    Fire effect on soil microorganisms has been studies for decades in several ecosystems and different microbial response can be found in the bibliography depending on numerous intrinsic and extrinsic soil factors. These factors will determine preliminary soil microbial community composition, subsequent pos-fire initial colonizers and even post-fire growth media characteristics that microbial community will find to start recolonisation. Fire-induced soil bacterial proliferation is a common pattern found after fire, usually related to pH and C availability increased. But when original soil pH is not altered by fire in acid soils, microbial response can be different and fungal response can be crucial to ecosystem recovery. In this study we have compile data related to high mountain soil from Sierra Nevada National park which was affected by a wildfire in 2006 and data obtained by laboratory heating experiment, trying to elucidate the ecological role of fungi in this fragile ecosystem. On the one hand we can observe fire-induced fungal abundance proliferation estimated by plate count method 8 and 32 months after wildfire and even in a short-term (21 d) after laboratory heating at 300 °C. Six years after fire, fungal abundance was similar between samples collected in burnt and unburnt-control area but we found higher proportion of species capable to degrade PAHs (lacase activity) in burnt soil than I the unburnt one. This finding evidences the crucial role of fungal enzymatic capacities to detoxify burnt soils when fire-induced recalcitrant and even toxic carbon compounds could be partially limiting total ecosystem recovery.

  5. Management Impacts on Carbon Dynamics in a Sierra Nevada Mixed Conifer Forest.

    PubMed

    Dore, Sabina; Fry, Danny L; Collins, Brandon M; Vargas, Rodrigo; York, Robert A; Stephens, Scott L

    2016-01-01

    Forest ecosystems can act as sinks of carbon and thus mitigate anthropogenic carbon emissions. When forests are actively managed, treatments can alter forests carbon dynamics, reducing their sink strength and switching them from sinks to sources of carbon. These effects are generally characterized by fast temporal dynamics. Hence this study monitored for over a decade the impacts of management practices commonly used to reduce fire hazards on the carbon dynamics of mixed-conifer forests in the Sierra Nevada, California, USA. Soil CO2 efflux, carbon pools (i.e. soil carbon, litter, fine roots, tree biomass), and radial tree growth were compared among un-manipulated controls, prescribed fire, thinning, thinning followed by fire, and two clear-cut harvested sites. Soil CO2 efflux was reduced by both fire and harvesting (ca. 15%). Soil carbon content (upper 15 cm) was not significantly changed by harvest or fire treatments. Fine root biomass was reduced by clear-cut harvest (60-70%) but not by fire, and the litter layer was reduced 80% by clear-cut harvest and 40% by fire. Thinning effects on tree growth and biomass were concentrated in the first year after treatments, whereas fire effects persisted over the seven-year post-treatment period. Over this period, tree radial growth was increased (25%) by thinning and reduced (12%) by fire. After seven years, tree biomass returned to pre-treatment levels in both fire and thinning treatments; however, biomass and productivity decreased 30%-40% compared to controls when thinning was combined with fire. The clear-cut treatment had the strongest impact, reducing ecosystem carbon stocks and delaying the capacity for carbon uptake. We conclude that post-treatment carbon dynamics and ecosystem recovery time varied with intensity and type of treatments. Consequently, management practices can be selected to minimize ecosystem carbon losses while increasing future carbon uptake, resilience to high severity fire, and climate related

  6. The Hurd Peak gneiss of the Long Lake shear zone, eastern Sierra Nevada, California

    SciTech Connect

    Holland, K.S.; Reed, W.E. . Dept. of Earth and Space Sciences)

    1993-04-01

    The Hurd Peak gneiss is located within the Long Lake valley of the east-central Sierra Nevada, California. This unit is the principle orthogneiss in Hathaway's (1993) Long Lake shear zone. The rock shows porphyroclasts of plagioclase and quartz, abundant mafic enclaves, and cross-cutting field associations which suggest that the gneiss had a plutonic protolith. The gneiss varies from biotite-poor nearest the contact with the Lamarck to biotite-rich nearest Long Lake. The contact zone between the gneiss and the Lamarck pluton ranges from sharp to gradational and from migmatitic to mixed, i.e., the mixed zone being greater than 50% intermingled dikes of 10 cm or greater thickness. In places this contact is marked by a quartz-free biotite hornfels approximately 5 m thick. Based on their relative deformation, at least 3 suites of aplite dikes cross-cut the gneiss, and 5 other lithologies, including basaltic, mixed, composite, andesitic, and quartz dioritic compositions, also cross-cut the gneiss. The Rb-Sr whole rock isochron age of the Hurd Peak gneiss has been determined to be 90.2 Ma. The authors interpret this isochron to be the result of mobilization of the Rb-Sr isotopic system during intrusion of the Lamarck Granodiorite (90 Ma); this may represent a regional cooling age. The initial [sup 87]/Sr[sup 86]Sr ratio of the gneiss is 0.7098, i.e., much more evolved than the surrounding plutons which have [sup 87]Sr/[sup 86]Sr ratios near 0.706. Sr model ages indicate that the protolith of the gneiss is considerably older than 90 Ma, one such calculation suggests an age of approximately 250 Ma. Single crystals of zircon have been isolated from the gneiss for U-Pb dating, and analytical work on the zircons is presently on-going.

  7. The geology of the Inconsolable Range, east-central Sierra Nevada, California

    SciTech Connect

    Hathaway, G.M; Reed, W.E. . Dept. of Earth and Space Sciences)

    1993-04-01

    Detailed mapping of the Inconsolable Range in the east-central Sierra Nevada reveals a structurally and lithologically complex region of multi-phase intrusions. Some plutons are compositionally-zoned [e.g., Inconsolable (100 Ma) and Lamarck (90 Ma)]; others may be the result of magma mixing. Intrusive borders vary from brittle to ductile and sharp to gradational, and are bounded by contact aureoles of varying metamorphic grade. A shear zone (Long Lake shear zone -- LLSZ) bounds the western margin of the Inconsolable Range for 8 km; this is truncated in the south by the Cretaceous Lamarck intrusive suite, and is tectonically overlain in the north by the Bishop Creek Pendant (Ordovician ). The LLSZ is a complex zone of interleaved septa of biotite schists, orthogneisses, aplitic screens, and calc-silicate gneisses approximately 500 to 800 m wide. Preliminary interpretation suggests that the LLSZ is the sheared remnant of a Triassic-Jurassic igneous terrane complete with metasedimentary pendants. Juxtaposition of greenschist facies meta-sedimentary rocks of the Chocolate Peak klippe over highly deformed amphibolite grade meta-igneous rocks of the LLSZ postdates movement along the LLSZ. Metamorphic grades suggest that deeper structural levels are exposed within the LLSZ near its southern terminus. Twenty plutonic lithologies have been mapped and informally named (e.g., Spotted biotite quartz diorite), including 3 compositionally-zoned plutons. Zonation within the Lamarck, Inconsolable, and Spotted intrusions are the result of multiple emplacement events into partially crystallized host plutons. Along the eastern border of the Lamarck intrusive suite field evidence indicates four separate intrusive events. The Inconsolable body is a compositionally-zoned biotite, clinopyroxene, quartz diorite with irregular granodiorite margins. The base of the Spotted intrusion appears to have been magmatically eroded by a pulse of the younger Lamarck intrusion.

  8. Conservation of Avian Diversity in the Sierra Nevada: Moving beyond a Single-Species Management Focus

    PubMed Central

    White, Angela M.; Zipkin, Elise F.; Manley, Patricia N.; Schlesinger, Matthew D.

    2013-01-01

    Background As a result of past practices, many of the dry coniferous forests of the western United States contain dense, even-aged stands with uncharacteristically high levels of litter and downed woody debris. These changes to the forest have received considerable attention as they elevate concerns regarding the outcome of wildland fire. However, attempts to reduce biomass through fuel reduction (i.e., thinning of trees) are often opposed by public interest groups whose objectives include maintaining habitat for species of concern such as the spotted owl, Strix occidentalis, the northern goshawk, Accipiter gentilis, and the Pacific fisher, Martes pennanti. Whether protection of these upper-trophic level species confers adequate conservation of avian forest diversity is unknown. Methodology and Principal Findings We use a multi-species occurrence model to estimate the habitat associations of 47 avian species detected at 742 sampling locations within an 880-km2 area in the Sierra Nevada. Our approach, which accounts for variations in detectability of species, estimates occurrence probabilities of all species in a community by linking species occurrence models into one hierarchical community model, thus improving inferences on all species, especially those that are rare or observed infrequently. We address how the avian community is influenced by covariates related to canopy cover, tree size and shrub cover while accounting for the impacts of abiotic variables known to affect species distributions. Conclusions and Significance Environmental parameters estimated through our approach emphasize the importance of within and between stand-level heterogeneity in meeting biodiversity objectives and suggests that many avian species would increase under more open canopy habitat conditions than those favored by umbrella species of high conservation concern. Our results suggest that a more integrated approach that emphasizes maintaining a diversity of habitats across

  9. Comparison of Interpolation Techniques and Model Simulations of Snow Water Equivalent in the Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Wrzesien, M.; Durand, M. T.; Howat, I. M.; Margulis, S. A.

    2015-12-01

    Seasonal water storage in mountain snowpack is a critical water resource but its variability is highly uncertain in time and space. Here we compare methods for analyzing the spatial distribution of snow water equivalent (SWE) over the Sierra Nevada Mountains. Using progressively more complex techniques, we interpolate measurements from over 250 snow courses and 100 automatic snow sensors to obtain a map of SWE over the entire mountain range. Interpolation methods range from simple regressions utilizing only latitude, longitude, and elevation, to more complex approaches that additionally consider temperature, precipitation, aspect, and others. We explore the differences between maps obtained from interpolations of only snow courses, only snow pillows, and the combined datasets. We additionally consider a model simulation from the Weather Research and Forecast (WRF) model run at 3-km resolution. Biases from the interpolations and the WRF simulation are determined through evaluation against an existing 90-m resolution product based upon data assimilation and SWE reconstruction techniques. Comparisons of the SWE maps will allow us to determine if one method overestimates or underestimates with regards to the others and whether interpolation is useful for a spatially heterogeneous variable such as SWE. We select three different years to study in order to capture a range of snowpack conditions. Water year 2009 (October 2008 through September 2009) was an average snow accumulation year for the region. We also select water year 2005 for a high accumulation year and water year 2014 for a low accumulation year. It is likely that each method will result in different SWE estimates, revealing the uncertainty involved in snow hydrology.

  10. Evaposublimation from the snow in the Mediterranean mountains of Sierra Nevada (Spain)

    NASA Astrophysics Data System (ADS)

    Herrero, Javier; José Polo, María

    2016-12-01

    In this study we quantify the evaposublimation and the energy balance of the seasonal snowpack in the Mediterranean semiarid region of Sierra Nevada, Spain (37° N). In these kinds of regions, the incidence of this return of water to the atmosphere is particularly important to the hydrology and water availability. The analysis of the evaposublimation from snow allows us to deduct the losses of water expected in the short and medium term and is critical for the efficient planning of this basic and scarce resource. To achieve this, we performed 10 field campaigns from 2009 to 2015, during which detailed measurements of mass fluxes of a controlled volume of snow were recorded using a modified version of an evaporation pan with lysimeter. Meteorological data at the site of the snow control volume were extensively monitored during the tests. With these data, a point energy balance snowmelt model was validated for the area. This model, fed with the complete meteorological data set available at the Refugio Poqueira Station (2500 m a.s.l.), let us estimate that evaposublimation losses for this site can range from 24 to 33 % of total annual ablation. This ratio is very variable throughout the year and between years, depending on the particular occurrence of snowfall and mild weather events, which is generally quite erratic in this semiarid region. Evaposublimation proceeds at maximum rates of up to 0.49 mm h-1, an order of magnitude less than maximum melt rates. However, evaposublimation occurs during 60 % of the time that snow lies, while snowmelt only takes up 10 % of this time. Hence, both processes remain close in magnitude on the annual scale.

  11. Isotopic variation in the Tuolumne Intrusive Suite, central Sierra Nevada, California

    USGS Publications Warehouse

    Kistler, R.W.; Chappell, B.W.; Peck, D.L.; Bateman, P.C.

    1986-01-01

    Granitoid rocks of the compositionally zoned Late Cretaceous Toulumne Intrusive Suite in the central Sierra Nevada, California, have initial87Sr/86Sr values (Sri) and143Nd/144Nd values (Ndi) that vary from 0.7057 to 0.7067 and from 0.51239 to 0.51211 respectively. The observed variation of both Sri and Ndi and of chemical composition in rocks of the suite cannot be due to crystal fractionation of magma solely under closed system conditons. The largest variation in chemistry, Ndi, and Sri is present in the outer-most equigranular units of the Tuolumne Intrusive Suite. Sri varies positively with SiO2, Na2O, K2O, and Rb concentrations, and negatively with Ndi, Al2O3, Fe2O3, MgO, FeO, CaO, MnO, P2O5, TiO2, and Sr concentrations. This covariation of Sri, Ndi and chemistry can be modeled by a process of simple mixing of basaltic and granitic magmas having weight percent SiO2 of 48.0 and 73.3 respectively. Isotopic characteristic of the mafic magma are Sri=0.7047, Ndi=0.51269 and ??18O=6.0, and of the felsic magma are Sri=0.7068, Ndi=0.51212 and ??18O=8.9. The rocks sampled contain from 50 to 80% of the felsic component. An aplite in the outer equigranular unit of the Tuolumne Intrusive Suite apparently was derived by fractional crystallization of plagioclase and hornblende from magma with granudiorite composition that was a product of mixing of the magmas described above. Siliceous magmas derived from the lower crust, having a maximum of 15 percent mantle-derived mafic component, are represented by the inner prophyritic units of the Tuolumne Intrusive Suite. ?? 1986 Springer-Verlag.

  12. Drought effects on evapotransiration and subsurface water storage in the southern Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Bales, R. C.; Goulden, M.; Hunsaker, C. T.; Conklin, M. H.; Hartsough, P. C.; O'Geen, T. T.; Hopmans, J. W.; Safeeq, M.

    2015-12-01

    Multi-year measurements of evapotranspiration (ET) at three elevations in the southern Sierra Nevada show the extent to which subsurface water storage in the regolith provides a buffer against multi-year dry periods. ET in a 2000-m elevation mixed-conifer forest showed a 24% decrease in ET in water-year 2014, the third dry year, as compared to the wet year of 2011. This decrease reflected reduced transpiration for the July to September period. Over half of the annual ET in both wet and dry years came from below the 1-m depth mapped soil, and with come coming from below the 2.5 m depth of our soil-moisture measurements. The ability of trees to access water from these depths does provide a 2-3 year buffer for ET, which also depends on forest density and the balance between perennial overstory and annual understory vegetation. An equally dense lower-elevation pine-oak forest (1160 m) showed nearly a 50% decrease in ET during the third year of drought, with significant visible effects on vegetation. While this lower elevation forest may have as much or more subsurface storage as does that at 2000-m elevation, the combination of lower precipitation as one goes down in elevation and very high forest density provides only a one-year buffer for ET in dry years. Regaining resiliency in this forest will only occur with significant reductions in biomass and commensurate lowering of ET. In a 400-m elevation oak savannah ET responds to annual precipitation, with essentially no multi-year buffer provided by subsurface storage.

  13. Precipitation chemistry in and ionic loading to an Alpine Basin, Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Williams, Mark W.; Melack, John M.

    1991-07-01

    Wet deposition of solutes to an alpine catchment in the southern Sierra Nevada was measured from October 1984 through March 1988. Rainfall had a volume-weighted pH of 4.9, and snowfall had a volume-weighted pH of 5.3. Acetic and formic acids were important components of all wet deposition, contributing 25-30% of the measured anions in snowfall and, through analysis of charge balance deficits, the same percentage in rainfall. The NO3- to SO42- equivalent ratio for all wet deposition was 1.16. Ammonium concentration was tenfold greater than H+ in rainfall; ammonium nitrate and ammonium sulfate appear to be the principal nitrate and sulfate containing aerosols in wet deposition. Snowmelt runoff (1985 and 1986) or snowpack runoff plus rainfall during the period of snowpack runoff (1987) supplied 90% of the annual solute flux from wet deposition to the catchment. The amount of snow water equivalence (mm m-2) and H+, SO42-, and Cl- (eq m-2) in cumulative snowfall measured on snowboards was similar to the accumulated deposition of these parameters measured in snowpils at midwinter and during maximum snow accumulation periods, while about 20% of the NO3- in snowfall was not stored in the winter snowpack. Dry deposition was therefore not an important contributor of H+, NO3-, and SO42- to the winter snowpack. The source of the ions in snowfall was air masses that originated over the Pacific Ocean, while low Cl- and Na+ relative to NO3- and NH4+ in rainfall indicate that local urban and agricultural areas were the major source of the ions in rainfall.

  14. Dwarf mistletoe-host interactions in mixed-conifer forests in the sierra nevada.

    PubMed

    Maloney, Patricia E; Rizzo, David M

    2002-06-01

    ABSTRACT We determined the spatial pattern of dwarf mistletoe (Arceuthobium spp.) associated with two different conifer hosts, white fir (Abies concolor) and Jeffrey pine (Pinus jeffreyi), in forests around the Lake Tahoe Basin and at the Teakettle Experimental Forest, both located in the Sierra Nevada. We also examined a number of host variables and bark beetle incidence to determine how these factors might be involved in the Arceuthobium-conifer interaction. There was no significant relationship between dwarf mistletoe-infected trees and associated bark beetles. We found the highest incidence of dwarf mistletoe on Jeffrey pine in Lake Tahoe (87%), followed by dwarf mistletoe on white fir in Lake Tahoe (30%), with the lowest incidence on white fir at Teakettle (27%). Dwarf mistletoe incidence on white fir in our Lake Tahoe grid was not correlated to density but the dwarf mistletoe rating (DMR) was positively correlated to host size. At the Teakettle Forest, dwarf mistletoe incidence on white fir was not correlated with host density but the DMR was correlated with host size. Dwarf mistletoe incidence and DMR on Jeffrey pine were correlated with host density. Individuals, of both conifer species, in all diameter size classes were susceptible to dwarf mistletoe, with the lowest infection rate in the seedling-10-cm-diameter class. Arceuthobium on white fir in Lake Tahoe showed spatial dependence to a range of 20 m. However, Arceuthobium on Jeffrey pine in Lake Tahoe and on white fir at Teakettle showed no clear pattern of spatial structuring. The degree of infection and stand history appear to be important in the spatial dynamics of Arceuthobium spp.

  15. Management Impacts on Carbon Dynamics in a Sierra Nevada Mixed Conifer Forest

    PubMed Central

    Dore, Sabina; Fry, Danny L.; Collins, Brandon M.; Vargas, Rodrigo; York, Robert A.; Stephens, Scott L.

    2016-01-01

    Forest ecosystems can act as sinks of carbon and thus mitigate anthropogenic carbon emissions. When forests are actively managed, treatments can alter forests carbon dynamics, reducing their sink strength and switching them from sinks to sources of carbon. These effects are generally characterized by fast temporal dynamics. Hence this study monitored for over a decade the impacts of management practices commonly used to reduce fire hazards on the carbon dynamics of mixed-conifer forests in the Sierra Nevada, California, USA. Soil CO2 efflux, carbon pools (i.e. soil carbon, litter, fine roots, tree biomass), and radial tree growth were compared among un-manipulated controls, prescribed fire, thinning, thinning followed by fire, and two clear-cut harvested sites. Soil CO2 efflux was reduced by both fire and harvesting (ca. 15%). Soil carbon content (upper 15 cm) was not significantly changed by harvest or fire treatments. Fine root biomass was reduced by clear-cut harvest (60–70%) but not by fire, and the litter layer was reduced 80% by clear-cut harvest and 40% by fire. Thinning effects on tree growth and biomass were concentrated in the first year after treatments, whereas fire effects persisted over the seven-year post-treatment period. Over this period, tree radial growth was increased (25%) by thinning and reduced (12%) by fire. After seven years, tree biomass returned to pre-treatment levels in both fire and thinning treatments; however, biomass and productivity decreased 30%-40% compared to controls when thinning was combined with fire. The clear-cut treatment had the strongest impact, reducing ecosystem carbon stocks and delaying the capacity for carbon uptake. We conclude that post-treatment carbon dynamics and ecosystem recovery time varied with intensity and type of treatments. Consequently, management practices can be selected to minimize ecosystem carbon losses while increasing future carbon uptake, resilience to high severity fire, and climate related

  16. Mineral dust transport to the Sierra Nevada, California: Loading rates and potential source areas

    NASA Astrophysics Data System (ADS)

    Vicars, William C.; Sickman, James O.

    2011-03-01

    The transport and deposition of aeolian dust represents an important material input pathway for many marine and terrestrial ecosystems and may be an ecologically significant source of exogenous phosphorus (P) to alpine lakes. In order to assess the abundance and elemental composition of atmospheric mineral dust over the Sierra Nevada of California, we collected size-fractionated atmospheric particulate matter (PM) samples during July 2008 to March 2009 at a mixed conifer site located in Sequoia National Park. PM concentrations were at their highest levels during the dry season, averaging 8.8 ± 3.7 and 11.1 ± 7.5 μg m-3 for the coarse (1 μm < Da < 15 μm) and fine (Da < 1 μm) fractions, respectively, while winter months were characterized by low (<1 μg m-3) PM concentrations in both size fractions. Using Al as a diagnostic tracer for mineral aerosol, we observed a significant and uniform contribution (50-80%) from aeolian dust to the total coarse PM load, whereas submicron particles contained comparatively little crustal material (7-33%). The mass concentrations of elements (Fe, Ca, Mg, P, and V) in the coarse PM fraction were significantly correlated with Al throughout the study, and coarse PM exhibited elemental signatures that were temporally consistent and distinguishable from those of other sites. Conversely, higher elemental enrichments were observed in the fine PM fraction for Fe, V, and P, indicating a greater contribution from anthropogenic emissions to the fine particle load. Fe/Al and Fe/Ca ratios suggest a mixture of mineral dust from regional agricultural activities and long-range transport of mineral dust from Asia. Asian sources comprised 40-90% of mineral dust in July 2008 and then declined to between 10 and 30% in August and early September.

  17. Forest thinning and soil respiration in a ponderosa pine plantation in the Sierra Nevada.

    PubMed

    Tang, Jianwu; Qi, Ye; Xu, Ming; Misson, Laurent; Goldstein, Allen H

    2005-01-01

    Soil respiration is controlled by soil temperature, soil water, fine roots, microbial activity, and soil physical and chemical properties. Forest thinning changes soil temperature, soil water content, and root density and activity, and thus changes soil respiration. We measured soil respiration monthly and soil temperature and volumetric soil water continuously in a young ponderosa pine (Pinus ponderosa Dougl. ex P. Laws. & C. Laws.) plantation in the Sierra Nevada Mountains in California from June 1998 to May 2000 (before a thinning that removed 30% of the biomass), and from May to December 2001 (after thinning). Thinning increased the spatial homogeneity of soil temperature and respiration. We conducted a multivariate analysis with two independent variables of soil temperature and water and a categorical variable representing the thinning event to simulate soil respiration and assess the effect of thinning. Thinning did not change the sensitivity of soil respiration to temperature or to water, but decreased total soil respiration by 13% at a given temperature and water content. This decrease in soil respiration was likely associated with the decrease in root density after thinning. With a model driven by continuous soil temperature and water time series, we estimated that total soil respiration was 948, 949 and 831 g C m(-2) year(-1) in the years 1999, 2000 and 2001, respectively. Although thinning reduced soil respiration at a given temperature and water content, because of natural climate variability and the thinning effect on soil temperature and water, actual cumulative soil respiration showed no clear trend following thinning. We conclude that the effect of forest thinning on soil respiration is the combined result of a decrease in root respiration, an increase in soil organic matter, and changes in soil temperature and water due to both thinning and interannual climate variability.

  18. On the relative contributions of wind vs. animals to seed dispersal of four Sierra Nevada pines.

    PubMed

    Vander Wall, Stephen B

    2008-07-01

    Selective pressures that influence the form of seed dispersal syndromes are poorly understood. Morphology of plant propagules is often used to infer the means of dispersal, but morphology can be misleading. Several species of pines, for example, have winged seeds adapted for wind dispersal but owe much of their establishment to scatter-hoarding animals. Here the relative importance of wind vs. animal dispersal is assessed for four species of pines of the eastern Sierra Nevada that have winged seeds but differed in seed size: lodgepole pine (Pinus contorta murrayana, 8 mg); ponderosa pine (Pinus ponderosa ponderosa, 56 mg); Jeffrey pine (Pinus jeffreyi, 160 mg); and sugar pine (Pinus lambertiana, 231 mg). Pre-dispersal seed mortality eliminated much of the ponderosa pine seed crop (66%), but had much less effect on Jeffrey pine (32% of seeds destroyed), lodgepole pine (29%), and sugar pine (7%). When cones opened most filled seeds were dispersed by wind. Animals removed > 99% of wind-dispersed Jeffrey and sugar pine seeds from the ground within 60 days, but animals gathered only 93% of lodgepole pine seeds and 38% of ponderosa pine seeds during the same period. Animals gathered and scatter hoarded radioactively labeled ponderosa, Jeffrey, and sugar pine seeds, making a total of 2103 caches over three years of study. Only three lodgepole pine caches were found. Caches typically contained 1-4 seeds buried 5-20 mm deep, depths suitable for seedling emergence. Although Jeffrey and sugar pine seeds are initially wind dispersed, nearly all seedlings arise from animal caches. Lodgepole pine is almost exclusively wind dispersed, with animals acting as seed predators. Animals treated ponderosa pine in an intermediate fashion. Two-phased dispersal of large, winged pine seeds appears adaptive; initial wind dispersal helps to minimize pre-dispersal seed mortality whereas scatter hoarding by animals places seeds in sites with a higher probability of seedling establishment.

  19. The accuracy of matrix population model projections for coniferous trees in the Sierra Nevada, California

    USGS Publications Warehouse

    van Mantgem, P.J.; Stephenson, N.L.

    2005-01-01

    1 We assess the use of simple, size-based matrix population models for projecting population trends for six coniferous tree species in the Sierra Nevada, California. We used demographic data from 16 673 trees in 15 permanent plots to create 17 separate time-invariant, density-independent population projection models, and determined differences between trends projected from initial surveys with a 5-year interval and observed data during two subsequent 5-year time steps. 2 We detected departures from the assumptions of the matrix modelling approach in terms of strong growth autocorrelations. We also found evidence of observation errors for measurements of tree growth and, to a more limited degree, recruitment. Loglinear analysis provided evidence of significant temporal variation in demographic rates for only two of the 17 populations. 3 Total population sizes were strongly predicted by model projections, although population dynamics were dominated by carryover from the previous 5-year time step (i.e. there were few cases of recruitment or death). Fractional changes to overall population sizes were less well predicted. Compared with a null model and a simple demographic model lacking size structure, matrix model projections were better able to predict total population sizes, although the differences were not statistically significant. Matrix model projections were also able to predict short-term rates of survival, growth and recruitment. Mortality frequencies were not well predicted. 4 Our results suggest that simple size-structured models can accurately project future short-term changes for some tree populations. However, not all populations were well predicted and these simple models would probably become more inaccurate over longer projection intervals. The predictive ability of these models would also be limited by disturbance or other events that destabilize demographic rates. ?? 2005 British Ecological Society.

  20. Solute chemistry of snowmelt and runoff in an alpine basin, Sierra Nevada

    SciTech Connect

    Williams, M.W.; Melack, J.M. )

    1991-07-01

    Snowpack runoff contributions to the hydrochemistry of an alpine catchment in the Sierra Nevada were evaluated n 1986 and 1987 by analyzing snowpack, meltwater, and stream water samples for major inorganic ions, conductance, acid neutralizing capacity (ANC), and silicate. Maximum concentrations of ions in meltwater were inversely related to the rate of snowmelt. Hydrogen concentration in meltwater was buffered by ANC produced in part by the dissolution of particulates. The anionic pulse in meltwater was observed in stream waters during the first 30 days of snowpack runoff, with NO{sub 3}{sup {minus}} concentrations in stream waters at this time about 1.6-fold greater than the average NO{sub 3}{sup {minus}} concentration for the time period of snowpack runoff, Cl{sup {minus}} about 1.5-fold greater and SO{sub 4}{sup 2{minus}} about 1.3-fold greater. Maximum H{sup +} concentration during snowpack runoff (increase of 170% over winter concentrations) occurred near maximum discharge. ANC minima occurred at maximum discharge as a result of dilution, with a decrease from winter concentrations of 70% in 1986 and 60% in 1987. Eighty to ninety percent of the H{sup +} stored in the snowpack was consumed before it reached the base of the catchment. Soils were a sink for NH{sub 4}{sup +} from snowpack was consumed before it reached the base of the catchment. Soils were a sink for NH{sub 4}{sup +} from snowpack meltwater, with less than 1% of the NH{sub 4}{sup +}{sub 4} released from snowpack storage exported from the basin as NH{sub 4}{sup +}. Sulfate concentrations in stream waters were less variable than NO{sub 3}{sup {minus}} or Cl{sup {minus}} concentrations.

  1. Fire suppression impacts on postfire recovery of Sierra Nevada chaparral shrublands

    USGS Publications Warehouse

    Keeley, J.E.; Pfaff, A.H.; Safford, H.D.

    2005-01-01

    A substantial portion of chaparral shrublands in the southern part of California's Sierra Nevada Mountain Range has never had a recorded fire since record keeping began in 1910. We hypothesised that such long periods without fire are outside the historical range of variability and that when such areas burn, postfire recovery is weaker than in younger stands. We predicted that long fire-free periods will result in loss of shrub species and deterioration of soil seed banks, which, coupled with higher fire intensities from the greater accumulation of dead biomass, will lead to poorer postfire regeneration. The 2002 McNally Fire burned ancient stands that were as much as 150 years old, as well as much younger (mature) stands. Based on shrub skeletons in the burned area as a surrogate for prefire density, we found that ancient stands change in structure, owing primarily to the loss of obligate seeding Ceanothus cuneatus; other species appear to have great longevity. Despite the reduction in C. cuneatus, postfire shrub-seedling recruitment remained strong in these ancient stands, although some seed bank deterioration is suggested by the three-quarters lower seedling recruitment than recorded from mature stands. Total diversity and the abundance of postfire endemic annuals are two other response variables that suggest that these ancient stands are recovering as well as mature stands. The one area of some concern is that non-native species richness and abundance increased in the ancient stands, suggesting that these are more open to alien colonisers. It is concluded that chaparral more than a century old is resilient to such long fire-free periods and fire severity impacts are indistinguishable from those in younger chaparral stands.

  2. Flows, droughts, and aliens: factors affecting the fish assemblage in a Sierra Nevada, California, stream.

    PubMed

    Kiernan, Joseph D; Moyle, Peter B

    2012-06-01

    The fishes of Martis Creek, in the Sierra Nevada of California (USA), were sampled at four sites annually over 30 years, 1979-2008. This long-term data set was used to examine (1) the persistence and stability of the Martis Creek fish assemblage in the face of environmental stochasticity; (2) whether native and alien fishes responded differently to a natural hydrologic regime (e.g., timing and magnitude of high and low flows); and (3) the importance of various hydrologic and physical habitat variables in explaining the abundances of native and alien fish species through time. Our results showed that fish assemblages were persistent at all sample sites, but individual species exhibited marked interannual variability in density, biomass, and relative abundance. The density and biomass of native fishes generally declined over the period of study, whereas most alien species showed no significant long-term trends. Only alien rainbow trout increased in both density and biomass at all sites over time. Redundancy analysis identified three hydrologic variables (annual 7-day minimum discharge, maximum winter discharge, and number of distinct winter floods) and two habitat variables (percentage of pool habitat and percentage of gravel substrate) that each explained a significant portion of the annual variation in fish assemblage structure. For alien taxa, their proportional contribution to the total fish assemblage was inversely related to mean annual streamflow, one-day maximum discharge in both winter and spring, and the frequency of springtime floods. Results of this study highlight the need for continuous annual monitoring of streams with highly variable flow regimes to evaluate shifts in fish community structure. Apparent successes or failures in stream management may appear differently depending on the time series of available data.

  3. Interannual Variations in Aerosol Sources and Their Impact on Orographic Precipitation over California's Central Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Creamean, J.; Ault, A. P.; White, A. B.; Neiman, P. J.; Minnis, P.; Prather, K. A.

    2014-12-01

    Aerosols that serve as cloud condensation nuclei (CCN) and ice nuclei (IN) have the potential to profoundly influence precipitation processes. Furthermore, changes in orographic precipitation have broad implications for reservoir storage and flood risks. As part of the CalWater I field campaign (2009-2011), the impacts of aerosol sources on precipitation were investigated in the California Sierra Nevada Mountains. In 2009, the precipitation collected on the ground was influenced by both local biomass burning and long-range transported dust and biological particles, while in 2010, by mostly local sources of biomass burning and pollution, and in 2011 by mostly long-range transport of dust and biological particles from distant sources. Although vast differences in the sources of residues were observed from year-to-year, dust and biological residues were omnipresent (on average, 55% of the total residues combined) and were associated with storms consisting of deep convective cloud systems and larger quantities of precipitation initiated in the ice phase. Further, biological residues were dominant during storms with relatively warm cloud temperatures (up to -15°C), suggesting biological components were more efficient IN than mineral dust. On the other hand, when precipitation quantities were lower, local biomass burning and pollution residues were observed (on average 31% and 9%, respectively), suggesting these residues potentially served as CCN at the base of shallow cloud systems and that lower level polluted clouds of storm systems produced less precipitation than non-polluted (i.e., marine) clouds. The direct connection of the sources of aerosols within clouds and precipitation type and quantity can be used in models to better assess how local emissions versus long-range transported dust and biological aerosols play a role in impacting regional weather and climate, ultimately with the goal of more accurate predictive weather forecast models and water resource

  4. Detection, attribution, and sensitivity of trends toward earlier streamflow in the Sierra Nevada

    USGS Publications Warehouse

    Maurer, E.P.; Stewart, I.T.; Bonfils, Celine; Duffy, P.B.; Cayan, D.

