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1

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

USGS Publications Warehouse

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.

Stevens, C. H.; Stone, P.

2005-01-01

2

Death Valley, California  

NASA Technical Reports Server (NTRS)

This is an image of Death Valley, California, centered at 36.629 degrees north latitude, 117.069 degrees west longitude. The image shows Furnace Creek alluvial fan and Furnace Creek Ranch at the far right, and the sand dunes near Stove Pipe Wells at the center. The dark fork-shaped feature between Furnace Creek fan and the dunes is a smooth flood-plain which encloses Cottonball Basin. The bright dots near the center of the image are corner refectors that have been set-up to calibrate the radar as the Shuttle passes overhead with the SIR-C/X-SAR system. The Jet Propulsion Laboratory alternative photo number is P-43883.

1994-01-01

3

Death Valley California as seen from STS-59  

NASA Technical Reports Server (NTRS)

This oblique handheld Hasselblad 70mm photo shows Death Valley, near California's border with Nevada. The valley -- the central feature of Death Valley National Monument -- extends north to south for some 140 miles (225 kilometers). Hemmed in to the east by the Amargosa Range and to the west by the Panamints, its width varies from 5 to 15 miles (8 to 24 kilometers).

1994-01-01

4

36 CFR 7.26 - Death Valley National Monument.  

...NATIONAL PARK SYSTEM § 7.26 Death Valley National Monument. (a) Mining. Mining in Death Valley National Monument... (b) Use of water. No works or water system of any...office of the Superintendent, Death Valley National Monument,...

2014-07-01

5

Death Valley TronaWestend  

E-print Network

Johannesburg Red Mountain Pahrump Shoshone Blue Diamond Tecopa Goodsprings Jean Roach Tonopah Warm Springs Nevada Test Site East Mormon Mountain Gold Point Delamar Valley Amargosa Valley Millers Dry Lake Dry Lake County Nye County Lincoln County Beaver County Iron County State Line County Boundary Solar Energy Study

Laughlin, Robert B.

6

Geology of Death Valley National Park  

NSDL National Science Digital Library

This site of the United States Geologic Survey (USGS) and the National Park Service (NPS) highlights the geologic history of Death Valley National Park in Nevada and California. The story begins 1.8 billion years ago with the formation of rocks and continues through uplift, faulting, volcanism, early animals of the area, glaciers, and the making of deserts and dunes. A geologic timescale connects to specific events in the history of Death Valley. There are topographic maps of the area, a field trip of the park, an image gallery, and technical papers available to download.

7

Death Valley bright spot: A midcrustal magma body in the southern Great Basin, California?  

Microsoft Academic Search

A previously unrecognized midcrustal magma body may have been detected by COCORP deep seismic reflection profiles in the Death Valley region of the southern Great Basin. High-amplitude, relatively broad-band reflections at 6 s (15 km) are attributed to partially molten material within a subhorizontal intrusion. This ``bright spot'' extends laterally at least 15 km beneath central Death Valley. A moderately

Beatrice de Voogd; Laura Serpa; Larry Brown; Ernest Hauser; Sidney Kaufman; Jack Oliver; Bennie W. Troxel; James Willemin; Lauren A. Wright

1986-01-01

8

Geology Fieldnotes: Death Valley National Park, California/Nevada  

NSDL National Science Digital Library

This Death Valley National Park site contains park geology information, park maps, photographs, visitor information, and teacher features (resources for teaching geology using National Park examples). The Park Geology section contains an exaggerated cross-section showing the vertical rise within Death Valley. A link is provided to Death Valley's expanded geology page.

9

The Shape of Trail Canyon Alluvial Fan, Death Valley  

NASA Technical Reports Server (NTRS)

A modified conic equation has been fit to high-resolution digital topographic data for Trail Canyon alluvial fan in Death Valley, California. Fits were accomplished for 3 individual fan units of different age.

Farr, Tom G.; Dohrenwend, John C.

1993-01-01

10

Curie Point Depth Estimates from Aeromagnetic Data from Death Valley and Surrounding Regions, California  

NASA Astrophysics Data System (ADS)

Aeromagnetic data were analyzed to determine the Curie point depth (CPD) by power density spectral and three-dimensional inversion methods within and surrounding Death Valley in southern California. We calculated the CPD for 0.5° regions using 2D power density spectral methods and found that the CPDs varied between 8 and 17 km. However, the 0.5° region may average areas that include shallow and deep CPDs, and because of this limitation, we used the 3D inversion method to determine if this method may provide better resolution of the CPDs. The final 3D model indicates that the depth to the bottom of the magnetic susceptible bodies varies between 5 and 23 km. Even though both methods produced roughly similar results, the 3D inversion method produced a higher lateral resolution of the CPDs. The shallowest CPDs occur within the central and southern Death Valley, Panamint Valley, Coso geothermal field and the Tecopa hot springs region. Deeper (>15 km) CPDs occur over outcropping granitic and Precambrian lithologies in the Panamint Range, Grapevine Mountains, Black Mountains and the Argus Range. The shallowest CPD occurs within the central Death Valley over a possible seismically imaged magma body and slightly deeper values occur within the Panamint Valley, southern Death Valley and Tecopa Hot Springs. The shallow CPD values suggest that partially molten material may also be found in these latter regions. The CPD computed heat flow values for the region suggest that the entire area has high heat flow values (>100 mW m-2), on the other hand, locally extremely high values (>200 mW m-2) occur within the Panamint Valley, the southern and central Death Valley and Tecopa Hot Springs region. These locally high heat flow values may be related to midcrustal magma bodies; but additional geophysical experiments are needed to determine if the magma bodies exist.

Hussein, Musa; Mickus, Kevin; Serpa, Laura F.

2013-04-01

11

G-SRT Mt. Whitney to Death Valley  

NSDL National Science Digital Library

This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: The Morris family is on a road trip through California. One day they are driving from Death Valley to Sequoia National Park. Death Valley is home to th...

12

Recent landscape change in California's Central Valley  

NASA Astrophysics Data System (ADS)

Long term monitoring of land use and land cover in California's intensively farmed Central Valley reveals several key physical and socioeconomic factors driving landscape change. As part of the USGS Land Cover Trends Project, we analyzed modern land-use/land-cover change for the California Central Valley ecoregion between 2000 and 2010, monitoring annual change between 2005 and 2010, while creating two new change intervals (2000-2005 and 2005-2010) to update the existing 27-year, interval-based analysis. Between 2000 and 2010, agricultural lands fluctuated due to changes in water allocations and emerging drought conditions, or were lost permanently to development (240 square km). Land-use pressure from agriculture and development also led to a decline in grasslands and shrublands across the region (280 square km). Overall, 400 square km of new developed lands were added in the first decade of the 21st century. From 2007 to 2010, development only expanded by 50 square km, coinciding with defaults in the banking system, the onset of historic foreclosure crisis in California and the global economic downturn. Our annual LULC change estimates capture landscape-level change in response to regional policy changes, climate, and fluctuations (e.g., growth or decline) in the national and global economy. The resulting change data provide insights into the drivers of landscape change in the California Central Valley and the combination of two consistent mapping efforts represents the first continuous, 37-year endeavor of its kind.

Soulard, C. E.; Wilson, T. S.

2012-12-01

13

Technology push, market pull, and the Valley of Death  

NASA Astrophysics Data System (ADS)

The Valley of Death is the gap between fundamental research and product development, where apparently promising technologies can stall or disappear. Fundamental researchers may hope for potential applications of their work, and they try to push technology based on their research. Businesses may hope that new technology might serve their market needs, and they try to find promising new technologies that can be pulled toward practical use. The valley between the researchers and the businesses can be surprisingly twisted and thorny, despite government attempts to build roads across it. The histories of cryogenic engineering in the late 20th century and of thermoacoustics work at Los Alamos offer examples of both useful and misguided strategies in this valley. Although global thermoacoustics R&D has not (yet?) been as successful as cryogenic engineering, thermoacoustics has thus far avoided some of the worst pitfalls in the valley.

Swift, Gregory W.

2005-09-01

14

A 100 ka record of water tables and paleoclimates from salt cores, Death Valley, California  

Microsoft Academic Search

Sedimentary and petrographic features of evaporites and associated sediments from a 185 m deep core taken in Death Valley, CA, together with uranium-series dating have been used to reconstruct the history of water table fluctuations and climate changes in Death Valley for the past 100 ka. Death Valley has been arid during the Holocene (0–10 ka), with predominantly mudflat and

Jianren Li; Tim K. Lowenstein; Christopher B. Brown; Teh-Lung Ku; Shangde Luo

1996-01-01

15

Hydrology of modern and late Holocene lakes, Death Valley, California  

SciTech Connect

Above-normal precipitation and surface-water runoff, which have been generally related to the cyclic recurrence of the El Nino-Southern Oscillation, have produced modern ephemeral lakes in the closed-basin Death Valley watershed. This study evaluates the regional hydroclimatic relations between precipitation, runoff, and lake transgressions in the Death Valley watershed. Recorded precipitation, runoff, and spring discharge data for the region are used in conjunction with a closed-basin, lake-water-budget equation to assess the relative contributions of water from these sources to modern lakes in Death Valley and to identify the requisite hydroclimatic changes for a late Holocene perennial lake in the valley. As part of the Yucca Mountain Site Characterization Program, an evaluation of the Quaternary regional paleoflood hydrology of the potential nuclear-waste repository site at Yucca Mountain, Nevada, was planned. The objectives of the evaluation were (1) to identify the locations and investigate the hydraulic characteristics of paleofloods and compare these with the locations and characteristics of modern floods, and (2) to evaluate the character and severity of past floods and debris flows to ascertain the potential future hazards to the potential repository during the pre-closure period (US Department of Energy, 1988). This study addresses the first of these objectives, and the second in part, by assessing and comparing the sizes, locations, and recurrence rates of modern, recorded (1962--83) floods and late Holocene paleofloods for the 8,533-mi{sup 2}, closed-basin, Death Valley watershed with its contributing drainage basins in the Yucca Mountain site area.

Grasso, D.N.

1996-07-01

16

Microscopic Identification of Prokaryotes in Modern and Ancient Halite, Saline Valley and Death Valley, California  

NASA Astrophysics Data System (ADS)

Primary fluid inclusions in halite crystallized in Saline Valley, California, in 1980, 2004-2005, and 2007, contain rod- and coccoid-shaped microparticles the same size and morphology as archaea and bacteria living in modern brines. Primary fluid inclusions from a well-dated (0-100,000 years), 90 m long salt core from Badwater Basin, Death Valley, California, also contain microparticles, here interpreted as halophilic and halotolerant prokaryotes. Prokaryotes are distinguished from crystals on the basis of morphology, optical properties (birefringence), and uniformity of size. Electron micrographs of microparticles from filtered modern brine (Saline Valley), dissolved modern halite crystals (Saline Valley), and dissolved ancient halite crystals (Death Valley) support in situ microscopic observations that prokaryotes are present in fluid inclusions in ancient halite. In the Death Valley salt core, prokaryotes in fluid inclusions occur almost exclusively in halite precipitated in perennial saline lakes 10,000 to 35,000 years ago. This suggests that trapping and preservation of prokaryotes in fluid inclusions is influenced by the surface environment in which the halite originally precipitated. In all cases, prokaryotes in fluid inclusions in halite from the Death Valley salt core are miniaturized (<1 ?m diameter cocci, <2.5 ?m long, very rare rod shapes), which supports interpretations that the prokaryotes are indigenous to the halite and starvation survival may be the normal response of some prokaryotes to entrapment in fluid inclusions for millennia. These results reinforce the view that fluid inclusions in halite and possibly other evaporites are important repositories of microbial life and should be carefully examined in the search for ancient microorganisms on Earth, Mars, and elsewhere in the Solar System.

Schubert, Brian A.; Lowenstein, Tim K.; Timofeeff, Michael N.

2009-06-01

17

Imaging Radar Applications in the Death Valley Region  

NASA Technical Reports Server (NTRS)

Death Valley has had a long history as a testbed for remote sensing techniques (Gillespie, this conference). Along with visible-near infrared and thermal IR sensors, imaging radars have flown and orbited over the valley since the 1970's, yielding new insights into the geologic applications of that technology. More recently, radar interferometry has been used to derive digital topographic maps of the area, supplementing the USGS 7.5' digital quadrangles currently available for nearly the entire area. As for their shorter-wavelength brethren, imaging radars were tested early in their civilian history in Death Valley because it has a variety of surface types in a small area without the confounding effects of vegetation. In one of the classic references of these early radar studies, in a semi-quantitative way the response of an imaging radar to surface roughness near the radar wavelength, which typically ranges from about 1 cm to 1 m was explained. This laid the groundwork for applications of airborne and spaceborne radars to geologic problems in and regions. Radar's main advantages over other sensors stems from its active nature- supplying its own illumination makes it independent of solar illumination and it can also control the imaging geometry more accurately. Finally, its long wavelength allows it to peer through clouds, eliminating some of the problems of optical sensors, especially in perennially cloudy and polar areas.

Farr, Tom G.

1996-01-01

18

Inventory of amphibians and reptiles at Death Valley National Park  

USGS Publications Warehouse

As part of the National Park Service Inventory and Monitoring Program in the Mojave Network, we conducted an inventory of amphibians and reptiles at Death Valley National Park in 2002-04. Objectives for this inventory were to: 1) Inventory and document the occurrence of reptile and amphibian species occurring at DEVA, primarily within priority sampling areas, with the goal of documenting at least 90% of the species present; 2) document (through collection or museum specimen and literature review) one voucher specimen for each species identified; 3) provide a GIS-referenced list of sensitive species that are federally or state listed, rare, or worthy of special consideration that occur within priority sampling locations; 4) describe park-wide distribution of federally- or state-listed, rare, or special concern species; 5) enter all species data into the National Park Service NPSpecies database; and 6) provide all deliverables as outlined in the Mojave Network Biological Inventory Study Plan. Methods included daytime and nighttime visual encounter surveys, road driving, and pitfall trapping. Survey effort was concentrated in predetermined priority sampling areas, as well as in areas with a high potential for detecting undocumented species. We recorded 37 species during our surveys, including two species new to the park. During literature review and museum specimen database searches, we recorded three additional species from DEVA, elevating the documented species list to 40 (four amphibians and 36 reptiles). Based on our surveys, as well as literature and museum specimen review, we estimate an overall inventory completeness of 92% for Death Valley and an inventory completeness of 73% for amphibians and 95% for reptiles. Key Words: Amphibians, reptiles, Death Valley National Park, Inyo County, San Bernardino County, Esmeralda County, Nye County, California, Nevada, Mojave Desert, Great Basin Desert, inventory, NPSpecies.

Persons, Trevor B.; Nowak, Erika M.

2006-01-01

19

Principal facts for gravity stations in the Death Valley region, California  

USGS Publications Warehouse

Observed gravity values, station locations, terrain corrections, and Bouguer gravity data are provided in tabular form for approximately 1,500 gravity observations in eastern California. Coverage includes Saline Valley, Panamint Valley, Searles Basin, Death Valley, the southern Amargosa Desert and the enclosed and adjoining highlands. These data were used in preparation of -- Mabey, Don R., 1963, Complete Bouguer anomaly map of the Death Valley region, California: U.S. Geol. Survey Geophys. Inv. Map GP-305.

Mabey, Don R.