    2007-01-01

    Observed changes in the timing of snowmelt dominated streamflow in the western United States are often linked to anthropogenic or other external causes. We assess whether observed streamflow timing changes can be statistically attributed to external forcing, or whether they still lie within the bounds of natural (internal) variability for four large Sierra Nevada (CA) basins, at inflow points to major reservoirs. Streamflow timing is measured by "center timing" (CT), the day when half the annual flow has passed a given point. We use a physically based hydrology model driven by meteorological input from a global climate model to quantify the natural variability in CT trends. Estimated 50-year trends in CT due to natural climate variability often exceed estimated actual CT trends from 1950 to 1999. Thus, although observed trends in CT to date may be statistically significant, they cannot yet be statistically attributed to external influences on climate. We estimate that projected CT changes at the four major reservoir inflows will, with 90% confidence, exceed those from natural variability within 1-4 decades or 4-8 decades, depending on rates of future greenhouse gas emissions. To identify areas most likely to exhibit CT changes in response to rising temperatures, we calculate changes in CT under temperature increases from 1 to 5??. We find that areas with average winter temperatures between -2??C and -4??C are most likely to respond with significant CT shifts. Correspondingly, elevations from 2000 to 2800 in are most sensitive to temperature increases, with CT changes exceeding 45 days (earlier) relative to 1961-1990. Copyright 2007 by the American Geophysical Union.

  5. Detection, attribution, and sensitivity of trends toward earlier streamflow in the Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Maurer, E. P.; Stewart, I. T.; Bonfils, C.; Duffy, P. B.; Cayan, D.

    2007-06-01

    Observed changes in the timing of snowmelt dominated streamflow in the western United States are often linked to anthropogenic or other external causes. We assess whether observed streamflow timing changes can be statistically attributed to external forcing, or whether they still lie within the bounds of natural (internal) variability for four large Sierra Nevada (CA) basins, at inflow points to major reservoirs. Streamflow timing is measured by "center timing" (CT), the day when half the annual flow has passed a given point. We use a physically based hydrology model driven by meteorological input from a global climate model to quantify the natural variability in CT trends. Estimated 50-year trends in CT due to natural climate variability often exceed estimated actual CT trends from 1950 to 1999. Thus, although observed trends in CT to date may be statistically significant, they cannot yet be statistically attributed to external influences on climate. We estimate that projected CT changes at the four major reservoir inflows will, with 90% confidence, exceed those from natural variability within 1-4 decades or 4-8 decades, depending on rates of future greenhouse gas emissions. To identify areas most likely to exhibit CT changes in response to rising temperatures, we calculate changes in CT under temperature increases from 1 to 5°. We find that areas with average winter temperatures between -2°C and -4°C are most likely to respond with significant CT shifts. Correspondingly, elevations from 2000 to 2800 m are most sensitive to temperature increases, with CT changes exceeding 45 days (earlier) relative to 1961-1990.

  6. Representing atmospheric moisture content along mountain slopes: Examination using distributed sensors in the Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Feld, Shara I.; Cristea, Nicoleta C.; Lundquist, Jessica D.

    2013-07-01

    Atmospheric moisture content is critical in hydrological modeling yet is sparsely measured in mountainous environments. We compared densely distributed measurements of dew point temperature in two study sites in the Sierra Nevada, California, against (1) simple empirical algorithms, (2) the Parameter-elevation Regressions on Independent Slopes Model (PRISM), (3) radiosonde data, and (4) the Weather Research and Forecasting (WRF) mesoscale model. Empirical algorithms that used only one sea-level measurement of dew point to extrapolate to higher elevations often did not match local dew point lapse rates and could be biased as high as 9.9°C. PRISM improved upon these methods by using local observations to determine the local average dew point lapse rate, with median bias values of -0.3°C and 3.3°C in our two study sites. Empirical algorithms that derived dew point from air temperature showed a seasonal variation in performance; summer median bias values were 0.6°C-8.2°C wetter than winter bias values. Radiosonde readings showed median biases of -6.5°C and -8.0°C from observations in our study sites. WRF improved on the radiosonde data, performing well in representing both the overall trends in the basin (with median biases of -0.9°C and -1.0°C in our study sites). One base station within the basin paired with PRISM lapse rates showed small biases from overall moisture trends. However, a physically resolved model such as WRF was better equipped to represent daily dew point variations and in basins with nonlinear trends.

  7. Interannual Variations in Aerosol Sources and Their Impact on Orographic Precipitation Over California's Central Sierra Nevada

    NASA Technical Reports Server (NTRS)

    Creamean, J. M.; Ault, A. P.; White, A. B.; Neiman, P. J.; Ralph, F. M.; Minnis, Patrick; Prather, K. A.

    2014-01-01

    Aerosols that serve as cloud condensation nuclei (CCN) and ice nuclei (IN) have the potential to profoundly influence precipitation processes. Furthermore, changes in orographic precipitation have broad implications for reservoir storage and flood risks. As part of the CalWater I field campaign (2009-2011), the impacts of aerosol sources on precipitation were investigated in the California Sierra Nevada. In 2009, the precipitation collected on the ground was influenced by both local biomass burning (up to 79% of the insoluble residues found in precipitation) and long-range transported dust and biological particles (up to 80% combined), while in 2010, by mostly local sources of biomass burning and pollution (30-79% combined), and in 2011 by mostly long-range transport from distant sources (up to 100% dust and biological). Although vast differences in the source of residues was observed from year-to-year, dust and biological residues were omnipresent (on average, 55% of the total residues combined) and were associated with storms consisting of deep convective cloud systems and larger quantities of precipitation initiated in the ice phase. Further, biological residues were dominant during storms with relatively warm cloud temperatures (up to -15 C), suggesting these particles were more efficient IN compared to mineral dust. On the other hand, lower percentages of residues from local biomass burning and pollution were observed (on average 31% and 9%, respectively), yet these residues potentially served as CCN at the base of shallow cloud systems when precipitation quantities were low. The direct connection of the source of aerosols within clouds and precipitation type and quantity can be used in models to better assess how local emissions versus long-range transported dust and biological aerosols play a role in impacting regional weather and climate, ultimately with the goal of more accurate predictive weather forecast models and water resource management.

  8. Dissolved Organic Matter Composition and Microbial Diversity In The Lake Tahoe Basin, Sierra Nevada, California.

    NASA Astrophysics Data System (ADS)

    Aluwihare, L.; Goldberg, S. J.; Ball, G. I.; Mendoza, W. G.; Simpson, A.; Kharbush, J.; Nelson, C. E.

    2014-12-01

    Dissolved organic matter (DOM) inputs into high elevation lakes of the Sierra Nevada, California are seasonally segregated, and this enables an examination of the dominant compositional features and microbial responses associated with allochthonous versus autochthonous DOM inputs. Furthermore, because lakes within this watershed have very different hydraulic residence times, extending from days (e.g., Upper Angora Lake) to centuries (Lake Tahoe), the Tahoe Basin represents an ideal experimental system in which to characterize long-lived DOM. We used a variety of analytical tools, including elemental, stable isotope and radiocarbon measurements, nuclear magnetic resonance (NMR) spectroscopy, comprehensive 2D gas chromatography coupled to time of flight (TOF) mass spectrometry and fluorescence measurements, to characterize solid phase extracted (SPE) DOM, and in some cases, whole DOM. Our data show that DOM with typical terrestrial characteristics is quickly removed in lakes with >annual water residence time, leaving behind SPE DOM that is extremely N-rich, with a functional group distribution that is consistent with protein. Furthermore, our radiocarbon measurements estimate a 100-200 year residence time for the N-rich DOM accumulating in Lake Tahoe. All of the analytical techniques distinguish samples based on lake water residence time, which indicates that the lacustrine reactor plays an important role in determining the composition of DOM that accumulates on long timescales. We also examined temporal variations in the microbial community of Lake Tahoe to identify taxa that may be involved in processing DOM from distinct sources. Our results confirm the importance of DOM as a currency for carbon and nitrogen exchange between different compartments of the terrestrial ecosystem and argue for its inclusion in models that examine the response of lake ecosystems to global change.

  9. Seasonal and event-scale variations in solute chemistry for four Sierra Nevada catchments

    USGS Publications Warehouse

    Holloway, J.M.; Dahlgren, R.A.

    2001-01-01

    Hydrobiogeochemical processes controlling stream water chemistry were examined in four small (<5 km2) catchments having contrasting bedrock lithologies in the western Sierra Nevada foothills of California. The Mediterranean climate with its cool/wet and hot/dry cycle produces strong seasonal patterns in hydrological, biological and geochemical processes. Stream water solutes fall into three general groups according to seasonal fluctuation in concentration: Strong, rainy season minimum-dry season maximum (Cl-, SO42-, base cations); weak, rainy season minimum-dry season maximum (Si); and rainy season maximum-dry season minimum (NO3- and K+). Solute dynamics in soil solutions and stream water suggest that mixing of drainage waters from bedrock and soil sources regulate stream water solute concentrations. Patterns are further altered by the leaching of solutes accumulated in the soil over the summer period of desiccation and the temporal discoupling of nutrient cycles that occurs due to differences in the timing between vegetation growth (late spring) and leaching (early winter). Solute concentrations are remarkably similar between watersheds with varying bedrock types, with the exception of nitrate, sulfate and bicarbonate. Three watersheds have nitrogen-bearing metasedimentary bedrock that contributes to elevated nitrate concentrations in stream waters. Watersheds whose bedrock includes mineralized veins of sulfide and carbonate minerals similarly have greater sulfate and bicarbonate concentrations in stream water. Hydrobiogeochemical processes are highly dynamic at the seasonal and storm-event temporal scales and spatially complex at the watershed scale making management of stream water chemical composition, such as nitrate concentrations, very challenging. ?? 2001 Elsevier Science B.V.

  10. Land-Cover Trends of the Sierra Nevada Ecoregion, 1973-2000

    USGS Publications Warehouse

    Raumann, Christian G.; Soulard, Christopher E.

    2007-01-01

    The U.S. Geological Survey has developed and is implementing the Land Cover Trends project to estimate and describe the temporal and spatial distribution and variability of contemporary land-use and land-cover change in the United States. As part of the Land Cover Trends project, the purpose of this study was to assess land-use/land-cover change in the Sierra Nevada ecoregion for the period 1973 to 2000 using a probability sampling technique and satellite imagery. We randomly selected 36 100-km2 sample blocks to derive thematic images of land-use/land-cover for five dates of Landsat imagery (1973, 1980, 1986, 1992, 2000). We visually interpreted as many as 11 land-use/land-cover classes using a 60-meter minimum mapping unit from the five dates of imagery yielding four periods for analysis. Change-detection results from post-classification comparison of our mapped data showed that landscape disturbance from fire was the dominant change from 1973-2000. The second most-common change was forest disturbance resulting from harvest of timber resources by way of clear-cutting. The rates of forest regeneration from temporary fire and harvest disturbances coincided with the rates of disturbance from the previous period. Relatively minor landscape changes were caused by new development and reservoir drawdown. Multiple linear regression analysis suggests that land ownership and the proportion of forest and developed cover types were significant determinants of the likelihood of direct human-induced change occurring in sampling units. Driving forces of change include land ownership, land management such as fire suppression policy, and demand for natural resources.

  11. Zircon trace element, and O and Hf isotopic records of magma sources and pluton assembly in the Sierra Crest intrusions (Sierra Nevada batholith, USA)

    NASA Astrophysics Data System (ADS)

    Miller, J. S.; Lackey, J. S.; Davies, G. R.; Sendek, C.

    2014-12-01

    The Sierra Crest Intrusions of the Sierra Nevada Batholith are the last major magmatic pulse associated with the Cretaceous flare-up. They are characterized by long assembly times (several 106 years), and are normally zoned from marginal, horblende-biotite granodiorites to more felsic, K-feldspar megacrystic, biotite granodiorites. Combined trace element and O and Hf isotopes on zircon are presented from the major Sierra Crest Intrusions. Zircon saturation temperatures (TZrc,sat) are similar and low (ca. 700°C) for most of the individual units, but Ti-in-zircon temperatures (TZrn,Ti) and trace element ratios contrast strongly between outer marginal units and inner megacrystic units (low TZrn,Ti ≈ TZrc,sat, high Yb/Gd, low Th/U, high and similar Hf, and high Eu/Eu*). Zircon O and Hf isotopes vary markedly across the suite (ΔɛHf = 15; Δδ18O = 2.5‰). Individual intrusive suites (gabbro to high-silica granite) record variable O-Hf variations; no correlation (John Muir), subtle binary or ternary arrays (e.g., Whitney, Sonora), or bimodal distribution of values (Tuolumne). In some cases single hand samples (small-volume mafic or felsic units), may record the entire variability within a suite. Inner megacrystic units generally have lower ɛHf than outer marginal units. Whole rock geochemical data for the intrusive suites also show an increase in the "garnet signature" with time (higher Sr/Y and Dy/Yb). The isotopic data are consistent with variable mantle sources and progressively cooler, more water-rich magmatism with a simultaneous shift to greater crustal involvement, and deepening of the magma sources. Magmatic underplating and intraplating of mafic arc magmas produced increasing crustal assimilation but under PT conditions that allowed production of more felsic, zircon-saturated, magmas. The isotopic variability requires that plutons are amalgams of many magmas mixed at varying scales before final solidification.

  12. The Fluid Evolution of a Ductile-To Dextral Shear Zone in the Central Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Holk, G. J.; Lojasiewicz, I.; Hartman, S. M.; Compton, K.; Paterson, S. R.; Kirkpatrick, J. D.

    2015-12-01

    The application of stable isotopes in conjunction with detailed mapping of the dextral Steelhead Lake shear zone (SLSZ) in the central Sierra Nevada reveals a complex fluid history as the system transitioned from ductile-to-brittle behavior at shallow crustal depth in response to cooling of the adjacent Tuolumne Batholith (TB) at ~85 Ma. This system has a multi-stage alteration history that includes: (1) ductiley deformed tourmaline-bearing leucogranite dikes, (2) ductile-to-brittle quartz+tourmaline veins, (3) brittle calc-silicate-rich leach zones, and (4) 1-10-m-thick quartz veins with crack-seal textures. High and variable quartz δ18O values (> +13‰) from metasedimentary rocks belonging to the Saddlebag pendant outside the SLSZ indicate metamorphic fluids at low water/rock ratio. Leucogranite dikes associated with the TB have δ18O (plagioclase = +9.5±0.3‰) and δD (~ -80‰) values consistent with magmatic fluids. Quartz+tourmaline veins that record the ductile-to-brittle transition display a range of δ18O values (quartz: +3.4 to +16.4‰; tourmaline: +8.0‰) that indicate a complex fluid system involving magmatic, metamorphic, and meteoric-hydrothermal fluids. Variable mineral δ18O (-1.5 to +11.3‰) and δD (-140 to -77‰) values from the Sawmill Sequence calc-silicates and Koip Sequence metavolcanics are the product of a fluid system with magmatic (TB) and meteoric-hydrothermal end-member sources, with lowest values found within a pull-apart zone and the highest values are outside this zone. Quartz δ18O (-3.2 to +14.5‰) and fluid inclusion δD values (-137 to -79‰) define a mixing line with magmatic (TB) and meteoric-hydrothermal water end members for the crack-seal veins. Detailed studies of one 10-m-thick vein reveal a trend of decreasing isotope values from the margin to the median plane. Most mineral pairs failed to reach isotopic equilibrium, indicating a very complex and short-lived fluid evolution for this system. This study documents

  13. Distribution of Brook Trout and Their Food Sources in Meadow vs. Wooded Areas of Sierra Nevada Headwater Streams

    NASA Astrophysics Data System (ADS)

    Basile, N. J.; Blumenshine, S.

    2005-05-01

    Stocked eastern brook trout are now well established in historically fishless, small headwater streams in the Sierra Nevada. Although non-native, brook trout have maintained healthy populations since stocking ended 60-80 years ago. Our primary research question was whether brook trout distribution and feeding ecology is influenced by variation in headwater stream habitats and food sources. Stream habitat characteristics and trout demographic data were collected during June and August 2004 from four forested and three meadow sites among five tributaries to Bull Creek in the Sierra Nevada. Both mean fish mass and total fish biomass were greater in forested versus meadow reaches. Macroinvertebrate drift rate did not differ between meadow versus wooded reaches, but were greater in June than August. However, despite higher fish biomass, trout in forests apparently selected prey from drift, whereas trout diets in meadows reflected availability in drift. The results of this research will ultimately be used in a larger, collaborative, whole-ecosystem study conducted by the USDA-Forest Service addressing how current forest management practices affect stream ecosystems.

  14. Winter sowings produce 1-0 sugar pine planting stock in the Sierra Nevada. Forest Service research paper

    SciTech Connect

    Jenkinson, J.L.; McCain, A.H.

    1993-09-01

    Seed source and sowing date effects on first-year seedling growth and Fusarium root and collar rot of sugar pine were analyzed in two consecutive nursery tests at the Pacific Southwest Research Station's Institute of Forest Genetics, near Placerville in the western Sierra Nevada. The experimental design in both tests consisted of four replications of a randomized complete block of split-split plots, with sowing date split for disease treatment and seed source. Seed sources were natural stands at low, middle, and high elevations on the western slope of the northern Sierra Nevada. Seeds were soaked 36 hours in aerated water at 25 deg (77 deg F), chilled 90 days at 1 deg C (34 deg F), and sown in fumigated soil in February, March, April, and May. Treatment plots were drenched with fungicides just before sowing in the first test, and were inoculated with Fusarium oxysporum at time of sowing in the second test. Seedling emergence averaged 96 to 99 percent, regardless of sowing date.

  15. Vegetation Cover Change in the Upper Kings River Basin of the Sierra Nevada Detected Using Landsat Satellite Image Analysis

    NASA Technical Reports Server (NTRS)

    Potter, Christopher S.

    2015-01-01

    The Sierra Nevada of California is a region where large wildfires have been suppressed for over a century. A detailed geographic record of recent changes in vegetation cover across the Sierra Nevada remains a gap that can be filled with satellite remote sensing data. Results from Landsat image analysis over the past 25 years in the Upper Kings River basin showed that consistent, significant increases in the normalized difference vegetation index (NDVI) have not extended above 2000 m elevation, where cold temperatures presumably limit the growing season. Moreover, mean increases in NDVI since 1986 at elevations below 2000 m (which cover about half of the total basin area) have not exceeded 9%, even in the most extreme precipitation yearly comparisons. NDVI has decreased significantly at elevations above 2000 m throughout the basin in relatively wet year comparisons since the mid-1980s. These findings conflict with any assumptions that ET fluxes and river flows downstream could have been markedly altered by vegetation change over most of the Upper Kings River basin in recent decades.

  16. Structure and regional significance of the Late Permian(?) Sierra Nevada - Death Valley thrust system, east-central California

    USGS Publications Warehouse

    Stevens, C.H.; Stone, P.

    2005-01-01

    An imbricate system of north-trending, east-directed thrust faults of late Early Permian to middle Early Triassic (most likely Late Permian) age forms a belt in east-central California extending from the Mount Morrison roof pendant in the eastern Sierra Nevada to Death Valley. Six major thrust faults typically with a spacing of 15-20 km, original dips probably of 25-35??, and stratigraphic throws of 2-5 km compose this structural belt, which we call the Sierra Nevada-Death Valley thrust system. These thrusts presumably merge into a de??collement at depth, perhaps at the contact with crystalline basement, the position of which is unknown. We interpret the deformation that produced these thrusts to have been related to the initiation of convergent plate motion along a southeast-trending continental margin segment probably formed by Pennsylvanian transform truncation. This deformation apparently represents a period of tectonic transition to full-scale convergence and arc magmatism along the continental margin beginning in the Late Triassic in central California. ?? 2005 Elsevier B.V. All rights reserved.

  17. Holocene vegetation and climate change recorded in alpine bog sediments from the Borreguiles de la Virgen, Sierra Nevada, southern Spain

    NASA Astrophysics Data System (ADS)

    Jiménez-Moreno, Gonzalo; Anderson, R. Scott

    2012-01-01

    High-resolution pollen and magnetic susceptibility (MS) analyses have been carried out on a sediment core taken from a high-elevation alpine bog area located in Sierra Nevada, southern Spain. The earliest part of the record, from 8200 to about 7000 cal yr BP, is characterized by the highest abundance of arboreal pollen and Pediastrum, indicating the warmest and wettest conditions in the area at that time. The pollen record shows a progressive aridification since 7000 cal yr BP that occurred in two steps, first shown by a decrease in Pinus, replaced by Poaceae from 7000 to 4600 cal yr BP and then by Cyperaceae, Artemisia and Amaranthaceae from 4600 to 1200 cal yr BP. Pediastrum also decreased progressively and totally disappeared at ca. 3000 yr ago. The progressive aridification is punctuated by periodically enhanced drought at ca. 6500, 5200 and 4000 cal yr BP that coincide in timing and duration with well-known dry events in the Mediterranean and other areas. Since 1200 cal yr BP, several changes are observed in the vegetation that probably indicate the high-impact of humans in the Sierra Nevada, with pasturing leading to nutrient enrichment and eutrophication of the bog, Pinus reforestation and Olea cultivation at lower elevations.

  18. Intra-arc strike-slip fault exposed at batholithic levels in the southern Sierra Nevada, California

    SciTech Connect

    Busby-Spera, C.J. ); Saleeby, J.B. )

    1990-03-01

    The Kern Canyon fault is a major north-trending fault that is continuous for a distance of 140 km in the southern Sierra Nevada, California. Previous geologic mapping and geochronological work along the northern third of the fault indicate that dextral offset occurred sometime after 80 Ma and before 3.5 Ma; this offset was interpreted to be the result of Cenozoic basin-and-range extension. Our new results from the central third of the fault (Kernville-Lake Isabella region) indicate an earlier right-lateral movement history, contemporaneous with emplacement of the largest plutons in the Sierra Nevada. The older structure is termed the proto-Kern Canyon fault zone. The Cenozoic fault trace is a narrow zone of brittle deformation, whereas the Cretaceous fault zone is a broad zone of ductile deformation. U-Pb zircon geochronology on plutonic and metavolcanic rocks involved int he ductile deformation, as well as a pluton that postdates ductile deformation, demonstrate that the proto-Kern Canyon fault zone was active at 85 Ma, and may have begun to move as early as 105 Ma. Longitudinal strike-slip faults are common in modern magmatic arcs where convergence is oblique. The proto-Kern Canyon fault zone may have originated in response to a moderate northward component in subduction of the Farallon plate or perhaps a strong northward component for the Kula plate.

  19. Global to local scale simulations of streamflow in the Merced, American, and Carson Rivers, Sierra Nevada, California

    USGS Publications Warehouse

    Dettinger, M.D.; Cayan, D.R.; Mo, K.; Jeton, A.E.

    1999-01-01

    Atmospheric moisture transport and moisture budgets during winter (December-April) simulated by the National Centers for Environmental Prediction (NCEP) regional spectral model (RSM) are examined and used to simulate streamflow variations in the Sierra Nevada. The RSM was nested in 2"-latitude x 2"-longitude NCEPreanalyzed atmospheric-data fields (as a surrogate for a perfect forecast system operating at the global scale). Precipitation, temperature, and solar insolation simulated by the RSM on a 50-km grid were inputted directly to precipitation-runoff models of the Merced, American, and Carson Rivers in an evaluation of the potential for end-to-end forecasting of streamflow and snowmelt runoff from the Sierra Nevada, near 39"N 120"W. Over the western United States, the RSM captures both patterns and magnitudes of precipitation (e.g., Fig. I illustrates observed and simulated precipitation for winter 1982-83). The RSM has dry biases in the Southeast and over the Gulf of Mexico, but it captures interannual and intraseasonal variations well. During most El Nifios, it simulates a precipitation dipole over the western states with wetter-than-normal conditions in California and drier-than-normal in the Pacific Northwest. The Northeast is relatively dry and the southern states are wet, as in observations. The RSM did equally well during La Niiia winters.

  20. Patterns of orographic uplift in the Sierra Nevada and their relationship to upper-level atmospheric circulation

    USGS Publications Warehouse

    Aguado, Edward; Cayan, Daniel R.; Reece, Brian D.; Riddle, Larry

    1993-01-01

    We examine monthly and seasonal patterns of precipitation across various elevations of the eastern Central Valley of California and the Sierra Nevada. A measure of the strength of the orographic effect called the “precipitation ratio” is calculated, and we separate months into four groups based on being wet or dry and having low or high precipitation ratios. Using monthly maps of mean 700-mb height anomalies, we describe the northern hemisphere mid-tropospheric circulation patterns associated with each of the four groups. Wet months are associated with negative height anomalies over the eastern Pacific, as expected. However, the orientation of the trough is different for years with high and low precipitation ratios. Wet months with high ratios typically have circulation patterns factoring a west-southwest to east-northeast storm track from around the Hawaiian Islands to the Pacific Northwest of the United States. Wet months with low precipitation ratios are associated with a trough centered near the Aleutians and a northwest to southeast storm track. Dry months are marked by anticyclones in the Pacific, but this feature is more localized to the eastern Pacific for months with low precipitation ratios than for those with high ratios. Using precipitation gauge and snow course data from the American River and Truckee-Tahoe basins, we determined that the strength of the orographic effect on a seasonal basis is spatially coherent at low and high elevations and on opposite sides of the Sierra Nevada crestline.

  1. Valuing year-to-go hydrologic forecast improvements for a peaking hydropower system in the Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Rheinheimer, David E.; Bales, Roger C.; Oroza, Carlos A.; Lund, Jay R.; Viers, Joshua H.

    2016-05-01

    We assessed the potential value of hydrologic forecasting improvements for a snow-dominated high-elevation hydropower system in the Sierra Nevada of California, using a hydropower optimization model. To mimic different forecasting skill levels for inflow time series, rest-of-year inflows from regression-based forecasts were blended in different proportions with representative inflows from a spatially distributed hydrologic model. The statistical approach mimics the simpler, historical forecasting approach that is still widely used. Revenue was calculated using historical electricity prices, with perfect price foresight assumed. With current infrastructure and operations, perfect hydrologic forecasts increased annual hydropower revenue by 0.14 to 1.6 million, with lower values in dry years and higher values in wet years, or about $0.8 million (1.2%) on average, representing overall willingness-to-pay for perfect information. A second sensitivity analysis found a wider range of annual revenue gain or loss using different skill levels in snow measurement in the regression-based forecast, mimicking expected declines in skill as the climate warms and historical snow measurements no longer represent current conditions. The value of perfect forecasts was insensitive to storage capacity for small and large reservoirs, relative to average inflow, and modestly sensitive to storage capacity with medium (current) reservoir storage. The value of forecasts was highly sensitive to powerhouse capacity, particularly for the range of capacities in the northern Sierra Nevada. The approach can be extended to multireservoir, multipurpose systems to help guide investments in forecasting.

  2. Field guide to geologic excursions in southwestern Utah and adjacent areas of Arizona and Nevada

    USGS Publications Warehouse

    Lund, William R.; Lund, William R.

    2002-01-01

    This field guide contains road logs for field trips planned in conjunction with the 2002 Rocky Mountain Section meeting of the Geological Society of America held at Southern Utah University in Cedar City, Utah. There are a total of eight field trips, covering various locations and topics in southwestern Utah and adjacent areas of Arizona and Nevada. In addition, the field guide contains a road log for a set of Geological Engineering Field Camp Exercises run annually by the University of Missouri at Rolla in and around Cedar City. Two of the field trips address structural aspects of the geology in southwestern Utah and northwestern Arizona; two trips deal with ground water in the region; and along with the Field Camp Exercises, one trip, to the Grand Staircase, is designed specifically for educators. The remaining trips examine the volcanology and mineral resources of a large area in and around the Tusher Mountains in Utah; marine and brackish water strata in the Grand Staircase-Escalante National Monument; and the Pine Valley Mountains, which are cored by what may be the largest known laccolith in the world. The "Three Corners" area of Utah, Arizona, and Nevada is home to truly world-class geology, and I am confident that all of the 2002 Rocky Mountain Section meeting attendees will find a field trip suited to their interests.

  3. Groundwater-quality data for the Sierra Nevada study unit, 2008: Results from the California GAMA program

    USGS Publications Warehouse

    Shelton, Jennifer L.; Fram, Miranda S.; Munday, Cathy M.; Belitz, Kenneth

    2010-01-01

    Groundwater quality in the approximately 25,500-square-mile Sierra Nevada study unit was investigated in June through October 2008, as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The GAMA Priority Basin Project is being conducted by the U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board (SWRCB). The Sierra Nevada study was designed to provide statistically robust assessments of untreated groundwater quality within the primary aquifer systems in the study unit, and to facilitate statistically consistent comparisons of groundwater quality throughout California. The primary aquifer systems (hereinafter, primary aquifers) are defined by the depth of the screened or open intervals of the wells listed in the California Department of Public Health (CDPH) database of wells used for public and community drinking-water supplies. The quality of groundwater in shallower or deeper water-bearing zones may differ from that in the primary aquifers; shallow groundwater may be more vulnerable to contamination from the surface. In the Sierra Nevada study unit, groundwater samples were collected from 84 wells (and springs) in Lassen, Plumas, Butte, Sierra, Yuba, Nevada, Placer, El Dorado, Amador, Alpine, Calaveras, Tuolumne, Madera, Mariposa, Fresno, Inyo, Tulare, and Kern Counties. The wells were selected on two overlapping networks by using a spatially-distributed, randomized, grid-based approach. The primary grid-well network consisted of 30 wells, one well per grid cell in the study unit, and was designed to provide statistical representation of groundwater quality throughout the entire study unit. The lithologic grid-well network is a secondary grid that consisted of the wells in the primary grid-well network plus 53 additional wells and was designed to provide statistical representation of groundwater quality in each of the four major lithologic units in the Sierra

  4. Altered precipitation patterns with a shift from snow to rain in the Sierra Nevada Mountains of California

    NASA Astrophysics Data System (ADS)

    Pavelsky, T. M.; Sobolowski, S.; Kapnick, S. B.; Barnes, J. B.

    2011-12-01

    Precipitation patterns in mountain environments affect global water resources and major hazards such as floods and landslides. In mid-latitude mountain ranges such as the Sierra Nevada Mountains of California, much of the precipitation falls as snow, which accumulates and acts as a natural reservoir. As in many snowfall-dependent regions, California water infrastructure has been designed to capture warm season snowmelt runoff and transport it to otherwise dry areas where it is needed. Recent studies suggest that anthropogenic climate change is likely to result in a substantial shift from snow to rain in the Sierra Nevada during the 21st century. One mechanism for changing spatial patterns in precipitation that has not received substantial attention arises directly from a phase change associated with winter temperatures rising above freezing with greater frequency. Because the fall speed of rain is greater than snow, it is not advected as far as snow by the prevailing winds. We hypothesize that an extreme change from snow to rain will result in a substantial westward shift in annual precipitation under a warming climate. To test this hypothesis, we conducted two climate simulations over the central Sierra Nevada using the WRF regional climate model version 3.1.1 for the period October 2001 to September 2002. Both simulations used nested domains with grid spacings of 27 km, 9 km, and 3 km. The first simulation is a control run, while the second run is an idealized simulation in which fall speeds for snow and graupel are set to be identical to those of raindrops. Comparison of the two runs suggests that a change from snow to rain would yield substantial changes in the spatial patterns of precipitation. However, these patterns are fully realized only in the 3 km domain. In the 9 km and especially the 27 km domain these patterns are substantially attenuated, likely due to less detailed orographic forcing. In the 3 km domain, precipitation increases substantially on

  5. Multiyear Evidence from Ground-based Observations and Modeling of the Impact of Dust on Snowfall in the Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Creamean, J.; Ault, A. P.; Collins, D. B.; Cahill, J. F.; Fitzgerald, E.; White, A. B.; Neiman, P. J.; Wick, G. A.; Fan, J.; Leung, L.; Ralph, F. M.; Prather, K. A.

    2011-12-01

    Aerosols that have the ability to act as ice nuclei (IN) can impact cloud formation and alter the type, amount, and location of precipitation. IN such as dust and biological aerosols can lead to early initiation of the ice phase that enhances riming and thus precipitation. Depending on temperature conditions, this can lead to increased snowfall at the surface. Potential snowfall enhancement in mountainous regions such as California's Sierra Nevada has large implications on regional water supply, which in turn can affect agricultural and ecosystem productivity, the amount of renewable energy from hydropower, and many other water uses. However, the magnitude of the effect of IN on precipitation intensity, form, and patterns during intense winter storms in the Sierra Nevada is poorly understood. During three consecutive winters (2009-2011) of the CalWater field campaign, the chemical composition of precipitation residues were measured at Sugar Pine Dam, a remote rural site in the Sierra Nevada. Some precipitation events occurred during storms that were characterized by atmospheric river (AR) conditions, which are ideal for generating copious amounts of orographic precipitation. Large fractions of dust and biological aerosols were measured as residues in precipitation samples collected during storms with increased snowfall and lower surface temperatures. In most cases, higher fractions of dust were measured in samples during stronger ARs, while higher fractions of biological or water-insoluble organic residues were measured during weaker ARs throughout all three winters. During the winter storms of CalWater, we observed an increase over time in the fraction of dust and biological residues combined, from 20% in 2009 to 82% in 2011 of the total residues in all precipitation samples, in addition to a decrease in average surface temperature (from 4.8 to 2.3 °C), an increase in the total amount of precipitation (from 253 to 374 mm), and an increase in the frequency of

  6. Application of ERTS-1 imagery and underflight photography in the detection and monitoring of forest insect infestations in the Sierra Nevada Mountains of California

    NASA Technical Reports Server (NTRS)

    Hall, R. C.