1972-01-01

20

Imaging Radar in the Mojave Desert-Death Valley Region  

NASA Technical Reports Server (NTRS)

The Mojave Desert-Death Valley region has had a long history as a test bed for remote sensing techniques. Along with visible-near infrared and thermal IR sensors, imaging radars have flown and orbited over the area since the 1970's, yielding new insights into the geologic applications of these technologies. More recently, radar interferometry has been used to derive digital topographic maps of the area, supplementing the USGS 7.5' digital quadrangles currently available for nearly the entire area. As for their shorter-wavelength brethren, imaging radars were tested early in their civilian history in the Mojave Desert-Death Valley region because it contains a variety of surface types in a small area without the confounding effects of vegetation. The earliest imaging radars to be flown over the region included military tests of short-wavelength (3 cm) X-band sensors. Later, the Jet Propulsion Laboratory began its development of imaging radars with an airborne sensor, followed by the Seasat orbital radar in 1978. These systems were L-band (25 cm). Following Seasat, JPL embarked upon a series of Space Shuttle Imaging Radars: SIRA (1981), SIR-B (1984), and SIR-C (1994). The most recent in the series was the most capable radar sensor flown in space and acquired large numbers of data swaths in a variety of test areas around the world. The Mojave Desert-Death Valley region was one of those test areas, and was covered very well with 3 wavelengths, multiple polarizations, and at multiple angles. At the same time, the JPL aircraft radar program continued improving and collecting data over the Mojave Desert Death Valley region. Now called AIRSAR, the system includes 3 bands (P-band, 67 cm; L-band, 25 cm; C-band, 5 cm). Each band can collect all possible polarizations in a mode called polarimetry. In addition, AIRSAR can be operated in the TOPSAR mode wherein 2 antennas collect data interferometrically, yielding a digital elevation model (DEM). Both L-band and C-band can be operated in this way, with horizontal resolution of about 5 m and vertical errors less than 2 m. The findings and developments of these earlier investigations are discussed.

Farr, Tom G.

2001-01-01

21

U-Series Chronology of Lacustrine Deposits in Death Valley, California  

Microsoft Academic Search

Uranium-series dating on a 186-m core (DV93-1) drilled from Badwater Basin in Death Valley, California, and on calcareous tufas from nearby strandlines shows that Lake Manly, the lake that periodically flooded Death Valley during the late Pleistocene, experienced large fluctuations in depth and chemistry over the last 200,000 yr. Death Valley has been occupied by a long-standing deep lake, perennial

Teh-Lung Ku; Shangde Luo; Tim K. Lowenstein; Jianren Li; Ronald J. Spencer

1998-01-01

22

Spatial variations in slip rate along the Death Valley-Fish Lake Valley fault system determined from LiDAR topographic data and  

E-print Network

- FLVFZ) is a prominent dextral fault system in the eastern California shear zone (ECSZ). Combining offsetSpatial variations in slip rate along the Death Valley-Fish Lake Valley fault system determined; accepted 11 July 2007; published 19 September 2007. [1] The Death Valley-Fish Lake Valley fault zone (DV

Frankel, Kurt L.

23

2 Spatial variations in slip rate along the Death Valley-Fish Lake Valley 3 fault system determined from LiDAR topographic data and  

E-print Network

FLVFZ) is a prominent dextral fault system in the eastern 11 California shear zone (ECSZ). Combining2 Spatial variations in slip rate along the Death Valley-Fish Lake Valley 3 fault system determined; accepted 11 July 2007; published XX Month 2007. 9 [1] The Death Valley-Fish Lake Valley fault zone (DV- 10

Black, Robert X.

24

California's Central Valley Groundwater Study: A Powerful New Tool to Assess Water Resources in California's Central Valley  

USGS Publications Warehouse

Competition for water resources is growing throughout California, particularly in the Central Valley. Since 1980, the Central Valley's population has nearly doubled to 3.8 million people. It is expected to increase to 6 million by 2020. Statewide population growth, anticipated reductions in Colorado River water deliveries, drought, and the ecological crisis in the Sacramento-San Joaquin Delta have created an intense demand for water. Tools and information can be used to help manage the Central Valley aquifer system, an important State and national resource.

Faunt, Claudia C.; Hanson, Randall T.; Belitz, Kenneth; Rogers, Laurel

2009-01-01

25

Seafloor-precipitated carbonate fans in the Neoproterozoic Rainstorm Member, Johnnie Formation, Death Valley Region, USA  

E-print Network

, Death Valley Region, USA Sara Brady Pruss ,a , Frank A. Corsetti b , Woodward W. Fischer c a Department Member of the Johnnie Formation, Death Valley, USA. The fans formed in a mixed carbonate of carbonates that cap low latitude glacial deposits of the Neoproterozoic (e.g. Kennedy, 1996; Hoffman et al

Fischer, Woodward

26

Geology, 2000, v. 33, p. 958-959 PrecambrianCambrian transition: Death Valley, United  

E-print Network

Geology, 2000, v. 33, p. 958-959 Precambrian­Cambrian transition: Death Valley, United States of Technology Pasadena, CA 91125 We thank Graham for alerting Geology readers to his work in Mongolia, it is important to note that our manuscript was not an attempt to tout the Death Valley section as the "best

Hagadorn, Whitey

27

Preliminary Assessment of Urban Growth in California's Central Valley  

NSDL National Science Digital Library

This preliminary assessment of urban growth in the Central Valley of California is intended to illustrate the dramatic changes to the Central Valley landscape over the past 100 years. Data products include an urban growth timeline for the years 1900 to 1996, an animated version of the same timeline, and graphs showing the increase in population and built-up land for the same period.

28

The Central Valley Winegrape IndustryThe Central Valley Winegrape Industry and the World Market for Wine  

E-print Network

Agricultural Issues Center January 5, 2011 The Central Valley is a Central Part of the Competitive World to fall in traditional big wine producing European countries · Much of world trade is within the EU South and the World Market for Wine Daniel A. Sumner U i it f C lif i A i lt l I C tUniversity of California

Ferrara, Katherine W.

29

Quaternary tilt of Death Valley determined from landform modelling of alluvial fans  

SciTech Connect

Alluvial fans along the east side of central Death Valley are being actively back-tilted along the Death Valley fault zone. Initial modelling of the Copper Canyon and Furnace Creek fans led to recognition of distinct segments. Field reconnaissance and aerial photo mapping were conducted to check model results and improve segment discrimination. Surface roughness, relative position, vegetation distribution, and drainage patterns provided independent evidence for segment discrimination. Subsequent modelling of individual segments produced a range of tilt values from 0.275[degree] to 0.559[degree] down to the northeast. Continued analysis of these fan segments is concentrated on: (1) assigning confidence and error values to the tilt values; and (2) dating individual segments. Further work will compare the tilt rates of east-side fans with those from the west. The mean squared error (MSE) is currently being used as a first order assessment of the quality of the model's fit to data digitized from 1:24,000 scale USGS topographic maps. MSE values of 1 m or less can be expected for relatively young or actively aggrading segments. Previous fan models have found the expected range of misfits to be between 2 m and 5 m. This seven parameter least squares model has produced fits with less than 2 m total range in misfits. Previous models have not accounted for tilt or have relied on simplifying assumptions to fix apex position.

West, R.B.; Wilson, D.S. (Univ. of California, Santa Barbara, CA (United States). Dept. of Geology)

1993-04-01

30

Morphological and Geomicrobiological Characteristics of an Endolithic Microbial Community from the Badwater Basin, Death Valley, California  

NASA Technical Reports Server (NTRS)

ESEM-EDS studies of an endolithic evaporite community from Death Valley revealed its ability to sequester water and affect the partitioning of trace metals in this environment. Additional information is contained in the original extended abstract.

Douglas, S.

2001-01-01

31

Geologic Map of the Death Valley Ground-water Model Area, Nevada and California  

SciTech Connect

The purpose of this map is to provide the surface expression of the geology in the Death Valley ground-water model area to be incorporated initially into a 3-D geologic framework model and eventually into a transient ground-water flow model by the U.S. Geological Survey (D'Agnese, 2000; D'Agnese and Faunt, 1999; Faunt and others, 1999; and O'Brien and others, 1999). This work has been conducted in collaboration with the U.S. Department of Energy in order to assess regional ground water flow near the Nevada Test Site (NTS) and the potential radioactive waste repository at Yucca Mountain. The map is centered on the NTS and its perimeter encircles the entire boundary of the numerical flow model area, covering a total area of 57,000 km2. The physiography, geology, and tectonics of the model area are extremely complex (Hunt and Mabey, 1966; Stewart, 1980; Jennings, 1994; Slate and others, 2000; Wright and others, 1999b). The northern and eastern part of the area includes typical Basin and Range topography consisting of north-trending block-faulted ranges and intervening valleys. The central part contains diverse ranges, plateaus, basins, and alluvial flats (for example, the NTS volcanic highlands and Amargosa Valley). The rugged ranges and deep basins of the Death Valley region in eastern California are characteristic of the topography of the southern and western parts of the map area. The map spans numerous tectonic subdivisions of the Great Basin. Deformation includes several generations of upper Paleozoic to Mesozoic thrust faulting that have been dismembered by extensive regional Tertiary to Quaternary normal and strike-slip faults. Much of this extensional and translational deformation is active today, with rates and amounts that vary from low to moderate in the central, eastern, and northern parts of the study area in southern Nevada, to very high in the southwestern and western parts in eastern California. For detailed discussion of the tectonic framework of the map area, the reader is referred to Workman and others (2002).

J.B. Workman; C.M. Menges; W.R. Page; E.M. Taylor; E.B. Ekren; P.D. Rowley; G.L. Dixon; R.A. Thompson; L.A. Wright

2003-04-21

32

Student and School Indicators for Youth in California's Central Valley  

ERIC Educational Resources Information Center

Twenty percent of California's public-school students attend schools in the Central Valley. Many of these students are at risk of poor educational outcomes: One-quarter of the children in grades K-5 do not speak English or do not speak it well; one-half of all K-12 students participate in a subsidized lunch program. This sourcebook provides a…

Danenberg, Anne; Jepsen, Christopher; Cerdan, Pedro

2002-01-01

33

The Decline of Amphibians in California's Great Central Valley  

Microsoft Academic Search

Declines in amphibian populations are rarely reported on the community or ecosystem level. We combined broad-scale field sampling with historical analyses of museum records to quantify amphibian de- clines in California's Great Central Valley. Overall, amphibians showed an unambiguous pattern of decline, although the intensity of decline varied both geographically and taxonomically. The greatest geographical de- cline was detected in

Robert N. Fisher; H. Bradley Shaffer

1996-01-01

34

Sediment Flux Variation in Two Central Valley Rivers  

Microsoft Academic Search

Physical processes such as water and sediment movement exert strong influences on species and habitats in Central Valley streams and the Sacramento-San Joaquin Delta. In particular, accrual of sediment is critical to restoring ecological function to those areas that have previously been isolated from streams by levees. The present work quantifies the differences in flow and sediment flux regimes in

E. Fleenor; S. Geoffrey Schladow

35

Predictors of Chinook salmon extirpation in California's Central Valley  

E-print Network

Predictors of Chinook salmon extirpation in California's Central Valley S . C . Z E U G Department, University of California-Santa Barbara, Santa Barbara, CA, USA Abstract Chinook salmon, Oncorhynchus. These results suggest that regional extirpation of Chinook salmon has been driven by multiple forms

Cardinale, Bradley J.

36

Geologic map of the southern Funeral Mountains including nearby groundwater discharge sites in Death Valley National Park, California and Nevada  

USGS Publications Warehouse

This 1:50,000-scale geologic map covers the southern part of the Funeral Mountains, and adjoining parts of four structural basins—Furnace Creek, Amargosa Valley, Opera House, and central Death Valley—in California and Nevada. It extends over three full 7.5-minute quadrangles, and parts of eleven others—an area of about 1,000 square kilometers (km2). The boundaries of this map were drawn to include all of the known proximal hydrogeologic features that may affect the flow of groundwater that discharges from springs of the Furnace Creek basin, in the west-central part of the map. These springs provide the main potable water supply for Death Valley National Park. Major hydrogeologic features shown on this map include: (1) springs of the Furnace Creek basin, (2) a large Pleistocene groundwater discharge mound in the northeastern part of the map, (3) the exposed extent of limestones and dolomites that constitute the Paleozoic carbonate aquifer, and (4) the exposed extent of the alluvial conglomerates that constitute the Funeral Formation aquifer.

Fridrich, C.J.; Thompson, R.A.; Slate, J.L.; Berry, M.E.; Machette, M.N.

2012-01-01

37

Application of multispectral radar and LANDSAT imagery to geologic mapping in death valley  

NASA Technical Reports Server (NTRS)

Side-Looking Airborne Radar (SLAR) images, acquired by JPL and Strategic Air Command Systems, and visible and near-infrared LANDSAT imagery were applied to studies of the Quaternary alluvial and evaporite deposits in Death Valley, California. Unprocessed radar imagery revealed considerable variation in microwave backscatter, generally correlated with surface roughness. For Death Valley, LANDSAT imagery is of limited value in discriminating the Quaternary units except for alluvial units distinguishable by presence or absence of desert varnish or evaporite units whose extremely rough surfaces are strongly shadowed. In contrast, radar returns are most strongly dependent on surface roughness, a property more strongly correlated with surficial geology than is surface chemistry.

Daily, M.; Elachi, C.; Farr, T.; Stromberg, W.; Williams, S.; Schaber, G.

1978-01-01

38

Mapping playa evaporite minerals with AVIRIS data - A first report from Death Valley, California  

NASA Technical Reports Server (NTRS)

The feasibility of using imaging spectrometry in studies of playa evaporites is demonstrated by mapping efflorescent salt crusts in Death Valley (California), using Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data and a recently developed least-squares spectral band-fitting algorithm. It is shown that it was possible to remotely identify eight different saline minerals, including three borates that have not been previously reported for the Death Valley efflorescent crusts: hydroboracite, pinnoite, and rivadavite. The three borates are locally important phases in the crusts; at least one of them, rivadavite, appears to be forming directly from brine.

Crowley, James K.

1993-01-01

39

Evolution of a forearc basin, Luzon central valley, Philippines  

SciTech Connect

The Cenozoic history of the 14 km-thick Luzon Central Valley sequence illustrates the development of a forearc basin. Forearc basins are important both as major sediment traps and as sites of hydrocarbon accumulations. The Luzon basin is floored by oceanic crust on the seaward (western) side and older accreted terranes on the arc (eastern) side. Initial sedimentation on this oceanic crust occurred during early Tertiary northward translation and emplacement of the crust as an ophiolite along a strike-slip or oblique-slip zone. The basal sediments consist of pelagic limestones and thin ash layers overlain by sandy turbidites derived from uplift and progressive dissection of the opmolite. A sequence of arc-derived sediments at least 26,000 ft (8 km) thick was shed into the eastern (arc) side of the basin during late Paleogene to Quaternary convergence along the western margin of Luzon. By the middle Miocene, the Central Valley became a continuous, elongate basin fringed by extensive shelf deposits, along both the uplifted seaward and arc sides of the basin. Detritus shed from both flanks filled the subsiding basin and resulted in progressively shallower depths. Nonmarine deposition began in central portions of the basin in the Pliocene and migrated with time both north and south along the basin axis. Late Miocene to Holocene movement along the Philippine fault zone caused uplift and folding of adjacent parts of the basin. Exploration models for the Central Valley predict gasprone hydrocarbon generation in central portions of the basin at times that coincide with and postdate the formation of both structural and stratigraphic traps. Previous drilling in the basin has either been in areas with thermally immature source rocks or has failed to reach prospective intervals where thermal maturation is inferred. The hydrocarbon potential has not been determined adequately.

Bachman, S.B.; Lewis, S.D.; Schweller, W.J.