    1973-01-01

    The analysis of ERTS-1 imagery of areas in the Sierra Nevada Mountains of California is discussed. The data is used to detect two types of insect infestational and to determine the extent of timber resources. Addition applications are the mapping of stream courses, mountain meadows, lakes, rock outcrops, and grazing land. The ERTS-1 data and underflight photography are used for this purpose.

  7. EFFECTS OF CLIMATE VARIABILITY ON THE CARBON DIOXIDE, WATER, AND SENSIBLE HEAT FLUXES ABOVE A PONDEROSA PINE PLANTATION IN THE SIERRA NEVADA, CA. (R826601)

    EPA Science Inventory

    Abstract

    Fluxes of CO2, water vapor, and sensible heat were measured by the eddy covariance method above a young ponderosa pine plantation in the Sierra Nevada Mountains (CA) over two growing seasons (1 June¯10 September 1997 and 1 May&#...

  8. Inexistence of permafrost at the top of the Veleta peak (Sierra Nevada, Spain).

    PubMed

    Oliva, M; Gómez-Ortiz, A; Salvador-Franch, F; Salvà-Catarineu, M; Palacios, D; Tanarro, L; Ramos, M; Pereira, P; Ruiz-Fernández, J

    2016-04-15

    A 114.5m deep drilling was carried out in August 2000 in the bedrock of the Veleta peak, at 3380m in the massif of Sierra Nevada, Southern Spain. The objective of this work is to analyse temperatures at the first 60m depth of this drilling from September 2002 to August 2013 based on 11 UTL-1 thermal loggers located at different depths, together with air temperatures at the summit of the Veleta peak. Permanent negative temperatures have not been detected in the borehole, which shows evidence of the absence of widespread permafrost conditions nowadays in the highest lands of this massif. Bedrock temperatures oscillated between 3.2°C at 0.6m depth and 2°C at 20m below the surface. The largest temperature ranges were recorded on the most external sensors until 1.2m depth, where values reached 22.3°C. Seasonal temperature variations were significant until 10m depth. The thickness of the seasonal frozen layer was highly variable (0.6-2m) and dependent on annual climate conditions. The mean air temperature at the Veleta peak increased by 0.12°C during the study period. Bedrock temperatures followed diverging trends: a drop of 0.3-0.4°C down to 0.6m depth, a decrease of up to 0.7°C between 4 and 10m, thermal stability at 20m and a rise of 0.2°C that occurred in 2009 at the deepest sensor at 60m. The calculation of the thermal wave damping in the subsoil of the Veleta peak has allowed for quantifying the thermal diffusivity of the rock as (7.05±0.03)10(-7)m(2)/s, which means that the external climate signal arrives with an 8.5-year lag to the sensor at 60m deep. This allows to deduce a trend change in the climate of the area, moving from warmer conditions towards a trend of cooling from 2006 to 2007.

  9. Recent Motion on the Kern Canyon Fault, Southern Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Nadin, E. S.; Saleeby, J. B.

    2005-12-01

    Evidence suggests that the Kern Canyon Fault (KCF), the longest fault in the southern Sierra Nevada, is an active fault. Along the 140-km-long KCF, batholithic and metamorphic rocks were displaced up to 16~km in apparent dextral strike slip during at least three discrete phases of deformation throughout the past ~90~Myr. Early ductile shear is preserved along a 1.5-km-wide zone of S-C mylonites and phyllonites that constitutes the Proto-KCF; a later phase of brittle faulting led to through-going cataclasis along the 50-m-wide KCF; and finally, late-stage minor faulting resulted in thin, hematitic gouge zones. The KCF has been considered inactive since 3.5~Ma based on a dated basalt flow reported to cap the fault. However, we believe this basalt to be disturbed, and several pieces of evidence support the idea that the KCF has been reactivated in a normal sense during the Quaternary. Fresh, high-relief fault scarps at Engineer Point in Lake Isabella and near Brush Creek, suggest recent, west-side-up vertical offset. And seismicity in the area hints at local motion. The center of activity during the 1983--1984 Durrwood Meadows earthquake swarm, a series of more than 2,000 earthquakes, the largest of which was M = 4.5, was 10~km east of the KCF. The swarm spanned a discrete, 100~km-long north-south trajectory between latitudes 35° 20'N and 36° 30'N, and its focal mechanisms were consistent with pure normal faulting, but the KCF has been disqualified as too far west and too steep to accommodate the seismic activity. But it could be part of the fault system: Near latitude 36°N, we documented a well-preserved expression of the KCF, which places Cretaceous granitic rocks against a Quaternary glacial debris flow. This fault plane strikes N05°E and is consistent with west-side-up normal faulting, in agreement with the focal mechanism slip planes of the Durrwood Meadows swarm. It is possible that the recent swarm represents a budding strand of the KCF system, much like

  10. Characterizing Runoff and Water Yield from Headwater Catchments in the Southern Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Safeeq, M.; Hunsaker, C. T.

    2015-12-01

    In a mediterranean climate where much of the annual precipitation falls during winter, the snow-capped Sierra Nevada serves as the primary source of dry season runoff that supports agriculture, industries, urban, and other ecosystems. Increased warming has led to significant reductions in mountain snowpack accumulation and earlier snowmelt throughout the western United States where most of the snow accumulates at temperatures near the freezing point. As a result, declines in dry season runoff magnitude, earlier runoff timing, and altered flood risk have been reported across the region. An important question in this context is, how to best manage forested catchments for water and other ecosystem services? We depict the differences in hydrologic response of ten catchments in the Kings River Experimental Watersheds (KREW) research project using continuous precipitation, snow, and runoff data during 2004-2014. The size of these catchments ranges from 50 to 475 ha, and they span a 600-m elevation range in the rain snow transitional zone. In terms of soil, Shaver and Gerle-Cagwin dominate the lower elevation Providence catchments, and Cagwin soils dominate the higher elevation Bull catchments. The majority of these catchments have southwest aspect, moderate average slope (i.e. <25%), and a well-developed drainage network with drainage density ranging from 4.6 to 10.1 km/km2. Bull catchments, on average, have higher runoff than the Providence catchments across all hydrologic signatures extracted from daily hydrographs. Mean annual runoff ranges between 281 to 408 mm in Providence and 436 to 656 mm in Bull catchments despite no significant difference in precipitation among KREW's four meteorological stations. However, high elevation Bull catchments receive significantly more precipitation as snow than the low elevation Providence catchments. The average runoff ratio ranges from 18% to as high as 43% among different catchments, indicating that the catchment

  11. Atmospheric deposition and solute export in giant sequoia: mixed conifer watersheds in the Sierra Nevada, California

    USGS Publications Warehouse

    Stohlgren, Thomas J.; Melack, John M.; Esperanza, Anne M.; Parsons, David J.

    1991-01-01

    Atmospheric depostion and stream discharge and solutes were measured for three years (September 1984 - August 1987) in two mixed conifer watersheds in Sequoia National Park, in the southern Sierra Nevada of California. The Log Creek watershed (50 ha, 2067-2397 m elev.) is drained by a perennial stream, while Tharp's Creek watershed (13 ha, 2067-2255 m elev.) contains an intermittent stream. Dominant trees in the area include Abies concolor (white fir), Sequoiadendron giganteum (giant sequoia), A. magnifica (red fir), and Pinus lambertiana (sugar pine). Bedrock is predominantly granite and granodiorite, and the soils are mostly Pachic Xerumbrepts. Over the three year period, sulfate (SO42-), nitrate (NO3-), and chloride (Cl-) were the major anions in bulk precipitation with volume-weighted average concentrations of 12.6, 12.3 and 10.0 μeq/1, respectively. Annual inputs of NO3-N, NH4-N and SO4-S from wet deposition were about 60 to 75% of those reported from bulk deposition collectors. Discharge from the two watersheds occurs primarily during spring snowmelt. Solute exports from Log and Tharp's Creeks were dominated by HCO3-, Ca2+ and Na+, while H+, NO3-, NH4+ and PO43- outputs were relatively small. Solute concentrations were weakly correlated with instantaneous stream flow for all solutes (r2 3- (Log Cr. r2=0.72; Tharp's Cr. r2=0.38), Na+ (Log Cr. r2=0.56; Tharp's Cr. r2=0.47), and silicate (Log Cr. r2=0.71; Tharp's Cr. r2=0.49). Mean annual atmospheric contributions of NO3-N (1.6 kg ha-1), NH4-N (1.7 kg ha-1), and SO4-S (1.8 kg ha-1), which are associated with acidic deposition, greatly exceed hydrologic losses. Annual watershed yields (expressed as eq ha-1) of HCO3- exceeded by factors of 2.5 to 37 the annual atmospheric deposition of H+.

  12. Climate and hillslope degradation vary in concert; 85 ka to present, eastern Sierra Nevada, CA, USA

    NASA Astrophysics Data System (ADS)

    Madoff, Risa D.; Putkonen, Jaakko

    2016-08-01

    Degradation in the landscape results when the interactions of climate, substrate, and biota dislodge and transport sediment that is mantling landforms. Rates of degradation through time control landform stability and resiliency. Therefore, records of past degradation rates can be used to inform us on how a given landscape responded to significant changes in past climates. For example, climate has varied at many temporal scales, and some of the largest recent shifts enabled the glacial advances and retreats in time scales of 20-100 ka. Therefore, it is reasonable to expect that the rate of landscape degradation has also varied at similar time scales. However, the general hillslope diffusion equation that is commonly used to model cross-profiles of hillslopes on time scales of thousands to tens of thousands of years typically relies on a constant and optimized rate parameter to generate a model cross-profile approximating the current observed landform cross-profile. Using a time-varying diffusivity parameter, we generated three separate degradation scenarios for the Mono Basin moraine in the eastern Sierra Nevada, CA, USA, in order to assess the potential impact of varying past climates on sediment transport. We used published paleoclimate records in the study area and modern rates of surface degradation from climates that correspond broadly to those paleoclimates. The results indicate that, in this case, the climate driven and, therefore, time-dependent degradation model produces a good fit between the modeled and observed landform profiles. Results showed that, when the surface elevations of the reference case (constant optimized diffusivity) were compared through time to the surface elevations of the time-dependent model, the differences were relatively small. The largest deviation was found to occur during the Last Glacial Maximum (LGM). We found that for investigations into the geological effects of climate change in glacial and polar regions, the use of time

  13. Early Neogene unroofing of the Sierra Nevada de Santa Marta along the Bucaramanga -Santa Marta Fault

    NASA Astrophysics Data System (ADS)

    Piraquive Bermúdez, Alejandro; Pinzón, Edna; Bernet, Matthias; Kammer, Andreas; Von Quadt, Albrecht; Sarmiento, Gustavo

    2016-04-01

    Plate interaction between Caribbean and Nazca plates with Southamerica gave rise to an intricate pattern of tectonic blocks in the Northandean realm. Among these microblocks the Sierra Nevada de Santa Marta (SNSM) represents a fault-bounded triangular massif composed of a representative crustal section of the Northandean margin, in which a Precambrian to Late Paleozoic metamorphic belt is overlain by a Triassic to Jurassic magmatic arc and collateral volcanic suites. Its western border fault belongs to the composite Bucaramanga - Santa Marta fault with a combined left lateral-normal displacement. SE of Santa Marta it exposes remnants of an Oligocene marginal basin, which attests to a first Cenoizoic activation of this crustal-scale lineament. The basin fill consists of a sequence of coarse-grained cobble-pebble conglomerates > 1000 m thick that unconformably overlay the Triassic-Jurassic magmatic arc. Its lower sequence is composed of interbedded siltstones; topwards the sequence becomes dominated by coarser fractions. These sedimentary sequences yields valuable information about exhumation and coeval sedimentation processes that affected the massif's western border since the Upper Eocene. In order to analyse uplifting processes associated with tectonics during early Neogene we performed detrital zircon U-Pb geochronology, detrital thermochronology of zircon and apatites coupled with the description of a stratigraphic section and its facies composition. We compared samples from the Aracataca basin with analog sequences found at an equivalent basin at the Oca Fault at the northern margin of the SNSM. Our results show that sediments of both basins were sourced from Precambrian gneisses, along with Mesozoic acid to intermediate plutons; sedimentation started in the Upper Eocene-Oligocene according to palynomorphs, subsequently in the Upper Oligocene a completion of Jurassic to Cretaceous sources was followed by an increase of Precambrian input that became the dominant

  14. Inexistence of permafrost at the top of the Veleta peak (Sierra Nevada)

    NASA Astrophysics Data System (ADS)

    Gómez-Ortiz, Antonio; Salvador-Franch, Ferran; Salvà-Catarineu, Montserrat; Oliva, Marc; Palacios, David; Tanarro, Luis Miguel; Schulte, Lothar

    2014-05-01

    Several deep drillings wew carried out along a latitudinal transect from Svalbard (78°N) to Sierra Nevada (37°N, Spain) within the project Permafrost and Climate Change in Europe (PACE). In this abstract we discuss the data corresponding to the drilling existing at the top of the Veleta peak, at an altitude of 3380 m. This drilling reach a depth of 114.5 m depth, although we analyze here the data of the first 60 m depth. UTL-1 loggers were installed at depths of 0.2, 0.6, 1.2, 2.6, 4, 7, 10, 13, 15, 20 and 60 m. The observation period spans from 2002 to 2013 with data being taken every 2 h. The most surficial loggersrecorded the largest annual temperature oscillations, reaching 22.6°C at 20 cm. Down to 10 m depth the annual temperature amplitude is still remarkable and seasonal temperature changes are even observed at depths of 15 to 20 m. Below this level the temperature remains constant. The logger installed at 60 m depth recorded small temperature changes between 2006 and 2009, oscillating between 2.38 and 2.61ºC. Since January 2010 the temperatures stabilized at 2.61°C. However, this slight temperature increase must be framed within the margin of instrumentation error of the devices. Data shows evidence of the inexistence ofpermanent negative temperatures at depth. In contrast to what happens in the nearby Veleta cirque floor (3100 m), where marginal permafrost conditions have been recorded, in the Veleta peak (3380 m) data points to the absence of a permafrost regime. This may be due to several factors: a) The existence of permafrost in the Veletacirque is directly related to the presence of fossil glacier ice corresponding to a glacier that existed there during the Little Ice Age. b ) The early melting of snow cover in the Veleta peak due to wind effect and incidence of solar radiation condition the absence of permafrost conditions at the summitin contrast to the Veleta cirquefloor, where the longer persistence of snow favours the presence of continuous

  15. Forest Vertical Structure of Sierra Nevada Observed by the First Spaceborne Tandem SAR Mission

    NASA Astrophysics Data System (ADS)

    Qi, W.; Swatantran, A.; Dubayah, R.

    2015-12-01

    DLR's TerraSAR-X (TSX, 2007 launched) /TanDEM-X (TDX, 2010 launched) (abbreviated as TDM) mission is the first and sole Spaceborne tandem SAR mission, allowing for consistent and continuous mappings of global forest structure without any temporal decorrelation. This study tested performance of three single-polarized (HH) TDM acquisitions for forest structure estimation over a coniferous forest of Sierra Nevada. Complex interferometric coherences were calculated and applied in a widely used scattering model - the Random Volume over Ground (RVoG) model to retrieve the forest structural properties. Scattering phase height (SPH) was derived from the interferometric phase for an evaluation of the average scattering height of this forest and the overall penetration capability of TDM X-band signal over this area. Since only single-polarized TDM data are available, in order to keep the RVoG inversion balanced and solvable, either one of the following two strategies can be applied: 1) simulating the ground phase using a digital terrain model (DTM) from Lidar, and 2) assuming a fixed extinction coefficient value for the entire study area when a Lidar DTM is not used. This study firstly used a 5-m Lidar DTM to estimate the SPH and RVoG forest height. All SPH of the three TDM acquisitions have demonstrated strong correlations to the Lidar RH100 (canopy top height) with r2 of 0.75~0.77, bias of -11.60~-12.58m (i.e. the mean height difference between SPH and canopy top height; this bias can be associated to the average penetration depth) and RMSE of 12.79~13.73m at 90m. An r2 of 0.79~0.81, bias of 0.37~1.97m and RMSE of 5.11~5.56m was observed between all the RVoG forest height and Lidar RH100. The study also tested the second method by fixing the extinction value, i.e. without applying a Lidar DTM for the ground phase. Despite the large variety of forest density and height over this area, the derived RVoG forest height has a surprisingly good correlation to the Lidar RH100 with

  16. Nutrient and mercury deposition and storage in an alpine snowpack of the Sierra Nevada, USA

    NASA Astrophysics Data System (ADS)

    Pearson, C.; Schumer, R.; Trustman, B. D.; Rittger, K.; Johnson, D. W.; Obrist, D.

    2015-01-01

    Bi-weekly snowpack core samples were collected at seven sites along two elevation gradients in the Tahoe Basin during two consecutive snow years to evaluate total wintertime snowpack accumulation of nutrients and pollutants in a high elevation watershed of the Sierra Nevada. Additional sampling of wet deposition and detailed snow pit profiles was conducted the following year to compare wet deposition to snowpack storage and assess the vertical dynamics of snowpack chemicals. Results show that on average organic N comprised 48% of all snowpack N, while nitrate (NO3--N) and TAN (total ammonia nitrogen) made up 25 and 27%, respectively. Snowpack NO3--N concentrations were relatively uniform across sampling sites over the sampling seasons and showed little difference between seasonal wet deposition and integrated snow pit concentrations in agreement with previous studies that identify wet deposition as the dominant source of wintertime NO3--N deposition. However, vertical snow pit profiles showed highly variable concentrations of NO3--N within the snowpack indicative of additional deposition and in snowpack dynamics. Unlike NO3--N, snowpack TAN doubled towards the end of winter and in addition to wet deposition, had a strong dry deposition component. Organic N concentrations in snowpack were highly variable (from 35 to 70%) and showed no clear temporal or spatial dependence throughout the season. Integrated snowpack organic N concentrations were up to 2.5 times higher than seasonal wet deposition, likely due to microbial immobilization of inorganic N as evident by coinciding increases of organic N and decreases of inorganic N, in deeper, aged snowpack. Spatial and temporal deposition patterns of snowpack P were consistent with particulate-bound dry deposition inputs and strong impacts from in-basin sources causing up to 6 times enrichment at urban locations compared to remote sites. Snowpack Hg showed little temporal variability and was dominated by particulate

  17. Unprecedented remote sensing data over King and Rim megafires in the Sierra Nevada Mountains of California.

    PubMed

    Stavros, E Natasha; Tane, Zachary; Kane, Van R; Veraverbeke, Sander; McGaughey, Robert J; Lutz, James A; Ramirez, Carlos; Schimel, David

    2016-11-01

    Megafires have lasting social, ecological, and economic impacts and are increasing in the western contiguous United States. Because of their infrequent nature, there is a limited sample of megafires to investigate their unique behavior, drivers, and relationship to forest management practices. One approach is to characterize critical information pre-, during, and post-fire using remote sensing. In August 2013, the Rim Fire burned 104,131 ha and in September 2014, the King Fire burned 39,545 ha. Both fires occurred in California's Sierra Nevada. The areas burned by these fires were fortuitously surveyed by airborne campaigns, which provided the most recent remote sensing technologies not currently available from satellite. Technologies include an imaging spectrometer spanning the visible to shortwave infrared (0.38-2.5 μm), a multispectral, high-spatial resolution thermal infrared (3.5-13 μm) spectroradiometer, and Light Detection and Ranging that provide spatial resolutions of pixels from 1 × 1 m to 35 × 35 m. Because of the unique information inherently derived from these technologies before the fires, the areas were subsequently surveyed after the fires. We processed and provide free dissemination of these airborne datasets as products of surface reflectance, spectral metrics and forest structural metrics ( http://dx.doi.org/10.3334/ORNLDAAC/1288). These data products provide a unique opportunity to study relationships among and between remote sensing observations and fuel and fire characteristics (e.g., fuel type, condition, structure, and fire severity). The novelty of these data is not only in the unprecedented types of information available from them before, during, and after two megafires, but also in the synergistic use of multiple state of the art technologies for characterizing the environment. The synergy of these data can provide novel information that can improve maps of fuel type, structure, abundance, and condition that may improve

  18. Post-Subduction Pleistocene Volcanism in Tahoe City Area, Northern Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Kortemeier, W. T.; Farmer, G.; Schweickert, R. A.

    2011-12-01

    source rocks may be part of the Mesozoic Sierra Nevada lithosphere. Migration of Basin and Range extension into the Tahoe area within the last 3 Ma, possibly combined with removal of deep Sierran lithosphere ("delamination"), may have triggered lithospheric thinning and melting within the deep lithosphere.

  19. Ecosystem Consequences of Prolonged Ozone Pollution in the Southern Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Cousins, S.; Battles, J. J.; Cisneros, R.; Esperanza, A.; Swenson, D.

    2015-12-01

    While acute O3 exposure is widely known to damage plant tissues, the chronic effects on long lived organisms such as trees remain unclear. In the southern Sierra Nevada, O3 pollution has afflicted pine-dominated forests for over 40 years. Here we report the results of a long-term study of O3 impact on tree injury, growth, and mortality. Our study employed a network of forest plots along a gradient of O3 pollution with recurring measurements from 1991-2012. Over the same period and locations, summer O3 was monitored via partnership with USNPS and USFS, making this one of the longest known ecosystem studies of O3 pollution and its effects. We found that exposure at the most polluted sites declined 33%, from a W126 index of 20.12 ppm-hrs in 1992 to 13.5 ppm-hrs in 2012. The severity of foliar pollution damage at these sites also declined, from 43.9 on the 0-100 Ozone Injury Index (OII) scale to 34.2, a drop of 22%. At locations with lower O3 exposure, damage declined from OII of 16.9 to 9.2. Mean annual tree mortality rates over the 20 year period, calculated with a profile likelihood approach, were 0.5%/yr (95% CI 0.3 to 0.8 %/yr). This rate is similar to that of healthy canopy trees in similar unpolluted stands. However, low and declining tree growth rates reveal possible ecosystem impacts of prolonged exposure to pollution. Across affected sites, mean relative growth rates were 1.1%/yr in 1991-2000, and just 0.9%/yr in 2000-2011, a decline of 15.6% in the second decade. Initial analyses suggest that tree damage is positively correlated with June-October O3, as indicated by previous studies. Further analysis will explore the drivers of ecosystem impacts and roles of other natural and anthropogenic stressors, including variation in climatic water deficit. Understanding the consequences of prolonged O3 exposure on both individual trees and complex forest ecosystems helps identify the hidden environmental costs of tropospheric O3 and potential benefits of cleaner air.

  20. Impact of interannual variations in aerosol particle sources on orographic precipitation over California's Central Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Creamean, J. M.; Ault, A. P.; White, A. B.; Neiman, P. J.; Ralph, F. M.; Minnis, P.; Prather, K. A.

    2015-01-01

    Aerosols that serve as cloud condensation nuclei (CCN) and ice nuclei (IN) have the potential to profoundly influence precipitation processes. Furthermore, changes in orographic precipitation have broad implications for reservoir storage and flood risks. As part of the CalWater field campaign (2009-2011), the variability and associated impacts of different aerosol sources on precipitation were investigated in the California Sierra Nevada using an aerosol time-of-flight mass spectrometer for precipitation chemistry, S-band profiling radar for precipitation classification, remote sensing measurements of cloud properties, and surface meteorological measurements. The composition of insoluble residues in precipitation samples collected at a surface site contained mostly local biomass burning and long-range transported dust and biological particles (2009), local sources of biomass burning and pollution (2010), and long-range transport from distant sources (2011). Although differences in the sources were observed from year-to-year, the most consistent source of dust and biological residues were associated with storms consisting of deep convective cloud systems with significant quantities of precipitation initiated in the ice phase. Further, biological residues were dominant (up to 40%) during storms with relatively warm cloud temperatures (up to -15 °C), supporting the important role bioparticles can play as ice nucleating particles. On the other hand, lower percentages of residues from local biomass burning and pollution were observed over the three winter seasons (on average 31 and 9%, respectively). When precipitation quantities were relatively low, these residues most likely served as CCN, forming smaller more numerous cloud droplets at the base of shallow cloud systems, and resulting in less efficient riming processes. The correlation between the source of aerosols within clouds and precipitation type and quantity will be further probed in models to understand the

  1. Potential effects of tree-to-shrub type conversion on streamflow in California's Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Baguskas, S. A.; Bart, R.; Molinari, N.; Tague, C.; Moritz, M.

    2014-12-01

    There is widespread concern that changes in climate and fire regime may lead to vegetation change across California, which in turn may influence watershed hydrology. Although plant cover is known to affect numerous hydrological processes, sensitivities to vegetation type and spatial arrangement of species within watersheds are not well understood. The primary objective of our research was to generate mechanistically-based projections of how potential type conversion from forested to shrub dominated systems may affect streamflow. During the 2014 growing season, we measured ecophysiological responses (plant water status and leaf gas exchange rates) of two dominant tree and shrub species to changes in seasonal water availability at two sites within the southern Sierra Nevada Critical Zone Observatory. Plant physiological observations were used to parameterize a process-based eco-hydrological model, RHESSys. This model was used to evaluate the impact of changes in seasonal water availability and vegetation type-conversion on streamflow. Based on our field observations, shrubs and trees had similar access to water through the early part of the growing season (April-early June); however, by late July, available water to shrubs was twice that of trees (shrubs, -0.55 ± 0.08 MPa; trees, -1.07 ± 0.08 MPa, p<0.05). Likewise, maximum transpiration (E) and carbon assimilation (A) rates per unit leaf area were twice as high for shrubs then trees in July (shrubs, A= 21 ± 2.3 μmol m-2 s-1, E=6.6 ± 1.8 mmol m-2 s-1; trees, A=8.2 ± 1.9 μmol m-2 s-1, E=2.4 ± 0.3 mmol m-2 s-1). Preliminary modeled changes in streamflow following simulated vegetation conversion were found to affect both the timing and amount of discharge. Controls on pre vs. post-conversion streamflow included changes in interception, rooting depth, energy balance, and plant response to changes in seasonal water availability. Our research demonstrates how linking strategic field data collection and mechanistic

  2. Environmental changes in Sierra Nevada during the last 6 ky BP inferred from solifluction lobes and lake sediments

    NASA Astrophysics Data System (ADS)

    Oliva, M.; Gómez Ortiz, A.; Schulte, L.

    2009-04-01

    Holocene climate variability drove important landscape changes in Sierra Nevada, heightened due to the emplacement of Sierra Nevada at 37°N in southwestern Europe and, therefore, the different crossing influences in this region: geographical Europe/Africa), maritime (Atlantic/Mediterranean), climatic (subtropical high-pressure belt/ mid-latitude westerlies). Despite the existence of several kinds of sedimentary records in Sierra Nevada, only two of them can provide further information about Holocene landscape changes in this massif: solifluction lobes and mountain lakes. The numerous sedimentological changes inferred from terrestrial and aquatic records suggest the proximity of geomorphological processes in the massif of their climate boundaries and the small climate range necessary to carry environmental changes in the summits of the Sierra Nevada. Sierra Nevada holds the highest lakes in Europe, all of them related to a glacial origin. Four lakes were cored in Sierra Nevada, three of them southern exposed (Aguas Verdes, Rio Seco and Rio Seco lagoon) and only one with northern orientation (San Juan lagoon). Sedimentological properties of these cores assert evidences of different phases of coarse-grained inputs into the lakes, with low organic matter proportion and high mineral contents. These pulses correspond to geomorphic periods with enhanced slope instability, interfingered in phases with lower sediment transfer onto the lakes. These relative stable periods show a fine-grained texture with less mineral fraction and increases in the organic composition of the sediments. The similar evolution of the C/N ratio and Corg contents reflects the low productivity of these oligotrophic lakes and the terrestrial origin of the organic matter present in their sediments; both proxies also confirm a general pattern characterized in Sierra Nevada by an arid trend since the HWP, when the headwaters of the highest catchments stored a denser vegetation cover. We report an

  3. Correlation and analysis of Miocene paleochannels in the central Sierra Nevada, California, as displayed by the Stanislaus Group

    NASA Astrophysics Data System (ADS)

    Jones, S.; Pluhar, C. J.; Farner, M. J.; Deino, A. L.

    2013-12-01

    The proposed Neogene uplift of the Sierra Nevada has been debated for several decades. Although multiple lines of evidence indicate substantial uplift of the Sierran crest over the last ten million years, recent isotopic and paleobotanical methods have called the validity of these calculations into question. Our study focuses on the discontinuous units of the Miocene Stanislaus Group: Table Mountain Formation lavas, Dardenelles Formation lavas, and Eureka Valley Tuff (EVT) lava and tuffs. These units are significant because they have been used as a tilt indicator to calculate the uplift of the Sierra Nevada crest since their emplacement, 9.0-10.2 million years ago. Our research increased the quantity of primary data, which will be used to develop and verify a digitally-derived model of the paleodrainage systems of the ancient Sierra Nevada. The localities, Dorrington, Pikes Peak, Rancheria Mountain, Three Chimneys, and Sonora Pass are significant because they may represent the few remaining Table Mountain Formation (trachyandesite) outcrops of previously unmapped paleodrainage channels. To test this hypothesis, geochemical and paleomagnetic data were used to correlate the localities and thereby reconstruct the paleochannels. Outcrops near Dorrington, California contain biotite, display eutaxitic textures and are characterized by a reverse polarity indistinguishable from the Tollhouse Flat Member of the EVT. Previously mapped as Table Mountain Latite, we reclassify these units as Tollhouse Flat Member and eliminate the hypothesis that the units were once part of a potentially lava-back-flooded tributary of the paleo-Stanislaus River. The high potassium, columnar jointed lava at Pikes Peak, exhibits normal polarity; it is plausibly part of the Stanislaus Group and may be correlated to flows along the main 'cataract channel' of the Stanislaus Group. Results from Rancheria Mountain verify the presence of Stanislaus Group lavas and the EVT, previously mapped by Huber et

  4. Mercury concentrations and pools in four Sierra Nevada forest sites, and relationships to organic carbon and nitrogen

    NASA Astrophysics Data System (ADS)

    Obrist, D.; Johnson, D. W.; Lindberg, S. E.

    2009-05-01

    This study presents data on mercury (Hg) concentrations, stochiometric relations to carbon (C) and nitrogen (N), and Hg pool sizes in four Sierra Nevada forest sites of similar exposure and precipitation regimes, and hence similar atmospheric deposition, to evaluate how ecosystem parameters control Hg retention in ecosystems. In all four sites, the largest amounts of Hg reside in soils which account for 94-98% of ecosystem pools. Hg concentrations and Hg/C ratios increase in the following order: Green Needles/LeavesSierra Nevada forest sites. This suggests that soil organic N and C groups provide sorption sites for Hg to retain atmospheric deposition. However, the patterns could be due to indirect relationships where high soil N and C levels reflect high ecosystem productivity which leads to corresponding high atmospheric Hg deposition inputs via leaf litterfall and plant senescence. Our results also show that two of the sites previously affected by prescribed burning and wildfires show significant depletion of above-ground Hg pools but that belowground Hg pools

  5. Mercury concentrations and pools in four Sierra Nevada forest sites, and relationships to organic carbon and nitrogen

    NASA Astrophysics Data System (ADS)

    Obrist, D.; Johnson, D. W.; Lindberg, S. E.

    2009-02-01

    This study presents data on Hg concentrations, stochiometric relations to carbon (C) and nitrogen (N), and Hg pool sizes in four Sierra Nevada forest sites of similar exposure and precipitation regimes, and hence similar atmospheric deposition, to evaluate how ecosystem parameters control Hg retention in ecosystems. In all four sites, the largest amounts of Hg reside in soils which account for 94-98% of ecosystem pools. Hg concentrations and Hg/C ratios increase in the following order: Green Needles/Leaves < Dry Needles/Leaves < Oi litter < Oe litter < Oa litter. Stochiometric relations show negative correlations between Hg and C (r2=0.58) and N and C (r2=0.64) in decomposing litter, but a positive correlation between litter Hg and N (r2=0.70). These inverse relations may reflect preferential retention of N and Hg over C during decomposition, or may be due to older age of decomposed litter layers which are exposed to longer-term atmospheric Hg deposition in the field. The results indicate that litter Hg levels depend on decomposition stage and may not follow generally observed positive relationships between Hg and organic C. Mineral soil layers show strong positive correlations of Hg to C across all sites and soil horizons (r2=0.83), but Hg concentrations are even more closely related to N with a similar slope to that observed in litter (r2=92%). Soil N levels alone explain over 90% of Hg pool sizes across the four Sierra Nevada forest sites. This suggest that soil organic N and C groups provide sorption sites for Hg to retain atmospheric deposition. However, the patterns could be due indirect relationships where high soil N and C levels reflect high ecosystem productivity which leads to corresponding high atmospheric Hg deposition inputs via leaf litterfall and plant senescence. Our results also show that two of the sites previously affected by prescribed burning and wildfires show significant depletion of above-ground Hg pools but that belowground Hg pools remain

  6. Dedradation of buried ice and permafrost in the Veleta Cirque (Sierra Nevada, Spain) from 2006-2013

    NASA Astrophysics Data System (ADS)

    Gómez-Ortiz, A.; Oliva, M.; Salvador-Franch, F.; Salvà-Catarineu, M.; Palacios, D.; de Sanjosé-Blasco, J. J.; Tanarro-García, L. M.