1983-07-01

40

Comparison of inversion models using AIRSAR data for Death Valley, California  

NASA Technical Reports Server (NTRS)

Polarimetric Airborne Synthetic Aperture Radar (AIRSAR) data were collected for the Geologic Remote Sensing Field Experiment (GRSFE) over Death Valley, California, USA, in September 1989. AIRSAR is a four-look, quid-polarizaiton, three frequency instrument. It collects measurements at C-band (5.66 cm), L-band (23.98 cm), and P-band (68.13 cm), and has a GIFOV of 10 meters and a swath width of 12 kilometers. Because the radar measures at three wavelengths, different scales of surface roughness are measured. Also, dielectric constants can be calculated from the data. The scene used in this study is in Death Valley, California and is located over Trail Canyon alluvial fan, the valley floor, and Artists Drive alluvial fan. The fans are very different in mineralogic makeup, size, and surface roughness. Trail Canyon fan is located on the west side of the valley at the base of the Panamint Range and is a large fan with older areas of desert pavement and younger active channels. The source for the material on southern part of the fan is mostly quartzites and there is an area of carbonate source on the northern part of the fan. Artists Drive fan is located at the base of the Black Mountains on the east side of the valley and is a smaller, young fan with its source mostly from volcanic rocks. The valley floor contains playa and salt deposits that range from smooth to Devil's Golf course type salt pinnacles.

Kierein-Young, Kathryn S.

1993-01-01

41

Isotopic evidence for climatic influence on alluvial-fan development in Death Valley, California  

SciTech Connect

At least three semiarid to arid cycles are recorded by ..delta../sup 13/C values of organic matter in layers of rock varnishes on surfaces of Hanaupah Canyon and Johnson Canyon alluvial fans, Death Valley, California. These isotopic paleoenvironmental signals are interpreted as indicating major periods of fan aggradation during relatively more humid periods and fan entrenchment during subsequent lengthy arid periods.

Dorn, R.I.; DeNiro, M.J.; Ajie, H.O.

1987-02-01

42

Effects of Groundwater Development on Uranium: Central Valley, California, USA  

USGS Publications Warehouse

Uranium (U) concentrations in groundwater in several parts of the eastern San Joaquin Valley, California, have exceeded federal and state drinking water standards during the last 20 years. The San Joaquin Valley is located within the Central Valley of California and is one of the most productive agricultural areas in the world. Increased irrigation and pumping associated with agricultural and urban development during the last 100 years have changed the chemistry and magnitude of groundwater recharge, and increased the rate of downward groundwater movement. Strong correlations between U and bicarbonate suggest that U is leached from shallow sediments by high bicarbonate water, consistent with findings of previous work in Modesto, California. Summer irrigation of crops in agricultural areas and, to lesser extent, of landscape plants and grasses in urban areas, has increased Pco2 concentrations in the soil zone and caused higher temperature and salinity of groundwater recharge. Coupled with groundwater pumping, this process, as evidenced by increasing bicarbonate concentrations in groundwater over the last 100 years, has caused shallow, young groundwater with high U concentrations to migrate to deeper parts of the groundwater system that are tapped by public-supply wells. Continued downward migration of U-affected groundwater and expansion of urban centers into agricultural areas will likely be associated with increased U concentrations in public-supply wells. The results from this study illustrate the potential longterm effects of groundwater development and irrigation-supported agriculture on water quality in arid and semiarid regions around the world.

Jurgens, Bryant; Fram, Miranda S.; Belitz, Kenneth; Burow, Karen R.; Landon, Matthew K.

2009-01-01

43

InSAR Reveals a Potpourri of Deformation Signals in the Yucca Mountain -- Amargosa Valley -- Death Valley Region, Southwestern Nevada\\/Southeastern California  

Microsoft Academic Search

InSAR studies have revealed a variety of surface deformation signals attributed to several causes in the Yucca Mountain -- Amargosa Valley -- Death Valley region. This study utilizes 26 ERS 1 and 2 scenes to produce 34 interferometric pairs that cover the period of 1992 - 2000. Prominent signals that have been previously studied include the 1992 Little Skull Mountain

K. W. Katzenstein; J. W. Bell

2005-01-01

44

64 FR 69018 - Applications for the 2005 Resource Pool Power Allocations, Central Valley Project  

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF ENERGY Western Area Power Administration Applications for the 2005 Resource Pool Power Allocations, Central Valley Project AGENCY: Western Area Power Administration, DOE. ACTION: Notice of...

1999-12-09

45

Effects of Groundwater Development on Uranium: Central Valley, California, USA  

USGS Publications Warehouse

Uranium (U) concentrations in groundwater in several parts of the eastern San Joaquin Valley, California, have exceeded federal and state drinking water standards during the last 20 years. The San Joaquin Valley is located within the Central Valley of California and is one of the most productive agricultural areas in the world. Increased irrigation and pumping associated with agricultural and urban development during the last 100 years have changed the chemistry and magnitude of groundwater recharge, and increased the rate of downward groundwater movement. Strong correlations between U and bicarbonate suggest that U is leached from shallow sediments by high bicarbonate water, consistent with findings of previous work in Modesto, California. Summer irrigation of crops in agricultural areas and, to lesser extent, of landscape plants and grasses in urban areas, has increased Pco2 concentrations in the soil zone and caused higher temperature and salinity of groundwater recharge. Coupled with groundwater pumping, this process, as evidenced by increasing bicarbonate concentrations in groundwater over the last 100 years, has caused shallow, young groundwater with high U concentrations to migrate to deeper parts of the groundwater system that are tapped by public-supply wells. Continued downward migration of U-affected groundwater and expansion of urban centers into agricultural areas will likely be associated with increased U concentrations in public-supply wells. The results from this study illustrate the potential long-term effects of groundwater development and irrigation-supported agriculture on water quality in arid and semiarid regions around the world. Journal compilation ?? 2009 National Ground Water Association. No claim to original US government works.

Jurgens, B.C.; Fram, M.S.; Belitz, K.; Burow, K.R.; Landon, M.K.

2010-01-01

46

Ground-Water Modeling of the Death Valley Region, Nevada and California  

USGS Publications Warehouse

The Death Valley regional ground-water flow system (DVRFS) of southern Nevada and eastern California covers an area of about 100,000 square kilometers and contains very complex geology and hydrology. Using a computer model to represent the complex system, the U.S. Geological Survey simulated ground-water flow in the Death Valley region for use with U.S. Department of Energy projects in southern Nevada. The model was created to help address contaminant cleanup activities associated with the underground nuclear testing conducted from 1951 to 1992 at the Nevada Test Site and to support the licensing process for the proposed geologic repository for high-level nuclear waste at Yucca Mountain, Nevada.

Belcher, W. R.; Faunt, C. C.; Sweetkind, D. S.; Blainey, J. B.; San Juan, C. A.; Laczniak, R. J.; Hill, M. C.

2006-01-01

47

Insiders Views of the Valley of Death Behavioral and Institutional Perspectives  

SciTech Connect

Valley of death describes the metaphorical depths to which promising science and technology too often plunge, never to emerge and reach their full potential. Behavioral and institutional perspectives help in understanding the implications of choices that inadvertently lead into rather than over the valley of death. A workshop conducted among a diverse set of scientists, managers, and technology transfer staff at a U.S. national laboratory is a point of departure for discussing behavioral and institutional elements that promote or impede the pathway from research toward use, and for suggesting actionable measures that can facilitate the flow of information and products from research toward use. In the complex systems that comprise research institutions, where competing pressures can create barriers to information or technology transfer, one recommendation is to re-frame the process as a more active ushering toward use.

Wolfe, Amy K [ORNL] [ORNL; Bjornstad, David J [ORNL] [ORNL; Shumpert, Barry L [ORNL] [ORNL; Wang, Stephanie [ORNL] [ORNL; Lenhardt, W Christopher [ORNL] [ORNL; Campa Ayala, Maria F [ORNL] [ORNL

2014-01-01

48

Quantitative analysis of surface characteristics and morphology in Death Valley, California using AIRSAR data  

NASA Technical Reports Server (NTRS)

The Jet Propulsion Laboratory Airborne Synthetic Aperture Radar (JPL-AIRSAR) is used to collect full polarimetric measurements at P-, L-, and C-bands. These data are analyzed using the radar analysis and visualization environment (RAVEN). The AIRSAR data are calibrated using in-scene corner reflectors to allow for quantitative analysis of the radar backscatter. RAVEN is used to extract surface characteristics. Inversion models are used to calculate quantitative surface roughness values and fractal dimensions. These values are used to generate synthetic surface plots that represent the small-scale surface structure of areas in Death Valley. These procedures are applied to a playa, smooth salt-pan, and alluvial fan surfaces in Death Valley. Field measurements of surface roughness are used to verify the accuracy.

Kierein-Young, K. S.; Kruse, F. A.; Lefkoff, A. B.

1992-01-01

49

200 k.y. paleoclimate record from Death Valley salt core  

Microsoft Academic Search

A 186-m-long core (DV93-1) from Death Valley, California, composed of interbedded salts and muds contains a 200 k.y. record of closed-basin environments and paleoclimates, interpreted on the basis of sedimentology, ostracodes, homogenization temperatures of fluid inclusions in halite, and correlation with shoreline tufa. The 200 k.y. paleoclimate record is dominated by two dry and\\/or warm and wet and cold cycles

Tim K. Lowenstein; Jianren Li; Christopher Brown; Sheila M. Roberts; Teh-Lung Ku; Shangde Luo; Wenbo Yang

1999-01-01

50

In-Situ Arsenic Remediation in Carson Valley, Douglas County, West-Central Nevada  

E-print Network

In-Situ Arsenic Remediation in Carson Valley, Douglas County, West-Central Nevada Scientific County U.S. Department of the Interior U.S. Geological Survey #12;#12;In-Situ Arsenic Remediation.G., and Welch, A.H., 2010, In-situ arsenic remediation in Carson Valley, Douglas County, west-central Nevada: U

51

200 k.y. paleoclimate record from Death Valley salt core  

SciTech Connect

A 186-m-long core (DV93-1) from Death Valley, California, composed of interbedded salts and muds contains a 200 k.y. record of closed-basin environments and paleoclimates, interpreted on the basis of sedimentology, ostracodes, homogenization temperatures of fluid inclusions in halite, and correlation with shoreline tufa. The 200 k.y. paleoclimate record is dominated by two dry and/or warm and wet and cold cycles that occurred on a 100 k.y. time scale. These cycles begin with mud-flat deposits (192 ka to bottom of core, and 60 ka to 120 ka). Wetter and/or colder conditions produced greater effective moisture; saline pan and shallow saline lake evaporites overlie mud-flat sediments (186 ka to 192 ka and 35 ka to 60 ks). Eventually, enough water entered Death Valley to sustain perennial lakes that had fluctuating water levels and salinities (120 ka to 186 ka and 10 ka to 35 ka). When more arid conditions returned, mud-flat deposits accumulated on top of the perennial lake sediments, completing the cycle (120 ka and 10 ka). Of particular significance are the major lacustrine phases, 10 ka to 35 ka and 120 ka to 186 ka (oxygen isotope stages 2 and 5e--6), which represent markedly colder and wetter conditions than those of modern Death Valley. Of the two major lake periods, the penultimate glacial lakes were deeper and far longer lasting than those of the last glacial.

Lowenstein, T.K.; Li, J.; Brown, C. [State Univ. of New York, Binghamton, NY (United States). Dept. of Geological Sciences and Environmental Studies] [State Univ. of New York, Binghamton, NY (United States). Dept. of Geological Sciences and Environmental Studies; Roberts, S.M. [Western Montana Coll., Dillon, MT (United States). Environmental Sciences Dept.] [Western Montana Coll., Dillon, MT (United States). Environmental Sciences Dept.; Ku, T.L.; Luo, S. [Univ. of Southern California, Los Angeles, CA (United States). Dept. of Earth Sciences] [Univ. of Southern California, Los Angeles, CA (United States). Dept. of Earth Sciences; Yang, W. [State Univ. of New York, Stony Brook, NY (United States). Marine Science Research Center] [State Univ. of New York, Stony Brook, NY (United States). Marine Science Research Center

1999-01-01

52

Integration of AIRSAR and AVIRIS data for Trail Canyon alluvial fan, Death Valley, California  

NASA Technical Reports Server (NTRS)

Combining quantitative geophysical information extracted from the optical and microwave wavelengths provides complementary information about both the surface mineralogy and morphology. This study combines inversion results from two remote sensing instruments, a polarimetric synthetic aperture radar, AIRSAR, and an imaging spectrometer, AVIRIS, for Trail Canyon alluvial fan in Death Valley, California. The NASA/JPL Airborne Synthetic Aperture Radar (AIRSAR) is a quad-polarization, three frequency instrument. AIRSAR collects data at C-band = 5.66 cm, L-band = 23.98 cm, and P-band = 68.13 cm. The data are processed to four-looks and have a spatial resolution of 10 m and a swath width of 12 km. The AIRSAR data used in this study were collected as part of the Geologic Remote Sensing Field Experiment (GRSFE) over Death Valley on 9/14/89. The Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) is a NASA/JPL instrument that flies in an ER-2 aircraft at an altitude of 20 km. AVIRIS uses four spectrometers to collect data in 224 spectral channels from 0.4 micrometer to 2.45 micrometer. The width of each spectral band is approximately 10 nm. AVIRIS collects data with a swath width of 11 km and a pixel size of 20 m. The AVIRIS data used in this study were collected over Death Valley on 5/31/92.

Kierein-Young, Kathryn S.

1995-01-01

53

Slip Rates, Recurrence Intervals and Earthquake Event Magnitudes for the southern Black Mountains Fault Zone, southern Death Valley, California  

Microsoft Academic Search

The normal-oblique Black Mountain Fault zone (BMFZ) is part of the Death Valley fault system. Strong ground-motion generated by earthquakes on the BMFZ poses a serious threat to the Las Vegas, NV area (pop. ~1,428,690), the Death Valley National Park (max. pop. ~20,000) and Pahrump, NV (pop. 30,000). Fault scarps offset Holocene alluvial-fan deposits along most of the 80-km length

M. Fronterhouse Sohn; J. R. Knott; D. D. Bowman

2005-01-01

54

78 FR 5162 - Designation of a Nonessential Experimental Population of Central Valley Spring-Run Chinook Salmon...  

Federal Register 2010, 2011, 2012, 2013

...of Central Valley Spring-Run Chinook Salmon Below Friant Dam in the San Joaquin...of Central Valley spring-run Chinook salmon under section 10(j) of the...of Central Valley spring-run Chinook salmon under section 10(j) of...

2013-01-24

55

Appraisal of the water resources of Death Valley, California-Nevada  

USGS Publications Warehouse

The hydrologic system in Death Valley is probably in a steady-state condition--that is, recharge and discharge are equal, and net changes in the quantity of ground water in storage are not occurring. Recharge to ground water in the valley is derived from interbasin underflow and from local precipitation. The two sources may be of the same magnitude. Ground water beneath the valley moves toward the lowest area, a 200-square-mile saltpan, much of which is underlain by rock salt and other saline minerals, probably to depths of hundreds of feet or even more than 1,000 feet. Some water discharges from the saltpan by evaportranspiration. Water beneath the valley floor, excluding the saltpan, typically contains between 3,000 and 5,000 milligrams per liter of dissolved solids. Water from most springs and seeps in the mountains contains a few hundred to several hundred milligrams per liter of dissolved solids. Water from large springs that probably discharge from interbasin flow systems typically contains between 500 and 1,000 milligrams per liter dissolved solids. Present sites of intensive use by man are supplied by springs, with the exception of the Stovepipe Wells Hotel area. Potential sources of supply for this area include (1) Emigrant Spring area, (2) Cottonwood Spring, and (3) northern Mesquite Flat. (Woodard-USGS)

Miller, Glenn Allen

1977-01-01

56

An evaluation of Skylab (EREP) remote sensing techniques applied to investigation of crustal structure. [Death Valley and Greenwater Valley (CA)  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. A study of Greenwater Valley indicates that the valley is bounded on the north and east by faults, on the south by a basement high, and on the west by the dip slope of the black mountains, movement of ground water from the valley is thus Movement of ground water from the valley is thus restricted, indicating the valley is a potential water reservoir.

Bechtold, I. C. (principal investigator)

1974-01-01

57

Characterization of the Mid Summer Drought in the Central Valley of Costa Rica, Central America  

NASA Astrophysics Data System (ADS)

The IAS region is characterized by climate features of unique nature, one of them is the Mid-Summer Drought (MSD) or "veranillo", an atmospheric feature rarely observed in other tropical regions. On the Pacific slope of Central America, the precipitation annual cycle is characterized by two rainfall maxima in June and September-October, an extended dry season from November to May, and a secondary precipitation minima during July-August (MSD). Three daily gauge stations records, e.g. La Argentina, Fabio Baudrit and Juan Santamaria, located in the Central Valley of Costa Rica were studied to characterize the MSD from 1937 to 2010. Among the aspects considered are the MSD duration, intensity, timing and seasonal predictability. The modulation of these aspects by climate variability sources as Equatorial Eastern Pacific and Tropical North Atlantic was lately explored, including their interannual and decadal variability. The MSD signal strongly impact social and economic life in the region like energy and the agriculture sector. Additionally, the Central Valley of Costa Rica hosts most of the Costa Rican population with the higher level of exposure and vulnerability to hydro-meteorological hazards.

Alfaro, E.

2013-05-01

58

Emission rates of organics from vegetation in California's Central Valley  

NASA Astrophysics Data System (ADS)

Rates of emission of speciated hydrocarbons have been determined for more than 30 of the most dominant (based on acreage) agricultural and natural plant types found in California's Central Valley. These measurements employed flow-through Teflon chambers, sample collection on solid adsorbent and thermal desorption gas chromatography (GC) and GC-mass spectrometry analysis to identify more than 40 individual organic compounds. In addition to isoprene and the monoterpenes, we observed sesquiterpenes, alcohols, acetates, aldehydes, ketones, ethers, esters, alkanes, alkenes and aromatics as emissions from these plant species. Mean emission rates for total monoterpenes ranged from none detected in the case of beans, grapes, rice and wheat, to as high as 12-30 ?g h -1 g -1 for pistachio and tomato (normalized to dry leaf and total biomass, respectively). Other agricultural species exhibiting substantial rates of emission of monoterpenes included carrot, cotton, lemon, orange and walnut. All of the plant species studied showed total assigned compound emission rates in the range between 0.1 and 36 ?g h -1 g -1.

Winer, Arthur M.; Arey, Janet; Atkinson, Roger; Aschmann, Sara M.; Long, William D.; Morrison, C. Lynn; Olszyk, David M.

59

Geophysical surveys of a pluvial lake barrier deposit, Beatty Junction, Death Valley, California, USA  

NASA Astrophysics Data System (ADS)

We used ground penetrating radar (GPR) and seismic refraction to image the internal stratigraphy of a beach barrier deposit at Beatty Junction, Northern Death Valley, to better understand its depositional environment in the context of variations in the level of the former Lake Manly. The deposit is a gravelly bar ~ 500 m long with 4 m of surface relief that formed at a shoreline of Lake Manly during the end of the last Pleistocene ice age. The GPR profiles provide subsurface images that we interpret as progradational foreset beachface strata in the uppermost 2 m and the surface of an earlier bar at depths of 2 to 6 m. We conclude that the crest of the bar migrated in a landward direction during the construction of the uppermost 4 m of the bar as lake level rose. The seismic survey indicates a sharp velocity increase from 760 m/s to 1510 m/s at the base of the bar, which we interpret as the boundary between well-sorted gravelly beach deposits, and underlying older fan deposits. The depth of the base of the bar varies between 5 m and 10 m. The elevation of the bar is comparable to that of other shoreline features in Death Valley that formed during the MIS 6/5e (186-120 ka) highstand. Measurements of fault slip on the nearby Northern Death Valley fault have documented only strike-slip motion. In absence of any evidence for significant vertical uplift in the area during the late Pleistocene and Holocene, we conclude that the bar probably formed during MIS 6/5e. This conclusion is subject to uncertainty due to discrepancies in age dates reported for the deposit.

Craig, Mitchell S.; Jol, Harry M.; Teitler, Lora; Warnke, Detlef A.

2012-08-01

60

AVIRIS study of Death Valley evaporite deposits using least-squares band-fitting methods  

NASA Technical Reports Server (NTRS)

Minerals found in playa evaporite deposits reflect the chemically diverse origins of ground waters in arid regions. Recently, it was discovered that many playa minerals exhibit diagnostic visible and near-infrared (0.4-2.5 micron) absorption bands that provide a remote sensing basis for observing important compositional details of desert ground water systems. The study of such systems is relevant to understanding solute acquisition, transport, and fractionation processes that are active in the subsurface. Observations of playa evaporites may also be useful for monitoring the hydrologic response of desert basins to changing climatic conditions on regional and global scales. Ongoing work using Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data to map evaporite minerals in the Death Valley salt pan is described. The AVIRIS data point to differences in inflow water chemistry in different parts of the Death Valley playa system and have led to the discovery of at least two new North American mineral occurrences. Seven segments of AVIRIS data were acquired over Death Valley on 31 July 1990, and were calibrated to reflectance by using the spectrum of a uniform area of alluvium near the salt pan. The calibrated data were subsequently analyzed by using least-squares spectral band-fitting methods, first described by Clark and others. In the band-fitting procedure, AVIRIS spectra are fit compared over selected wavelength intervals to a series of library reference spectra. Output images showing the degree of fit, band depth, and fit times the band depth are generated for each reference spectrum. The reference spectra used in the study included laboratory data for 35 pure evaporite spectra extracted from the AVIRIS image cube. Additional details of the band-fitting technique are provided by Clark and others elsewhere in this volume.

Crowley, J. K.; Clark, R. N.

1992-01-01

61

Stream Seepage and Groundwater Levels, Wood River Valley, South-Central Idaho, 2012-13.  

National Technical Information Service (NTIS)

Stream discharge and water levels in wells were measured at multiple sites in the Wood River Valley, south.central Idaho, in August 2012, October 2012, and March 2013, as a component of data collection for a groundwater-flow model of the Wood River Valley...

J. R. Bartolino

2014-01-01

62

Interbasin flow in the Great Basin with special reference to the southern Funeral Mountains and the source of Furnace Creek springs, Death Valley, California, U.S.  

USGS Publications Warehouse

Interbasin flow in the Great Basin has been established by scientific studies during the past century. While not occurring uniformly between all basins, its occurrence is common and is a function of the hydraulic gradient between basins and hydraulic conductivity of the intervening rocks. The Furnace Creek springs in Death Valley, California are an example of large volume springs that are widely accepted as being the discharge points of regional interbasin flow. The flow path has been interpreted historically to be through consolidated Paleozoic carbonate rocks in the southern Funeral Mountains. This work reviews the preponderance of evidence supporting the concept of interbasin flow in the Death Valley region and the Great Basin and addresses the conceptual model of pluvial and recent recharge [Nelson, S.T., Anderson, K., Mayo, A.L., 2004. Testing the interbasin flow hypothesis at Death Valley, California. EOS 85, 349; Anderson, K., Nelson, S., Mayo, A., Tingey, D., 2006. Interbasin flow revisited: the contribution of local recharge to high-discharge springs, Death Valley, California. Journal of Hydrology 323, 276-302] as the source of the Furnace Creek springs. We find that there is insufficient modern recharge and insufficient storage potential and permeability within the basin-fill units in the Furnace Creek basin for these to serve as a local aquifer. Further, the lack of high sulfate content in the spring waters argues against significant flow through basin-fill sediments and instead suggests flow through underlying consolidated carbonate rocks. The maximum temperature of the spring discharge appears to require deep circulation through consolidated rocks; the Tertiary basin fill is of insufficient thickness to generate such temperatures as a result of local fluid circulation. Finally, the stable isotope data and chemical mass balance modeling actually support the interbasin flow conceptual model rather than the alternative presented in Nelson et al. [Nelson, S.T., Anderson, K., Mayo, A.L., 2004. Testing the interbasin flow hypothesis at Death Valley, California. EOS 85, 349] and Anderson et al. [Anderson, K., Nelson, S., Mayo, A., Tingey, D., 2006. Interbasin flow revisited: the contribution of local recharge to high-discharge springs, Death Valley, California. Journal of Hydrology 323, 276-302]. In light of these inconsistencies, interbasin flow is the only readily apparent explanation for the large spring discharges at Furnace Creek and, in our view, is the likely explanation for most large volume, low elevation springs in the Great Basin. An understanding of hydrogeologic processes that control the rate and direction of ground-water flow in eastern and central Nevada is necessary component of regional water-resource planning and management of alluvial and bedrock aquifers.

Belcher, W. R.; Bedinger, M. S.; Back, J. T.; Sweetkind, D. S.

2009-01-01

63

Stable sulfur isotope hydrogeochemical studies using desert shrubs and tree rings, Death Valley, California, USA  

NASA Astrophysics Data System (ADS)

The ? 34S values of two dominant xerophytes, Atriplex hymenehytra and Larrea tridentata, in Death Valley, California, vary similarly from +7 to +18‰, corresponding isotopically to sulfate in the water supplies at a given location. Going radially outwards, tree ring data from a phreatophyte tree, Tamarix aphylla, show a distinct time dependence, with ? 34S values increasing from +13.5 to +18‰ for soluble sulfate and from +12 to +17‰ for total sulfur. These data are interpreted in terms of sulfur sources, water sources and flow paths, and tree root growth.

Yang, Wenbo; Spencer, Ronald J.; Krouse, H. Roy

1996-08-01

64

Description of Tylenchorhynchus thermophilus n. sp. (Nematoda: Tylenchina) from Saltgrass in Death Valley, California  

PubMed Central

A stunt nematode, Tylenchorhynchus thermophilus n. sp., is described and illustrated from soil collected around roots of saltgrass (Distichlis spicata) in Death Valley, California. It is distinguished from the similar species, T. ewingi, T. mexicanus, and T. mashoodi, in having a longer female body, longer tail with more annules, and larger phasmids. Physical and chemical analysis of soil from saltgrass roots showed it to consist of 71% sand and possess high salinity (salt content of 0.51%) and a pH of 9.3. PMID:19277294

Golden, A. Morgan; Baldwin, James G.; Mundo-Ocampo, M.

1995-01-01

65

Description of Tylenchorhynchus thermophilus n. sp. (Nematoda: Tylenchina) from Saltgrass in Death Valley, California.  

PubMed

A stunt nematode, Tylenchorhynchus thermophilus n. sp., is described and illustrated from soil collected around roots of saltgrass (Distichlis spicata) in Death Valley, California. It is distinguished from the similar species, T. ewingi, T. mexicanus, and T. mashoodi, in having a longer female body, longer tail with more annules, and larger phasmids. Physical and chemical analysis of soil from saltgrass roots showed it to consist of 71% sand and possess high salinity (salt content of 0.51%) and a pH of 9.3. PMID:19277294

Golden, A M; Baldwin, J G; Mundo-Ocampo, M

1995-09-01

66

63 FR 41561 - Collections From Central Valley Project Power Contractors to Carry Out the Restoration...  

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF ENERGY Western Area Power Administration Collections From Central Valley Project Power Contractors to Carry Out the Restoration...Improvement Act of 1992 AGENCY: Western Area Power Administration, DOE. ACTION: Notice...

1998-08-04

67

63 FR 18005 - Collections From Central Valley Project Power Contractors to Carry Out the Restoration...  

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF ENERGY Western Area Power Administration Collections From Central Valley Project Power Contractors to Carry Out the Restoration...Improvement Act of 1992 AGENCY: Western Area Power Administration, DOE. ACTION: Notice...

1998-04-13

68

67 FR 65974 - Collections From Central Valley Project Power Contractors To Carry Out the Restoration...  

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF ENERGY Western Area Power Administration Collections From Central Valley Project Power Contractors To Carry Out the Restoration...Improvement Act of 1992 AGENCY: Western Area Power Administration, DOE. ACTION: Notice...

2002-10-29

69

68 FR 18621 - Collections from Central Valley Project Power Contractors to Carry Out the Restoration...  

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF ENERGY Western Area Power Administration Collections from Central Valley Project Power Contractors to Carry Out the Restoration...Improvement Act of 1992 AGENCY: Western Area Power Administration, DOE. ACTION: Notice...

2003-04-16

70

RELATIONSHIPS BETWEEN ENVIRONMENTAL VARIABLES AND BENTHIC DIATOM ASSEMBLAGES IN CALIFORNIA CENTRAL VALLEY STREAMS (USA)  

EPA Science Inventory

Streams and rivers in the California Central Valley Ecoregion have been substantially modified by human activities. This study examines distributional patterns of benthic diatom assemblages in relation to environmental characteristics in streams and rivers of this region. Benthic...

71

Holocene fluvial geomorphic change in the central Mississippi Valley  

SciTech Connect

Four distinct Mississippi River (MR) channel patterns are distinguished on the basis of geomorphic expression and cross-cutting relationships between the Missouri River mouth and Thebes Gap (TG). In order of decreasing age, they are (1) a multi-channeled braided system superimposed on a sandy substrate that correlates with the Kingston Terrace (KT); (2) a relatively large amplitude, large sinuosity, meandering system; (3) a smaller amplitude, smaller sinuosity, meandering system with a marked increase in associated overbank sheetwash and splays; and, (4) an island-braided pattern aligned with the modern (MR). After the (KT) formed, the (MR) had a net westward migration and episodically decreased in sinuosity. Decreasing sinuosity is possibly in response to a general decrease in sediment yield. Channel pattern changes are bracketed somewhat by available radiocarbon ages and the geomorphic location of archaeological deposit with temporally diagnostic artifacts. The KT formed between about 10,400 and 9800 B.P.; the superimposed braid pattern has fill consisting of Lake Superior source reddish brown clay deposited by large, and possibly catastrophic, floods between 9800 and 9500 B.P. The large sinuosity meandering pattern was active from before 4400 B.P. until about 2400 B.P. at the latest. It was probably initiated millennia earlier. The small sinuosity meandering pattern was initiated by about 2500 B.P. and abandoned before 1100 B.P. The geomorphic mapping is the first component of a geoarchaeological investigation to aid cultural resource management to aid cultural resource management in the central MR Valley. At the same time, it provides some constraints on the origin and age of some long-recognized landforms, such as the TG.

Hajic, E.R. (Illinois State Museum, Springfield, IL (United States))

1992-01-01

72

Paeloredox Conditions During Deposition of Neoproterozoic Low Latitude Glacial Strata of the Death Valley Region, CA  

NASA Astrophysics Data System (ADS)

Considerable debate surrounds the extent of late Neoproterozoic glaciations and their effect on ocean circulation, chemistry, and the evolution of life. Glacially interpreted diamictites are associated with banded iron formations suggesting the existence of a reduced ocean possibly caused by ice blocking ocean water- atmosphere oxygen exchange. However, differences in the stratigraphic position of the banded iron formations relative to the diamictite complicate their interpretation as indicators of widespread reducing conditions during deposition. To date little other evidence has been reported to substantiate the extent of ocean circulation or to examine the link between productivity, decomposition and the generation of reducing conditions. This work examines the geochemistry of two Neoproterozoic outcrops containing diamictite/cap carbonate pairs in Death Valley, CA to better understand their depositional environments. Paleoredox conditions are inferred from trace element concentrations and speciation. Geochemical evidence from the Death Valley sedimentary record does not support the existence of anoxic or euxinic ocean conditions during deposition. Neither the Marinoan diamictite nor the associated cap carbonate sequences show a major enrichment in trace metals. Minor enrichment in uranium and vanadium concentrations is seen at the diamictite/carbonate boundary and suggests that ocean conditions may have been mildly suboxic immediately following glaciation. Thus, these data indicate that the ocean basin experienced significant mixing and ocean-atmosphere gas exchange during and after glaciation.

Meyer, E. E.; Bostick, B. C.; Landis, J. D.; Quicksall, A. N.; Theissen, K. M.