    2014-04-01

    The Veleta cirque is located at the foot of the Veleta peak, one of the highest summits of the Sierra Nevada National Park (Southern Spain). This cirque was the source of a glacier valley during the Quaternary cold periods. During the Little Ice Age it sheltered a small glacier, the most southerly in Europe, about which we have possessed written records since the XVII century. This glacier still had ice residues until the mid-XX century. This ice is no longer visible, but a residue persists along with discontinuous permafrost trapped under strata of rock blocks that make up an incipient rock glacier. From 2006 to 2013, this rock glacier was monitored by measurement of the temperature of the active layer, the degree of snow cover on the ground, movements of the body of the rock glacier and geophysical prospection inside it. The results show that the relict ice and trapped permafrost have been steadily declining. The processes that explain this degradation occur in chain, starting from the external radiation that affects the ground in summer, which is when the temperatures are higher. In effect, when this radiation steadily melts the snow on the ground, the thermal expansive wave advances into the heart of the active layer, reaching the ceiling of the frozen mass, which it then degrades and melts. In this entire linked process, the circulation of melt waters fulfil a highly significant function, as they act as heat transmitters. The complementary nature of these processes explains the subsidence and continuous changes in the entire clastic pack and the melting of the frozen ceiling on which it rests. This happens in summer in just a few weeks. All these events, in particular the geomorphological ones, take place on the Sierra Nevada peaks within certain climate conditions that are at present unfavourable to the maintenance of snow on the ground in summer. These conditions could be related to recent variations in the climate, starting in the mid-XIX century and most

  7. Is the Isabella anomaly a fossil slab or the foundered lithospheric root of the Sierra Nevada batholith?

    NASA Astrophysics Data System (ADS)

    Hoots, C. R.; Schmandt, B.; Clayton, R. W.; Hansen, S. M.; Dougherty, S. L.

    2015-12-01

    The Isabella Anomaly is a volume of relatively high seismic velocity upper mantle beneath the southern Great Valley in California. We deployed ~45 broadband seismometers in central California to test two main hypotheses for the origin of the Isabella Anomaly. One suggests that the Isabella Anomaly is the foundered lithospheric root of the southern Sierra Nevada batholith, which delaminated on account of eclogite-rich composition and translated westward as it began to sink into the asthenosphere. The other hypothesis suggests that the Isabella Anomaly is a fossil slab fragment attached to the Monterey microplate that lies offshore of central California and thus it is mechanically coupled to the Pacific plate. Prior seismic imaging with ~70 km station spacing cannot resolve the landward termination of Monterey microplate lithosphere beneath coastal California or where/if the Isabella Anomaly is attached to North America lithosphere beneath the Great Valley. The new temporary broadband array consists of 40 broadband seismometers with ~7 km spacing extending from the central California coast to the western Sierra Nevada batholith, plus some outliers to fill gaps in the regional network coverage. The temporary array was initially deployed in early 2014 and will continue to record until October 2015 so the complete data are not yet available. Preliminary Ps scattered wave images show an abrupt ~6 km increase in Moho depth eastward across the San Andreas fault, a strong positive impedance contrast that dips westward from ~7-25 km beneath Great Valley, and a sharp Moho with a slight westward dip beneath the western edge of the Sierra Nevada batholith. Apparently low impedance contrast characterizes the Moho beneath the eastern Great Valley and foothills, consistent with near mantle velocities in the lower crust. Processing of the cumulative data that will be available in October 2015 and incorporation of new tomography models into scattered wave imaging are needed before

  8. Geohydrologic and drill-hole data for test well USW H-1, adjacent to Nevada Test Site, Nye County, Nevada

    USGS Publications Warehouse

    Rush, F. Eugene; Thordarson, William; Bruckheimer, Laura

    1983-01-01

    This report presents data collected to determine the hydraulic characteristics of rocks penetrated in test well USW H-1. The well is one of a series of test wells drilled in and near the southwestern part of the Nevada Test Site, Nye County, Nevada, in a program conducted on behalf of the U.S. Department of Energy. These investigations are part of the Nevada Nuclear Waste Storage Investigations to identify suitable sites for storage of high-level radioactive wastes. Data on drilling operations, lithology, borehole geophysics, hydrologic monitoring, core analysis, ground-water chemistry and pumping and injection tests for well USW H-1 are contained in this report.

  9. The ancestral cascades arc: Cenozoic evolution of the central Sierra Nevada (California) and the birth of the new plate boundary

    USGS Publications Warehouse

    Busby, C.J.; Hagan, J.C.; Putirka, K.; Pluhar, C.J.; Gans, P.B.; Wagner, D.L.; Rood, D.; DeOreo, S.B.; Skilling, I.

    2008-01-01

    We integrate new stratigraphic, structural, geochemical, geochronological, and magnetostratigraphic data on Cenozoic volcanic rocks in the central Sierra Nevada to arrive at closely inter-related new models for: (1) the paleogeography of the ancestral Cascades arc, (2) the stratigraphic record of uplift events in the Sierra Nevada, (3) the tectonic controls on volcanic styles and compositions in the arc, and (4) the birth of a new plate margin. Previous workers have assumed that the ancestral Cascades arc consisted of stratovolcanoes, similar to the modern Cascades arc, but we suggest that the arc was composed largely of numerous, very small centers, where magmas frequently leaked up strands of the Sierran frontal fault zone. These small centers erupted to produce andesite lava domes that collapsed to produce block-and-ash flows, which were reworked into paleocanyons as volcanic debris flows and streamflow deposits. Where intrusions rose up through water-saturated paleocanyon fill, they formed peperite complexes that were commonly destabilized to form debris flows. Paleocanyons that were cut into Cretaceous bedrock and filled with Oligocene to late Miocene strata not only provide a stratigraphic record of the ancestral Cascades arc volcanism, but also deep unconformities within them record tectonic events. Preliminary correlation of newly mapped unconformities and new geochronological, magnetostratigraphic, and structural data allow us to propose three episodes of Cenozoic uplift that may correspond to (1) early Miocene onset of arc magmatism (ca. 15 Ma), (2) middle Miocene onset of Basin and Range faulting (ca. 10 Ma), and (3) late Miocene arrival of the triple junction (ca. 6 Ma), perhaps coinciding with a second episode of rapid extension on the range front. Oligocene ignimbrites, which erupted from calderas in central Nevada and filled Sierran paleocanyons, were deeply eroded during the early Miocene uplift event. The middle Miocene event is recorded by growth

  10. Projected changes in seasonal drought and flood conditions in the Sierra Nevada and Colorado River basins (USA)

    NASA Astrophysics Data System (ADS)

    Stewart-Frey, Iris; Ficklin, Darren; Carrillo, Carlos; McIntosh, Russell

    2014-05-01

    The Sierra Nevada and Colorado River mountain ranges are the principal source of water for large urban and agricultural demands in the North American Southwest. In this region, GCM ensemble output suggests varying and modest precipitation changes, while air surface temperatures are expected to increase by several degrees by the end of the century. This study used the downscaled output of an ensemble of 16 GCMs and 2 emission scenarios to drive the SWAT watershed model, and to assess the impact of projected climatic changes on water availability and water quality through 2100. We then assess the changes in likelihood of occurrence of high (> 125%, > 150%) and low (< 75%, 150% of historic averages in high elevation regions and in main channels. The occurrence of extreme low flows are likely to significantly increase for the spring and summer seasons, with low flows of

  11. Status and understanding of groundwater quality in the Sierra Nevada Regional study unit, 2008: California GAMA Priority Basin Project

    USGS Publications Warehouse

    Fram, Miranda S.; Belitz, Kenneth

    2014-01-01

    Statistical tests were used to evaluate relations between constituent concentrations and potential explanatory factors descriptive of land use, geography, depth, geochemical conditions, and groundwater age. Higher concentrations of trace elements, radioactive constituents, and constituents with aesthetic-based benchmarks generally were associated with anoxic conditions, higher pH, and location within a particular compositional band in the Sierra Nevada batholith corresponding to the southwestern part of the study unit. High concentrations of organic constituents generally were associated with greater proportions of urban land use. No significant relations were observed between the concentrations of organic constituents and measures of well depth or groundwater age, perhaps because of the high proportions of springs and modern groundwater in the dataset.

  12. A reconnaissance space sensing investigation of crustal structure for a strip from the eastern Sierra Nevada to the Colorado Plateau

    NASA Technical Reports Server (NTRS)

    Liggett, M. A. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. Research progress in an investigation using ERTS-1 MSS imagery to study regional tectonics and related natural resources is summarized. Field reconnaissance guided by analysis of ERTS-1 imagery has resulted in development of a tectonic model relating strike-slip faulting to crustal extension in the southern Basin Range Province. The tectonics of the northern Death Valley-Furnace Creek Fault Zone and spacially associated volcanism and mercury mineralization were also investigated. Field work in the southern Sierra Nevada has confirmed the existence of faults and diabase dike swarms aligned along several major lineaments first recognized in ERTS-1 imagery. Various image enhancement and analysis techniques employed in the study of ERTS-1 data are summarized.

  13. Abies concolor growth responses to vegatation changes following shrub removal, northern Sierra Nevada, California. Forest Service research paper (Final)

    SciTech Connect

    Conard, S.G.; Sparks, S.R.

    1993-08-01

    Conifer productivity in western North America is often severely inhibited by competing vegetation. Abies concolor (Gord, and Glendl.) Lindl. (white fir) is an important species over much of this area, yet little information is available on response of A. concolor to vegetation management treatments. We revisited two sites in the northern Sierra Nevada to assess the responses of naturally regenerated A. concolor saplings to vegetation recovery 8-9 years after release treatments. Treatments caused major and persistent shifts in vegetation structure and composition on both sites. Differences in individual tree growth within treatments were strongly correlated with structure and composition of neighboring vegetation, even where no treatment effects were observed. Great variability in response between sites illustrates the strong effect of site characteristics on response to release treatments and the importance to managers of anticipating such differences before making treatment decisions.

  14. Estimating contribution of wildland fires to ambient ozone levels in National Parks in the Sierra Nevada, California.

    PubMed

    Preisler, Haiganoush K; Zhong, Shiyuan Sharon; Esperanza, Annie; Brown, Timothy J; Bytnerowicz, Andrzej; Tarnay, Leland

    2010-03-01

    Data from four continuous ozone and weather monitoring sites operated by the National Park Service in Sierra Nevada, California, are used to develop an ozone forecasting model and to estimate the contribution of wildland fires on ambient ozone levels. The analyses of weather and ozone data pointed to the transport of ozone precursors from the Central Valley as an important source of pollution in these National Parks. Comparisons of forecasted and observed values demonstrated that accurate forecasts of next-day hourly ozone levels may be achieved by using a time series model with historic averages, expected local weather and modeled PM values as explanatory variables. Results on fire smoke influence indicated occurrence of significant increases in average ozone levels with increasing fire activity. The overall effect on diurnal ozone values, however, was small when compared with the amount of variability attributed to sources other than fire.

  15. A reconnaissance space sensing investigation of crustal structure for a strip from the eastern Sierra Nevada to the Colorado Plateau

    NASA Technical Reports Server (NTRS)

    Liggett, M. A. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. Studies were conducted in key field areas in the Sierra Nevada, the Basin Range Province and the Colorado Plateau to evaluate the origins and significance of geologic and structural anomalies expressed in the ERTS-1 data. The investigation included development of image enhancement and analysis techniques and comparison of remote sensing data available over the test site. The ERTS-1 MSS imagery has proven to be an effective tool for studying the interrelationsships between Cenozoic tectonic patterns and the distributions of Cenozoic plutonism and volcanism, seismic activity, geologic hazards, and known mineral, geothermal and ground water resources. Recommendations are made for applications of ERTS-1 data to natural and resource exploration and management.

  16. Characterizing the extreme 2015 snowpack deficit in the Sierra Nevada (USA) and the implications for drought recovery

    NASA Astrophysics Data System (ADS)

    Margulis, Steven A.; Cortés, Gonzalo; Girotto, Manuela; Huning, Laurie S.; Li, Dongyue; Durand, Michael

    2016-06-01

    Analysis of the Sierra Nevada (USA) snowpack using a new spatially distributed snow reanalysis data set, in combination with longer term in situ data, indicates that water year 2015 was a truly extreme (dry) year. The range-wide peak snow volume was characterized by a return period of over 600 years (95% confidence interval between 100 and 4400 years) having a strong elevational gradient with a return period at lower elevations over an order of magnitude larger than those at higher elevations. The 2015 conditions, occurring on top of three previous drought years, led to an accumulated (multiyear) snowpack deficit of ~ -22 km3, the highest over the 65 years analyzed. Early estimates based on 1 April snow course data indicate that the snowpack drought deficit will not be overcome in 2016, despite historically strong El Niño conditions. Results based on a probabilistic Monte Carlo simulation show that recovery from the snowpack drought will likely take about 4 years.

  17. Quantitative estimation of granitoid composition from thermal infrared multispectral scanner (TIMS) data, Desolation Wilderness, northern Sierra Nevada, California

    NASA Technical Reports Server (NTRS)

    Sabine, Charles; Realmuto, Vincent J.; Taranik, James V.

    1994-01-01

    We have produced images that quantitatively depict modal and chemical parameters of granitoids using an image processing algorithm called MINMAP that fits Gaussian curves to normalized emittance spectra recovered from thermal infrared multispectral scanner (TIMS) radiance data. We applied the algorithm to TIMS data from the Desolation Wilderness, an extensively glaciated area near the northern end of the Sierra Nevada batholith that is underlain by Jurassic and Cretaceous plutons that range from diorite and anorthosite to leucogranite. The wavelength corresponding to the calculated emittance minimum lambda(sub min) varies linearly with quartz content, SiO2, and other modal and chemical parameters. Thematic maps of quartz and silica content derived from lambda(sub min) values distinguish bodies of diorite from surrounding granite, identify outcrops of anorthosite, and separate felsic, intermediate, and mafic rocks.

  18. An ecologic study comparing distribution of Pasteurella trehalosi and Mannheimia haemolytica between Sierra Nevada bighorn sheep, White Mountain bighorn sheep, and domestic sheep.

    PubMed

    Tomassini, Letizia; Gonzales, Ben; Weiser, Glen C; Sischo, William

    2009-10-01

    The prevalence and phenotypic variability of Pasteurella and Mannheimia isolates from Sierra Nevada bighorn sheep (Ovis canadensis sierrae), White Mountain bighorn sheep (Ovis canadensis nelsoni), and domestic sheep (Ovis aries) from California, USA, were compared. The White Mountain bighorn sheep population had a recent history of pneumonia-associated mortality, whereas the Sierra Nevada bighorn sheep population had no recent history of pneumonia-associated mortality. The domestic sheep flocks were pastured in areas geographically near both populations but were not known to have direct contact with either bighorn sheep population. Oropharyngeal swab samples were collected from healthy domestic and bighorn sheep and cultured to characterize bacterial species, hemolysis, biogroups, and biovariants. Pasteurella trehalosi and Mannheimia haemolytica were detected in all of the study populations, but the relative proportion of each bacterial species differed among sheep populations. Pasteurella trehalosi was more common than M. haemolytica in the bighorn sheep populations, whereas the opposite was true in domestic sheep. Mannheimia haemolytica was separated into 11 biogroups, and P. trehalosi was characterized into two biogroups. Biogroup distributions for M. haemolytica and P. trehalosi differed among the three populations; however, no difference was detected for the distribution of P. trehalosi biogroups between the Sierra Nevada bighorn sheep and domestic sheep. The prevalence odds ratios (pOR) for the distribution of M. haemolytica biogroups suggested little difference between White Mountain bighorn sheep and domestic sheep compared with Sierra Nevada bighorn sheep and domestic sheep, although these comparisons had relatively large confidence intervals for the point estimates. Hemolytic activity of the isolates was not different among the sheep populations for M. haemolytica but was different for P. trehalosi. No clear evidence of association was found in the

  19. A Mantle Cross-Section Through Western And Central Nevada From Young Basaltic Magmas In The Sierra Nevada And Western Great Basin

    NASA Astrophysics Data System (ADS)

    Gupta, V.; Cousens, B. L.; Henry, C. D.

    2007-12-01

    The geochemistry of basaltic magmas erupted in the Basin and Range province of the western USA has demonstrated that at least two mantle sources exist, one with a subduction signature and another with an "ocean island basalt" (OIB) signature. Here we investigate the distribution of these two sources during the Pleistocene and Holocene in a 250 km-long transect from the eastern Sierra Nevada near Reno, NV, into central Nevada. Samples were collected from young, dated mafic lava flows from the Carson Range (2.5 to 1.4 Ma), Steamboat Hills (2.6 Ma), Virginia City and Chalk Hills (1.5 to 1.44 Ma), east of Carson City (1.36 Ma), Rattlesnake Hill (1.2 to 0.9 Ma), Buffalo Valley (1.1 to 0.95 Ma), Upsal Hogback (0.6 Ma), and Soda Lake (Holocene). With the exception of Carson Range andesites, all of the lavas are alkaline basalts and basaltic trachyandesites with K2O/Na2O > 0.4. Incompatible element abundances, incompatible element ratios, and radiogenic isotope ratios vary widely between locations. Many key incompatible element ratios, such as Ce/Pb, Sr/P, Ba/Nb, and Nb/La, and isotopic ratios vary as a function of age and longitude. Lavas less than 1 Ma in age have low Ba/Nb, Sr/P, 87Sr/86Sr, 206Pb/204Pb, and high Ce/Pb and Nd/La compared to lavas greater than 1Ma in age. These ratios vary more strongly as a function of longitude, from high Ba/Nb, Sr/P, 206Pb/204Pb, 87Sr/86Sr and low Ce/Pb and Nb/La (subduction signature mantle) lavas in the Sierra Nevada margin to lavas with the opposite characteristics (OIB signature mantle) in central Nevada. La/Sm does not vary with either age or longitude. The relationship with longitude indicates that two mantle sources currently exist beneath western Nevada, subduction-modified mantle to the west and OIB-type mantle to the east, and that these two mantle types probably taper in thickness towards one another. The termination of subduction beneath the Reno area at 5-3 Ma, in conjunction with 87Sr/86Sr greater than modern Cascade arc

  20. Dispersal limitation does not control high elevational distribution of alien plant species in the southern Sierra Nevada, California

    USGS Publications Warehouse

    Rundel, Philip W.; Keeley, Jon E.

    2016-01-01

    Patterns of elevational distribution of alien plant species in the southern Sierra Nevada of California were used to test the hypothesis that alien plant species invading high elevations around the world are typically climate generalists capable of growing across a wide elevational range. The Sierra Nevada has been heavily impacted for more than a century and a half, first by heavy grazing up into high elevation meadows, followed by major logging, and finally, by impacts associated with recreational use. The comparative elevational patterns of distribution and growth form were compared for native and alien plant species in the four families (Asteraceae, Brassicaceae, Fabaceae, and Poaceae) that contribute the majority of naturalized aliens in the study area. The distribution of realized climatic niche breadth, as measured by elevational range of occurrence, was virtually identical for alien and native species, with both groups showing a roughly Gaussian distribution peaking with species whose range covers a span of 1500–1999 m. In contrast to alien species, which only rarely occurred at higher elevations, native species showed a distribution of upper elevation limits peaking at 3000–3499 m, an elevation that corresponds to the zone of upper montane and subalpine forests. Consistent with a hypothesis of abiotic limitations, only a few alien species have been ecologically successful invaders at subalpine and alpine elevations above 2500 m. The low diversity of aliens able to become established in these habitats is unlikely due to dispersal limitations, given the long history of heavy grazing pressure at high elevations across this region. Instead, this low diversity is hypothesized to be a function of life history traits and multiple abiotic stresses that include extremes of cold air and soil temperature, heavy snowfall, short growing seasons, and low resource availability. These findings have significant implications for resource managers.

  1. Biological characterization of Trypanosoma cruzi stocks from domestic and sylvatic vectors in Sierra Nevada of Santa Marta, Colombia.

    PubMed

    Téllez-Meneses, Jair; Mejía-Jaramillo, Ana María; Triana-Chávez, Omar

    2008-10-01

    Sierra Nevada of Santa Marta is one of the most endemic regions of Chagas disease in Colombia. In this study, we compared the biological behavior and genetic features of Trypanosoma cruzi stocks that were isolated from domestic and sylvatic insects in this area. Rhodnius prolixus (from domestic environments) and Triatoma dimidiata (from sylvatic, peridomestic and domestic environments) are the most important vectors in this region. Genetic characterization showed that all stocks corresponded to T. cruzi I, but LSSP-PCR analyses indicated that some genotypes were present in both environments. Biological characterization in vitro showed a low growth rate in sylvatic T. cruzi stocks and in some domestic T. cruzi stocks, possibly indicating the presence of stocks with similar behavior in both transmission cycles. In parallel, in vivo behavioral analysis also indicated that T. cruzi stocks are variable and this species did not show a correlation between the environments where they were isolated. In addition, all stocks demonstrated a low mortality rate and histopathological lesions in heart, skeletal muscle and colon tissue. Moreover, our data indicated that experimentally infected chagasic mice displayed a relation between their myocardial inflammation intensity, parasitism tissue and parasite load using the qPCR. In conclusion, our results indicate that the T. cruzi stocks present in SNSM have similar biological behavior and do not show a correlation with the different transmission cycles. This could be explained by the complex transmission dynamics of T. cruzi in Sierra Nevada of Santa Marta, where hosts, vectors (e.g., T. dimidiata) and reservoirs circulate in both environments due to the close contact between the two transmission cycles, favoring environment overlapping. This knowledge is an important key to understanding the epidemiology and pathology of Chagas disease in this Colombian region. Furthermore, our findings could be of significant use in the design of

  2. Wall Rock Assimilation and Magma Migration in the Sierra Nevada Batholith: A Study of the Courtright Intrusive Zone, Central California

    NASA Astrophysics Data System (ADS)

    Torrez, G.; Putirka, K. D.

    2010-12-01

    The Sierra Nevada Batholith is composed of various plutons that interact with each other, and with pre- and syn-batholith metamorphic rocks. In the central part of the Sierra Nevada Batholith, at Courtright Reservoir in California, the younger Mt. Givens Pluton (87-93 Ma; McNulty et al., 2000) intrudes the Dinkey pluton (103 Ma; Bateman et al., 1964), and metasediments (a metamorphic screen) that, in places, separate the two plutons. This Courtright Reservoir Intrusive zone, as termed by Bateman et al. (1964), provides an ideal setting to examine the dynamics of intrusion and assimilation. Whole rock major and trace element compositions of the plutons, their mafic enclaves, and the metasediments, show that all such samples, from both plutons, fall on a single mixing trend. We thus infer that magmas parental to both plutons were roughly similar in composition, and assimilated significant amounts of the same, or very similar metasedimentary wall rocks. We also examined changes in whole rock compositions within the Mt. Givens pluton, as a function of distance from the two rock units with which it is now in contact (the metasediments, and the Dinkey Creek). In the vicinity of the contact between are an abundance of enclaves that are rounded, and appear to have been transported in vertical pipes. Whole rock analysis of the host granitoid material that surrounds these enclaves is clearly more mafic than the granitoid magmas from interior parts of the pluton. These whole rock compositions indicate that the pluton becomes more homogenous moving away from the contact, with a compositional decay occurring over a span of about 50-100 m. There are at least two possible interpretations. The compositional decay may represent a diffusive exchange of mass between an early crystallizing marginal phase of the pluton and the pluton interior. Another (not mutually incompatible) possibility is that the mafic margins represent pipes or tubes (Paterson, 2010), related to some convective

  3. The Effect of Past Climate Change on Regolith Erosion Rates for the Past 100 ka in the Eastern Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Madoff, R. D.; Putkonen, J.

    2014-12-01

    Global climate change over the last 100 ka is known to have resulted in glacial fluctuations in the eastern Sierra Nevada evidenced today by moraines. The effect of past climate on regolith erosion rates is quantified by modeling hillslope diffusion and evolution of a profile cross-section of Mono Basin moraine in the eastern Sierra Nevada. The degradation in the model is described by the linear transport law, q = -κ(dz/dx), where the diffusivity coefficient, κ, is a parameter to account for factors affecting regolith transport rate (q) unrelated to slope (dz/dx), such as climate and substrate. Three scenarios were modeled with respective κ values. In the first, κ is held constant through the age of the landform and optimized to reproduce the current moraine cross-section. In the second, κ varies with time based on the documented variation in the paleoclimate and related degradation rate. In the third, κ is held constant and defined by present-day degradation values measured in the region. In all the scenarios the moraine initial slopes are at the angle of repose. Comparisons of the first (constant κ) and second (variable κ) scenarios show that the former can generate erosion rates that overestimate crest elevation by 30% during the first quarter of the landform age and underestimate it by 20% during the latter three-quarters. However, the third (current κ) scenario underestimates the degradation up to 58% of the current profile. This indicates that the past erosion rates were higher than what is observed today. Increased regolith erosion rates in the past were driven by climates colder and wetter than the present.

  4. Pre-eruptive conditions of the ~31 ka rhyolitic magma of Tlaloc volcano, Sierra Nevada Volcanic Range, Central Mexico

    NASA Astrophysics Data System (ADS)

    Macias, J.; Arce, J.; Rueda, H.; Gardner, J.

    2008-12-01

    Tlaloc volcano is located at the northern tip of the Sierra Nevada Volcanic Range in Central Mexico. This Pleistocene to Recent volcanic range consists from north to south of Tlaloc-Telapón-Teyotl-Iztaccíhuatl-and- Popocatépetl volcanoes. While andesitic to barely dacitic volcanism dominates the southern part of the range (i.e. Popocatépetl and Iztaccíhuatl); dacitic and rare rhyolithic volcanism (i.e. Telapón, Tlaloc) dominates the northern end. The known locus of rhyolitic magmatism took place at Tlaloc volcano with a Plinian-Subplinian eruption that occurred 31 ka ago. The eruption emplaced the so-called multilayered fallout and pumiceous pyroclastic flows (~2 km3 DRE). The deposit consists of 95% vol. of juvenile particles (pumice + crystals) and minor altered lithics 5% vol. The mineral association of the pumice fragments (74-76 % wt. SiO2) consists of quartz + plagioclase + sanidine + biotite and rare oxides set in a glassy groundmass with voids. Melt inclusions in quartz phenocrysts suggest that prior to the eruption the rhyolitic contain ~7% of H2O and <110 ppm of CO 2, suggesting pressure conditions around ~2500 bars and therefore depths ~8 km below the volcano. Such depths suggest that inception of rhyolitic magmatism at Tlaloc volcano halted at deeper conditions than andesitic to dacitic eruptions of Popocatépetl volcano (~6 km) in the southern part of the Sierra Nevada Volcanic Range and than Nevado de Toluca volcano (~6 km) some 50 km to the southwest.

  5. Modeling Forest Composition and Carbon Dynamics Under Projected Climate-Fire Interactions in the Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Liang, S.; Hurteau, M. D.; Westerling, A. L.

    2014-12-01

    The Sierra Nevada Mountains are occupied by a diversity of forest types that sort by elevation. The interaction of changing climate and altered disturbance regimes (e.g. fire) has the potential to drive changes in forest distribution as a function of species-specific response. Quantifying the effects of these drivers on species distributions and productivity under future climate-fire interactions is necessary for informing mitigation and adaptation efforts. In this study, we assimilated forest inventory and soil survey data and species life history traits into a landscape model, LANDIS-II, to quantify the response of forest dynamics to the interaction of climate change and large wildfire frequency in the Sierra Nevada. We ran 100-year simulations forced with historical climate and climate projections from three models (GFDL, CNRM and CCSM3) driven by the A2 emission scenario. We found that non-growing season NPP is greatly enhanced by 15%-150%, depending on the specific climate projection. The greatest increase occurs in subalpine forests. Species-specific response varied as a function of life history characteristics. The distribution of drought and fire-tolerant species, such as ponderosa pine, expanded by 7.3-9.6% from initial conditions, while drought and fire-intolerant species, such as white fir, showed little change in the absence of fire. Changes in wildfire size and frequency influence species distributions by altering the successional stage of burned patches. The range of responses to different climate models demonstrates the sensitivity of these forests to climate variability. The scale of climate projections relative to the scale of forest simulations presents a source of uncertainty, particularly at the ecotone between forest types and for identifying topographically mediated climate refugia. Improving simulations will likely require higher resolution climate projections.

  6. The Relationships Between Insoluble Precipitation Residues, Clouds, and Precipitation Over California's Southern Sierra Nevada During Winter Storms

    NASA Technical Reports Server (NTRS)

    Creamean, Jessie M.; White, Allen B.; Minnis, Patrick; Palikonda, Rabindra; Spangenberg, Douglas A.; Prather, Kimberly A.

    2016-01-01

    Ice formation in orographic mixed-phase clouds can enhance precipitation and depends on the type of aerosols that serve as ice nucleating particles (INP). The resulting precipitation from these clouds is a viable source of water, especially for regions such as the California Sierra Nevada. Thus, a better understanding of the sources of INP that impact orographic clouds is important for assessing water availability in California. This study presents a multi-site, multi-year analysis of single particle insoluble residues in precipitation samples that likely influenced cloud ice and precipitation formation above Yosemite National Park. Dust and biological particles represented the dominant fraction of the residues (64% on average). Cloud glaciation, determined using GOES satellite observations, not only depended on high cloud tops (greater than 6.2 km) and low temperatures (less than -26 C), but also on the composition of the dust and biological residues. The greatest prevalence of ice-phase clouds occurred in conjunction with biologically-rich residues and mineral dust rich in calcium, followed by iron and aluminosilicates. Dust and biological particles are known to be efficient INP, thus these residues are what likely influenced ice formation in clouds above the sites and subsequent precipitation quantities reaching the surface during events with similar meteorology. The goal of this study is to use precipitation chemistry information to gain a better understanding of the potential sources of INP in the south-central Sierra Nevada, where cloud-aerosol-precipitation interactions are under-studied and where mixed-phase orographic clouds represent a key element in the generation of precipitation and thus the water supply in California.

  7. The relationships between insoluble precipitation residues, clouds, and precipitation over California's southern Sierra Nevada during winter storms

    NASA Astrophysics Data System (ADS)

    Creamean, Jessie M.; White, Allen B.; Minnis, Patrick; Palikonda, Rabindra; Spangenberg, Douglas A.; Prather, Kimberly A.

    2016-09-01

    Ice formation in orographic mixed-phase clouds can enhance precipitation and depends on the type of aerosols that serve as ice nucleating particles (INPs). The resulting precipitation from these clouds is a viable source of water, especially for regions such as the California Sierra Nevada. Thus, a better understanding of the sources of INPs that impact orographic clouds is important for assessing water availability in California. This study presents a multi-site, multi-year analysis of single-particle insoluble residues in precipitation samples that likely influenced cloud ice and precipitation formation above Yosemite National Park. Dust and biological particles represented the dominant fraction of the residues (64% on average). Cloud glaciation, determined using satellite observations, not only depended on high cloud tops (>5.9 km) and low temperatures (<-23 °C), but also on the presence of what were likely dust and biological INPs. The greatest prevalence of ice-phase clouds occurred in conjunction with biologically-rich residues and mineral dust rich in calcium, followed by iron and aluminosilicates. Dust and biological particles are known to be efficient INPs, thus these residues likely influenced ice formation in clouds above the sites and subsequent precipitation quantities reaching the surface during events with similar meteorology. The goal of this study is to use precipitation chemistry information to gain a better understanding of the potential sources of INPs in the south-central Sierra Nevada, where cloud-aerosol-precipitation interactions are poorly understood and where mixed-phase orographic clouds represent a key element in the generation of precipitation and thus the water supply in California.

  8. Nutrient and mercury deposition and storage in an alpine snowpack of the Sierra Nevada, USA

    NASA Astrophysics Data System (ADS)

    Pearson, C.; Schumer, R.; Trustman, B. D.; Rittger, K.; Johnson, D. W.; Obrist, D.

    2015-06-01

    Biweekly snowpack core samples were collected at seven sites along two elevation gradients in the Tahoe Basin during two consecutive snow years to evaluate total wintertime snowpack accumulation of nutrients and pollutants in a high-elevation watershed of the Sierra Nevada. Additional sampling of wet deposition and detailed snow pit profiles were conducted the following year to compare wet deposition to snowpack storage and assess the vertical dynamics of snowpack nitrogen, phosphorus, and mercury. Results show that, on average, organic N comprised 48% of all snowpack N, while nitrate (NO3--N) and TAN (total ammonia nitrogen) made up 25 and 27%, respectively. Snowpack NO3--N concentrations were relatively uniform across sampling sites over the sampling seasons and showed little difference between seasonal wet deposition and integrated snow pit concentrations. These patterns are in agreement with previous studies that identify wet deposition as the dominant source of wintertime NO3--N deposition. However, vertical snow pit profiles showed highly variable concentrations of NO3--N within the snowpack indicative of additional deposition and in-snowpack dynamics. Unlike NO3--N, snowpack TAN doubled towards the end of winter, which we attribute to a strong dry deposition component which was particularly pronounced in late winter and spring. Organic N concentrations in the snowpack were highly variable (from 35 to 70%) and showed no clear temporal, spatial, or vertical trends throughout the season. Integrated snowpack organic N concentrations were up to 2.5 times higher than seasonal wet deposition, likely due to microbial immobilization of inorganic N as evident by coinciding increases in organic N and decreases in inorganic N in deeper, aged snow. Spatial and temporal deposition patterns of snowpack P were consistent with particulate-bound dry deposition inputs and strong impacts from in-basin sources causing up to 6 times greater enrichment at urban locations compared

  9. Seasonal and inter-annual snowmelt patterns in the southern Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Musselman, K. N.; Molotch, N. P.; Margulis, S. A.