2006-12-01

73

Contractional Strain Related to Interference of Intersecting Sets of Strike-slip Faults in the Southern Death Valley Region, California  

NASA Astrophysics Data System (ADS)

Structural and geomorphic data reveal complex neotectonic deformation(Pliocene-Quaternary, post 3-4 Ma)derived in part from interactions among intersecting sets of strike-slip faults in the southern Death Valley area on the eastern margin of the Eastern California Shear Zone. A distinct 40-km-wide domain of strike-slip faulting and associated contractional strain is bounded on the north by the southern end of the Panamint and Death Valley extensional terrane and on the south by the eastern Garlock fault (EGF). The dominant regional structures are (a) two NW-trending dextral-slip faults—the southern Death Valley fault (SDVF) and southern Panamint Valley fault (SPVF), and (b) three E- to NE-oriented sinistral-slip faults. This latter set includes the EGF, an associated splay of the Owl Lake fault (OLF) and a diffuse fault zone associated with discontinuous surface rupture in upper and central Wingate Wash valley (WWF). The strike-slip faults intersect with one another in a complex interference pattern that produces on-fault zones of transpressive deformation. These faults, moreover, are embedded within widespread areas of off-fault contractional strain in the intervening crustal blocks. Specifically, secondary on-fault transpressive deformation occurs along the majority of the EGF and SDVF and sections of the OLF and SPVF. This transpression is manifested as commonly asymmetric flower structures that produce domal to elongate zones of uplifted topography along the fault trace. Surface deformation within the flower structure appears partitioned between (a)translation along strike-slip faults in the dissected core of the uplifts and (b) contraction and uplift accommodated on near-surface blind thrusts below fault-propagation folds on the flanks of the structure. Where two or more large strike-slip faults intersect one another, one or more of the structures typically merges with or is truncated against one primary though-going structure. The geometry and slip-sense of the through-going structure commonly is altered at this intersection by development of an arcuate bend in the fault trace and (or) enhancement of any reverse-slip component. In the most extreme case, the EGF terminates in the Avawatz Mts. behind the apparent SE-continuation of the SDVF. This structure is characterized in the area of intersection by a stacked set of blind to emergent thrust faults and associated fault-propagation folds bounding a prominent NE-oriented arcuate salient in the range- front. The intersections of faults with opposing slip sense are additionally surrounded by broad aureoles of off- fault uplift and (or) tilting that induce significant bedrock incision and drainage rearrangement. Many crustal blocks between intersecting faults are internally deformed by contractional structures ranging from localized strain on folds and pop-up structures to broad linear zones of synformal downwarping and antiformal uplift. For example, the Owlshead Mts. block (OMB) has experienced complex contractional deformation on both boundary and internal fault and fold structures. This deformation in part is derived from mutual interference between intersecting sets of dextral faults (SDVF and SPV) and sinistral faults (WWF and EGF) that completely bound the block. Further, the entire OMB may have been laterally extruded to the northeast above a blind thrust system, thereby producing a distinct transpressive right-step or kink to the northeast in the SDVF, which bounds the block on that side.

Menges, C. M.; Pavlis, T. L.; McMackin, M. R.; Serpa, L.

2006-12-01

74

Map showing depth to pre-Cenozoic basement in the Death Valley ground-water model area, Nevada and California  

SciTech Connect

This map shows the depth to pre-Cenozoic basement in the Death Valley ground-water model area. It was prepared utilizing gravity (Ponce and others, 2001), geologic (Jennings and others, 1977; Stewart and Carlson, 1978), and drill-hole information. Geophysical investigations of the Death Valley ground-water model area are part of an interagency effort by the U.S. Geological Survey (USGS) and the U.S. Department of Energy (Interagency Agreement DE-AI08-96NV11967) to help characterize the geology and hydrology of southwestern Nevada and parts of California. The Death Valley ground-water model is located between lat 35 degrees 00' and 38 degrees 15' N., and long 115 degrees and 118 degrees W.

Blakely, R.J.; Ponce, D.A.

2002-03-12

75

Geologic application of thermal inertia imaging using HCMM data. [Death Valley and Piggah Crater, California and Goldfield, Nevada  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. The day infrared and visible HCMM satellite data for Death Valley taken on 31 May 1978 were compared with aircraft data of the same area taken in March of the same year. In the visible image, it is possible to note the drying of the valley floor during the two month period between acquisition of the two data sets. On the IR image however, the valley floor remains cool, probably indicating that while the standing water has disappeared, the floor is still moist.

Paley, H. N.; Kahle, A. B. (principal investigators)

1979-01-01

76

Fault pattern at the northern end of the Death Valley - Furnace Creek fault zone, California and Nevada  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. The pattern of faulting associated with the termination of the Death Valley-Furnace Creek Fault Zone in northern Fish Lake Valley, Nevada was studied in ERTS-1 MSS color composite imagery and color IR U-2 photography. Imagery analysis was supported by field reconnaissance and low altitude aerial photography. The northwest-trending right-lateral Death Valley-Furnace Creek Fault Zone changes northward to a complex pattern of discontinuous dip slip and strike slip faults. This fault pattern terminates to the north against an east-northeast trending zone herein called the Montgomery Fault Zone. No evidence for continuation of the Death Valley-Furnace Creek Fault Zone is recognized north of the Montgomery Fault Zone. Penecontemporaneous displacement in the Death Valley-Furnace Creek Fault Zone, the complex transitional zone, and the Montgomery Fault Zone suggests that the systems are genetically related. Mercury mineralization appears to have been localized along faults recognizable in ERTS-1 imagery within the transitional zone and the Montgomery Fault Zone.

Liggett, M. A. (principal investigator); Childs, J. F.

1974-01-01

77

Information for EAS 4802KF/8802KF Field Trip Saturday, March 20th: students arrive in Las Vegas, NV by 12:00 pm and drive to Death Valley; several  

E-print Network

It will be difficult for someone to contact you in Death Valley. Cell phones will not work here in Las Vegas, NV by 12:00 pm and drive to Death Valley; several field trip stops after arrival at camp Sunday Tuesday, March 21st 23rd: field trips and exercises in Death Valley, CA; camp in Death

Frankel, Kurt L.

78

Cenozoic tectonic reorganizations of the Death Valley region, southeast California and southwest Nevada  

USGS Publications Warehouse

The Death Valley region, of southeast California and southwest Nevada, is distinct relative to adjacent regions in its structural style and resulting topography, as well as in the timing of basin-range extension. Cenozoic basin-fill strata, ranging in age from greater than or equal to 40 to approximately 2 million years are common within mountain-range uplifts in this region. The tectonic fragmentation and local uplift of these abandoned basin-fills indicate a multistage history of basin-range tectonism. Additionally, the oldest of these strata record an earlier, pre-basin-range interval of weak extension that formed broad shallow basins that trapped sediments, without forming basin-range topography. The Cenozoic basin-fill strata record distinct stratigraphic breaks that regionally cluster into tight age ranges, constrained by well-dated interbedded volcanic units. Many of these stratigraphic breaks are long recognized formation boundaries. Most are angular unconformities that coincide with abrupt changes in depositional environment. Deposits that bound these unconformities indicate they are weakly diachronous; they span about 1 to 2 million years and generally decrease in age to the west within individual basins and regionally, across basin boundaries. Across these unconformities, major changes are found in the distribution and provenance of basin-fill strata, and in patterns of internal facies. These features indicate rapid, regionally coordinated changes in strain patterns defined by major active basin-bounding faults, coincident with step-wise migrations of the belt of active basin-range tectonism. The regionally correlative unconformities thus record short intervals of radical tectonic change, here termed "tectonic reorganizations." The intervening, longer (about 3- to 5-million-year) interval of gradual, monotonic evolution in the locus and style of tectonism are called "tectonic stages." The belt of active tectonism in the Death Valley region has abruptly stepped westward during three successive tectonic reorganizations that intervened between four stages of basin-range tectonism, the youngest of which is ongoing. These three tectonic reorganizations also intervened between four stages of volcanic activity, each of which has been distinct in the compositions of magmas erupted, in eruption rates, and in the locus of volcanic activity—which has stepped progressively westward, in close coordination with the step-wise migrations in the locus of basin-range extension. The timing of the Cenozoic tectonic reorganizations in the Death Valley region correlates closely with the documented timing of episodic reorganizations of the boundary between the Pacific and North American plates, to the west and southwest. This supports models that explain the widely distributed transtensional tectonism in southwestern North America since approximately 40 million years ago as resulting from traction imposed by the adjacent, divergent Pacific plate.

Fridrich, Christopher J.; Thompson, Ren A.

2011-01-01

79

Hydrology of the San Luis Valley, south-central Colorado  

USGS Publications Warehouse

An investigation of the water resources of the Colorado part of the San Luis Valley was begun in 1966 by the U.S. Geological Survey, in cooperation with the Colorado Water Conservation Board. (See index map, fig. 1). The purpose of the investigation is to provide information for planning and implementing improved water-development and management practices. The major water problems in the San Luis Valley include (1) waterlogging, (2) waste of water by nonbeneficial evapotranspiration, (3) deterioration of ground-water chemical quality, and (4) failure of Colorado to deliver water to New Mexico and Texas in accordance with the Rio Grande Compact. This report describes the hydrologic environment, extent of water-resource development, and some of the problems related to that development. Information presented is based on data collected from 1966 to 1968 and on previous studies. Subsequent reports are planned as the investigation progresses. The San Luis Valley extends about 100 miles from Poncha Pass near the northeast corner of Saguache County, Colo., to a point about 16 miles south of the Colorado-New Mexico State line. The total area is 3,125 square miles, of which about 3,000 are in Colorado. The valley is nearly flat except for the San Luis Hills and a few other small areas. The Colorado part of the San Luis Valley, which is described in this report, has an average altitude of about 7,700 feet. Bounding the valley on the west are the San Juan Mountains and on the east the Sangre de Cristo Mountains. Most of the valley floor is bordered by alluvial fans deposited by streams originating in the mountains, the most extensive being the Rio Grande fan (see block diagram, fig. 2 in pocket). Most of the streamflow is derived from snowmelt from 4,700 square miles of watershed in the surrounding mountains. The northern half of the San Luis Valley is internally drained and is referred to as the closed basin. The lowest part of this area is known locally as the "sump." The remainder of the valley is drained by the Rio Grande and its tributaries. The climate of the San Luis Valley is arid, and a successful agricultural economy would not be possible without irrigation. It is characterized by cold winters, moderate summers, and much sunshine. The average annual precipitation on the valley floor ranges from 7 to 10 inches. More than half the precipitation occurs from July to September. Moisture deficiency in the valley is shown by the graph comparing pan evaporation and precipitation {fig. 3}. For the years 1961-67 average pan evaporation for the period April through September was 52.25 inches, but average precipitation for the period was only 5.02 inches. Average annual precipitation was 7.8 inches. Owing to the short growing season (90-120 days), crops a.re restricted mainly to barley, oats, potatoes, and other vegetables.

Emery, P. A.; Boettcher, A. J.; Snipes, R. J.; Mcintyre, H. J., Jr.

1969-01-01

80

GEOLOGY AND ORIGIN OF THE DEATH VALLEY URANIUM DEPOSIT, SEWARD PENINSULA, ALASKA.  

USGS Publications Warehouse

A uranium deposit discovered in 1977 in western Alaska, by means of airborne radiometric data, is the largest known in Alaska on the basis of industry reserve estimates. The deposit is apparently of epigenetic and supergene origin. The uranium was derived from the Cretaceous granite of the Darby pluton that forms part of the western side of Death Valley. Uranium from primary mineralization is in the subsurface in a marginal facies of the Tertiary sedimentary basin where nearshore coarse clastic rocks are interbedded with coal and lacustrine clay. The supergene enrichment is related to a soil horizon at the present ground surface. Extensive exploratory drilling took place from 1979 to 1981. The average grade of the potential ore is 0. 27 percent U//3O//8 and the average thickness is 3 m. The calculated reserves are 1,000,000 lbs U//3O//8; additional drilling would probably add to this figure. Additional study results are discussed.

Dickinson, Kendell A.; Cunningham, Kenneth D.; Ager, Thomas A.

1987-01-01

81

Death Valley regional groundwater flow model calibration using optimal parameter estimation methods and geoscientific information systems  

USGS Publications Warehouse

A three-layer Death Valley regional groundwater flow model was constructed to evaluate potential regional groundwater flow paths in the vicinity of Yucca Mountain, Nevada. Geoscientific information systems were used to characterize the complex surface and subsurface hydrogeological conditions of the area, and this characterization was used to construct likely conceptual models of the flow system. The high contrasts and abrupt contacts of the different hydrogeological units in the subsurface make zonation the logical choice for representing the hydraulic conductivity distribution. Hydraulic head and spring flow data were used to test different conceptual models by using nonlinear regression to determine parameter values that currently provide the best match between the measured and simulated heads and flows.

D'Agnese, F. A.; Faunt, C. C.; Hill, M. C.; Turner, A. K.

1996-01-01

82

Estimated ground-water discharge by evapotranspiration from Death Valley, California, 1997-2001  

USGS Publications Warehouse

The U.S. Geological Survey, in cooperation with the National Park Service and Inyo County, Calif., collected field data from 1997 through 2001 to accurately estimate the amount of annual ground-water discharge by evapotranspiration (ET) from the floor of Death Valley, California. Multispectral satellite-imagery and National Wetlands Inventory data are used to delineate evaporative ground-water discharge areas on the Death Valley floor. These areas are divided into five general units where ground-water discharge from ET is considered to be significant. Based upon similarities in soil type, soil moisture, vegetation type, and vegetation density; the ET units are salt-encrusted playa (21,287 acres), bare-soil playa (75,922 acres), low-density vegetation (6,625 acres), moderate-density vegetation (5,019 acres), and high-density vegetation (1,522 acres). Annual ET was computed for ET units with micrometeorological data which were continuously measured at six instrumented sites. Total ET was determined at sites that were chosen for their soil- and vegetated-surface conditions, which include salt-encrusted playa (extensive salt encrustation) 0.17 feet per year, bare-soil playa (silt and salt encrustation) 0.21 feet per year, pickleweed (pickleweed plants, low-density vegetation) 0.60 feet per year, Eagle Borax (arrowweed plants and salt grass, moderate-density vegetation) 1.99 feet per year, Mesquite Flat (mesquite trees, high-density vegetation) 2.86 feet per year, and Mesquite Flat mixed grasses (mixed meadow grasses, high-density vegetation) 3.90 feet per year. Precipitation, flooding, and ground-water discharge satisfy ET demand in Death Valley. Ground-water discharge is estimated by deducting local precipitation and flooding from cumulative ET estimates. Discharge rates from ET units were not estimated directly because the range of vegetation units far exceeded the five specific vegetation units that were measured. The rate of annual ground-water discharge by ET for each ET unit was determined by fitting the annual ground-water ET for each site with the variability in vegetation density in each ET unit. The ET rate representing the midpoint of each ET unit was used as the representative value. The rate of annual ground-water ET for the playa sites did not require scaling in this manner. Annual ground-water discharge by ET was determined for all five ET units: salt-encrusted playa (0.13 foot), bare-soil playa (0.15 foot), low-density vegetation (1.0 foot), moderate-density vegetation (2.0 feet), and high-density vegetation (3.0 feet), and an area of vegetation or bare soil not contributing to ground-water discharge unclassified (0.0 foot). The total ground-water discharge from ET for the Death Valley floor is about 35,000 acre-feet and was computed by summing the products of the area of each ET unit multiplied by a corresponding ET rate for each unit.

DeMeo, Guy A.; Laczniak, Randell J.; Boyd, Robert A.; Smith, J. LaRue; Nylund, Walter E.

2003-01-01

83

HELIOTHERMAL LAKE MODEL OF BORATE DEPOSITION IN THE MIOCENE FURNACE CREEK FORMATION, DEATH VALLEY REGION, CALIFORNIA.  