    2012-12-01

    In the Sierra Nevada, seasonal snow represents a critical component of California's water resource infrastructure in that it affords reliable water during otherwise arid summers. Complex spatial, seasonal and inter-annual snowmelt patterns determine when and where that meltwater is available. Our knowledge of snowmelt dynamics is typically limited to what we can infer from sparse, point-scale snow measurement stations. Limitations such as these motivate the use of numerical snowmelt models. We evaluate the ability of the Alpine3D model system to represent three years of snow dynamics over an 1800 km2 area of Sequoia National Park. The domain spans a 3600 m elevation gradient and ecosystems ranging from semi-arid grasslands to massive sequoia stands to alpine tundra. The model results were evaluated against data from a multi-scale measurement campaign that included airborne LiDAR, clusters of snow depth sensors, repeated manual snow surveys, and automated SWE stations. Compared to these measurements, Alpine3D consistently performed well in middle elevation conifer forests; compared to LiDAR data, the mean snow depth error in forested regions was < 2%. The model also simulated the snow disappearance date within two days of that measured by regional automated sensors. At upper elevations, however, the model tended to overestimate SWE by 50% to as much as 100% in some areas and the errors were linearly correlated (R2 > 0.80, p<0.01) with the distance of the SWE measurements from the nearest precipitation gauge used to derive the model forcing. The results suggest that Alpine3D is highly accurate during the melt season and that precipitation uncertainty may be a critical limitation on snow model accuracy. Finally, an analysis of seasonal and inter-annual snowmelt patterns highlighted distinct melt differences between lower, middle, and upper elevations. Snowmelt was generally most frequent (70% - 95% of the snow-covered season) at the lower elevations where snow cover

  10. Hydroclimatic alteration increases vulnerability of montane meadows in the Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Viers, J. H.; Peek, R.; Purdy, S. E.; Emmons, J. D.; Yarnell, S. M.

    2012-12-01

    Meadow ecosystems of the Sierra Nevada (California, USA) have been maintained by the interplay of biotic and abiotic forces, where hydrological functions bridge aquatic and terrestrial realms. Meadows are not only key habitat for fishes, amphibians, birds, and mammals alike, but also provide enumerable ecosystem services to humans, not limited to regulating services (eg, water filtration), provisioning services (eg, grazing), and aesthetics. Using hydroclimatic models and spatial distribution models of indicator species, a range wide assessment was conducted to assess and synthesize the vulnerability of meadow ecosystems to hydroclimatic alteration, a result of regional climate change. Atmospheric warming is expected to result in a greater fraction of total precipitation falling as winter rain (rather than snow) and earlier snowmelt. These predicted changes will likely cause more precipitation-driven runoff in winter and reduced snowmelt runoff in spring, leading to reduced annual runoff and a general shift in runoff timing to earlier in the year. These profound effects have consequences for hydrological cycling and meadow functioning, though such changes will not occur steadily through time or uniformly across the range, and each individual meadow will respond as a function of its composition and land use history. Most vulnerable is groundwater recharge, a fundamental component of meadow hydrology. As a result of shortened snow melt period and absence of diel snowmelt fluxes that would otherwise gradually refill meadow aquifers, recharge is expected to decline due to less infiltration. Diminished water tables will likely stress hydric and mesic vegetation, promoting more xeric conditions. Coupled with greater magnitude stream flows, these conditions promote channel incision and ultimate state shift to non-meadow conditions. The biological effects of hydroclimatic alteration, such as lower mean annual flow and earlier timing, will result in an overall decrease in

  11. Late Pleistocene displacement and slip rate for the Breckenridge fault, Walker Basin, southern Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Brossy, C. C.; Baldwin, J. N.; Kelson, K. I.; Rood, D. H.; Kozlowicz, B.; Simpson, D.; Ticci, M.; Amos, C. B.; Kozaci, O.; Lutz, A.

    2010-12-01

    The north-striking Breckenridge fault occurs along the 11-km-long western margin of Walker Basin, a west-tilted intermontane alluvial basin in the southern Sierra Nevada. This east-dipping normal fault has prominent geomorphic expression in the form of east-facing fault scarps on alluvial-fan deposits and distinct triangular facets of granitic bedrock along the range front. Steep, east-draining valleys are incised into bedrock west of the fault and are associated with inset or overlapping alluvial fan surfaces east of the fault. Detailed analysis of lidar-derived digital elevation models (DEMs) and field geomorphic mapping suggest that a 2-km-wide series of small right-stepovers separate the Breckenridge fault from the Holocene-active Kern Canyon fault to the north. Directly south of Walker Basin, prominent geomorphic expression of the Breckenridge fault dies out in an area of complex and distributed microseismicity, suggesting that the fault does not connect with the active White Wolf fault to the south. Herein, on the basis of geologic and geomorphic mapping, DEM interpretation, and cosmogenic radionuclide (CRN) dating, we report the first documented evidence for late Pleistocene normal faulting on the Breckenridge fault. At the Oak Tree site (38.431N, 118.545W), two alluvial-fan deposits (Qf1 and Qf3) exhibit east-down normal fault displacement. The active channel is entrenched about 8 and 14 m below these abandoned surfaces. Topographic profiles generated from DEMs along the extensive Qf1 and Qf3 surfaces show that fault scarp heights are progressively lower on younger surfaces. The oldest surface (Qf1) shows vertical separation of ~7 m, and the intermediate Qf3 surface exhibits ~4 m of vertical separation. The next youngest surface (Qf4) appears undeformed across the fault trace. Samples from granitic boulders exposed on the Qf1, Qf3, and Qf4 surfaces were collected for 10Be exposure dating. The CRN dates are consistent with stratigraphic position and yield

  12. Deciphering the environmental and landscape evolution of Sierra Nevada (S Iberia) from bog archives

    NASA Astrophysics Data System (ADS)

    Garcia Alix, Antonio; Toney, Jaime L.; Jiménez-Moreno, Gonzalo; Ramos-Román, Maria J.; Anderson, R. Scott; Jiménez-Espejo, Francisco; Delgado Huertas, Antonio; Ruano, Patricia

    2016-04-01

    Sierra Nevada is the southernmost mountain range in the Iberian Peninsula and one of the highest in Europe. Its geomorphology was the result of Pleistocene glaciations that carved out depressions, valleys and cirques at high elevations in the metamorphic basement. Depressions gave rise to lakes and wetlands during the Holocene. Geophysical and organic geochemical analyses of biomarkers (n-alkanes) and bulk sediment (C and N ratio and isotopes) from two high elevation bogs (locally called "Borreguiles"): Borreguiles de la Virgen (BdlV) and Borreguiles de la Caldera (BdlC), have allowed us to track the hydrological evolution of the area and its relationship to climatic fluctuations of the western Mediterranean during the Holocene. Most of the bogs of this area resulted from the natural evolution of former small lakes. The records are 56 cm and 169 cm long, respectively. Geophysical data suggest that we recovered the whole sedimentary record from BdlC; however, there are some post-glacial sediments remaining below the BdlV core that we could not recover due to hard-ground conditions. During the early and middle Holocene, aquatic conditions predominated in BdlV compared to the most recent part of the record (low C/N values and high proportion of aquatic plants (Paq) deduced from the n-alkanes) suggesting a lake environment whose water level gradually decreased until ˜5.5 cal ky BP. This aridity trend is also observed in nearby records such as at Laguna de Río Seco (LdRS), a result of the African Humid Period demise. Carbon and nitrogen isotopes were higher during this interval, which might suggest more algae activity, in agreement with the highest concentrations of the algae Pediastrum in the area. There is an important development of terrestrial plants, a real bog stage (C/N higher than 20, high TOC, lower Paq) in both records from ˜5.5 to 3.5-3.0 cal ky BP. Those hydrological changes in the landscape might be related to a possible change in the source of

  13. Pyroclasts Key to Age and Use of Meter-Size Granite Basins, Sierra Nevada, CA (Invited)

    NASA Astrophysics Data System (ADS)

    Moore, J. G.; Gorden, M. A.; Sisson, T. W.

    2010-12-01

    More than 1000 meter-size granite basins at more than 220 sites occur in a 240-km-long belt from Lake Isabella north to the San Joaquin River on the west slope of the southern Sierra Nevada. The circular basins are carved in granitic outcrops at an average elevation of 1950 m. They range in volume from 40 to 1400 liters, median 130 liters. The basins display features compatible with a man-made origin, but required enormous, sustained labor to excavate. Until now their apparent purpose was believed to be some aspect of food preparation (Moore, Gorden, Robinson, Moring, 2008). About 120 km north of this belt a separate cluster of more than 350 similar granite basins occurs near a rare salt spring. They were clearly made by Indians to contain saline water to produce salt by evaporation (Moore and Diggles, 2009). An early study identified rhyolitic volcanic ash in the bottom of many basins in Sequoia National Park at both Giant Forest and at Redwood Meadow 13 km ESE (Stewart, 1929). That ash is unavailable, having been removed in recent time. Subsequent study of meadowland soils identified two ash layers in the region from explosive eruptions in the Mono Lake area: Tephra 1 and Tephra 2 (Wood, 1977). Later work indicates that Tephra 1 was erupted from the Glass Creek vent of the Inyo Craters (Miller, 1985) and that its refined age by tree-ring techniques is AD 1350 (Millar, King, Westfall, Alden, Delany, 2006). A fossil forest killed by Tephra 1 differs from modern forests in that it grew in the warmer climate of the Medieval Warm Period (MWP)--a period when drought conditions prevailed at lower elevations (Stine, 1994; Millar et al, 2006). In July 2010 ash was discovered near the bottom of a pristine granite basin (TUL-496) in a remote area of Giant Sequoia National Monument 14.5 km NW of Giant Forest. High-beam-current electron microprobe analyses of pumice glasses give Zr 145-420 ppm, homogeneous within lapilli, and correlated with MgO and CaO concentrations. The

  14. Evaluating potential overlap between pack stock and Sierra Nevada bighorn sheep (Ovis canadensis sierrae) in Sequoia and Kings Canyon National Parks, California

    USGS Publications Warehouse

    Klinger, Robert C.; Few, Alexandra P.; Knox, Kathleen A.; Hatfield, Brian E.; Clark, Jonathan; German, David W.; Stephenson, Thomas R.

    2015-01-01

    The association analyses indicated the potential for overlap between pack stock and SNBS was minimal; only 1 percent of the potential meadow area in the SNBS herd home ranges overlapped that of pack stock meadows. There were no systematic differences in overall vegetation structure or composition, or in diversity, cover, or composition of forage species, that indicated pack stock were altering SNBS habitat or affecting their nutrition. Variation in plant species composition was influenced primarily by random differences among meadows and environmental gradients, and there was little evidence that pack stock use contributed in meaningful ways to this variation. The few differences among meadows with different levels of use by bighorn sheep and pack stock either were minor or were not in a direction consistent with negative effects of pack stock on SNBS. We conclude that the current plan for managing pack stock grazing has been successful in minimizing significant negative effects on Sierra Nevada bighorn sheep at Sequoia and Kings Canyon National Parks.

  15. Water and energy gradients produce resilience and thresholds in ecosystem function in the western Sierra Nevada Mountains

    NASA Astrophysics Data System (ADS)

    Kelly, A. E.; Goulden, M.; Bales, R. C.; Meadows, M. W.; Winston, G.

    2012-12-01

    Energy and water availability are fundamental controls on ecosystem properties such as ecosystem type, water use, phenology, and carbon uptake, allocation, and turnover. How availability of energy and water interact to produce stepwise changes in ecosystem properties across linear climate gradients remains an important question for ecology and predicting impacts of climate change. Previous work has focused on the climatic factors that determine individual species' mortality or locations of individual ecotones, but research is lacking that examines role of energy and water availability in controlling patterns of ecosystem trait shifts across a broad climatic gradient. We studied a 2600-m elevation gradient along the western slope of the Sierra Nevada Mountains in the Southern Sierra Critical Zone Observatory (SSCZO) to understand how water and energy availability interact to influence ecosystem properties across a broad range of climate conditions and ecosystem types. Eddy covariance, vegetation type, forest biomass and production, sap flux, and soil moisture were measured to understand nonlinear ecosystem responses to gradients in energy and water availability. We describe the small differences in temperature and water availability that produce sharp transitions in ecosystem type, productivity, water use, and phenology. Conversely, we describe how broad ranges of temperature and water availability produce stability in ecosystem properties and demonstrate ecosystem resilience to climate change. These findings can better inform predictions of impacts of a changing climate on ecosystem range shifts, mortality, seasonality, carbon cycling, and water use.

  16. In-situ monitoring of California's drought: Impacts on key hydrologic variables in the Southern Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Oroza, C.; Zheng, Z.; Zhang, Z.; Glaser, S. D.; Bales, R. C.; Conklin, M. H.

    2015-12-01

    Like many semi-arid regions, California relies on seasonal snowmelt from the Sierra Nevada mountain range to provide freshwater allocations for multiple stakeholders throughout the year. The magnitude and timing of runoff from these regions is being altered by consecutive years of drought, affecting downstream ecosystems, hydropower operations, and deliveries to agriculture and urban water users. Understanding the long-term effect of drought on the montane water balance requires temporally continuous, in-situ measurements of key hydrologic variables across large spatial domains. We discuss a seven-year dataset from the Southern Sierra Critical Zone Observatory, which includes co-located measurements of snowpack, soil moisture, and soil temperature in the Kings River watershed. We investigate how these key hydrologic variables are affected as the region transitions from winters that have nearly continuous snow cover (2008-2011) to winters with extended snow-on, snow-off periods (2012-2014). For water year 2014, we observe a 93% decline in average snowpack, a 35% decline in average soil moisture, and a 25% increase in average soil temperature compared to a wet-year index of each variable. We discuss the effect of physiographic features, including slope, aspect, elevation, and canopy coverage on the changes observed in each variable. Finally, we use sparse inverse covariance estimation to investigate the changing conditional relationships throughout the observatory in wet and dry years.

  17. Mercury Contamination and Bioaccumulation Associated with Historical Gold Mining in the Bear and Yuba River Watersheds, Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Alpers, C. N.; Hunerlach, M. P.; Hothem, R. L.; May, J. T.; Taylor, H. E.; DeWild, J. F.; Olson, M. L.; Krabbenhoft, D. P.; Marvin-DiPasquale, M.

    2001-12-01

    Extensive use of mercury in the mining and recovery of gold during the late 19th and early 20th centuries has led to widespread mercury contamination of water, sediment, and biota in the Sierra Nevada foothills of California. The watersheds of the Bear and Yuba Rivers were selected for study by the U.S. Geological Survey and other federal, state, and local agencies on the basis of (1) results of previous studies of bioaccumulation, (2) observations of visible elemental mercury at numerous mine sites and in river sediments, and (3) extensive historical mining on federal lands and adjacent private lands. Of 53 unfiltered water samples analyzed for total recoverable mercury (Hg-T), 17 samples (32 percent) had concentrations in excess of the U.S. Environmental Protection Agency (EPA) aquatic-life criterion of 50 nanograms per liter (ng/L). Water flowing from two separate tunnels in one mining district had Hg-T concentrations greater than 100,000 ng/L, exceeding the EPA drinking-water standard of 2,000 ng/L. Monthly sampling of the Bear River near its mouth revealed monomethylmercury (MeHg) concentrations in unfiltered water samples greater than 0.4 ng/L during July-August 1999 and January 2000. Game fish were collected from 5 reservoirs and 14 stream sites during 1999 to assess the distribution of mercury in the food chain and to examine the potential risk for humans and wildlife. Of 141 fish fillet samples of black basses (Micropterus spp.), sunfish (Lepomis macrochirus and Lepomis cyanellus), black crappie (Poxomis nigromaculatus), channel catfish (Ictularus punctatus), brown trout (Salmo trutta), and rainbow trout (Oncorhynchus mykiss) analyzed for Hg-T, 52 percent exceeded the EPA criterion of 0.3 parts per million (ppm), wet basis. Eighty-nine percent of the bass had Hg-T greater than 0.3 ppm total mercury. Based on these data, three counties issued a public health notification recommending limited consumption of game fish from the Bear and Yuba watersheds

  18. Simulated Climate Change Effects of Snowpack Manipulations on Soil Temperature and Moisture in the Sierra Nevada Mountains

    NASA Astrophysics Data System (ADS)

    Johnson, B. G.; Jasoni, R. L.; Arnone, J.

    2012-12-01

    Future changes in climate are predicted to significantly affect the type and amount of precipitation in the Sierra Nevada Mountains of California and Nevada. Because most of the yearly precipitation in this region falls as snow, changes in snowfall amount, snowfall timing, and duration of the snowpack may dramatically affect the timing and persistence of soil temperature and moisture, and biological processes dependent on these soil factors. The objective of our study was to quantify the effects of manipulating snowpack amounts on soil temperature and moisture over a two year period, including both the addition and removal of snow in a Pinus jeffreii (Jeffrey Pine) forest located northeast of Lake Tahoe, Nevada. Soil temperatures measured during the first winter (above average snow year) remained higher in control plots when snow was present, and in snow-addition plots, than in snow-removal plots. However, these effects did not persist in the second year when total snowfall amounted to only 20% of that occurring in the first year. Surprisingly, the effects on soil moisture persisted through the summer of year two with soil VWC in snow removal plots averaging approximately 50% drier than the snow addition plots (6.5% average VWC in snow removal and 13.2% in snow addition plots) and 13% drier on average than the control plots (7.5% average VWC in control plots).These results suggest the possibility of prolonged reductions in soil moisture, soil microbial activity, plant growth, and even increased danger of wildfires if anthropogenic climate change reduces snowfall amount and snowpack duration.

  19. Paleomagnetism, Geochronology, and Geochemistry of the Type Section of the Stanislaus Group: Reference Parameters from the Stable Sierra Nevada Microplate, CA

    NASA Astrophysics Data System (ADS)

    Farner, M. J.; Pluhar, C. J.; Asami, R.; Putirka, K. D.; Busby, C.; Renne, P. R.

    2012-12-01

    The Late Miocene Stanislaus Group, of California and Nevada is composed of Table Mountain Formation, Eureka Valley Tuff, and Dardanelles Formation. This ~9.0-~10.2 million year old unit interrupted Miocene andesitic arc volcanism in the Sierra Nevada, providing a regional lithostratigraphic marker that has been used extensively to reconstruct tilt and uplift of the range, Neogene tectonics of the Walker Lane Belt, magmagenetic processes beneath the Sierra Nevada, and lithospheric evolution of the Sierra Nevada and Eastern California. A recent study (Koerner et al, 2009) produced a measured section and geologic map of the Stanislaus Group type section, but until now this locality has never seen comprehensive multidisciplinary study of the geochronology, geochemistry, and magnetostratigraphy of the site and to integrate this into the overall understanding of the Stanislaus Group. Stratigraphy, geochemistry, and paleomagnetism from the type section suggest addition of a basal trachyte lava flow member to the Eureka Valley tuff and adds an additional intermediate-polarity lava flow to Table Mountain Formation magnetostratigraphy. This study dates the youngest member of the Stanislaus Group, the Dardanelles Formation, by 40Ar/39Ar radioisotopic dating for the first time, yielding an age of 9.048 ± 0.017 Ma. Paleomagnetic results verify the previous paleomagnetic reference direction from the Sierra Nevada microplate for the Tollhouse Flat Member of the Eureka Valley Tuff (King et al., 2007). However, our work revises the By-Day Member reference direction to D = 349.6°, I = 51.9° n = 8, α95 = 3.0°, k = 346. This difference is because the prior work analyzed By-Day localities within the tectonically-active Walker Lane Belt. The revised reference direction is critical for measurements of relative vertical-axis rotation studies in the Walker Lane. Our study also demonstrates that little to no vertical-axis rotation of the Sierra Nevada microplate has occurred since

  20. Past and future demographic dynamics of alpine species: limited genetic consequences despite dramatic range contraction in a plant from the Spanish Sierra Nevada.

    PubMed

    Blanco-Pastor, J L; Fernández-Mazuecos, M; Vargas, P

    2013-08-01

    Anthropogenic global climate change is expected to cause severe range contractions among alpine plants. Alpine areas in the Mediterranean region are of special concern because of the high abundance of endemic species with narrow ranges. This study combined species distribution models, population structure analyses and Bayesian skyline plots to trace the past and future distribution and diversity of Linaria glacialis, an endangered narrow endemic species that inhabits summits of Sierra Nevada (Spain). The results showed that: (i) the habitat of this alpine-Mediterranean species in Sierra Nevada suffered little changes during glacial and interglacial stages of late Quaternary; (ii) climatic oscillations in the last millennium (Medieval Warm Period and Little Ice Age) moderately affected the demographic trends of L. glacialis; (iii) future warming conditions will cause severe range contractions; and (iv) genetic diversity will not diminish at the same pace as the distribution range. As a consequence of the low population structure of this species, genetic impoverishment in the alpine zones of Sierra Nevada should be limited during range contraction. We conclude that maintenance of large effective population sizes via high mutation rates and high levels of gene flow may promote the resilience of alpine plant species when confronted with global warming.

  1. Paleofire reconstruction for high-elevation forests in the Sierra Nevada, California, with implications for wildfire synchrony and climate variability in the late Holocene

    NASA Astrophysics Data System (ADS)

    Hallett, Douglas J.; Anderson, R. Scott

    2010-03-01

    Here, we present two high-resolution records of macroscopic charcoal from high-elevation lake sites in the Sierra Nevada, California, and evaluate the synchroneity of fire response for east- and west-side subalpine forests during the past 9200 yr. Charcoal influx was low between 11,200 and 8000 cal yr BP when vegetation consisted of sparse Pinus-dominated forest and montane chaparral shrubs. High charcoal influx after ˜ 8000 cal yr BP marks the arrival of Tsuga mertensiana and Abies magnifica, and a higher-than-present treeline that persisted into the mid-Holocene. Coeval decreases in fire episode frequency coincide with neoglacial advances and lower treeline in the Sierra Nevada after 3800 cal yr BP. Independent fire response occurs between 9200 and 5000 cal yr BP, and significant synchrony at 100- to 1000-yr timescales emerges between 5000 cal yr BP and the present, especially during the last 2500 yr. Indistinguishable fire-return interval distributions and synchronous fires show that climatic control of fire became increasingly important during the late Holocene. Fires after 1200 cal yr BP are often synchronous and corroborate with inferred droughts. Holocene fire activity in the high Sierra Nevada is driven by changes in climate linked to insolation and appears to be sensitive to the dynamics of the El Niño-Southern Oscillation.

  2. Application of the ESRI Geostatistical Analyst for determining the adequacy and sample size requirements of ozone distribution models in the Carpathian and Sierra Nevada Mountains.

    PubMed

    Fraczek, W; Bytnerowicz, A; Arbaugh, M J

    2001-12-07

    Models of O3 distribution in two mountain ranges, the Carpathians in Central Europe and the Sierra Nevada in California were constructed using ArcGIS Geostatistical Analyst extension (ESRI, Redlands, CA) using kriging and cokriging methods. The adequacy of the spatially interpolated ozone (O3) concentrations and sample size requirements for ozone passive samplers was also examined. In case of the Carpathian Mountains, only a general surface of O3 distribution could be obtained, partially due to a weak correlation between O3 concentration and elevation, and partially due to small numbers of unevenly distributed sample sites. In the Sierra Nevada Mountains, the O3 monitoring network was much denser and more evenly distributed, and additional climatologic information was available. As a result the estimated surfaces were more precise and reliable than those created for the Carpathians. The final maps of O3 concentrations for Sierra Nevada were derived from cokriging algorithm based on two secondary variables--elevation and maximum temperature as well as the determined geographic trend. Evenly distributed and sufficient numbers of sample points are a key factor for model accuracy and reliability.

  3. Streamflow changes in the Sierra Nevada, California, simulated using a statistically downscaled general circulation model scenario of climate change

    USGS Publications Warehouse

    Wilby, Robert L.; Dettinger, Michael D.

    2000-01-01

    Simulations of future climate using general circulation models (GCMs) suggest that rising concentrations of greenhouse gases may have significant consequences for the global climate. Of less certainty is the extent to which regional scale (i.e., sub-GCM grid) environmental processes will be affected. In this chapter, a range of downscaling techniques are critiqued. Then a relatively simple (yet robust) statistical downscaling technique and its use in the modelling of future runoff scenarios for three river basins in the Sierra Nevada, California, is described. This region was selected because GCM experiments driven by combined greenhouse-gas and sulphate-aerosol forcings consistently show major changes in the hydro-climate of the southwest United States by the end of the 21st century. The regression-based downscaling method was used to simulate daily rainfall and temperature series for streamflow modelling in three Californian river basins under current-and future-climate conditions. The downscaling involved just three predictor variables (specific humidity, zonal velocity component of airflow, and 500 hPa geopotential heights) supplied by the U.K. Meteorological Office couple ocean-atmosphere model (HadCM2) for the grid point nearest the target basins. When evaluated using independent data, the model showed reasonable skill at reproducing observed area-average precipitation, temperature, and concomitant streamflow variations. Overall, the downscaled data resulted in slight underestimates of mean annual streamflow due to underestimates of precipitation in spring and positive temperature biases in winter. Differences in the skill of simulated streamflows amongst the three basins were attributed to the smoothing effects of snowpack on streamflow responses to climate forcing. The Merced and American River basins drain the western, windward slope of the Sierra Nevada and are snowmelt dominated, whereas the Carson River drains the eastern, leeward slope and is a mix of

  4. Delineation of the High Enthalpy Reservoirs of the Sierra Nevada Volcanic Geothermal System, South-Central Chile

    NASA Astrophysics Data System (ADS)

    Alam, M.; Muñoz, M.; Parada, M.

    2011-12-01

    Geothermal system associated with the Pleistocene-Holocene Sierra Nevada volcano (SNVGS) in the Araucanía Region of Chile has surface manifestations from the north-western flank of the volcano, up to Manzanar and Malalcahuello. Baños del Toro, located on the northwestern flank of the volcano, has numerous fumaroles and acid pools (acid sulfate waters, T=~90°C, pH=2.1, TDS=3080 mg/L); while Aguas de la Vaca, near the base of the volcano, has a bubbling spring (chloride-sulfate waters, T=~60°C, pH=7.0, TDS=950 mg/L). Five shallow (<120m) wells (2 at Manzanar and 3 at Malalcahuello) dug and drilled in the Cautín River Valley discharge alkaline (pH= 9-10) waters with relatively low TDS (130-210mg/L). The main heat source of the geothermal system is apparently the magmatic system of the Sierra Nevada volcano. Liquiñe-Ofqui Fault Zone (LOFZ) that transects the area forms excellent conduits for the flow of the geothermal waters. The geothermal reservoirs are hosted in the volcanic rocks interceded with glacial deposits over the North Patagonian Batholith that forms an impermeable barrier, and thus constitutes the lower boundary of the geothermal system and also controls the lateral flow of the fluids. An equilibrium temperature of ~210°C is derived from gas geothermometry (CO2/Ar-H2/Ar) of the discharges at Baños del Toro. Geothermal fluids from the upflow area on the northwestern flank of the volcano migrate northwards to the Cautín River Valley. The geothermal system has a high enthalpy reservoir(s) on the northwestern flank of the Sierra Nevada volcano and low-enthalpy reservoirs in the Cautín River Valley that have been tapped to form spas at Manzanar and Malalcahuello. While sub-vertical fractures of LOFZ facilitate the recharge of the system, lateral flow of the geothermal fluids is apparently controlled by lithology; Melipueclo Pluton in particular prevents the westward flow from the upflow zone, causing the flow only northwards to Malalcahuello and

  5. The ~ 31 ka rhyolitic Plinian to sub-Plinian eruption of Tlaloc Volcano, Sierra Nevada, central Mexico

    NASA Astrophysics Data System (ADS)

    Rueda, H.; Macías, J. L.; Arce, J. L.; Gardner, J. E.; Layer, P. W.

    2013-02-01

    Tlaloc is a late Pleistocene stratovolcano located NE of México City. It is the northernmost volcano of the N-S Sierra Nevada Volcanic Range, which consists from north to south of Tlaloc, Telapón, Iztaccíhuatl, and Popocatépetl volcanoes. Tlaloc has always been considered the oldest (and extinct) volcano of the Sierra Nevada Volcanic Range. Recent field data revealed that Tlaloc was very active during late Pleistocene through a series of explosive eruptions. One of these eruptions produced the Multilayered White Pumice (MWP) a rhyolitic pyroclastic sequence. The eruption began with a 24-km high Plinian column MWP-F1 that was dispersed to the NE by prevailing winds. It was interrupted by fountaining of the column with the generation of a pyroclastic density current that emplaced MWP-S1 layer. Then, followed five unstable sub-Plinian columns (MWP-F2 to F6) that reached altitudes between 16 and 19 km. Fall deposits as a whole are 1 m thick at 12 km from the vent, cover a minimum area of 577 km2 for a total volume of 4.68 km3 (DRE 1.58 km3). The eruption ejected a total mass of 3.45 × 1012 kg at different mass discharges. The last sub-Plinian column (MWP-F6) collapsed and produced dense pyroclastic density currents that deposited pumiceous pyroclastic flows (MWP-PF) following main ravines to the north and east of the vent. These density currents filled gullies with 23 m-thick deposits at a distance of 12 km from the vent totaling a minimum DRE volume of 0.2 km3. Pyroclastic flow deposits charred tree trunks that yielded an age of 31,490 + 1995/- 1595 yr B.P. that closely date the age of the eruption. Rain during this phase of the eruption generated syn-eruptive lahars (MWP-DF). Post-eruptive lahars (MWP-ED) finally swept the volcano flanks. The MWP deposits consist of abundant white pumice (up to 96 vol.%), rare gray pumice, cognate lithics, accidental altered lithics, xenocrysts. White and gray pumice clasts contain phenocrysts of quartz, plagioclase, sanidine

  6. Interpretation of snowcover from satellite imagery for use in water supply forecasts in the Sierra Nevada

    NASA Technical Reports Server (NTRS)

    Brown, A. J.; Hannaford, J. F.

    1975-01-01

    The California ASVT test area is composed of two study areas; one in Northern California covering the Upper Sacramento and Feather River Basins, and the other covering the Southern Sierra Basins of the San Joaquin, Kings, Kaweah, Tule, and Kern Rivers. Experiences of reducing snowcover from satellite imagery; the accuracy of present water supply forecast schemes; and the potential advantages of introducing snowcover into the forecast procedures are described.

  7. Surface temperature patterns in complex terrain: Daily variations and long-term change in the central Sierra Nevada, California

    USGS Publications Warehouse

    Lundquist, J.D.; Cayan, D.R.

    2007-01-01

    A realistic description of how temperatures vary with elevation is crucial for ecosystem studies and for models of basin-scale snowmelt and spring streamflow. This paper explores surface temperature variability using temperature data from an array of 37 sensors, called the Yosemite network, which traverses both slopes of the Sierra Nevada in the vicinity of Yosemite National Park, California. These data indicate that a simple lapse rate is often a poor description of the spatial temperature structure. Rather, the spatial pattern of temperature over the Yosemite network varies considerably with synoptic conditions. Empirical orthogonal functions (EOFs) were used to identify the dominant spatial temperature patterns and how they vary in time. Temporal variations of these surface temperature patterns were correlated with large-scale weather conditions, as described by National Centers for Environmental Prediction-National Center for Atmospheric Research Reanalysis data. Regression equations were used to downscale larger-scale weather parameters, such as Reanalysis winds and pressure, to the surface temperature structure over the Yosemite network. These relationships demonstrate that strong westerly winds are associated with relatively warmer temperatures on the east slope and cooler temperatures on the west slope of the Sierra, and weaker westerly winds are associated with the opposite pattern. Reanalysis data from 1948 to 2005 indicate weakening westerlies over this time period, a trend leading to relatively cooler temperatures on the east slope over decadal timescale's. This trend also appears in long-term observations and demonstrates the need to consider topographic effects when examining long-term changes in mountain regions. Copyright 2007 by the American Geophysical Union.

  8. Thirty Years of Change in Subalpine Forest Cover from Landsat Image Analysis in the Sierra Nevada Mountains of California

    NASA Technical Reports Server (NTRS)

    Potter, Christopher

    2015-01-01

    Landsat imagery was analyzed to understand changes in subalpine forest stands since the mid-1980s in the Sierra-Nevada region of California. At locations where long-term plot measurements have shown that stands are becoming denser in the number of small tree stems (compared to the early 1930s), the 30-year analysis of Landsat greenness index (NDVI) indicated that no consistent increases in canopy leaf cover have occurred at these same locations since the mid-1980s. Interannual variations in stand NDVI closely followed snow accumulation amounts recorded at nearby stations. In contrast, at eastern Sierra whitebark pine stand locations where it has been observed that widespread tree mortality has occurred, decreasing NDVI trends over the past 5-10 years were consistent with rapid loss of forest canopy cover. Landsat imagery was further analyzed to understand patterns of post-wildfire vegetation recovery, focusing on high burn severity (HBS) patches within burned areas dating from the late 1940s. Analysis of landscape metrics showed that the percentage of total HBS area comprised by the largest patch of recovered woody cover was relatively small in all fires that occurred since 1995, but increased rapidly with time since fire. Patch complexity of recovered woody cover decreased notably after more than 50 years of regrowth, but was not readily associated with time for fires that occurred since the mid 1990s. The aggregation level of patches with recovery of woody cover increased steadily with time since fire. The study approach using satellite remote sensing can be expanded to assess the consequences of stand-replacing wildfires in all forests of the region.