USGS Publications Warehouse

Heliothermal lakes are density-stratified with shallow submerged margins surrounding areally restricted deep pool(s) containing a dense brine overlain by a much less dense brine. The reflective brine interface allows solar energy to be trapped in the dense brine which may warm to over 90 degree C. Carbonate precipitated from the dense brine is the typical sediment produced in warm deep pool. Miocene borate deposits of the Death Valley region are typically contained within areally limited carbonate-rich pods that interfinger with a finely interlaminated (varve-like) mudstone and limestone. Primary borates there are predominately either Na-Ca borates or Ca-borates. This bimodal evaporite assemblage suggests that brine chemistries and (or) crystallization paths varied significantly in temporally and spatially related portions of this apparently continuous lacustrine deposit.

Barker, Charles E.; Barker, James M.

1988-01-01

84

High-angle origin of the currently low-angle Badwater Turtleback fault, Death Valley, California  

SciTech Connect

The late Cenozoic Badwater Turtleback fault separates an upper plate of volcanic and sedimentary rocks from a lower plate of predominantly mylonitic plutonic and metamorphic rocks. The Turtleback fault, however, is not a single continuous surface, but consists of a least three generations of faults. These faults occur as discrete, crosscutting segments that progressively decrease in age and increase in dip to the west. Therefore, they probably began at moderate to steep angles but rotated to lower angles with extensional strain. If so, lower plate mylonitic rocks also restore to steeper dips and suggest that transport of the upper plate occurred on moderate to steeply dipping surfaces in the middle and upper crust. The crosscutting nature of the fault segments and their initial moderate to steep dips, plus a possible offset marker on one of the segments, are most consistent with moderate amounts of extension in the Death Valley region.

Miller, M.G. (Univ. of Washington, Seattle (USA))

1991-04-01

85

Characterizing the hydrogeologic framework of the Death Valley region, Southern Nevada and California  

USGS Publications Warehouse

Three-dimensional (3-D) hydrogeologic modeling of the complex geology of the Death Valley region requires the application of a number of Geoscientific Information System (GSIS) techniques. This study, funded by United States Department of Energy as a part of the Yucca Mountain Project, focuses on an area of approximately 100,000 square kilometers (three degrees of latitude by three degrees of longitude) and extends up to ten kilometers in depth. The geologic conditions are typical of the Basin and Range province; a variety of sedimentary and igneous intrusive and extrusive rocks have been subjected to both compressional and extensional deformation. GSIS techniques allow the synthesis of geologic, hydrologic and climatic information gathered from many sources, including satellite imagery and published maps and cross-sections. Construction of a 3-D hydrogeological model is possible with the combined use of software products available from several vendors, including traditional GIS products and sophisticated contouring, interpolation, visualization, and numerical modeling packages.

Faunt, Claudia; D'Agnese, Frank; Downey, Joe S.; Turner, A. Keith

1993-01-01

86

Tectonic map of the Death Valley ground-water model area, Nevada and California  

SciTech Connect

The purpose of this map is to provide tectonic interpretations in the Death Valley ground-water model area to be incorporated into a transient ground-water flow model by the U.S. Geological Survey (D'Agnese, 2000; D'Agnese and Faunt, 1999; Faunt and others, 1999; and O'Brien and others, 1999). This work has been conducted in collaboration with the U.S. Department of Energy in order to assess regional ground-water flow near the Nevada Test Site (NTS) and the potential radioactive waste repository at Yucca Mountain. The map is centered on the NTS and its perimeter encircles the entire boundary of the numerical flow model area, covering a total area of 57,000 square kilometers. This tectonic map is a derivative map of the geologic map of the Death Valley ground-water model, Nevada and California (Workman and others, 2002). Structures portrayed on the tectonic map were selected from the geologic map based upon several criteria including amount of offset on faults, regional significance of structures, fault juxtaposition of rocks with significantly different hydrologic properties, and the hydrologic properties of the structures themselves. Inferred buried structures in the basins were included on the map (blue and light blue dotted lines) based on interpretation of geophysical data (Ponce and others, 2001; Ponce and Blakely, 2001; Blakely and Ponce, 2001). In addition, various regional trends of fault zones have been delineated which are composed of multiple smaller scale features. In some cases, these structures are deeply buried and their location is based primarily on geophysical evidence. In all cases, these zones (shown as broad red and blue stippled bands on the map) are significant structures in the region. Finally, surface exposures of Precambrian crystalline rocks and igneous intrusions of various ages are highlighted (red and blue patterns) on the map; these rocks generally act as barriers to groundwater flow unless significantly fractured.

J.B. Workman; C.M. Menges; W.R. Page; E.B. Ekren; P.D. Rowley; G.L. Dixon

2002-10-17

87

Guidelines for model calibration and application to flow simulation in the Death Valley regional groundwater system  

USGS Publications Warehouse

Fourteen guidelines are described which are intended to produce calibrated groundwater models likely to represent the associated real systems more accurately than typically used methods. The 14 guidelines are discussed in the context of the calibration of a regional groundwater flow model of the Death Valley region in the southwestern United States. This groundwater flow system contains two sites of national significance from which the subsurface transport of contaminants could be or is of concern: Yucca Mountain, which is the potential site of the United States high-level nuclear-waste disposal; and the Nevada Test Site, which contains a number of underground nuclear-testing locations. This application of the guidelines demonstrates how they may be used for model calibration and evaluation, and also to direct further model development and data collection.Fourteen guidelines are described which are intended to produce calibrated groundwater models likely to represent the associated real systems more accurately than typically used methods. The 14 guidelines are discussed in the context of the calibration of a regional groundwater flow model of the Death Valley region in the southwestern United States. This groundwater flow system contains two sites of national significance from which the subsurface transport of contaminants could be or is of concern: Yucca Mountain, which is the potential site of the United States high-level nuclear-waste disposal; and the Nevada Test Site, which contains a number of underground nuclear-testing locations. This application of the guidelines demonstrates how they may be used for model calibration and evaluation, and also to direct further model development and data collection.

Hill, M.C.; D'Agnese, F. A.; Faunt, C.C.

2000-01-01

88

Aerosol transport in the California Central Valley observed by airborne lidar.  

PubMed

An aerosol lidar system was deployed on the NASA DC-8 and used to measure aerosol vertical profiles in the California Central Valley. The nadir-pointing Nd:YAG lidar operated at 532 and 1064 nm at 20 Hz. The resulting aerosol profiles were plotted in a unique three-dimensional format that allowed the visual observation of the aerosol scattering ratio profiles, the valley topography, and corresponding backward trajectory air masses. The accumulation of aerosols from the Bakersfield area can be seen in the southern end of the valley due to topography and prevailing winds. PMID:16294873

De Young, Russell J; Grant, William B; Severance, Kurt

2005-11-01

89

STABLE ISOTOPE EVIDENCE OF HETEROGENEOUS FLUID INFILTRATION AT THE UBEHEBE PEAK CONTACT AUREOLE, DEATH VALLEY NATIONAL PARK, CALIFORNIA  

Microsoft Academic Search

Stable isotope ratios of carbon and oxygen are used to define quantitatively the effects of magmatic fluid infiltration in marbles contact meta- morphosed by the 173 Ma Ubehebe Peak quartz monzonite, Death Valley National Park, California. In previous studies of fluid infiltration, quantitative interpretation of aureole-wide isotopic data has been difficult due to small data sets. For this study, sampling

GREGORY T. ROSELLE; LUKAS P. BAUMGARTNER; JOHN W. VALLEY

90

Surface emittance, temperature, and thermal inertia derived from Thermal Infrared Multispectral Scanner (TIMS) data for Death Valley, California  

Microsoft Academic Search

The NASA airborne Thermal Infrared Multispectral Scanner (TIMS) was flown over Death Valley, Califor- nia on both a daytime flight and a nighttime flight within a two-day period in July 1983. This Daedulus scanner has six channels in the thermal infrared, be- tween 8 and 12 pm. Calibrated digital spectral radiance data from these flights, along with Landsat Thematic Mapper

Anne B. Kahle

1987-01-01

91

Kinematics at the intersection of the Garlock and Death Valley fault zones, California: Integration of TM data and field studies  

NASA Technical Reports Server (NTRS)

The Garlock and Death Valley fault zones in SE California are two active strike-slip faults coming together on the east side of the Avawatz Mtns. The kinematics of this intersection, and the possible continuation of either fault zone, are being investigated using a combination of field mapping, and processing and interpretation of remotely sensed image data. Regional and local relationships are derivable from Thematic Mapper data (30 m resolution), including discrimination and relative age dating of alluvial fans, bedrock mapping, and fault mapping. Aircraft data provide higher spatial resolution over more limited areas. Hypotheses being considered are: (1) the Garlock fault extends east of the intersection; (2) the Garlock fault terminates at the intersection and the Death Valley fault continues southeastward; and (3) the Garlock fault has been offset right laterally by the Death Valley fault which continues to the southeast. Preliminary work indicates that the first hypothesis is invalid. From kinematic considerations, image analysis, and field work the third hypothesis is favored. The projected continuation of the Death Valley zone defines the boundary between the Mojave crustal block and the Basin and Range block.

Abrams, Michael; Verosub, Ken; Finnerty, Tony; Brady, Roland

1987-01-01

92

Winter fog is decreasing in the fruit growing region of the Central Valley of California  

NASA Astrophysics Data System (ADS)

Central Valley of California is home to a variety of fruit and nut trees. These trees account for 95% of the U.S. production, but they need a sufficient amount of winter chill to achieve rest and quiescence for the next season's buds and flowers. In prior work, we reported that the accumulation of winter chill is declining in the Central Valley. We hypothesize that a reduction in winter fog is cooccurring and is contributing to the reduction in winter chill. We examined a 33 year record of satellite remote sensing to develop a fog climatology for the Central Valley. We find that the number of winter fog events, integrated spatially, decreased 46%, on average, over 32 winters, with much year to year variability. Less fog means warmer air and an increase in the energy balance on buds, which amplifies their warming, reducing their chill accumulation more.

Baldocchi, Dennis; Waller, Eric

2014-05-01

93

Thirty Years of Cloud Cover Patterns from Satellite Data: Fog in California's Central Valley and Coast  

NASA Astrophysics Data System (ADS)

In an effort to assess long term trends in winter fog in the Central Valley of California, custom maps of daily cloud cover from an approximately 30 year record of AVHRR (1981-1999) and MODIS (2000-2012) satellite data were generated. Spatial rules were then used to differentiate between fog and general cloud cover. Differences among the sensors (e.g., spectral content, spatial resolution, overpass time) presented problems of consistency, but concurrent climate station data were used to resolve systematic differences in products, and to confirm long term trends. The frequency and extent of Central Valley ("Tule") fog appear to have some periodic oscillation, but also appear to be on the decline, especially in the Sacramento Valley and in the "shoulder" months of November and February. These results may have strong implications for growers of fruit and nut trees in the Central Valley dependent on winter chill hours that are augmented by the foggy daytime conditions. Conclusions about long term trends in fog are limited to daytime patterns, as results are primarily derived from reflectance-based products. Similar analyses of daytime cloud cover are performed on other areas of concern, such as the coastal fog belt of California. Large area and long term patterns here appear to have periodic oscillation similar to that for the Central Valley. However, the relatively coarse spatial resolution of the AVHRR LTDR (Long Term Data Record) data (~5-km) may be limiting for fine-scale analysis of trends.

Waller, E.; Baldocchi, D. D.

2012-12-01

94

Habitat conservation planning for California`s Central Valley grassland prairie/vernal pool landscapes  

SciTech Connect

Vernal Pools are shallow seasonal ponds that form in poorly drained depressions scattered across California`s vast Central Valley. The valley`s rolling terrain and Mediterranean climate, together with an essentially impervious soil horizon, are the key environmental factors affecting distribution of the habitat across valley grassland landscapes. Interest in this habitat heightened in 1993 when vernal pools were the first wetland type in the country to be designated as {open_quotes}Aquatic Resources of National importance{close_quotes} (ARNI). The 1994 listing of four invertebrate species, endemic to California vernal pools, for protection under the endangered Species Act placed further emphasis on them. A 90% loss hypothesis resulted in a strict regulatory policy of {open_quotes}on site{close_quotes} conservation where urbanization interfaces with valley grassland and vernal pool resources. Approximately 2.1 million acres of historic habitat were identified. The current resource covers approximately 1.0 million acres distributed primarily in expansive rangland tracts across 20 California counties. A GIS data base was developed for the Central Valley, with an emphasis on rapidly urbanizing Sacramento County, to provide resource planners with the information to develop a sound conservation strategy for acres was completed in 1994. Restoration and preservation can continue to conserve large tracts that have been well managed historically by ranchers. The findings indicate a tremendous conservation opportunity--thought to have been lost--is extant, and planning decisions can now be based upon sound science.

Sugnet, P. [Sugnet & Associates, Rosseville, CA (United States)

1995-12-01

95

Interpretive geologic cross sections for the Death Valley regional flow system and surrounding areas, Nevada and California  

SciTech Connect

This report presents a network of 28 geologic cross sections that portray subsurface geologic relations within the Death Valley regional ground-water system, a ground-water basin that encompasses a 3 degree x 3 degree area (approximately 70,000 square kilometers) in southern Nevada and eastern California. The cross sections transect that part of the southern Great Basin that includes Death Valley, the Nevada Test Site, and the potential high-level nuclear waste underground repository at Yucca Mountain. The specific geometric relationships portrayed on the cross sections are discussed in the context of four general sub-regions that have stratigraphic similarities and general consistency of structural style: (1) the Nevada Test Site vicinity; (2) the Spring Mountains, Pahrump Valley and Amargosa Desert region; (3) the Death Valley region; and (4) the area east of the Nevada Test Site. The subsurface geologic interpretations portrayed on the cross sections are based on an integration of existing geologic maps, measured stratigraphic sections, published cross sections, well data, and geophysical data and interpretations. The estimated top of pre-Cenozoic rocks in the cross sections is based on inversion of gravity data, but the deeper parts of the sections are based on geologic conceptual models and are more speculative.

D.S. Sweetkind; R.P. Dickerson; R.J. Blakely; P.D. Denning

2001-11-09

96

Style of deformation along the Death Valley-Furnace Creek fault zone and other faults in the southern Walker Lane, Nevada and California  

SciTech Connect

Quaternary normal and right-lateral faults and associated lineaments in the southern part of the Walker Lane are anomalous with respect to the north-striking normal faults in most of the central Great Basin. The authors identify and characterize many faults and lineaments that were previously unmapped, with the exception of faults in the Death Valley-Furnace Creek fault zone (DVFCFZ) and some faults in and near the Nevada Test Site. Faults and associated lineaments in deposits of late Cenozoic age are distinguished on the basis of age of most recent activity and orientation, and are grouped into two domains. One domain is characterized by northwest-striking faults and lineaments and associated north-striking en echelon structures within the DVFCFZ and the Pahrump fault zone; the other domain is characterized by north- to northeast-striking faults and linearments within a broad region east of the DVFCFZ that narrows southward toward the Pahrump fault zone. Preliminary observations of faults and linearments suggest dominantly right-oblique slip in the first domain and dominantly dip-slip in the second domain. The DVFCFZ is a regional right-lateral strike-slip system that shows changes in style of deformation along strike. Numerous normal faults at the northern end of the DVFCFZ in northern fish Lake Valley and the Volcanic Hills form an extensional right step that links the DVFCFZ with northwest-striking right-lateral faults of the northern part of the Walker Lane. South of this extensional step, the DVFCFZ trends southeast along strike-slip faults from central Fish Lake Valley to the latitude of Furnace Creek. From Furnace Creek, the fault zone apparently steps left to the Pahrump fault zone in the area of Ash Meadows where a complex zone of folds and faults of diverse orientation suggest local compression. This stepover coincides with east-northeast-striking faults that appear to be an extension of the left-lateral Rock Valley fault zone.