  9. Soil moisture trends in mountainous areas: a 50-yr analysis of modelled soil moisture over Sierra Nevada Mountains (Spain).

    NASA Astrophysics Data System (ADS)

    José Pérez-Palazón, María; Pimentel, Rafael; Herrero, Javier; José Polo, María

    2016-04-01

    Soil moisture conditions the energy and water fluxes through the ground surface and constitutes a major hydrological state variable in the analysis of environmental processes. Detecting potential changes in soil moisture and analyzing their trend over a long period of study can help to understand its evolution in other similar areas and to estimate its future role. In mountainous areas, the snow distribution highly conditions soil water content and its implications on the local water cycle. Sierra Nevada, Southern Spain, is a linear mountain range, with altitude higher than 3000 m.a.s.l., where Mediterranean and alpine climates coexist. The snow dynamics dominates the hydrological regime, and the medium and long term trends observed in the snow persistence constitute one of the main potential drivers for soil moisture changes both on a seasonal and annual basis. This work presents a 50-yr study of the soil moisture trends in Sierra Nevada (SN); the distributed monthly mean soil moisture evolution during the recent past (1960-2010) is simulated and its relationship with meteorological variables (precipitation and temperature) analyzed in the five head river basins that the SN area comprises. For this, soil water content is simulated throughout the area by means of WiMMed, a distributed and physically based hydrological model developed for Mediterranean regions that includes snow modelling, which had been previously calibrated and validated in the study area. The analysis of soil moisture shows a globally decreasing annual rate, with a mean value of 0.0011 mmṡmm-1ṡyear-1 during the study period averaged over the whole study area, which locally ranges between 0.174 mmṡmm-1ṡyear-1 and 0.0014 mmṡmm-1ṡyear-1. As previous studies reported, the observed trend in precipitation is more influent than temperature on the snowfall regime change; therefore, as expected, the estimated trends of soil moisture are more related to this variable. Moreover, an increase of

  10. A tree-ring based reconstruction of North Pacific Jet variability and its influence on Sierra Nevada fire regimes

    NASA Astrophysics Data System (ADS)

    Trouet, V.; Babst, F.; Betancourt, J. L.

    2013-12-01

    Over the last decade, the northern hemisphere polar jet stream - the fast-flowing, high-altitude westerly air current that flows over mid and northern latitudes - has experienced a more meridional (north-south) and slower wave progression. This anomalous behavior contributed to extreme mid-latitude weather events across the globe, including drought and forest fires in the American Southwest (2012), summer heatwaves in Russia (2010), and floods in central and western Europe (2007). The position of the North Pacific Jet (NPJ) strongly modulates winter hydroclimatology in the Sierra Nevada and the Central Rocky Mountains; moreover, a persistent southerly (northerly) trajectory can offset (reinforce) losses in regional snowpack predicted with greenhouse warming . Snowpack variability has a fundamental impact on water resources and ecosystem disturbances. An increase in wildfire activity in the American West since the mid-1980s, for instance, has been related to decreasing snowpacks and earlier and faster snowmelt. Recent anomalous, high-amplitude, jet stream fluctuations are consistent with model projections forced by greenhouse gases. By weakening the pole-equator temperature gradient, enhanced Arctic warming in particular may cause the jet to slow and extreme weather patterns (e.g., blocking high pressure cells) to persist. Questions exist about the ability of climate models to simulate jet stream dynamics, however, and the instrumental record is still too short to fully evaluate the natural range of jet stream variability. We developed a reconstruction of winter NPJ variability from tree-ring data at two locations where climate is strongly influenced by the latitudinal NPJ position. We combined Blue Oak (Quercus douglasii) data from central California with climate-sensitive tree-ring series from multiple species in the northern Rockies in a nested PCA model that explained up to 41% of the variance in the instrumental NPJ target. The resulting reconstruction (1409

  11. Impacts of forest thinning and climate change on transpiration and runoff rates in Sierra Nevada mixed-conifer headwater catchments

    NASA Astrophysics Data System (ADS)

    Saksa, P. C.; Ray, R. L.; Bales, R. C.; Conklin, M. H.

    2013-12-01

    Using a spatially explicit hydro-ecological model, impacts from forest thinning and climate change on snowpack, evapotranspiration (ET) rates, soil moisture storage, and runoff were investigated in Sierra Nevada headwater catchments spanning elevations of 1,500 to 2,000-m. Along this elevation gradient, precipitation changes from rain-dominated to snow-dominated, so precipitation phase will be strongly impacted by increases in temperature. Mixed-conifer forests in the Sierra Nevada near the 2,000-m elevation band also transpire at a high rate relative to upper elevation forests that are more restricted by colder winter temperatures and lower elevation forests that are more restricted by lower summer soil moisture, increasing the potential of reduced transpiration with vegetation thinning. Forest treatment and climate change scenarios were modeled using the Regional Hydro-Ecological Simulation System (RHESSys), calibrated with two years of snow, soil moisture, and streamflow observations. Simulations of forest thinning at moderate (66% of current vegetation density) and restoration (33% density) levels were combined with precipitation changes up to 20% and temperature increases up to 6οC for projecting impacts on ET and runoff rates. Model results indicated that moderate thinning alone could increase runoff by 3%, but additional temperature increases of 2-4οC could increase runoff rates another 6% - similar to a restoration level thinning. Modifying temperature and precipitation separately showed that the two methods of climate forcing both led to fluctuations in soil moisture, caused by changes in precipitation phase (snow/rain) and final day of snowpack melt. The snowmelt timing affected runoff rates by causing changes in the spring soil moisture recession, and showed that it may be one of the critical processes that affects annual runoff rates, not just runoff timing. Simulations of precipitation and temperature changes together showed that precipitation would

  12. Favorable areas for prospecting adjacent to the Roberts Mountains thrust in southern Lander County, Nevada

    USGS Publications Warehouse

    Stewart, John Harris; McKee, Edwin H.

    1968-01-01

    Recent geologic mapping by the U.S. Geological Survey of more than 2,500 square miles of a relatively little-studied part of central Nevada has outlined four areas favorable for the discovery of metallic mineral deposits. In these areas, lower Paleozoic carbonate rocks crop out below the Roberts Mountains thrust, a widespread fault in central and north-central Nevada. These areas have a stratigraphic and structural setting similar to that of the areas where large, open-pit gold deposits have been discovered recently at Carlin and Cortez in north-central Nevada.

  13. Investigating Planetary Boundary Layer and Land Surface Model Schemes in the WRF Model for the Sierra Nevada Region

    NASA Astrophysics Data System (ADS)

    Rayne, S.; Holmes, H.; Zielinska, B.; Gertler, A.

    2014-12-01

    The Lake Tahoe Basin is located on the border of California and Nevada northeast of the Central Valley in the Sierra Nevada Mountains. Despite its pristine beauty and water clarity, the Lake Tahoe Basin is facing problems related to air pollution including ambient ozone levels. The meteorology in this region is unusually complex due to mountainous terrain and other topographical features. Thermally driven wind systems are a common phenomenon found in mountainous regions throughout the world. These wind systems, along with the structure of the atmospheric boundary layer are important for understanding the distribution and transport of atmospheric pollutants in complex terrain. Therefore, it is essential in air pollution modeling to correctly represent the planetary boundary layer (PBL) physics that governs the vertical mixing of pollutants and PBL height, where both impact the surface pollutant concentrations. Multiple PBL and Land Surface Model (LSM) parameterization schemes are available in the Weather Research and Forecast (WRF) model and have different assumptions determining the transport of mass, moisture and energy. During the period of July 21 -26, 2012, a field study was conducted in the Basin designed to characterize the precursors and pathways of secondary pollutant formation, including ozone and secondary organic aerosol (SOA). Using the observations obtained from the field study, this analysis looks at various WRF PBL schemes used in the Community Multiscale Air Quality (CMAQ) model and evaluates their performance for this area as well as investigates thermally forced small-scale processes within the Lake Tahoe Basin. The goal of this work is to understand the impact of PBL/LSM schemes on the micrometeorology in complex terrain in order to investigate the impact of transport phenomena on rural ozone concentrations in the Lake Tahoe Basin.

  14. Water Resources of the Basin and Range Carbonate-Rock Aquifer System, White Pine County, Nevada, and Adjacent Areas in Nevada and Utah

    USGS Publications Warehouse

    Welch, Alan H.; Bright, Daniel J.; Knochenmus, Lari A.

    2008-01-01

    INTRODUCTION This report summarizes results of a water-resources study for White Pine County, Nevada, and adjacent areas in east-central Nevada and western Utah. The Basin and Range carbonate-rock aquifer system (BARCAS) study was initiated in December 2004 through Federal legislation (Section 301(e) of the Lincoln County Conservation, Recreation, and Development Act of 2004; PL108-424) directing the Secretary of the Interior to complete a water-resources study through the U.S. Geological Survey, Desert Research Institute, and State of Utah. The study was designed as a regional water-resource assessment, with particular emphasis on summarizing the hydrogeologic framework and hydrologic processes that influence ground-water resources. The study area includes 13 hydrographic areas that cover most of White Pine County; in this report however, results for the northern and central parts of Little Smoky Valley were combined and presented as one hydrographic area. Hydrographic areas are the basic geographic units used by the State of Nevada and Utah and local agencies for water-resource planning and management, and are commonly defined on the basis of surface-water drainage areas. Hydrographic areas were further divided into subbasins that are separated by areas where bedrock is at or near the land surface. Subbasins are the subdivisions used in this study for estimating recharge, discharge, and water budget. Hydrographic areas are the subdivision used for reporting summed and tabulated subbasin estimates.

  15. Water Resources of the Basin and Range Carbonate-Rock Aquifer System, White Pine County, Nevada, and Adjacent Areas in Nevada and Utah - Draft Report

    USGS Publications Warehouse

    Welch, Alan H.; Bright, Daniel J.

    2007-01-01

    Summary of Major Findings This report summarizes results of a water-resources study for White Pine County, Nevada, and adjacent areas in east-central Nevada and western Utah. The Basin and Range carbonate-rock aquifer system (BARCAS) study was initiated in December 2004 through Federal legislation (Section 131 of the Lincoln County Conservation, Recreation, and Development Act of 2004) directing the Secretary of the Interior to complete a water-resources study through the U.S. Geological Survey, Desert Research Institute, and State of Utah. The study was designed as a regional water-resource assessment, with particular emphasis on summarizing the hydrogeologic framework and hydrologic processes that influence ground-water resources. The study area includes 13 hydrographic areas that cover most of White Pine County; in this report however, results for the northern and central parts of Little Smoky Valley were combined and presented as one hydrographic area. Hydrographic areas are the basic geographic units used by the State of Nevada and Utah and local agencies for water-resource planning and management, and are commonly defined on the basis of surface-water drainage areas. Hydrographic areas were further divided into subbasins that are separated by areas where bedrock is at or near the land surface. Subbasins represent subdivisions used in this study for estimating recharge, discharge, and water budget. Hydrographic areas represent the subdivision used for reporting summed and tabulated subbasin estimates.

  16. Magnetic susceptibility and relation to initial 87Sr/86Sr for granitoids of the central Sierra Nevada, California

    USGS Publications Warehouse

    Bateman, P.C.; Dodge, F.C.W.; Kistler, R.W.

    1991-01-01

    Measurement of the magnetic susceptibility of more than 6000 samples of granitic rock from the Mariposa 1?? by 2?? quadrangle, which crosses the central part of the Sierra Nevada batholith between 37?? and 38??N latitude, shows that magnetic susceptibility values are above 10-2 SI units in the east and central parts of the batholith and drop abruptly to less than 10-3 SI units in the western foothills. In a narrow transitional zone, intermediate values (10-3 to 10-2) prevail. Magnetic susceptibility appears to decrease slightly westward within the zones of both high and low values. Magnetic susceptibility in plutonic rocks is chiefly a function of the abundance of magnetite, which depends, in turn, on the total iron content of the rocks and their oxidation ratio. Correlations of magnetic susceptibility with initial 87Sr/86Sr suggest that oxidation ratios have been inherited from the source regions for the magmas from which the rocks crystallized. Reduction of Fe3+ to Fe2+ by organic carbon or other reducing substances may also have affected magnetic susceptibility. -from Authors

  17. Deep critical zone weathering at the southern Sierra Nevada Critical Zone Observatory imaged by seismic waveform tomography

    NASA Astrophysics Data System (ADS)

    Hayes, J. L.; Holbrook, W.; Riebe, C. S.

    2012-12-01

    We present seismic velocity profiles that constrain the extent of weathering and frequency of velocity heterogeneities at depths less than 40 m in the southern Sierra Nevada Critical Zone Observatory (SSCZO) from waveform tomography modeling of a seismic refraction experiment. Near-surface variations in seismic velocity reflect differences in alteration of parent material by chemical, hydrological and biological processes. Previous traveltime tomography models from these data suggest that the depth to bedrock in the SSCZO is typically ~25 m; thus the potential for subsurface water storage in regolith may be a larger component of water storage than previously thought. Traveltime tomography is unable to resolve heterogeneities with horizontal wavelengths less than 10 m, such as those observed along a surveyed road cut beneath our seismic profile. For a higher resolution seismic image, we apply waveform tomography, which is more robust than traveltime tomography at approximating the wave equation and thus should provide images of subsurface heterogeneities such as corestones and fracture networks. This technique uses a weak scattering approximation to account for the amplitude and phase of the recorded waveforms, rather than just the traveltimes. A 48-channel vertical geophone array and hammer source was deployed over a 7 m high road cut with receiver and shot spacing of 2 m and 4 m respectively. The road cut displays lateral variation in weathering from a friable saprolite to coherent granodiorite which are compared to velocity variations modeled using waveform tomography.

  18. Millennial-scale variations in western Sierra Nevada precipitation during the last glacial cycle MIS 4/3 transition

    NASA Astrophysics Data System (ADS)

    Oster, Jessica L.; Montañez, Isabel P.; Mertz-Kraus, Regina; Sharp, Warren D.; Stock, Greg M.; Spero, Howard J.; Tinsley, John; Zachos, James C.

    2014-07-01

    Dansgaard-Oeschger (D-O) cycles had far-reaching effects on Northern Hemisphere and tropical climate systems during the last glacial period, yet the climatic response to D-O cycles in western North America is controversial, especially prior to 55 ka. We document changes in precipitation along the western slope of the central Sierra Nevada during early Marine Oxygen Isotope Stages (MIS) 3 and 4 (55-67 ka) from a U-series dated speleothem record from McLean's Cave. The timing of our multi-proxy geochemical dataset is coeval with D-O interstadials (15-18) and stadials, including Heinrich Event 6. The McLean's Cave stalagmite indicates warmer and drier conditions during Greenland interstadials (GISs 15-18), signified by elevated δ18O, δ13C, reflectance, and trace element concentrations, and less radiogenic 87Sr/86Sr. Our record extends evidence of a strong linkage between high-latitude warming and reduced precipitation in western North America to early MIS 3 and MIS 4. This record shows that the linkage persists in diverse global climate states, and documents the nature of the climatic response in central California to Heinrich Event 6.

  19. Long-term effects of prescribed fire on mixed conifer forest structure in the Sierra Nevada, California

    USGS Publications Warehouse

    van Mantgem, Phillip J.; Stephenson, Nathan L.; Knapp, Eric; Keeley, Jon E.

    2011-01-01

    The capacity of prescribed fire to restore forest conditions is often judged by changes in forest structure within a few years following burning. However, prescribed fire might have longer-term effects on forest structure, potentially changing treatment assessments. We examined annual changes in forest structure in five 1 ha old-growth plots immediately before prescribed fire and up to eight years after fire at Sequoia National Park, California. Fire-induced declines in stem density (67% average decrease at eight years post-fire) were nonlinear, taking up to eight years to reach a presumed asymptote. Declines in live stem biomass were also nonlinear, but smaller in magnitude (32% average decrease at eight years post-fire) as most large trees survived the fires. The preferential survival of large trees following fire resulted in significant shifts in stem diameter distributions. Mortality rates remained significantly above background rates up to six years after the fires. Prescribed fire did not have a large influence on the representation of dominant species. Fire-caused mortality appeared to be spatially random, and therefore did not generally alter heterogeneous tree spatial patterns. Our results suggest that prescribed fire can bring about substantial changes to forest structure in old-growth mixed conifer forests in the Sierra Nevada, but that long-term observations are needed to fully describe some measures of fire effects.

  20. Aquatic amphibians in the Sierra Nevada: Current status and potential effects of acidic deposition on populations. Final report

    SciTech Connect

    Bradford, D.F.; Gordon, M.S.

    1992-05-01

    Toxicity testing indicated that amphibians are at little risk from low pH in water acidified to a pH of 5.0 and aluminum concentrations from 39 to 80 micrograms/l. However, sublethal effects (reduced growth rate and earlier hatching) were observed for pH as high as 5.25 and the aluminum concentrations tested. The authors tested the hypothesis that acidification of habitats in the field has resulted in elimination of populationss from waters most vulnerable to acidification, i.e., low in pH or ANC, or from waters low in ionic strength a condition that increases the sensitivity of amphibians to low pH. The authors surveyed potential breeding sites for two declining and one non-declining species at high elevation within 30 randomly selected survey areas, and compared chemical parameters between sites containing a species and sites lacking the species. No significant differences were found that were consistent with the hypothesis, and water chemistry did not differ among sites inhabited by the three species. These findings imply that acidic deposition is unlikely to have been a cause of recent amphibian population declines in the Sierra Nevada.

  1. Different fire-climate relationships on forested and non-forested landscapes in the Sierra Nevada ecoregion

    USGS Publications Warehouse

    Keeley, Jon E.; Syphard, Alexandra D.

    2015-01-01

    In the California Sierra Nevada region, increased fire activity over the last 50 years has only occurred in the higher-elevation forests on US Forest Service (USFS) lands, and is not characteristic of the lower-elevation grasslands, woodlands and shrublands on state responsibility lands (Cal Fire). Increased fire activity on USFS lands was correlated with warmer and drier springs. Although this is consistent with recent global warming, we found an equally strong relationship between fire activity and climate in the first half of the 20th century. At lower elevations, warmer and drier conditions were not strongly tied to fire activity over the last 90 years, although prior-year precipitation was significant. It is hypothesised that the fire–climate relationship in forests is determined by climatic effects on spring and summer fuel moisture, with hotter and drier springs leading to a longer fire season and more extensive burning. In contrast, future fire activity in the foothills may be more dependent on rainfall patterns and their effect on the herbaceous fuel load. We predict spring and summer warming will have a significant impact on future fire regimes, primarily in higher-elevation forests. Lower elevation ecosystems are likely to be affected as much by global changes that directly involve land-use patterns as by climate change.

  2. Pesticides in mountain yellow-legged frogs (Rana muscosa) from the Sierra Nevada Mountains of California, USA

    USGS Publications Warehouse

    Fellers, G.M.; McConnell, L.L.; Pratt, D.; Datta, S.

    2004-01-01

    In 1997, pesticide concentrations were measured in mountain yellow-legged frogs (Rana muscosa) from two areas in the Sierra Nevada Mountains of California, USA. One area (Sixty Lakes Basin, Kings Canyon National Park) had large, apparently healthy populations of frogs. A second area (Tablelands, Sequoia National Park) once had large populations, but the species had been extirpated from this area by the early 1980s. The Tablelands is exposed directly to prevailing winds from agricultural regions to the west. When an experimental reintroduction of R. muscosa in 1994 to 1995 was deemed unsuccessful in 1997, the last 20 (reintroduced) frogs that could be found were collected from the Tablelands, and pesticide concentrations in both frog tissue and the water were measured at both the Tablelands and at reference sites at Sixty Lakes. In frog tissues, dichlorodiphenyldichloroethylene (DDE) concentration was one to two orders of magnitude higher than the other organochlorines (46 ?? 20 ng/g wet wt at Tablelands and 17 ?? 8 Sixty Lakes). Both ??-chlordane and trans-nonachlor were found in significantly greater concentrations in Tablelands frog tissues compared with Sixty Lakes. Organophosphate insecticides, chlorpyrifos, and diazinon were observed primarily in surface water with higher concentrations at the Tablelands sites. No contaminants were significantly higher in our Sixty Lakes samples.

  3. Thin pseudotachylytes in faults of the Mt. Abbot quadrangle, Sierra Nevada: Physical constraints for small seismic slip events

    NASA Astrophysics Data System (ADS)

    Griffith, W. Ashley; Di Toro, Giulio; Pennacchioni, Giorgio; Pollard, David D.

    2008-09-01

    We document the occurrence of pseudotachylyte (solidified melt produced during seismic slip) along strike-slip faults in the Lake Edison granodiorite of the Mt. Abbot quadrangle, Sierra Nevada, California and provide constraints on ambient conditions during seismic faulting. The pseudotachylytes are less than 0.3 mm thick and are found in faults typically up to 1 cm in thickness. Total measured left-lateral offset along sampled faults is approximately 20 cm. Field and microstructural evidence indicate that the faults exploited pre-existing mineralized joints and show the following overprinting structures (with inferred ambient temperatures): mylonites are more or less coeval with quartz veins (>400 °C), cataclasites and pseudotachylytes (˜250 °C) more or less coeval with epidote veins, and zeolite veins (<200 °C). Based on observations of the microstructural textures of faults combined with theoretical heat transfer and energy budget calculations, we suggest that only a fraction (<30%) of the total offset was associated with seismic slip (i.e. pseudotachylyte). The presence of pseudotachylyte in sub-millimeter thick zones lends support for the concept of extreme shear localization during seismic slip. The elusive nature of these pseudotachylytes demonstrates that observations in outcrop and optical microscope are not sufficient to rule out frictional melting as a consequence of seismic slip in similar fault rocks.

  4. Episodic dike intrusions in the northwestern Sierra Nevada, California: Implications for multistage evolution of a Jurassic arc terrane

    SciTech Connect

    Dilek, Y.; Moores, E.M. ); Thy, P. )

    1991-02-01

    In the northwestern Sierra Nevada, California, volcanic and plutonic rocks of the Smartville and Slate Creek complexes, both fragments of a Jurassic arc terrane, are tectonically juxtaposed against ophiolitic and marine rocks that represent late Paleozoic-early Mesozoic oceanic basement. This oceanic basement is intruded by Early Jurassic dikes that are coeval with hypabyssal and plutonic rocks within the Smartville and Slate Creek complexes. These dikes have geochemical characteristics reflecting a depleted and metasomatized source, as commonly observed in modern fore-arc settings and incipient volcanic arcs, and are interpreted to be the conduits for the Early Jurassic arc volcanism, which was built on and across the disrupted oceanic basement. Late Jurassic sheeted dikes intruding the Smartville complex have basaltic compositions compatible with an intra-arc or back-arc origin and indicate that a spreading event occurred within the arc in early Late Jurassic time. These interpretations support models for a complex multistage evolution via episodic magmatism and deformation within a singly ensimatic Jurassic arc terrane west of the North American continent.

  5. Elevation and vegetation determine Cryptosporidium oocyst shedding by yellow-bellied marmots (Marmota flaviventris) in the Sierra Nevada Mountains.

    PubMed

    Montecino-Latorre, Diego; Li, Xunde; Xiao, Chengling; Atwill, Edward R

    2015-08-01

    Wildlife are increasingly recognized as important biological reservoirs of zoonotic species of Cryptosporidium that might contaminate water and cause human exposure to this protozoal parasite. The habitat range of the yellow-bellied marmot (Marmota flaviventris) overlaps extensively with the watershed boundaries of municipal water supplies for California communities along the foothills of the Sierra Nevada. We conducted a cross-sectional epidemiological study to estimate the fecal shedding of Cryptosporidium oocysts by yellow-bellied marmots and to quantify the environmental loading rate and determine risk factors for Cryptosporidium fecal shedding in this montane wildlife species. The observed proportion of Cryptosporidium positive fecal samples was 14.7% (33/224, positive number relative to total number samples) and the environmental loading rate was estimated to be 10,693 oocysts animal(-1) day(-1). Fecal shedding was associated with the elevation and vegetation status of their habitat. Based on a portion of the 18s rRNA gene sequence of 2 isolates, the Cryptosporidium found in Marmota flaviventris were 99.88%-100% match to multiple isolates of C. parvum in the GenBank.

  6. Erosion rates as a potential bottom-up control of forest structural characteristics in the Sierra Nevada Mountains.

    PubMed

    Milodowski, David T; Mudd, Simon M; Mitchard, Edward T A

    2015-01-01

    The physical characteristics of landscapes place fundamental constraints on vegetation growth and ecosystem function. In actively eroding landscapes, many of these characteristics are controlled by long-term erosion rates: increased erosion rates generate steeper topography and reduce the depth and extent of weathering, limiting moisture storage capacity and impacting nutrient availability. Despite the potentially important bottom-up control that erosion rates place on substrate characteristics, the relationship between the two is largely unexplored. We investigate spatial variations in aboveground biomass (AGB) across a structurally diverse mixed coniferous/deciduous forest with an order of magnitude erosion-rate gradient in the Northern Californian Sierra Nevada, USA, using high resolution LiDAR data and field plots. Mean basin slope, a proxy for erosion rate, accounts for 32% of variance in AGB within our field area (P < 0.001), considerably outweighing the effects of mean annual precipitation, temperature, and bedrock lithology. This highlights erosion rate as a potentially important, but hitherto unappreciated, control on AGB and forest structure.

  7. Assessing the Value of Improved Hydrologic Forecasting for Hydropower in the Sierra Nevada at Multiple Spatial Scales

    NASA Astrophysics Data System (ADS)

    Rheinheimer, D. E.; Bales, R. C.; Lund, J. R.; Viers, J. H.

    2014-12-01

    Increased accuracy of snowpack measurements can potentially greatly improve planning for rest-of-year water allocations, particularly when coupled with improvements in hydrologic modeling skill. In California, the degree to which investments in improved hydrologic information systems, such as wireless sensor networks, is worth the cost remains poorly quantified. We conducted a numerical study to assess the value of improvements in snowpack measurements and hydrologic prediction for a single representative hydropower system in the Sierra Nevada considering different measurement and prediction accuracy levels and prediction intervals. Additionally, we examined the value of these improvements for a range of different infrastructure, operational, and hydrologic characteristics, such as reservoir capacity, hydropower capacity, electricity demand, instream flow requirements, and hydrologic regime. Operations were represented with a linear programming model using hydrologic information inaccuracy mimicked by perturbing assumed known hydrologic conditions. Results demonstrate that under current system physical and operational characteristics, improved snowpack estimation and hydrologic prediction generally improve optimal hydropower management compared to current estimation capabilities, particularly in drier years. However, improvements vary by infrastructure characteristics, as well as by management and hydrologic assumptions, such as energy demand and hydrologic stationarity. This approach and the specific results presented will help resource managers understand where investments in hydrologic sensor network and prediction systems will be most beneficial.

  8. Description and DNA barcoding of a new Iberian species of Pijnackeria (Scali, 2009) from Sierra Nevada, Spain (Phasmida: Diapheromeridae).

    PubMed

    Valero, Pablo; Ortiz, Antonio S

    2015-12-18

    Male, female and egg of Pijnackeria recondita sp. n. are described from specimens collected at about 2,000 m in Sierra Nevada (Spain) feeding on Cytisus scoparius. The number of antennae segments in males, the smooth thorax in females and the different sculpturing of the egg capsule are the main differences from the other species of the genus. In addition, DNA barcode sequences (COI and COII) clearly differ from the other Iberian species of the genus. For COI, K2P minim-um distance between the new species and the most morphological related species, Pijnackeria hispanica (Bolívar, 1878), showed a mean of 8%. In the case of COII, comparison with the other species of Pijnackeria, showed a K2P minimum distance range from 8 to 10.5% (mean 9.2%); and comparison with the species of the related genus Leptynia, showed a K2P minimum distance range from 7.1 to 10.5%.

  9. Evidence for Moho-lower crustal transition depth diking and rifting of the Sierra Nevada microplate

    NASA Astrophysics Data System (ADS)

    Smith, Kenneth D.; Kent, Graham M.; Seggern, David P.; Driscoll, Neal W.; Eisses, Amy

    2016-10-01

    Lithospheric rifting most often initiates in continental extensional settings where "breaking of a plate" may or may not progress to sea floor spreading. Generally, the strength of the lithosphere is greater than the tectonic forces required for rupture (i.e., the "tectonic force paradox"), and it has been proposed that rifting requires basaltic magmatism (e.g., dike emplacement) to reduce the strength and cause failure, except for the case of a thin lithosphere (<30 km thick). Here we isolate two very similar and unprecedented observations of Moho-lower crustal transition dike or fluid injection earthquake swarms under southern Sierra Valley (SV: 2011-2012) and North Lake Tahoe (LT: 2003-2004), California. These planar distributions of seismicity can be interpreted to define the end points, and cover 25% of the length, of an implied 56 km long structure, each striking N45°W and dipping 50°NE. A single event at 30 km depth that locates on the implied dipping feature between the two swarms is further evidence for a single Moho-transition depth structure. We propose that basaltic or fluid emplacement at or near Moho depths weakens the upper mantle lid, facilitating lithospheric rupture of the Sierra Microplate. Similar to the LT sequence, the SV event is also associated with increased upper crustal seismicity. An 27 October 2011, Mw 4.7 earthquake occurred directly above the deep SV sequence at the base of the upper crustal seismogenic zone ( 15 km depth).

  10. Geochronological constraints (40Ar/39Ar and U/Pb) on the thermal history of the Tolumne Intrusive Suite (Sierra Nevada, California)

    NASA Astrophysics Data System (ADS)

    Mundil, R.; Nomade, S.; Paterson, S. R.; Renne, P. R.

    2004-12-01

    The Tuolumne Intrusive Suite (TIS) in the Eastern Sierra Nevada is considered a type example of a batholith and represents a spectacularly exposed, protracted record of internal differentiation and plutonic assembly in a large, open-system, continental arc magma chamber. One of the recent advances in our understanding of magmatic systems is the recognition that a substantial number are constructed episodically over timescales of up to millions of years for larger plutons. The main objective of this study is to investigate the episodic growth and evolution of magmatic systems by integrating thermal, geochronologic, geochemical, and crystal size distribution (CSD) studies with ongoing field studies of the TIS. Here we present high-resolution U/Pb and 40Ar/39Ar geochronology from the TIS (which was assembled between 93 and 85 Ma, Coleman et al., 2004) and adjacent older units in order to unravel the time scales of its assemblage and thermal history. 25 Samples were collected along a SW-NE corridor (ca 30 km) across the TIS, including older plutons to the SW (El Capitan) and the NE (Soldier Lake (SDL) and Green Lake plutons (GRL)). So far, conventional U/Pb single-zircon analyses yield weighted mean 206Pb/238U ages of 165.0 ± 0.3 Ma for the GRL and a preliminary age of ca. 95 Ma for the SDL, which are interpreted as emplacement ages (all uncertainties are given at the 2σ level). 40Ar/39Ar analyses were performed on two different biotite and hornblende grain size fractions (800-900μ m and 150-180μ m) from each sample. As expected, isotherms in the eastern pendant of the Sierra Nevada move towards the TIS as a result of its cooling between 85 to 80 Ma. The gradient of temperature at the time of the emplacement of the Cathedral Peak (CP) Pluton (U/Pb zircon age of ca 88 Ma, Coleman, 2004) was about 150° C to 200° C per 5 km. The western margin of the GRL (at 5 km distance from the TIS) is thermally affected by the TIS as indicated by biotite ages that are reset (ca

  11. Calculation of the Rate of M>6.5 Earthquakes for California and Adjacent Portions of Nevada and Mexico

    USGS Publications Warehouse

    Frankel, Arthur; Mueller, Charles

    2008-01-01

    One of the key issues in the development of an earthquake recurrence model for California and adjacent portions of Nevada and Mexico is the comparison of the predicted rates of earthquakes with the observed rates. Therefore, it is important to make an accurate determination of the observed rate of M>6.5 earthquakes in California and the adjacent region. We have developed a procedure to calculate observed earthquake rates from an earthquake catalog, accounting for magnitude uncertainty and magnitude rounding. We present a Bayesian method that corrects for the effect of the magnitude uncertainty in calculating the observed rates. Our recommended determination of the observed rate of M>6.5 in this region is 0.246 ? 0.085 (for two sigma) per year, although this rate is likely to be underestimated because of catalog incompleteness and this uncertainty estimate does not include all sources of uncertainty.

  12. Using ecological forecasting of future vegetation transition and fire frequency change in the Sierra Nevada to assess fire management strategies

    NASA Astrophysics Data System (ADS)

    Thorne, J. H.; Schwartz, M. W.; Holguin, A. J.; Moritz, M.; Batllori, E.; Folger, K.; Nydick, K.

    2013-12-01

    Ecological systems may respond in complex manners as climate change progresses. Among the responses, site-level climate conditions may cause a shift in vegetation due to the physiological tolerances of plant species, and the fire return interval may change. Natural resource managers challenged with maintaining ecosystem health need a way to forecast how these processes may affect every location, in order to determine appropriate management actions and prioritize locations for interventions. We integrated climate change-driven vegetation type transitions with projected change in fire frequency for 45,203 km2 of the southern Sierra Nevada, California, containing over 10 land management agencies as well as private lands. This Magnitude of Change (MOC) approach involves classing vegetation types in current time according to their climate envelopes, and identifying which sites will in the future have climates beyond what that vegetation currently occurs in. Independently, fire models are used to determine the change in fire frequency for each site. We examined 82 vegetation types with >50 grid cell occurrences. We found iconic resources such as the giant sequoia, lower slope oak woodlands, and high elevation conifer forests are projected as highly vulnerable by models that project a warmer drier future, but not as much by models that project a warmer future that is not drier than current conditions. Further, there were strongly divergent vulnerabilities of these forest types across land ownership (National Parks versus US Forest Service lands), and by GCM. For example, of 50 giant sequoia (Sequoiadendron giganteum) groves and complexes, all but 3 (on Sierra National Forest) were in the 2 highest levels of risk of climate and fire under the GFDL A2 projection, while 15 groves with low-to-moderate risk were found on both the National Parks and National Forests 18 in the 2 under PCM A2. Landscape projections of potential MOC suggest that the region is likely to experience

  13. Relationship between the trajectory of mid-latitude cyclones in the eastern Pacific Ocean and the isotopic composition of snowfall in the Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Vasquez, K. T.; Sickman, J. O.; Heard, A.; Lucero, D.

    2013-12-01

    Diatoms, preserved in lake sediments, provide a potential archive of snowfall variability in the Sierra Nevada through their sensitivity to changes in water chemistry (a proxy for runoff volume) and by recording the isotopic composition of snow-melt (potentially a proxy for sources of atmospheric moisture). In the Sierra Nevada, we hypothesize that the oxygen isotopic composition of diatom silica is principally controlled by snow and that the isotopic composition of snow varies as a function of the tracks of mid-latitude cyclonic storms in the eastern Pacific Ocean. Snow samples from discrete storms were collected from December 2012 to March 2013 at 2042 meters a.s.l. in Sequoia National Park. The δ18O and δ2H values of the snow samples were measured using a temperature-conversion elemental analyzer coupled to a Delta V isotope ratio mass spectrometer. The isotopic measurements were then coupled to 3, 5 and 7-day air mass back trajectories using the NOAA HYSPLIT model. The measured δ18O values ranged from -17.6 to -7.8 per mil and the δ2H ranged from -119.8 to -73.3 per mil. Both δ18O and δ2H were inversely related to the latitude of the storm origin (R^2 values of 0.67 and 0.57, respectively). Winter storms from the Gulf of Alaska were the most isotopically depleted while storms originating in the subtropical/tropical Pacific were the most isotopically enriched, reflecting the overall latitudinal pattern of ocean-water isotope composition in the Pacific Ocean. Our results suggest that the isotopic composition of Sierra Nevada snowfall is influenced by storm track trajectory and this relationship could be useful in interpreting the climatic significance of δ18O of diatom silica preserved in lake cores.

  14. Relationship between the trajectory of mid-latitude cyclones in the eastern Pacific Ocean and the isotopic composition of snowfall in the Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Vasquez, K. T.; Sickman, J. O.; Lucero, D. M.; Heard, A. M.

    2014-12-01

    Climate change has caused a change in the Sierra Nevada snowpack and the timing of its snowmelt, threatening a valuable water resource that provides for 25 million people and 5 million hectares of irrigated land. Understanding past and future variations in the snowpack is crucial in order to plan future water management. Of particular importance would be an archive of the variability of past snowfall, which can be recorded through the isotopic records found in local paleoproxies (e.g., diatoms). We propose to quantify the relationship between sources of atmospheric moisture in the Sierra Nevada and the isotopic composition of its snowpack to uncover whether isotopic variations recorded in paloearchives are a result of the isotopic composition of the precipitation, thereby showing whether these archives could serve as a reliable source of atmospheric moisture. Preliminary analysis conducted from December 2012 to March 2013 at Sequoia National Park resulted in statistically significant correlations between the isotopic composition of the winter snowfall and storm track trajectories. It was observed that storms originating from more northern latitudes had predominantly lighter isotopes (more negative δ 2H and δ18O) and sub-tropical/tropical Pacific storms showed more positive δ 2H and δ18O. This pattern reflects the isotopic gradient of the Pacific Ocean and can prove useful when interpreting the climatic significance of the δ2H and δ18O values in analyzed proxies. While our initial investigation was promising, the winter of 2012 -2013 was abnormally dry compared to long-term averages. Before directing our investigation to known paleoproxies, we aim to determine if the correlation between storm tracks and isotopic composition of precipitation holds in years with average and above average precipitation through analysis of archived samples from calendar years 2007 - 2011 from Giant Forest in Sequoia National Park (southern sierra) and Manzanita Lake in Lassen

  15. The genus Milnesium (Eutardigrada: Milnesiidae) in the Sierra Nevada de Santa Marta (Colombia), with the description of Milnesium kogui sp. nov.

    PubMed

    Londoño, Rosana; Daza, Anisbeth; Caicedo, Martín; Quiroga, Sigmer; Kaczmarek, Łukasz

    2015-05-06

    A new species, Milnesium kogui sp. nov. is described from the Sierra Nevada de Santa Marta, Colombia. The new species belongs to the tardigradum group and is most similar, by the claw configuration [2-2]-[2-2], to Milnesium dujiangensis and Milnesium katarzynae. Milnesium kogui sp. nov. differs from M. dujiangensis mainly by the presence of primary branches on all legs and from M. katarzynae by the absence of dorsal sculpture. Additionally, in this paper we present a list of all Milnesium species recorded in Colombia including Milnesium cf. barbadosense Meyer & Hinton, 2012 and M. brachyungue Binda & Pilato, 1990, new additions to the recorded fauna of Colombia.

  16. Pseudotachylyte in the Bench Canyon Shear Zone, central Sierra Nevada, California: Frictional melting in the brittle and semi-brittle fields

    SciTech Connect

    McNulty, B.A. )

    1993-04-01

    Many aspects of pseudotachylyte are controversial, particularly whether it is the product of intense comminution (e.g. ultracataclasite'') or frictional melting. Ubiquitous exposures of pseudotachylyte in the Bench Canyon shear Zone (BCSZ), central Sierra Nevada, California, provide an excellent opportunity for further study. Scanning electron microscopy (SEM) reveals vesicles, amygdules, crystallites and embayments of microxenocrysts, textures which are supportive of a melt origin for pseudotachylyte in the BCAZ. EDS and microprobe analyses indicate strong compositional contrasts between pseudotachylyte and granodiorite host; one explanation for this is preferential melting in order of individual mineral melting points.

  17. Influence of spatial location on the timing of the snow accumulation and melt in the Sierra Nevada: An analysis with FANOVA.

    NASA Astrophysics Data System (ADS)

    Montoya, E.; Meiring, W.; Dozier, J.

    2015-12-01

    In California, snow represents one of the primary water resources. California precipitation occurs predominately in the winter and spring months, whereas the summer and fall generally are dry. Variation in the timing of snowpack accumulation and melt in the Sierra Nevada can be quantified through statistical curve registration summaries of seasonal cycle variation in daily snow pillow records. This procedure provides a set of functional sample observations that may be used to study the characteristics that influence the timing of snowpack events. Using functional analysis of variance, we investigate differences in the timing of snowpack accumulation and melt associated with spatial location attributes.

  18. Evolution of the persistence of snow over Sierra Nevada Mountain (southern, Spain) in the last 55 years

    NASA Astrophysics Data System (ADS)

    Pimentel, Rafael; José Pérez-Palazón, María; Herrero, Javier; José Polo, María

    2016-04-01

    Snow plays a crucial role in mountainous areas, not only as water resources for human supply, irrigation and energy production, but also for the ecosystem, flora and fauna, over these areas. Sierra Nevada Mountains, southern Spain, constitutes a rich reservoir of endemic wildlife species, and it is considered the most important center of biodiversity in the wester Mediterranean region. The highest regions of the range were declared UNESCO Biosphere Reserve, Natural and National Parks. Climate trends over the last decades put a lot of pressure on both snowfall occurrence and snow persistence; this poses a risk for biodiversity and has led to its inclusion in the Global Change Observatory Network. This work quantifies the evolution of the persistence of snow over the Sierra Nevada area during the last fifty-five years (1960-2015) as a basis to assess the vulnerability of its ecosystem services. For this, the spatial distribution of the annual number of days with snow, SDS, was analyzed over a study area of 4583 km2 (140-3479 m.a.s.l.), which comprises the head of the five basins in these mountains. The following indicator variables were studied over the whole area and each one of the five head regions identified: 1) the trend of SDS; 2) the annual area where SDS exceeded selected percentiles in its distribution; and 3) the annual minimum altitude where SDS exceeded those percentiles. SDS was obtained during the study period by means of the snow module in WiMMed (Watershed Integrated Model in Mediterranean Environment), a physically-based hydrological model developed, calibrated and validated in the area; the model is based on an energy-mass balance over the snowpack that is spatially distributed through the use of depletion curves, and is operational at hourly and daily scales. A general decreasing trend of SDS (0.25 days year-1) was found over the whole study area for the study period. This value is higher in the more humid basins (0.45 and 0.41 days year-1) than in

  19. Impact of Summer Cattle Grazing on the Sierra Nevada Watershed: Aquatic Algae and Bacteria

    PubMed Central

    Derlet, Robert W.; Richards, John R.; Tanaka, Lidia L.; Hayden, Curtis; Ger, K. Ali; Goldman, Charles R.

    2012-01-01

    Introduction. We evaluated periphytic algal and microbial communities to assess the influence of human and cattle impact on Sierra water quality. Methods. 64 sites (lakes and streams from Lake Tahoe to Sequoia National Park, California) were sampled for suspended indicator bacteria and algae following standardized procedures. The potential for nonpoint pollution was divided into three categories: cattle-grazing areas (C), recreation use areas (R), or remote wildlife areas (W). Results. Periphyton was found at 100% of C sites, 89% of R sites, but only 25% of W sites. Eleven species of periphytic algae were identified, including Zygnema, Ulothrix, Chlorella, Spirogyra, mixed Diatoms, and Cladophoria. Mean benthic algae coverage was 66% at C sites compared to 2% at W sites (P < 0.05). The prevalence of E. coli associated with periphyton was 100% at C sites, 25% of R sites, and 0% of W sites. Mean E. coli CFU/gm of algae detected was: C = 173,000, R = 700, W = 0. (P < 0.05). Analysis of neighboring water for E. coli bacteria >100 CFU/100 mL: C = 91%, R = 8%, W = 0 (P < 0.05). Conclusion. Higher periphytic algal biomass and uniform presence of periphyton-attached E. coli corresponded to watersheds exposed to summer cattle grazing. These differences suggest cattle grazing compromises water quality. PMID:22505950

  20. Distribution of aquatic animals relative to naturally acidic waters in the Sierra Nevada. Final report

    SciTech Connect

    Bradford, D.F.; Cooper, S.D.; Brown, A.D.; Mahood, G.

    1994-01-01

    Lakes in the Bench Lake/Mount Pinchot area of Kings Canyon National Park were surveyed in summer 1992 and found to range in pH from 5.0 to 9.3. Ten lakes were acidic (pH < 6.0). Thirty three lakes were chosen for detailed analyses of their chemical and biological characteristics, including eight acidic lakes. Unlike typical Ca-Na-HCO3-dominated Sierra lakes, SO4 concentrations are high enough to classify 19 of these lakes with SO4 as the dominant anion. The source of acidity and SO4 is sulfuric acid produced by the oxidation of pyrite found in metamorphic and granitic rocks in the area. Faunal surveys revealed that yellow-legged frog tadpoles (Rana muscosa), limnephilid caddis larvae (Hesperophylax), and large microcrustaceans (Daphnia, Diaptomus) were rare or absent in acidic lakes and common in lakes with a pH > 6.0. Four species of trout were collected, and their presence appeared to be related to historical stocking patterns. Trout appeared to have large effects on the distributions and abundances of larval amphibians and large, mobile invertebrate taxa that were rare or absent in trout lakes, but common in lakes lacking trout.

  1. A global model simulation for 3-D radiative transfer impact on surface hydrology over the Sierra Nevada and Rocky Mountains

    DOE PAGES

    Lee, W.-L.; Gu, Y.; Liou, K. N.; ...

    2015-05-19

    We investigate 3-D mountain effects on solar flux distributions and their impact on surface hydrology over the western United States, specifically the Rocky Mountains and the Sierra Nevada, using the global CCSM4 (Community Climate System Model version 4; Community Atmosphere Model/Community Land Model – CAM4/CLM4) with a 0.23° × 0.31° resolution for simulations over 6 years. In a 3-D radiative transfer parameterization, we have updated surface topography data from a resolution of 1 km to 90 m to improve parameterization accuracy. In addition, we have also modified the upward-flux deviation (3-D–PP (plane-parallel)) adjustment to ensure that the energy balance atmore » the surface is conserved in global climate simulations based on 3-D radiation parameterization. We show that deviations in the net surface fluxes are not only affected by 3-D mountains but also influenced by feedbacks of cloud and snow in association with the long-term simulations. Deviations in sensible heat and surface temperature generally follow the patterns of net surface solar flux. The monthly snow water equivalent (SWE) deviations show an increase in lower elevations due to reduced snowmelt, leading to a reduction in cumulative runoff. Over higher-elevation areas, negative SWE deviations are found because of increased solar radiation available at the surface. Simulated precipitation increases for lower elevations, while it decreases for higher elevations, with a minimum in April. Liquid runoff significantly decreases at higher elevations after April due to reduced SWE and precipitation.« less

  2. High temperature fracturing and ductile deformation during cooling of a pluton: The Lake Edison granodiorite (Sierra Nevada batholith, California)

    NASA Astrophysics Data System (ADS)

    Pennacchioni, Giorgio; Zucchi, Eleonora

    2013-05-01

    In the Bear Creek area of the Sierra Nevada batholith, California, the high temperature postmagmatic deformation structures of the Lake Edison granodiorite include steeply-dipping orthogneiss foliations, joints, and ductile shear zones that nucleated on joints and leucocratic dykes. Exploitation of segmented joints resulted in sharply bounded, thin shear zones and in large slip gradients near the shear zone tips causing the deformation of the host rock at contractional domains. The orthogneiss foliation intensifies towards the contact with the younger Mono Creek granite and locally defines the dextral Rosy Finch Shear Zone (RFSZ), a major kilometre-wide zone crosscutting the pluton contacts. Joints predominantly strike at N70-90°E over most of the Lake Edison pluton and are exploited as sinistral shear zones, both within and outside the RFSZ. In a narrow (˜250 m thick) zone at the contact with the younger Mono Creek granite, within the RFSZ, the Lake Edison granodiorite includes different sets of dextral and sinistral shear zones/joints (the latter corresponding to the set that dominates over the rest of the Lake Edison pluton). These shear zones/joints potentially fit with a composite Y-R-R' shear fracture pattern associated with the RFSZ, or with a pattern consisting of Y-R-shear fractures and rotated T' mode I extensional fractures. The mineral assemblage of shear zones, and the microstructure and texture of quartz mylonites indicate that ductile deformation occurred above 500 °C. Joints and ductile shearing alternated and developed coevally. The existing kinematic models do not fully capture the structural complexity of the area or the spatial distribution of the deformation and magmatic structures. Future models should account more completely for the character of ductile and brittle deformation as these plutons were emplaced and cooled.

  3. A global model simulation for 3-D radiative transfer impact on surface hydrology over the Sierra Nevada and Rocky Mountains

    SciTech Connect

    Lee, W. -L.; Gu, Y.; Liou, K. N.; Leung, L. R.; Hsu, H. -H.

    2015-05-19

    We investigate 3-D mountain effects on solar flux distributions and their impact on surface hydrology over the western United States, specifically the Rocky Mountains and the Sierra Nevada, using the global CCSM4 (Community Climate System Model version 4; Community Atmosphere Model/Community Land Model – CAM4/CLM4) with a 0.23° × 0.31° resolution for simulations over 6 years. In a 3-D radiative transfer parameterization, we have updated surface topography data from a resolution of 1 km to 90 m to improve parameterization accuracy. In addition, we have also modified the upward-flux deviation (3-D–PP (plane-parallel)) adjustment to ensure that the energy balance at the surface is conserved in global climate simulations based on 3-D radiation parameterization. We show that deviations in the net surface fluxes are not only affected by 3-D mountains but also influenced by feedbacks of cloud and snow in association with the long-term simulations. Deviations in sensible heat and surface temperature generally follow the patterns of net surface solar flux. The monthly snow water equivalent (SWE) deviations show an increase in lower elevations due to reduced snowmelt, leading to a reduction in cumulative runoff. Over higher-elevation areas, negative SWE deviations are found because of increased solar radiation available at the surface. Simulated precipitation increases for lower elevations, while it decreases for higher elevations, with a minimum in April. Liquid runoff significantly decreases at higher elevations after April due to reduced SWE and precipitation.

  4. Interannual variability of snowmelt in the Sierra Nevada and Rocky Mountains, United States: examples from two alpine watersheds

    USGS Publications Warehouse

    Jepsen, Steven M.; Molotch, Noah P.; Williams, Mark W.; Rittger, Karl E.; Sickman, James O.

    2012-01-01

    The distribution of snow and the energy flux components of snowmelt are intrinsic characteristics of the alpine water cycle controlling the location of source waters and the effect of climate on streamflow. Interannual variability of these characteristics is relevant to the effect of climate change on alpine hydrology. Our objective is to characterize the interannual variability in the spatial distribution of snow and energy fluxes of snowmelt in watersheds of a maritime setting, Tokopah Basin (TOK) in California's southern Sierra Nevada, and a continental setting, Green Lake 4 Valley (GLV4) in Colorado's Front Range, using a 12 year database (1996–2007) of hydrometeorological observations and satellite-derived snow cover. Snowpacks observed in GLV4 exhibit substantially greater spatial variability than in TOK (0.75 versus 0.28 spatial coefficient of variation). In addition, modeling results indicate that the net turbulent energy flux contribution to snowmelt in GLV4 is, on average, 3 times greater in magnitude (mean 29% versus 10%) and interannual variability (standard deviation 17% versus 6%) than in TOK. These energy flux values exhibit strong seasonality, increasing as the melt season progresses to times later in the year (R2 = 0.54–0.77). This seasonality of energy flux appears to be associated with snowmelt rates that generally increase with onset date of melt (0.02 cm d-2). This seasonality in snowmelt rate, coupled to differences in hydrogeology, may account for the observed differences in correspondence between the timing of snowmelt and timing of streamflow in these watersheds.

  5. Does prescribed fire promote resistance to drought in low elevation forests of the Sierra Nevada, California, USA?

    USGS Publications Warehouse

    van Mantgem, Phillip J.; Caprio, Anthony C.; Stephenson, Nathan L.; Das, Adrian J.

    2016-01-01

    Prescribed fire is a primary tool used to restore western forests following more than a century of fire exclusion, reducing fire hazard by removing dead and live fuels (small trees and shrubs).  It is commonly assumed that the reduced forest density following prescribed fire also reduces competition for resources among the remaining trees, so that the remaining trees are more resistant (more likely to survive) in the face of additional stressors, such as drought.  Yet this proposition remains largely untested, so that managers do not have the basic information to evaluate whether prescribed fire may help forests adapt to a future of more frequent and severe drought.During the third year of drought, in 2014, we surveyed 9950 trees in 38 burned and 18 unburned mixed conifer forest plots at low elevation (<2100 m a.s.l.) in Kings Canyon, Sequoia, and Yosemite national parks in California, USA.  Fire had occurred in the burned plots from 6 yr to 28 yr before our survey.  After accounting for differences in individual tree diameter, common conifer species found in the burned plots had significantly reduced probability of mortality compared to unburned plots during the drought.  Stand density (stems ha-1) was significantly lower in burned versus unburned sites, supporting the idea that reduced competition may be responsible for the differential drought mortality response.  At the time of writing, we are not sure if burned stands will maintain lower tree mortality probabilities in the face of the continued, severe drought of 2015.  Future work should aim to better identify drought response mechanisms and how these may vary across other forest types and regions, particularly in other areas experiencing severe drought in the Sierra Nevada and on the Colorado Plateau.

  6. New control system for the 1.5m and 0.9m telescopes at Sierra Nevada Observatory

    NASA Astrophysics Data System (ADS)

    Costillo, Luis P.; Ramos, J. Luis; Ibáñez, J. Miguel; Aparicio, Beatriz; Herránz, Miguel; García, Antonio J.

    2006-06-01

    The Sierra Nevada Observatory (Granada, Spain) has a number of telescopes. Our study will focus on two Nasmyth telescopes with apertures of 1.5m and 0.9m and an equatorial mount. The system currently installed to control these telescopes is a 1995 centralized VME module. However, given the problems which have arisen due to the number of wires and other complications, we have decided to change this control module. We will control each telescope with a distributed control philosophy, using a serial linear communication bus between independent nodes, although all system capabilities are accessible from a central unit anywhere and at any time via internet. We have divided the tasks and have one node for alpha control, another for delta control, one for the dome, one for the focus and the central unit to interface with a pc. The nodes for alpha, delta and the dome will be used by means of FPGA's in order to efficiently sample the encoders and the control algorithms, and to generate the output for the motors and the servo. The focus will have a microcontroller, and the system is easy to expand in the event of the inclusion of more nodes. After having studied several fieldbus systems, we have opted for the CAN bus, because of its reliability and broadcasting possibilities. In this way, all the important information will be on the bus, and every node will be able to access the information at any time. This document explains the new design made in the IAA for the new consoles of control whose basic characteristics are, the distributed control, the hardware simplify, the cable remove, the safety and maintenance improve and facilitating the observation improving the interface with the user, and finally to prepare the system for the remote observation.

  7. The role of snow cover in ground thermal conditions in three sites with contrasted topography in Sierra Nevada (Spain)

    NASA Astrophysics Data System (ADS)

    Oliva, Marc; Salvador, Ferran; Gómez Ortiz, Antonio; Salvà, Montserrat

    2014-05-01

    Snow cover has a high capacity to insulate the soil from the external thermal influences. In regions of high snowfall, such as the summit areas of the highest Iberian mountain ranges, the presence of a thick snow cover may condition the existence or inexistence of permafrost conditions. In order to analyze the impact of the thickness, duration and interannual variability of snow cover on the ground thermal regime in the massif of Sierra Nevada, we have analyzed soil temperatures at a depth of 2 cm for the period 2006-2012 in three sites of contrasting topography as well as air temperatures for the same period: (a) Corral del Veleta (3100 m) in a rock glacier located in the northern Veleta cirque, with high and persistent snow cover. (b) Collado de los Machos (3300 m), in a summit area with relict stone circles, with little snow accumulation due to wind effect. (c) Río Seco (3000 m), in a solifluction lobe located in this southern glacial cirque with moderate snowfall. Considering the air and 2 cm depth soil temperature records, the freezing degree-days were calculated for each year from November to May in order to characterize the role of snow as a thermal insulator of the ground during the cold season (Frauenfeld et al., 2007). In all cases, the highest values of freezing degree-days correspond to years with little snowfall (2006-2007, 2007-2008, 2011-2012), while in years with a thicker snow cover (2008-2009, 2009-2010, 2010-2011) the total freezing degree-days were significantly lower. The accumulation of freezing degree-days is maximum at the wind-exposed site of Collado de los Machos, where the wind redistributes snow and favours the penetration of cold into the ground. The opposite pattern occurs in the Veleta cirque, where most persistent snow cover conditions determine lower accumulated freezing degree-days than in Collado de los Machos and Rio Seco.

  8. Long-term monitoring of 10 selected pathogens in wild boar (Sus scrofa) in Sierra Nevada National Park, southern Spain.

    PubMed

    Cano-Manuel, Francisco J; López-Olvera, Jorge; Fandos, Paulino; Soriguer, Ramón C; Pérez, Jesús M; Granados, José E

    2014-11-07

    Wild boar (Sus scrofa) populations are increasing in the Iberian Peninsula, and population management must include disease management and control. In this study, the epidemiology of 10 selected pathogens (Aujeszky's disease virus - ADV, porcine reproductive and respiratory syndrome virus - PRRSV, porcine influenza virus, porcine circovirus, porcine parvovirus, Erysipelotrix rhusiopathiae, Leptospira pomona, Chlamydia/Chlamydiaceae sp., Salmonella sp. and Mycobacterium bovis) in the wild boar population in Sierra Nevada National Park (SNNP), an open unfenced area, is reported, taking into account wild boar population abundance variation in space and time in an open unfenced environment. A total of 1103 wild boar were sampled in 141 hunting events randomly carried out for sampling in seven hunting seasons (October to February from 2002-2003 to 2009-2010 (except 2007-2008). Prevalence was overall lower than those previously reported for fenced wild boar populations in Spain, but all the pathogens analyzed except PRRSV were considered endemic in the SNNP. ADV, E. rhusiopathiae and total pathogen prevalence were positively correlated to wild boar density. Prevalence in the positive areas was significantly higher in females for ADV, E. rhusiopathiae, L. pomona, Chlamydia/Chlamydiaceae sp. and Salmonella sp., and in males for M. bovis. This longitudinal study provides the first data on the health status of the relatively unmanaged and low density wild boar population of SNNP. It is concluded that non-intensively managed wild boar populations are able to maintain the circulation of several pathogens, even in low prevalences and in open unfenced areas with natural density variation both in time and space.

  9. Impact of interannual variations in sources of insoluble aerosol species on orographic precipitation over California's central Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Creamean, J. M.; Ault, A. P.; White, A. B.; Neiman, P. J.; Ralph, F. M.; Minnis, P.; Prather, K. A.

    2015-06-01

    Aerosols that serve as cloud condensation nuclei (CCN) and ice nuclei (IN) have the potential to profoundly influence precipitation processes. Furthermore, changes in orographic precipitation have broad implications for reservoir storage and flood risks. As part of the CalWater field campaign (2009-2011), the variability and associated impacts of different aerosol sources on precipitation were investigated in the California Sierra Nevada using an aerosol time-of-flight mass spectrometer for precipitation chemistry, S-band profiling radar for precipitation classification, remote sensing measurements of cloud properties, and surface meteorological measurements. The composition of insoluble residues in precipitation samples collected at a surface site contained mostly local biomass burning and long-range-transported dust and biological particles (2009), local sources of biomass burning and pollution (2010), and long-range transport (2011). Although differences in the sources of insoluble residues were observed from year to year, the most consistent source of dust and biological residues were associated with storms consisting of deep convective cloud systems with significant quantities of precipitation initiated in the ice phase. Further, biological residues were dominant (up to 40%) during storms with relatively warm cloud temperatures (up to -15 °C), supporting the important role bioparticles can play as ice nucleating particles. On the other hand, lower percentages of residues from local biomass burning and pollution were observed over the three winter seasons (on average 31 and 9%, respectively). When precipitation quantities were relatively low, these insoluble residues most likely served as CCN, forming smaller more numerous cloud droplets at the base of shallow cloud systems, and resulting in less efficient riming processes. Ultimately, the goal is to use such observations to improve the mechanistic linkages between aerosol sources and precipitation processes

  10. Overview of mine drainage geochemistry at historical mines, Humboldt River basin and adjacent mining areas, Nevada. Chapter E.

    USGS Publications Warehouse

    Nash, J. Thomas; Stillings, Lisa L.

    2004-01-01

    Reconnaissance hydrogeochemical studies of the Humboldt River basin and adjacent areas of northern Nevada have identified local sources of acidic waters generated by historical mine workings and mine waste. The mine-related acidic waters are rare and generally flow less than a kilometer before being neutralized by natural processes. Where waters have a pH of less than about 3, particularly in the presence of sulfide minerals, the waters take on high to extremely high concentrations of many potentially toxic metals. The processes that create these acidic, metal-rich waters in Nevada are the same as for other parts of the world, but the scale of transport and the fate of metals are much more localized because of the ubiquitous presence of caliche soils. Acid mine drainage is rare in historical mining districts of northern Nevada, and the volume of drainage rarely exceeds about 20 gpm. My findings are in close agreement with those of Price and others (1995) who estimated that less than 0.05 percent of inactive and abandoned mines in Nevada are likely to be a concern for acid mine drainage. Most historical mining districts have no draining mines. Only in two districts (Hilltop and National) does water affected by mining flow into streams of significant size and length (more than 8 km). Water quality in even the worst cases is naturally attenuated to meet water-quality standards within about 1 km of the source. Only a few historical mines release acidic water with elevated metal concentrations to small streams that reach the Humboldt River, and these contaminants and are not detectable in the Humboldt. These reconnaissance studies offer encouraging evidence that abandoned mines in Nevada create only minimal and local water-quality problems. Natural attenuation processes are sufficient to compensate for these relatively small sources of contamination. These results may provide useful analogs for future mining in the Humboldt River basin, but attention must be given to

  11. Geochemical tectonomagnetic discrimination of metamorphosed Middle Jurassic volcanic rocks, northern Sierra Nevada, California

    SciTech Connect

    Templeton, J.H. . Dept. of Geosciences); Hanson, R.E. . Dept. of Geology); Harwood, D.S. )

    1993-04-01

    Jurassic island-arc rocks in the Northern Sierra terrane (NSt) are represented by the Lower to Middle Jurassic Sailor Canyon Formation, consisting mainly of distal andesitic turgidities, and the overlying, Middle Jurassic Tuttle Lake Formation (TLF); both units were metamorphosed to lower greenschist facies during Mesozoic orogenesis. The TLF is a 1.6-km-thick sequence of submarine tuff-breccia debris-flow deposits intercalated with minor isolated-pillow breccias and intruded by numerous cogenetic hypabyssal intrusions that underwent extensive interaction with wet sediments in near-vent setting. Here the authors report the first geochemical studies of these regionally significant arc rocks. Pillow breccias, hypabyssal intrusions, and clasts within debris-flow deposits are predominantly basalt to basaltic andesite in composition and contain abundant plagioclase and clinopyroxene phenocrysts. Although cpx is intensely altered to actinolite, microprobe analyses were carried out on relict cpx cores. Compositions are typical of cpx from orogenic lavas and fall in combined calc-alkaline and tholeiitic fields on cpx discrimination diagrams. Most major elements show significant scatter on Harker and AFM variation diagrams, reflecting the metamorphic overprint. Immobile trace element contents (Ti, Cr, Y, Yb, Zr, Hf, Ta, Th) clearly indicate volcanic arc and calc-alkaline affinities when plotted on a variety of discrimination diagrams. REE patterns show LREE-enrichment typical of calc-alkaline lavas, commonly with small negative Eu anomalies consistent with plagioclase fractionation. The TLF shows marked petrologic and stratigraphic differences from broadly coeval Jurassic arc rocks exposed in the fault-bounded Kettle Rock sequence in the northeastern part of the NSt. This may reflect relatively rapid along-strike variations within the Jurassic arc, or that the Kettle Rock sequence and the TLF arc rocks have been brought into proximity by later faulting.

  12. Isotope variations in a Sierra Nevada snowpack and their relation to meltwater

    USGS Publications Warehouse

    Unnikrishna, P.V.; McDonnell, Jeffery J.; Kendall, C.

    2002-01-01

    Isotopic variations in melting snow are poorly understood. We made weekly measurements at the Central Sierra Snow Laboratory, California, of snow temperature, density, water equivalent and liquid water volume to examine how physical changes within the snowpack govern meltwater ??18O. Snowpack samples were extracted at 0.1 m intervals from ground level to the top of the snowpack profile between December 1991 and April 1992. Approximately 800 mm of precipitation fell during the study period with ??18O values between -21.35 and -4.25???. Corresponding snowpack ??18O ranged from -22.25 to -6.25???. The coefficient of variation of ??18O in snowpack levels decreased from -0.37 to -0.07 from winter to spring, indicating isotopic snowpack homogenization. Meltwater ??18O ranged from -15.30 to -8.05???, with variations of up to 2.95??? observed within a single snowmelt episode, highlighting the need for frequent sampling. Early snowmelt originated in the lower snowpack with higher ??18O through ground heat flux and rainfall. After the snowpack became isothermal, infiltrating snowmelt displaced the higher ??18O liquid in the lower snowpack through a piston flow process. Fractionation analysis using a two-component mixing model on the isothermal snowpack indicated that ??18O in the initial and final half of major snowmelt was 1.30??? lower and 1.45??? higher, respectively, than the value from simple mixing. Mean snowpack ??18O on individual profiling days showed a steady increase from -15.15 to -12.05??? due to removal of lower ??18O snowmelt and addition of higher ??18O rainfall. Results suggest that direct sampling of snowmelt and snow cores should be undertaken to quantify tracer input compositions adequately. The snowmelt sequence also suggests that regimes of early lower ??18O and later higher ??18O melt may be modeled and used in catchment tracing studies. ?? 2002 Elsevier Science B.V. All rights reserved.

  13. Ecological gradients driven by a change in millennial erosion rates: eco-geomorphological trends from a transient landscape in the Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Milodowski, D. T.; Mudd, S. M.; Mitchard, E. T.