Noller, J.S. (William Lettis and Associates, Inc., Oakland, CA (United States)); Reheis, M.C. (Geological Survey, Denver, CO (United States))

1993-04-01

97

COMMUNITY AND EDAPHIC ANALYSIS OF MIXED OAK FORESTS IN RIDGE AND VALLEY PROVINCE OF CENTRAL PENNSYLVANIA  

Microsoft Academic Search

Forty-two relatively undisturbed mixed oak stands on nine different physiographic units in the Ridge and Valley Province of central Pennsylvania were surveyed to investigate the ecological status of oak species in the region. Quercus species were primarily restricted to the canopy, with the exception of Quercus ilicifolia Wangenh. (a shrub). The most species rich forest stands were located along an

Gregory J. Nowacki; Marc D. Abrams

98

Pigment Analysis of Short Cores from the Central Ethiopian Rift Valley Lakes  

Microsoft Academic Search

Pigment analysis (Chlorophyll Derivatives — CD, and Total Carotenoids — TC) from surface and core sediments of three lakes: Langano, Abijata and Shalla in the Central Ethiopian Rift Valley are presented. The results show that pigment concentration is very low in modern sediments with CD generally higher than TC. This is in accordance with the present low productivity of the

M. U. Mohammed; R. Bonnefille; Kebede Seifu

99

Drought resilience of the California Central Valley surface-groundwater-conveyance system  

Microsoft Academic Search

A series of drought simulations were performed for the California Central Valley using computer applications developed by the California Department of Water Resources and historical datasets representing a range of droughts from mild to severe for time periods lasting up to 60 years. Land use, agricultural cropping patterns, and water demand were held fixed at the 2003 level and water

N. L. Miller; L. L. Dale; C. Brush; S. Vicuna; T. N. Kadir; E. C. Dogrul; F. I. Chung

2009-01-01

100

Spatially distributed pesticide exposure assessment in the Central Valley, California, USA  

E-print Network

Spatially distributed pesticide exposure assessment in the Central Valley, California, USA Yuzhou of pesticide sources. a r t i c l e i n f o Article history: Received 24 September 2009 Received in revised level a b s t r a c t Field runoff is an important transport mechanism by which pesticides move

Zhang, Minghua

101

This is the Kunijok Valley in the north of Khibiny Low Mountains (central Kola  

E-print Network

This is the Kunijok Valley in the north of Khibiny Low Mountains (central Kola Peninsula in Arctic pines (Pinus sylvestris) from the Khibiny Mountains on the Kola Peninsula, situated between the Arctic, pine and birch. The samples came from three locations in the Khibiny Mountains close to recent

102

Groundwater depletion and sustainability of irrigation in the US High Plains and Central Valley  

E-print Network

Groundwater depletion and sustainability of irrigation in the US High Plains and Central Valley States (6). With growing dependence of agricultural production on un- sustainable groundwater use impact crop produc- tion in the United States because 60% of irrigation relies on groundwater

Paris-Sud XI, Université de

103

Historical Abundance and Decline of Chinook Salmon in the Central Valley Region of California  

Microsoft Academic Search

The Central Valley drainage of California formerly produced immense numbers of chinook salmon Oncorhynchus tshawytscha. Four seasonal runs occur in this system—fall, late-fall, winter, and spring runs. Differences in life history timing and spatial distribution enabled the four runs to use the drainage to the fullest possible extent and once made it one of the richest regions in the world

Ronald M. Yoshiyama; Frank W. Fisher; Peter B. Moyle

1998-01-01

104

Atmospheric Environment 35 (2001) 56295643 Chemistry of fog waters in California's Central ValleyFPart 3  

E-print Network

Atmospheric Environment 35 (2001) 5629­5643 Chemistry of fog waters in California's Central Valley deposition, almost nothing is known about its concentration or composition in fog waters. To address this gap, we have investigated the concentration and composition of ON in fog waters collected in Davis

Zhang, Qi

105

Geologic Map of the Warm Spring Canyon Area, Death Valley National Park, Inyo County, California, With a Discussion of the Regional Significance of the Stratigraphy and Structure  

USGS Publications Warehouse

Warm Spring Canyon is located in the southeastern part of the Panamint Range in east-central California, 54 km south of Death Valley National Park headquarters at Furnace Creek Ranch. For the relatively small size of the area mapped (57 km2), an unusual variety of Proterozoic and Phanerozoic rocks is present. The outcrop distribution of these rocks largely resulted from movement on the east-west-striking, south-directed Butte Valley Thrust Fault of Jurassic age. The upper plate of the thrust fault comprises a basement of Paleoproterozoic schist and gneiss overlain by a thick sequence of Mesoproterozoic and Neoproterozoic rocks, the latter of which includes diamictite generally considered to be of glacial origin. The lower plate is composed of Devonian to Permian marine formations overlain by Jurassic volcanic and sedimentary rocks. Late Jurassic or Early Cretaceous plutons intrude rocks of the area, and one pluton intrudes the Butte Valley Thrust Fault. Low-angle detachment faults of presumed Tertiary age underlie large masses of Neoproterozoic dolomite in parts of the area. Movement on these faults predated emplacement of middle Miocene volcanic rocks in deep, east-striking paleovalleys. Excellent exposures of all the rocks and structural features in the area result from sparse vegetation in the dry desert climate and from deep erosion along Warm Spring Canyon and its tributaries.

Wrucke, Chester T.; Stone, Paul; Stevens, Calvin H.

2007-01-01

106

Sudden death in the working population; a collaborative study in Central Japan  

Microsoft Academic Search

Aim Few epidemiological data are available describing the sudden death of persons in their prime. This study aims to elucidate when and how sudden death occurs among employees. Methods A total of 196 775 employees from 10 workplaces in Central Japan were surveyed for non-traumatic sudden death during 1989-1995. Demographic data and informa- tion regarding onset were collected by their

T. Kawamura; H. Kondo; M. Hirai; K. Wakai; A. Tamakoshi; T. Terazawa; S. Osugi; M. Ohno; N. Okamoto; T. Tsuchida; Y. Ohno; J. Toyama

1999-01-01

107

Trail formation by ice-shoved "sailing stones" observed at Racetrack Playa, Death Valley National Park  

NASA Astrophysics Data System (ADS)

Trails in the usually-hard mud of Racetrack Playa in Death Valley National Park attest to the seemingly-improbable movement of massive rocks on an exceptionally flat surface. The movement of these rocks, previously described as "sliding stones", "playa scrapers", "sailing stones" etc., has been the subject of speculation for almost a century but is an exceptionally rare phenomenon and until now has not been directly observed. Here we report documentation of multiple rock movement and trail formation events in the winter of 2013-2014 by in situ observation, video, timelapse cameras, a dedicated meteorological station and GPS tracking of instrumented rocks. Movement involved dozens of rocks, forming fresh trails typically of 10s of meters length at speeds of ~5 cm s-1 and were caused by wind stress on a transient thin layer of floating ice. Fracture and local thinning of the ice decouples some rocks from the ice movement, such that only a subset of rocks move in a given event.

Lorenz, R. D.; Norris, J. M.; Jackson, B. K.; Norris, R. D.; Chadbourne, J. W.; Ray, J.

2014-08-01

108

Potential hazards from floodflows in Grapevine Canyon, Death Valley National Monument, California and Nevada  

USGS Publications Warehouse

Grapevine Canyon is on the western slope of the Grapevine Mountains in the northern part of Death Valley National Monument , California and Nevada. Grapevine Canyon Road covers the entire width of the canyon floor in places and is a frequently traveled route to Scotty 's Castle in the canyon. The region is arid and subject to flash flooding because of infrequent but intense convective storms. When these storms occur, normally in the summer, the resulting floods may create a hazard to visitor safety and property. Historical data on rainfall and floodflow in Grapevine Canyon are sparse. Data from studies made for similar areas in the desert mountains of southern California provide the basis for estimating discharges and the corresponding frequency of floods in the study area. Results of this study indicate that high-velocity flows of water and debris , even at shallow depths, may scour and damage Grapevine Canyon Road. When discharge exceeds 4,900 cu ft/sec, expected at a recurrence interval of between 25 and 50 years, the Scotty 's Castle access road and bridge may be damaged and the parking lot partly inundated. A flood having a 100-year or greater recurrence interval probably would wash out the bridge and present a hazard to the stable and garage buildings but not to the castle buildings, whose foundations are higher than the predicted maximum flood level. (USGS)

Bowers, J.C.

1990-01-01

109

Preliminary digital geologic maps of the Mariposa, Kingman, Trona, and Death Valley Sheets, California  

SciTech Connect

Parts of four 1:250,000-scale geologic maps by the California Department of Natural Resources, Division of Mines and Geology have been digitized for use in hydrogeologic characterization. These maps include the area of California between lat. 35{degree}N; Long. 115{degree}W and lat. 38{degree}N, long. 118{degree}W of the Kingman Sheet (Jennings, 1961), Trona Sheet (Jennings and others, 1962), Mariposa Sheet (Strand, 1967), and Death Valley Sheet (Streitz and Stinson, 1974). These digital maps are being released by the US Geological Survey in the ARC/INFO Version 6.1 Export format. The digitized data include geologic unit boundaries, fault traces, and identity of geologic units. The procedure outlined in US Geological Survey Circular 1054 (Soller and others, 1990) was sued during the map construction. The procedure involves transferring hard-copy data into digital format by scanning manuscript maps, manipulating the digital map data, and outputting the data. Most of the work was done using Environmental Systems Research Institute`s ARC/INFO software. The digital maps are available in ARC/INFO Rev. 6.1 Export format, from the USGS, Yucca Mountain Project, in Denver, Colorado.

D`Agnese, F.A.; Faunt, C.C.; Turner, A.K. [Geological Survey, Denver, CO (United States)

1995-10-01

110

Extraction of quantitative surface characteristics from AIRSAR data for Death Valley, California  

NASA Technical Reports Server (NTRS)

Polarimetric Airborne Synthetic Aperture Radar (AIRSAR) data were collected for the Geologic Remote Sensing Field Experiment (GRSFE) over Death Valley, California, USA, in Sep. 1989. AIRSAR is a four-look, quad-polarization, three frequency instrument. It collects measurements at C-band (5.66 cm), L-band (23.98 cm), and P-band (68.13 cm), and has a GIFOV of 10 meters and a swath width of 12 kilometers. Because the radar measures at three wavelengths, different scales of surface roughness are measured. Also, dielectric constants can be calculated from the data. The AIRSAR data were calibrated using in-scene trihedral corner reflectors to remove cross-talk; and to calibrate the phase, amplitude, and co-channel gain imbalance. The calibration allows for the extraction of accurate values of rms surface roughness, dielectric constants, sigma(sub 0) backscatter, and polarization information. The radar data sets allow quantitative characterization of small scale surface structure of geologic units, providing information about the physical and chemical processes that control the surface morphology. Combining the quantitative information extracted from the radar data with other remotely sensed data sets allows discrimination, identification and mapping of geologic units that may be difficult to discern using conventional techniques.

Kierein-Young, K. S.; Kruse, F. A.

1992-01-01

111

Height changes along selected lines through the Death Valley region, California and Nevada, 1905-1984  

USGS Publications Warehouse

Comparisons among repeated levelings along selected lines through the Death Valley region of California and adjacent parts of Nevada have disclosed surprisingly large vertical displacements. The vertical control data in this lightly populated area is sparse; moreover, as much as a third of the recovered data is so thoroughly contaminated by systematic error and survey blunders that no attempt was made to correct these data and they were simply discarded. In spite of these limitations, generally episodic, commonly large vertical displacements are disclosed along a number of lines. Displacements in excess of 0.4 m, with respect to our selected control point at Beatty, Nevada, and differential displacements of about 0.7 m apparently occurred during the earlier years of the 20th century and continued episodically through at least 1943. While this area contains abundant evidence of continuing tectonic activity through latest Quaternary time, it is virtually devoid of historic seismicity. We have detected no clear connection between the described vertical displacements and fault zones reportedly active during Holocene time, although we sense some association with several more broadly defined tectonic features.

Castle, Robert O.; Gilmore, Thomas D.; Walker, James P.; Castle, Susan A.

2005-01-01

112

Sliding Rocks on Racetrack Playa, Death Valley National Park: First Observation of Rocks in Motion  

PubMed Central

The engraved trails of rocks on the nearly flat, dry mud surface of Racetrack Playa, Death Valley National Park, have excited speculation about the movement mechanism since the 1940s. Rock movement has been variously attributed to high winds, liquid water, ice, or ice flotation, but has not been previously observed in action. We recorded the first direct scientific observation of rock movements using GPS-instrumented rocks and photography, in conjunction with a weather station and time-lapse cameras. The largest observed rock movement involved >60 rocks on December 20, 2013 and some instrumented rocks moved up to 224 m between December 2013 and January 2014 in multiple move events. In contrast with previous hypotheses of powerful winds or thick ice floating rocks off the playa surface, the process of rock movement that we have observed occurs when the thin, 3 to 6 mm, “windowpane” ice sheet covering the playa pool begins to melt in late morning sun and breaks up under light winds of ?4–5 m/s. Floating ice panels 10 s of meters in size push multiple rocks at low speeds of 2–5 m/min. along trajectories determined by the direction and velocity of the wind as well as that of the water flowing under the ice. PMID:25162535

Lorenz, Ralph D.; Ray, Jib; Jackson, Brian

2014-01-01

113

Case Studies of Water Vapor and Surface Liquid Water from AVIRIS Data Measured Over Denver, CO and Death Valley, CA  

NASA Technical Reports Server (NTRS)

High spatial resolution column atmospheric water vapor amounts and equivalent liquid water thicknesses of surface targets are retrieved from spectral data collected by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). The retrievals are made using a nonlinear least squares curve fitting technique. Two case studies from AVIRIS data acquired over Denver-Platteville area, Colorado and over Death Valley, California are presented. The column water vapor values derived from AVIRIS data over the Denver-Platteville area are compared with those obtained from radiosondes, ground level upward-looking microwave radiometers, and geostationary satellite measurements. The column water vapor image shows spatial variation patterns related to the passage of a weather front system. The column water vapor amounts derived from AVIRIS data over Death Valley decrease with increasing surface elevation. The derived liquid water image clearly shows surface drainage patterns.

Gao, B.-C.; Kierein-Young, K. S.; Goetz, A. F. H.; Westwater, E. R.; Stankov, B. B.; Birkenheuer, D.

1991-01-01

114

Contractional Strain Related to Interference of Intersecting Sets of Strike-slip Faults in the Southern Death Valley Region, California  

Microsoft Academic Search

Structural and geomorphic data reveal complex neotectonic deformation(Pliocene-Quaternary, post 3-4 Ma)derived in part from interactions among intersecting sets of strike-slip faults in the southern Death Valley area on the eastern margin of the Eastern California Shear Zone. A distinct 40-km-wide domain of strike-slip faulting and associated contractional strain is bounded on the north by the southern end of the Panamint

C. M. Menges; T. L. Pavlis; M. R. McMackin; L. Serpa

2006-01-01

115

Two diamictites, two cap carbonates, two delta13C excursions, two rifts: The Neoproterozoic Kingston Peak Formation, Death Valley, California  

Microsoft Academic Search

Stratigraphic mapping of the Neoproterozoic glaciogenic Kingston Peak Formation (Death Valley, California) provides evidence for two temporally discrete extensional deformation episodes. These episodes are bracketed by the Sourdough Limestone and Noonday Dolomite, the facies characteristics and delta13C data (ranging between 2.15 and -2.560\\/00 and -1.88 and -4.860\\/00, respectively) of which make them equivalent to Sturtian and Varangian age cap carbonates,

A. R. Prave

1999-01-01

116

Geologic application of thermal inertia imaging using HCMM data. [Death Valley and Pisgah Crater, California and Goldfield, Nevada  

NASA Technical Reports Server (NTRS)

During the July to September 1980 quarter the final tapes were received completing the order and preliminary processing was done. Thermal Inertia images for each of the three test sites, Death Valley and Pisgah Crater, California and Goldfield, Nevada were created using registered HCMM day/night pairs and the JPL model. A comprehensive study and analysis of the geologic application of all acquired HCMM data is in progress.