    2013-12-01

    In actively eroding landscapes, the erosion rate dictates many critical aspects of the topography, including spatial variations in slope, the thickness, heterogeneity, geochemistry and particle size distribution of soils, and the style and temporal variability of sediment transport. In many ways, the erosion rate sets the dynamic template on which ecosystems develop and evolve, placing controls on their characteristics and productivity, and thus the spatial distribution of biomass within a landscape. In addition, vegetation itself is a geomorphic agent, fundamental to the dynamics of soil formation and sediment transport. The productivity and turnover rates of plants and trees are themselves a function of soil parameters, so there are complex feedbacks between vegetation structure and erosion rates that may affect how both ecosystems and landscapes respond to changes in external boundary conditions. Through a combination of field surveys and analysis of high resolution LiDAR (Light Detection and Ranging) data, we document the covariation of ecological and geomorphological characteristics of the mixed conifer forest in the Feather River region of the Californian Sierra Nevada Mountains. This study area features strong spatial gradients in erosion rates; cosmogenic radionuclide (CRN) analyses suggest the Feather River canyon is incising at approximately 250mm/ka, whereas adjacent plateau-like areas are eroding at 20-40mm/ka, with gradients in erosion rates in transition zones between the canyon and plateau. Our results indicate that there is a significant negative correlation between aboveground woody biomass, estimated across the landscape using field plots and the LiDAR data, and erosion rate. This is accompanied by an increase in surface roughness, due to increased rock exposure on more rapidly eroding hillslopes. We suggest that as erosion rates increase, ecosystem productivity and aboveground biomass is limited as a consequence of thinner, patchier soils that

  14. Fault-scarp morphology and amount of surface offset on late-Quaternary surficial deposits, eastern escarpment of the central Sierra Nevada, CA

    SciTech Connect

    Berry, M.E. . Dept. of Geology)

    1992-01-01

    Faults scarps, formed on glacial deposits and an alluvial fan near the east-central Sierra Nevada mountain front by late-Quaternary movement on the Hilton Creek (HCF), Wheeler Crest (WCFZ) and Coyote Warp (CWFZ) fault zones, were profiled to determine the amount and to estimate the recency of fault offset. Areas studied include McGee (N--near Lake Crowley), Pine, Mount Tom, Basin Mountain, McGee (S--near Bishop), and Bishop Creek drainages. The profile data indicate that movement of the range-front faults (HCF and WCFZ), which is characterized by normal slip, has offset Tioga-age deposits 6.5-26 m. Offset of Tahoe-age moraines cannot be measured directly because the landforms are buried at the mountain-front by moraines from later glaciations. However, the amount of offset is estimated at 52--130 m, based on crest-height differences between Tahoe and Tioga moraines. The rates of slip are highest on the northern end of the HCF, at McGee (N) Creek; the higher slip rates in this latter area may be related to its close proximity to the Long Valley caldera, where tectonic processes are complex and considered closely related to ongoing magmatic activity. The preservation of bevels on the fault scarps in both HCF and WCFZ, combined with the amounts of surface offset on the late-Pleistocene moraines, and AMS C-14 dates for charcoal found in fault-scarp colluvium, indicate that large ground-rupturing events have occurred on these faults during the Holocene. In contrast to the mountain-front faults, faults in the CWFZ, on a broad warp that separates the WCFZ from range-front faults to the south of Bishop, do not cross Tioga moraines, implying that surface rupture has not occurred in the CWFZ for at least 15,000-25,000 years. The degraded morphology of the fault scarps on adjacent Tahoe and pre-Tahoe moraines, which have been offset between 10.5 and 30 m, attests to the lack of late-Pleistocene and Holocene fault activity in this latter area.

  15. Reconnaissance for uranium-bearing carbonaceous rocks in California and adjacent parts of Oregon and Nevada

    USGS Publications Warehouse

    Moore, George Winfred; Stephens, James G.

    1954-01-01

    During the summer of 1952 a reconnaissance was conducted in California and parts of Oregon and Nevada in search of new deposits of uranium-bearing carbonaceous rocks. The principal localities found in California where uranium occurs in coal are listed here with. the uranium content of the coal: Newhall prospect, Los Angeles County, 0.020 percent; Fireflex mine, San Benito County, 0.005 percent; American licyaite mine, Amador County, 0.004 percent; and Tesla prospect, Alameda County, 0.003 percent. An oil-saturated sandstone near Edna, San Luis Obispo County, contains 0.002 percent uranium.

  16. Aquifer systems in the Great Basin region of Nevada, Utah, and adjacent states; a study plan

    USGS Publications Warehouse

    Harrill, James R.; Welch, A.H.; Prudic, D.E.; Thomas, J.M.; Carman, R.L.; Plume, R.W.; Gates, J.S.; Mason, J.L.

    1983-01-01

    The Great Basin Regional Aquifer Study includes about 140,000 square miles in parts of Nevada, Utah, California, Idaho, Oregon , and Arizona within which 240 hydrographic areas occupy structural depressions formed primarily by basin-and-range faulting. The principal aquifers are in basin-fill deposits; however, significant carbonate-rock aquifers underlie much of eastern Nevada and western Utah. In October 1980, the U.S. Geological Survey started a 4-year study to: (1) describe the ground-water systems, (2) analyze the changes that have led to the systems ' present conditions, (3) tie the results of this and previous studies together in a regional analysis, and (4) provide means by which effects of future ground-water development can be estimated. A plan of work is presented that describes the general approach to be taken. It defines the major tasks necessary to meet objectives and defines constraints on the scope of work. The approach has been influenced by the diverse nature of ground water flow systems and the large number of basins. A detailed appraisal of 240 individual areas would require more resources than are available. Consequently, the general approach is to study selected ' typical ' areas and key hydrologic processes. Effort during the first three years will be directed toward describing the regional hydrology, conducting detailed studies of ' type ' areas and studying selected hydrologic processes. Effort during the final year will be directed toward developing a regional analysis of results. Special studies will include evaluation of regional geochemistry , regional hydrogeology, recharge, ground-water discharge, and use of remote sensing. Areas to be studied using ground-water flow models include the regional carbonate-rock province in eastern Nevada and western Utah, six valleys--Las Vegas, Carson, Paradise, Dixie, Smith Creek, and Stagecoach--Nevada, plus Jordan Valley, the Millford area, and Tule Valley in Utah. The results will be presented in a

  17. Principal sources and dispersal patterns of suspended particulate matter in nearshore surface waters of the northeast Pacific Ocean and seasonal variation in snow cover in the Sierra Nevada

    NASA Technical Reports Server (NTRS)

    Carlson, P. R. (Principal Investigator); Harden, D. R.

    1973-01-01

    The author has identified the following significant results. ERTS-1 imagery used in conjunction with the surface-drift cards indicated a southerly flow direction of the central California near surface coastal currents during mid-June 1973. The near-surface currents off northern California and southern Oregon were more complex. Some drift cards were recovered north and some south of their release points; however, the prevalent direction of flow was northerly. General agreement in flow direction of coastal currents obtained from ERTS-1 imagery and drift card data reinforces the image interpretation. Complete seasonal coverage of nearshore circulation interpreted from ERTS-1 imagery will provide information necessary for proper coastal zone management. Extent of snow cover can be readily delimited on ERTS-1 band 5. In the central Sierra Nevada Mountains this past winter season, the snow line, as recorded by ERTS-1, reached an elevation of less than 1500 meters in January but had melted back to between 2500 and 3000 meters by the end of May. ERTS-1 imagery seems to provide sufficient resolution to make it a useful tool for monitoring changes in snow cover in the Sierra Nevada Mountains.

  18. Genomic scanning using AFLP to detect loci under selection in the moss Funaria hygrometrica along a climate gradient in the Sierra Nevada Mountains, Spain.

    PubMed

    Magdy, M; Werner, O; McDaniel, S F; Goffinet, B; Ros, R M

    2016-03-01

    The common cord moss Funaria hygrometrica has a worldwide distribution and thrives in a wide variety of environments. Here, we studied the genetic diversity in F. hygrometrica along an abiotic gradient in the Mediterranean high mountain of Sierra Nevada (Spain) using a genome scan method. Eighty-four samples from 17 locations from 24 to 2700 m were fingerprinted based on their amplified fragment length polymorphism (AFLP) banding pattern. Using PCA and Bayesian inference we found that the genetic diversity was structured in three or four clusters, respectively. Using a genome scan method we identified 13 outlier loci, which showed a signature of positive selection. Partial Mantel tests were performed between the Euclidean distance matrices of geographic and climatic variables, versus the pair-wise genetic distance of the AFLP dataset and AFLP-positive outliers dataset. AFLP-positive outlier data were significantly correlated with the gradient of the climatic variables, suggesting adaptive variation among populations of F. hygrometrica along the Sierra Nevada Mountains. We highlight the additional analyses necessary to identify the nature of these loci, and their biological role in the adaptation process.

  19. 78 FR 13374 - Notice of Public Meetings: Sierra Front-Northwestern Great Basin Resource Advisory Council, Nevada

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-27

    ..., Nevada AGENCY: Bureau of Land Management, Interior. ACTION: Notice of public meetings. SUMMARY: In...-Northwestern Great Basin Resource Advisory Council (RAC), will hold two meetings in Nevada in fiscal year 2013..., 5665 Morgan Mill Road in Carson City, Nevada and a field trip on April 5; August 8-9 at the...

  20. Application of the Water Evaluation and Planning (WEAP) System for Integrated Hydrologic and Scenario-based Water Resources Systems Modeling in the Western Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Mehta, V. K.; Purkey, D. R.; Young, C.; Joyce, B.; Yates, D.

    2008-12-01

    Rivers draining western slopes of the Sierra Nevada provide critical water supply, hydropower, fisheries and recreation services to California. Coordinated efforts are under way to better characterize and model the possible impacts of climate change on Sierra Nevada hydrology. Research suggests substantial end-of- century reductions in Sierra Nevada snowpack and a shift in the center of mass of the snowmelt hydrograph. Management decisions, land use change and population growth add further complexity, necessitating the use of scenario-based modeling tools. The Water Evaluation and Planning (WEAP) system is one of the suite of tools being employed in this effort. Unlike several models that rely on perturbation of historical runoff data to simulate future climate conditions, WEAP includes a dynamically integrated watershed hydrology module that is forced by input climate time series. This allows direct simulation of water management response to climate and land use change. This paper presents ABY2008, a WEAP application for the Yuba, Bear and American River (ABY) watersheds of the Sierra Nevada. These rivers are managed by water agencies and hydropower utilities through a complex network of reservoirs, dams, hydropower plants and water conveyances. Historical watershed hydrology in ABY2008 is driven by a 10 year weekly climate time series from 1991-2000. Land use and soils data were combined into 12 landclasses representing each of 324 hydrological response units. Hydrologic parameters were incorporated from a calibration against observed streamflow developed for the entire western Sierra. Physical reservoir data, operating rules, and water deliveries to water agencies were obtained from public documents of water agencies and power utilities that manage facilities in the watersheds. ABY2008 includes 25 major reservoirs, 39 conveyances, 33 hydropower plants and 14 transmission links to 13 major water demand points. In WEAP, decisions for transferring water at

  1. The Eastern delta-fan deposits on the Granada Basin as tectonic indicators of the Sierra Nevada uplift (Betic Cordillera, South Spain)

    NASA Astrophysics Data System (ADS)

    Roldán, Francisco Javier; Azañon, Jose Miguel; Mateos, Rosa Maria

    2014-05-01

    A geological mapping in detail of the Eastern sector of the Granada Basin (South Spain) reveals two different groups of Gilbert delta-fans related to the Sierra Nevada uplift. The first group, in the southern part and with a surface of 6 km2, has three major coarsening-upward sequences. They are composed of very coarse deposits, those of conglomerates, sands and silts. Progradational strata units to the basin have been observed. The dominantly fluvial facies association has locally developed shallow marine foreset deposits (partially with reef colonization) as well as topset red soils (Dabrio, et al., 1978; Braga et a., 1990; García-García, et al., 1999) . All the sequences are discordant over marine facies (calcarenites) dated over 8,26 Ma (Late Tortonian). The second group, in the northern part and with an extension of 12 km2, has similar characteristics, but some of the boulders have ostreids and lamellibranchs species which reveal their former position in a previous marine environment. The Sierra Nevada uplift caused the remobilization of these boulders, being transported by debris-flow inside the delta-fan bodies (García-García, et al., 2006). The dating of ostreids shells with Sr techniques reveals ages over 7,13, 6,61 and 5,45 Ma, from the lower to the upper delta-fan deposits, which are related to the three main sequences observed and with three major tectonic pulses during the Late Miocene. These interpretations are in agreement with apatite fision-track studies carried out in some boulders of these coarse delta-fan deposits (Clark and Dempster, 2013). They reveal a detailed record of Neogene denudation from the Sierra Nevada basement and with uplift periods between 5,45Ma- 2 Ma. The latest pulses affected the delta-fan sediments given rise to new fan systems in the Granada Basin (Alhambra Formation). The thoroughly study of the Miocene delta-fan sediments allows us to conclude that they were related to a sin-sedimentary tectonic activity linked to the

  2. High K volcanism in the Sierra Nevada: A signal for the initiation of Walker Lane Faulting, and range uplift, not lithosphere delamination

    NASA Astrophysics Data System (ADS)

    Putirka, K. D.; Busby, C. J.

    2007-12-01

    K2O contents have long been recognized as a potential indicator of tectonic processes, and based upon models developed for the Andes (Kay and Kay, 1993) and Tibet (Turner et al., 1996), high-K volcanism has been related to lithosphere delamination, by partial melting of a K-metasomatized lower crust or upper mantle (Feldstein and Lange, 1999; Manley et al., 2000). However, new data from the central Sierra Nevada cast doubt on this K2O-delamination link. Instead, high-K volcanism is better explained as low degree partial melts (F), where low F magmas are preferentially erupted over thick crust, under conditions of high tensile stress. In the central Sierra, a high tensile stress regime was imposed at the onset of Walker Lane transtension, at the eastern edge of the Basin and Range province. We surmise that high K volcanism is similarly controlled by the onset of tensile stresses throughout the Sierra, recording the initial phase of Sierra Nevada uplift. These conclusions stem from several observations. First, K2O contents are highly correlated with Th (R=0.82), Ba (R=0.83), U (R=0.85), Rb (R=0.88) and Pb (R=0.83), and other highly incompatible elements, suggesting a general enrichment mechanism, such as low degree partial melitng. Second, volcanic rocks with the highest K have the highest La/Nb and the lowest 143Nd/144Nd, indicative of a mantle lithosphere source - inconsistent with delamination. Third, maximum K contents increase from north (near Lassen) to south, following in increase in crustal thickness and the (87Sr/86Sr) i of basement granitoids, suggestive of a crustal control on volcanism. Finally, field evidence in the central Sierra shows that the pulse of high K2O volcanism there was synchronous with the development of a pull-apart, along a series of right-stepping dextral transtensional faults, at the onset of Walker Lane faulting. Partial melting calculations verify that primitive magma compositions from Lassen to the southern Sierra, can all be

  3. Mutli-temporal Imaging Spectroscopy Analysis for the Identification of Coniferous Forest Mortality Related to Drought Stress in the Central Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Tane, Z.; Roberts, D. A.; Koltunov, A.; Ramirez, C.; Ustin, S.; Roth, K. L.

    2015-12-01

    The ongoing drought in California has had a significant impact on the vegetation communities of California. As a result of the drought, there has been a notable increase in forest mortality throughout the state. In this presentation Airborne Visible / Infrared Imaging Spectrometer (AVIRIS) imagery acquired for the HyspIRI Preparatory Mission over the western Sierra Nevada Range in 2013 and 2014 was used to quantify the mortality of conifers in 2014. Data products provided by NASA's Jet Propulsion Lab (NASA-JPL) were re-sampled to a common 15meter pixel resolution, co-registered, and geo-referenced. Ecological cover type was first assessed using the random forest machine learning technique with training data produced from AVIRIS summer 2013 imagery and comparison with high-spatial resolution World View-2 imagery. Then, in areas identified as being primarily composed of needle-leaf tree cover, the change in fractional change in green vegetation cover was assessed using Multiple Endmember Spectral Mixture Analysis (MESMA) in fall 2013 and fall 2014 AVIRIS images. The source spectral library for the MESMA endmembers was created from AVIRIS-Next Generation (AVIRIS-NG) images taken over Sierra National Forest in 2014. False positives were further reduced using a spatio-temporal filtering approach. Final accuracy of the modeled areas of conifer mortality were assessed by comparison with 2015 WorldView-2 and WorldView-3 imagery over the study area, as well as with recently acquired field data within the southern Sierra Nevada. Early results support the need for increased fidelity data for providing timely information on ecosystem dynamics to land management agencies.

  4. Integrating multiple temporal scales of snowfall, soil, and plant processes at the Great Basin Desert - Sierra Nevada ecotone

    NASA Astrophysics Data System (ADS)

    Loik, M. E.

    2012-12-01

    Snowfall is the dominant hydrologic input for high elevations and latitudes of the arid- and semi-arid western United States. Many climate models envision changes in California's Sierra Nevada snow pack characteristics, which would severely impact the storage and release of water for one of the world's largest economies. Climate change threatens the sustainability of this water supply through altered snowfall timing, reduced snowpack depth, changes in snow water equivalents, earlier snowmelt, and highly-uncertain but plausible scenarios of rain-on-snow events. Climate model scenarios envision reduced snow pack and earlier melt under a warmer climate, but how will these changes affect soil and plant water relations and ecosystem processes, such as carbon storage? To address this question, experiments utilize large-scale, long-term snow fences to manipulate snow depth and melt timing at a desert-montane ecotone in eastern California, USA. A combination of instantaneous gas exchange and water potential measurements, plant community surveys, annual ring growth increments, in situ instrumentation, and long-term snow course data were used to couple physical and biological processes at daily, monthly, annual, and decadal scales. At this site, long-term April 1 snow pack depth averages 1344 mm (1928-2011) with a CV of 48%. Snow fences increased equilibrium drift snow depth by 200%. Soil moisture pulses were shorter in duration and lower in magnitude in low- than medium- or high-snowfall years. Evapotranspiration (ET) in this arid location accounted for about 37 mol m-2 d-1 of water loss from the snow pack between January 1 and May 1; sublimation was 10% of ET for the same period. Despite considerable interannual variation in snow depth and total precipitation, plant water potential stayed relatively constant over eight consecutive years, but photosynthesis was highly variable. Over the long-term, changes in snow depth and melt timing have impacted growth of only three

  5. A Multi-proxy Reconstruction of Hydrologic Variability over the Last Millennium from a Sierra Nevada Mountain Stalagmite

    NASA Astrophysics Data System (ADS)

    McCabe-Glynn, S. E.; Johnson, K. R.; Berkelhammer, M. B.; Sinha, A.; Cheng, H.; Edwards, R.

    2011-12-01

    Precipitation in the southwestern United States (SW US) is highly seasonal and exhibits inter-annual to inter-decadal variability which is linked to naturally recurring large scale atmospheric circulation patterns associated with sea surface temperature (SST) anomalies such as the Pacific Decadal Oscillation (PDO) and the El Nino-Southern Oscillation (ENSO). Proxy data from tree rings and lake sediments from the SW US indicate there were episodes of significantly decreased precipitation ~900-1250 (AD) that were of greater magnitude and longer duration than any episode seen in the 20th century. In order to determine the full range and understand the mechanisms controlling past precipitation variability in the SW US, we have developed an absolute dated, high resolution, millennial length (2008 to 852 AD) δ18O record from a stalagmite from Crystal Cave (CRC-3) in Sequoia National Park, California, on the south-western flank of the Sierra Nevada Mountains (36.58°N; 118.56°W; 1540 m). Results from an instrumental calibration study suggest that δ18O in the speleothem and precipitation at this site is not correlated to temperature or precipitation amount, but is strongly influenced by the moisture source and rainout history of landfalling storms. A comparison between the instrumental portion of the CRC-3 time series reveals a significant inverse relationship with the PDO index, indicating that speleothem δ18O at this site is highly sensitive to Pacific SST patterns. The CRC-3 time series exhibits a prominent decadal to multi-decadal scale variability which we infer to reflect the influence of changing SSTs on the precipitation patterns in the SW US. In order to provide insight into the mechanisms driving these variations and allow for a more confident interpretation of our longer-term δ18O record, we will present trace element results from the CRC-3 stalagmite. Variations in speleothem trace elemental composition likely reflect local hydrologic variability rather

  6. Soil mineral weathering in glacial deposits in the western Sierra Nevada and implication for U/Th geochronology

    NASA Astrophysics Data System (ADS)

    Aburto Guerrero, F. A.; Southard, R.

    2012-12-01

    During the Pleistocene vast alpine glaciers capped the Sierra Nevada range l and were a dominant force in shaping the post-glacial landscape. On the west side of the Lake Tahoe basin many moraine deposits stand out from the local morphology. Since their deposition these materials have been subject to physical and chemical weathering typical of this alpine environment. There is a general lack of information about soil weathering processes and rates for till deposits in alpine environments. We present the preliminary results of the mineralogical analysis of 13 granitic-derived soils located on Tioga (aprox. 19ka) and Tahoe age (aprox.118ka) moraine crests. A new light detection and ranging (LIDAR) dataset allowed geomorphic correlation of features using field reconnaissance and computer-based 3-D LIDAR data interpretation. A suite of mineralogical and elemental analyses, including XRD, DSC/TG and pXRF was performed, We also studied in-situ mineral transformations in selected durinodes by means of electron microprobe analysis and exploratory laser ablation coupled with mass spectrometry. Despite the large age difference in the deposits, Tahoe- and Tioga-age soils have very similar field morphology, making field discrimination extremely difficult. Mineralogical analysis reveals that soils on Tahoe-age moraines have clay mineralogy dominated by biotite and hydro-biotite, plus significant quantities of gibbsite and kaolinite. On the other hand, soils on Tioga-age moraines only have traces of gibbsite and kaolinite, and biotite is only slightly weathered. Elemental analysis suggests that Si and Al have been significantly mobilized exclusively in Tahoe-age soils. Increments in Al concentration coincide with relative gibbsite and kaolinite enrichment and plagioclase depletion. Si increment at deeper horizons seems to be associated with non-crystalline phases. Tioga-age durinodes are composed of till materials cemented by silica and contain coatings of micaceous materials

  7. Variations in Late Quaternary behavior along and among range-front faults of the Sierra Nevada, California

    SciTech Connect

    Clark, M.M. ); Gillespie, A.R. . Geological Sciences)

    1993-04-01

    Late Quaternary slip rates of the 11 or so recognized active range-front faults of the Sierra Nevada from Owens Lake northwestward to Carson Valley show enough variation with time and location that a proper understanding of slip behavior of these faults may require slip histories at many places for each. Late Quaternary traces of these normal faults vary in length from 13 to 45 km. Most faults trend more northerly than the [approximately]MW trend of the range front. The faults are separated by < 5 to > 20 km of apparently unfaulted terrain; many have echelon overlap. None of the faults has a significant component of strike slip, including those of Owens Valley. The largest late Quaternary slip rates (> 2 mm/yr) occur on the Hilton Creek fault at Long Valley and 20 km to the north on the Mono Lake fault. Slip rates > 1 mm/yr occur on at least one fault north of Mono Lake and in Round Valley, south of Long Valley. Farther south (Owens Valley) range-front faults have slip rates < 1 mm/yr and have notably discontinuous traces. Displacements of moraines across the Hilton Creek fault at 4 sites are compatible with slip rates that increase northward from the south end of the fault, but stay constant through time at a site. The slip rates are 0.1 to 0.4 mm/yr near the south end; 0.1 to 0.8 mm/yr at Hilton Lakes, 3 km to the northwest; 1.4 to 3 mm/yr at McGee Creek, 9 km farther northwest; and 1.1 to 2 mm/yr at Tobacco Flat, 5 km farther northwest in Long Valley and > 15 km from the north end of the fault. At McGee Creek, slip rate since 10--15 ka is 1.3--2.5 mm/yr; since 13--20 ka, 1.4--2.6 mm/yr; since 25--40 ka, 1.4--4.2 mm/yr, and since 65--140 ka, 1.1--3.5 mm/yr. The apparently uniform rate through time at McGee Creek (and also at Hilton Lakes and Tobacco Flat, but for fewer periods; the south end site is for only one period) is interesting, but not yet convincing, mainly because of uncertain dates.

  8. Origin and age of the Volcanic Rocks of Tláloc Volcano, Sierra Nevada, Central Mexico

    NASA Astrophysics Data System (ADS)

    Meier, M.; Grobéty, B.; Arce, J. L.; Rueda, H.

    2007-05-01

    The Tláloc volcano (TV) is a 4125 m high stratovolcano of the Trans Mexican Volcanic Belt (TMVB) and is located in the northern end of the N-S trending Sierra Nevada, 30 km NE of Mexico City. Few data on the petrological and temporal evolution of TV have been published to date. Recently dated deposits gave ages between 32'000 and 34'500±500 years BP (Huddart and Gonzalez, 2004). Mapping and sampling of extrusive rocks in the summit region of TV revealed a dome structure with radiating lava flows consisting of dacitic rocks containing plagioclase and hornblende phenocrysts. Some flows, however, seem to be associated with a collapse structure E of the main summit. Crossing relationships indicate that this structure is older (“Paleo Tláloc”). A stratigraphy of the pyroclastic deposits was established along the northern slope of TV. From the numerous pyroclastic flows, separated by paleosoils and fluviatile deposits, only two pumice and one block and ash flow (BAF) have regional extent. Their thickness - distance relationship and their granulometry point to major explosive events. A carbonized wood sample from the BAF deposit gave ages similar to the previous ages (33'180±550 yr BP and 23'170±270 yr BP), a sample from a pyroclastic flow gave even a younger age (16'620±110 yr BP), suggesting that TV remained active also after the volcanoes Iztaccíhuatl and Popocatépetl further to the South started their activity. Based on these preliminary data it may be necessary to reconsider the accepted scenario of the temporal evolution of the central section of the TMVB, which assumes that the activity migrates from North to South with time. Huddart, D. and Gonzalez, S., 2004. Pyroclastic flows and associated sediments, Tláloc-Telapón, piedmont fringe of the eastern basin of Mexico. In: G.J. Aguirre-Diaz, Macías, J.L., and Siebe, C., (Editor), Penrose Conference. UNAM, Metepec, Puebla, Mexico, pp. 35.

  9. High Temperature Solid-State Coeval Brittle and Ductile Deformation during Cooling of Lake Edison Granodiorite (Sierra Nevada, California)

    NASA Astrophysics Data System (ADS)

    Pennacchioni, G.

    2009-12-01

    In the Lake Edison (LE) granodiorite (88Ma) of the Bear Creek area (Cretaceous Mono Pass intrusive suite, Sierra Nevada, CA) different sets of fractures developed during the high temperature stages of post-magmatic cooling. These fractures strongly localized successive ductile and later brittle shear deformation, but many pristine fractures do not show any shear offset (i.e. are joints). Away from the contact with the younger (86Ma) Mono Creek granite, the LE granodiorite mainly show a single dominant set of steeply dipping fractures striking around E-W to ENE-WSW which were exploited as left-handed strike-slip ductile shear zones and later as faults with identical kinematics. In the proximity of the contact, a second (dominant) set of steeply dipping fractures is present, striking about NNE-SSW, with a right-handed ductile shear reactivation and forming a conjugate array with the E-W set; many leucocratic dykes (including pegmatite) also localized the shear deformation within the granodiorite. Left-handed shear zones commonly overprint the right-handed ones, but the opposite is also observed which suggests that the two sets developed at the same time. Ductile shear zones are associated with a background solid state foliation in the host granodiorite which is mainly developed towards the contact and which has been referred to the Rosy Finch Shear Zone in the area. The mineral fabric along the foliation and along both the left- and right-handed localized shear zones indicate deformation T>500°C. The overall structural association is consistent with a regional shortening direction oriented about NW-SE. Fractures, including joints (occurring with the same orientation of the conjugate shear fractures), which form the precursory structures of shear zones, developed at the same time of ductile deformation and locally overprint the shear zones. The geometry and spatial arrangement of these precursory fractures control the patterns of ductile deformation of the host rocks

  10. Eruption styles of Quaternary basalt in the southern Sierra Nevada Kern Plateau recorded in outcrop and mineral-scale stratigraphies

    NASA Astrophysics Data System (ADS)

    Browne, B. L.; Becerra, R. A.

    2015-12-01

    The Kern River Plateau in the southern Sierra Nevada contains Quaternary basalt (~0.1 km3) and rhyolite (~2 km3) that ascended through ~30 km of Mesozoic granitic crust. Basaltic vents include from oldest to youngest: Little Whitney Cone, Tunnel and South Fork Cones, and unglaciated Groundhog Cone. Little Whitney Cone is a 120-m-high pile of olivine-CPX-phyric scoria overlying two columnar jointed lava flows extending to the south and east. Tunnel Cone formed through a Hawaiian style eruption along a 400-m-long north-south trending fissure that excavated at least three 25-65-m-wide craters. Crater walls up to 12 meters high are composed of plagioclase-olivine-phyric spatter-fed flows that dip radially away from the crater center and crumble to form steep unconsolidated flanks. South Fork Cone is a 170-m-tall pile of plagioclase-olivine-phyric scoria that formed as a result of Strombolian to violent Strombolian eruptions. It overlies the South Fork Cone lava, the largest lava flow of the Kern Plateau (~0.05 km3), which flowed 7.5 km west into the Kern River Canyon. Scoria and ash fall deposits originating from South Fork Cone are found up to 2 km from the vent. Groundhog Cone is a 140-m-tall cinder and spatter cone breached on the north flank by a 0.03 km3 lava flow that partially buried the South Fork Cone lava and extends 5 km west to Kern River Canyon. Trends in mineral assemblage, texture, composition, and xenocryst abundance exist as a function of eruption style. Scoria and spatter deposits typically have (1) elevated olivine/plagioclase ratios, (2) oscillatory zoned (An63-An72) plagioclase phenocrysts surrounded by unzoned rims and (3) abundant xenocrysts, where up to 20% of plagioclase >200 micron diameter in some samples are granitoid xenocrysts with resorbed and/or reacted textures overprinted by abrupt compositional changes. In contrast, lava flow samples have (1) reduced olivine/plagioclase ratios and (2) plagioclase aggregates with oscillatory zoned

  11. Examining spatial and temporal variability in snow water equivalent using a 27 year reanalysis: Kern River watershed, Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Girotto, M.; Cortés, G.; Margulis, S. A.; Durand, M. T.

    2014-12-01

    This work used a data assimilation framework to estimate spatially and temporally continuous snow water equivalent (SWE) from a 27 year reanalysis (from water year 1985 to 2011) of the Landsat-5 record for the Kern River watershed in the Sierra Nevada, California. The data assimilation approach explicitly treats sources of uncertainty from model parameters, meteorological inputs, and observations. The method is comprised of two main components: (1) a coupled land surface model (LSM) and snow depletion curve (SDC) model, which is used to generate an ensemble of predictions of SWE and fractional snow cover area (FSCA) for a given set of prior (uncertain) inputs, and (2) a retrospective reanalysis step, which updates estimation variables to be consistent with the observed fractional snow cover time series. The final posterior SWE estimate is generated from the LSM-SDC using the posterior estimation variables consistently with all postulated sources of uncertainty in the model, inputs, and observations. A reasonable agreement was found between the SWE reanalysis and in situ SWE observations and streamflow data. The data set was studied to evaluate factors controlling SWE spatial and temporal variability. Elevation was found to be the primary control on spatial patterns of peak-SWE and day-of-peak. The easting coordinate had additional explanatory power, which is hypothesized to be related to rain shadow effects due to the prevailing storm track directions. The spatial patterns were found to be interannually inconsistent. However, drier years and lower elevations were found more variable than wetter years and higher elevations, respectively. Only a very small percentage of the Kern River watershed had a significant trend in peak-SWE and day-of-peak. Trends deemed to be significant were found to be positive (peak-SWE is increasing and day-of-peak occurs later) at higher elevations, but negative (peak-SWE is decreasing and day-of-peak occurs earlier) at lower elevations

  12. Examining spatial and temporal variability in snow water equivalent using a 27 year reanalysis: Kern River watershed, Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Girotto, Manuela; Cortés, Gonzalo; Margulis, Steven A.; Durand, Michael

    2014-08-01

    This paper used a data assimilation framework to estimate spatially and temporally continuous snow water equivalent (SWE) from a 27 year reanalysis (from water year 1985 to 2011) of the Landsat-5 record for the Kern River watershed in the Sierra Nevada, California. The data assimilation approach explicitly treats sources of uncertainty from model parameters, meteorological inputs, and observations. The method is comprised of two main components: (1) a coupled land surface model (LSM) and snow depletion curve (SDC) model, which is used to generate an ensemble of predictions of SWE and fractional snow cover area (FSCA) for a given set of prior (uncertain) inputs, and (2) a retrospective reanalysis step, which updates estimation variables to be consistent with the observed fractional snow cover time series. The final posterior SWE estimate is generated from the LSM-SDC using the posterior estimation variables consistently with all postulated sources of uncertainty in the model, inputs, and observations. A reasonable agreement was found between the SWE reanalysis and in situ SWE observations and streamflow data. The data set was studied to evaluate factors controlling SWE spatial and temporal variability. Elevation was found to be the primary control on spatial patterns of peak-SWE and day-of-peak. The easting coordinate had additional explanatory power, which is hypothesized to be related to rain shadow effects due to the prevailing storm track directions. The spatial patterns were found to be interannually inconsistent. However, drier years and lower elevations were found more variable than wetter years and higher elevations, respectively. Only a very small percentage of the Kern River watershed had a significant trend in peak-SWE and day-of-peak. Trends deemed to be significant were found to be positive (peak-SWE is increasing and day-of-peak occurs later) at higher elevations, but negative (peak-SWE is decreasing and day-of-peak occurs earlier) at lower elevations

  13. Cold-Air Pools and Regional Warming in the Lake Tahoe Region, Central Sierra Nevada of California—Observations and Considerations regarding the Future of Climate-Change Refugia

    NASA Astrophysics Data System (ADS)

    Dettinger, M. D.

    2015-12-01

    Naturally occurring climate refugia, specifically in the form of cold-air pools (CAPs) in mountain basins, are increasingly discussed as potential safe havens against some impacts of global warming on western ecosystems and cold-adapted species. A key concern in these discussions should be: How will CAPs react to regional warming? Several broad possibilities exist: CAPs may "resist" regional warming, remaining as cool as ever despite warming of their surroundings. CAPs may "reflect" regional warming, experiencing temperature increases that are roughly equal to the warming of their surroundings but that leave the CAP as cool relative to their surroundings as ever. Or CAPs might "disintegrate" in the face of regional warming, losing their special cool status relative to surroundings and in the process warming much more than their surroundings. An evalu