Paley, H. N.; Kahle, A. B. (principal investigators)

1980-01-01

117

EFFECTIVE MODEL CALIBRATION OF THE GEOLOGICALLY COMPLEX DEATH VALLEY REGIONAL GROUND-WATER FLOW SYSTEM, NEVADA AND CALIFORNIA  

Microsoft Academic Search

A numerical ground-water flow model is being constructed for the Death Valley regional ground-water system, an area that encompasses approximately 80,000 km² in southern Nevada and southeastern California. Effective construction and calibration of the regional-scale steady-state flow model, developed using MODFLOW-2000, is dependent upon integration of hydrogeologic data and parameter-estimation techniques. A three-dimensional hydrogeologic-framework model of the region was initially

G. M. OBrien; F. A. DAgnese; C. C. Faunt; W. R. Belcher

2000-01-01

118

Seroprevalence Survey of American Trypanosomiasis in Central Valley of Toluca  

PubMed Central

American trypanosomiasis is a growing health issue in the Americas. México is an endemic country, where some locations such as in the State of México are considered highly prevalent. In the valley of Toluca city, the capital of the State of Mexico, there exists an apparent high prevalence in dogs. The absence of triatomine vectors suggests that dogs may not be infected. Therefore, we conducted a directed survey to domiciliated and nondomiciliated dogs to reassess dogs' T. cruzi seroprevalence status. HAI and ELISA serologic tests were applied to 124 and 167 serums of domiciliated and nondomiciliated dogs in the target city. Risk factors were estimated, but the results did not show any evidence to assess them. No domiciliated dogs tested positive to both tests, whereas only one non-domiciliated dog resulted positive. This animal may have acquired the infection in an endemic area and then migrated to Toluca. Research results indicate that T. cruzi infection is not actively transmitted among dogs, and it is pointed out that dogs are the main sentinel animal population to evaluate a possible expansion of the territory affected by Chagas' disease. PMID:22649293

Quijano-Hernandez, Israel A.; Castro-Barcena, Alejandro; Barbabosa-Pliego, Alberto; Ochoa-GarcIa, Laucel; Del Angel-Caraza, Javier; Vazquez-Chagoyan, Juan C.

2012-01-01

119

Stable Ca Isotopes in Tamarix aphylla Tree Rings, Death Valley, California  

NASA Astrophysics Data System (ADS)

As a dune stabilizer and windbreak, Tamarix aphylla is an exotic perennial and evergreen tree in Death Valley. Its tap roots can reach down to 30 m depth and sub-superficial side roots may reach 50 m horizontally. The species can store large amounts of water in its roots and undergoes high evapotranspiration. Since Tamarix aphylla is a perennial tree growing in desert environments and its roots reach deep to the water table, it could be a proxy for desert ecological and hydrologic systems through time. We measured Ca isotopes in the soluble fraction of 8 tree ring samples from a 50-year-old specimen growing on an alluvial fan in Death Valley near Furnace Creek. Previous studies (Yang et al, GCA 60, 1996) indicate that this tree's rings contain high sulfur concentrations (4-6% expressed as sulfate) with chemical composition of CaSO4 (0.15-0.62 H2O). The ?34S values of soluble sulfate increase from +13.5 to +18 permil VCDT from the core to the bark, which are interpreted as reflecting deeper sulfate sources as the tree grew. The ?13C variations of the tree-ring cellulose (-27.6 to -24.0 permil VPDB) reflect changes in the local precipitation and show that Tamarix aphylla undergoes C3 photosynthesis. The ?44Ca for the soluble sulfate Ca through the tree-ring section, which covers a time period from 1945 to 1993, have an average value -2.52 permil (-3.4 permil relative to seawater). Only small variations are observed, from -2.69 to -2.28; the highest value (for 1990) occurs near the end of an extended drought. These are the first measurements of tree rings, but the low ?44Ca values are consistent with previous measurements of beech roots and stems from a temperate forest (Page et al., Biogeochem. 88, 2008). In our case, the tree has only one Ca source, which is expected to be isotopically uniform and similar to both local rainfall and limestones (?44Ca ~ -0.6 permil), and with the minimal vegetation and extensive deep root system it is unlikely that there is a significant depletion of soil Ca due to plant uptake. Thus the Ca isotopic fractionation between trunk and source (?Ca = -2 permil) is clearly defined by the data. By analogy to the results of Page et al., the Ca fractionation between root and source may be larger (?Ca ~ -3 permil). This biological Ca isotope fractionation is no doubt due to transport processes during root uptake of Ca, but the magnitude is significantly larger than that observed for inorganic processes such as mineral precipitation or aqueous diffusion. The slight increase in ?44Ca in drought conditions suggests that when the tree is stressed there may be less Ca isotope fractionation, either because the Ca is held more tightly in small pores in the soil, or because the available Ca pool shrinks such that the soil Ca starts to shift to more positive ?44Ca values due to depletion of light Ca by the plant. The slowly accumulating database on Ca isotopes in plants continues to suggest that systematic Ca isotope studies may be fruitful for understanding cation transport in plants, and soil ecological conditions in general.

Yang, W.; Depaolo, D. J.; Ingram, B. L.; Owens, T. L.

2008-12-01

120

Are the benches at Mormon Point, Death Valley, California, USA, scarps or strandlines?  

USGS Publications Warehouse

The benches and risers at Mormon Point, Death Valley, USA, have long been interpreted as strandlines cut by still-stands of pluvial lakes correlative with oxygen isotope stage (OIS) 5e/6 (120,000-186,000 yr B.P.) and OIS-2 (10,000-35,000 yr B.P.). This study presents geologic mapping and geomorphic analyses (Gilbert's criteria, longitudinal profiles), which indicate that only the highest bench at Mormon Point (~90 m above mean sea level (msl)) is a lake strandline. The other prominent benches on the north-descending slope immediately below this strandline are interpreted as fault scarps offsetting a lacustrine abrasion platform. The faults offsetting the abrasion platform most likely join downward into and slip sympathetically with the Mormon Point turtleback fault, implying late Quaternary slip on this low-angle normal fault. Our geomorphic reinterpretation implies that the OIS-5e/6 lake receded rapidly enough not to cut strandlines and was ~90 m deep. Consistent with independent core studies of the salt pan, no evidence of OIS-2 lake strandlines was found at Mormon Point, which indicates that the maximum elevation of the OIS-2 lake surface was -30 m msl. Thus, as measured by pluvial lake depth, the OIS-2 effective precipitation was significantly less than during OIS-5e/6, a finding that is more consistent with other studies in the region. The changed geomorphic context indicates that previous surface exposure dates on fault scarps and benches at Mormon Point are uninterpretable with respect to lake history. ?? 2002 University of Washington.

Knott, J.R.; Tinsley, J. C., III; Wells, S.G.

2002-01-01

121

Preliminary Characterization of a Microbial Community of Rock Varnish from Death Valley, California  

NASA Technical Reports Server (NTRS)

Rock varnish (also referred to as desert varnish in the literature because it is particularly noticeable in desert environments) is a dark, thin (typically 50-500 m thick), layered veneer composed of clay minerals cemented together by oxides and hydroxides of manganese and iron. Some scientists suggest that varnish may provide a historical record of environmental processes such as global warming and long-term climate change. However, despite more than 30 years of study using modern microanalytical and microbial culturing techniques, the nucleation and growth mechanisms of rock varnish remain a mystery. Rock varnish is of interest to the Mars science community because a varnish-like sheen has been reported on the rocks at the Viking Lander sites. It therefore important for us to understand the formation mechanisms of terrestrial varnish abiotic, biotic, or a combination of the two -- as this understanding may give us clues concerning the chemical and physical processes occurring on the surface of Mars. It is strongly believed by some in the biogeochemistry community that microbes have a role in forming rock varnish, and iron- and manganese-oxidation by microbes isolated from varnish has been extensively investigated. Only two of these studies have investigated the microbial genetics of varnish. These studies examined the morphological, physiological and molecular characteristics of microbes that had previously been cultured from various rock varnishes and identified the cultivars using 16S rDNA sequencing techniques. However, it is well known that most of organisms existing in nature are refractory to cultivation, so many important organisms would have been missed. The currently described work investigates the genetics of rock varnish microbial community from a site in the Whipple Mtns., south of Death Valley, CA, near Parker, Arizona. We employed both cultural and molecular techniques to characterize the microorganisms found within the varnish and surrounding soil with the objectives of (a) identifying microorganisms potentially involved in varnish formation, and (b) discovering microorganisms that simply use the varnish as an extreme habitat.

Kuhlman, K. R.; LaDuc, M. T.; Kuhlman, G. M.; Anderson, R. C.; Newcombe, D. A.; Fusco, W.; Steucker, T.; Allenbach, L.; Ball, C.; Crawford, R. L.

2003-01-01

122

Groundwater depletion and sustainability of irrigation in the US High Plains and Central Valley  

PubMed Central

Aquifer overexploitation could significantly impact crop production in the United States because 60% of irrigation relies on groundwater. Groundwater depletion in the irrigated High Plains and California Central Valley accounts for ?50% of groundwater depletion in the United States since 1900. A newly developed High Plains recharge map shows that high recharge in the northern High Plains results in sustainable pumpage, whereas lower recharge in the central and southern High Plains has resulted in focused depletion of 330 km3 of fossil groundwater, mostly recharged during the past 13,000 y. Depletion is highly localized with about a third of depletion occurring in 4% of the High Plains land area. Extrapolation of the current depletion rate suggests that 35% of the southern High Plains will be unable to support irrigation within the next 30 y. Reducing irrigation withdrawals could extend the lifespan of the aquifer but would not result in sustainable management of this fossil groundwater. The Central Valley is a more dynamic, engineered system, with north/south diversions of surface water since the 1950s contributing to ?7× higher recharge. However, these diversions are regulated because of impacts on endangered species. A newly developed Central Valley Hydrologic Model shows that groundwater depletion since the 1960s, totaling 80 km3, occurs mostly in the south (Tulare Basin) and primarily during droughts. Increasing water storage through artificial recharge of excess surface water in aquifers by up to 3 km3 shows promise for coping with droughts and improving sustainability of groundwater resources in the Central Valley. PMID:22645352

Scanlon, Bridget R.; Faunt, Claudia C.; Longuevergne, Laurent; Reedy, Robert C.; Alley, William M.; McGuire, Virginia L.; McMahon, Peter B.

2012-01-01

123

Groundwater depletion and sustainability of irrigation in the US High Plains and Central Valley.  

PubMed

Aquifer overexploitation could significantly impact crop production in the United States because 60% of irrigation relies on groundwater. Groundwater depletion in the irrigated High Plains and California Central Valley accounts for ~50% of groundwater depletion in the United States since 1900. A newly developed High Plains recharge map shows that high recharge in the northern High Plains results in sustainable pumpage, whereas lower recharge in the central and southern High Plains has resulted in focused depletion of 330 km(3) of fossil groundwater, mostly recharged during the past 13,000 y. Depletion is highly localized with about a third of depletion occurring in 4% of the High Plains land area. Extrapolation of the current depletion rate suggests that 35% of the southern High Plains will be unable to support irrigation within the next 30 y. Reducing irrigation withdrawals could extend the lifespan of the aquifer but would not result in sustainable management of this fossil groundwater. The Central Valley is a more dynamic, engineered system, with north/south diversions of surface water since the 1950s contributing to ~7× higher recharge. However, these diversions are regulated because of impacts on endangered species. A newly developed Central Valley Hydrologic Model shows that groundwater depletion since the 1960s, totaling 80 km(3), occurs mostly in the south (Tulare Basin) and primarily during droughts. Increasing water storage through artificial recharge of excess surface water in aquifers by up to 3 km(3) shows promise for coping with droughts and improving sustainability of groundwater resources in the Central Valley. PMID:22645352

Scanlon, Bridget R; Faunt, Claudia C; Longuevergne, Laurent; Reedy, Robert C; Alley, William M; McGuire, Virginia L; McMahon, Peter B

2012-06-12

124

Descriptions and chemical analyses for selected wells in the Central Sacramento Valley, California  

USGS Publications Warehouse

The Sacramento Valley occupies the northern one-third of the Great Central Valley of California. The study area of this report includes about 1,200 square miles (3,100 square kilometers) adjacent to the Sacramento River from Knights Landing to Los Molinos, in parts of Yolo, Sutter, Colusa, Glenn, Butte, and Tehama Counties. Between April and August 1975, 559 wells were canvassed, and during September and October 1975, water samples were collected for chemical analysis from 209 of these wells. Field determinations of alkalinity, conductance, pH , and temperature were made on the site at the time of sampling. Samples were prepared in the field for shipment and analysis for individual constituents at the Geological Survey Central Laboratory, Salt Lake City, Utah. Descriptive data for water wells are listed, chemical data are tabulated, and the location of wells is shown on maps. (Woodard-USGS)

Fogelman, Ronald P.

1976-01-01

125

Knickpoint retreat and landscape disequilibrium on the James River from the Piedmont through the Valley and Ridge, central Virginia, USA  

Microsoft Academic Search

Several lines of evidence indicate landscape disequilibrium in the James River basin in central Virginia. The river longitudinal profile possesses pronounced convexities and apparently migratory knickzones. Along much of its length, it flows in a narrow inner valley incised into a discontinuous, low-relief upland. In the inner Piedmont, the 150 m wide river channel occupies an incised valley that can

G. Hancock; D. Harbor; J. Felis

2003-01-01

126

Geophysical and Geological Evidence of Neotectonic Deformation Along the Hovey Lake Fault, Lower Wabash Valley Fault System, Central United States  

Microsoft Academic Search

High-resolution seismic (shear-wave) reflection profiles were collected over a segment of the Hovey Lake fault, a known Paleozoic fault within a system of faults in the southernmost Wabash River valley of the central United States. Although the system of faults, called the Wabash Valley fault system, lie in an area of recognized prehistoric and contemporary seismicity, their seismogenic potential remain

E. W. Woolery; F. A. Rutledge; Z. Wang

2004-01-01

127

Neotectonics of the Marikina Valley fault system (MVFS) and tectonic framework of structures in northern and central Luzon, Philippines  

Microsoft Academic Search

Recognition of neotectonic features along the Marikina Valley fault system (MVFS) in central Luzon, Philippines indicates a dominantly dextral strike-slip motion during its most recent activity believed to be Late Pleistocene to Holocene in age. Variations in the ratios of vertical to horizontal displacements for the segments imply a dominantly dextral motion of the West Marikina Valley fault (WMVF) and

Rolly E. Rimando; Peter L. K. Knuepfer

2006-01-01

128

Airborne Laser Swath Mapping as a Tool to Study Active Deformation Along the Death Valley Fault Zone, California  

NASA Astrophysics Data System (ADS)

The degree to which fault loading and strain release rates are constant in time and space is one of the most fundamental, unresolved issues in modern tectonics. In order to understand how strain is distributed across plate boundaries we must compare slip rate data over a wide range of time scales. The Death Valley fault zone (DVFZ) is one of the last major missing pieces of the kinematic puzzle in the eastern California shear zone (ECSZ). Published models of geodetic data suggest the DVFZ is storing much, and perhaps almost all, of the Pacific-North American plate boundary strain in the ECSZ north of the Garlock fault. However, the scarcity of geochronologically constrained long-term slip rates makes it difficult to determine whether strain storage and release have been constant along this part of the plate boundary. We are using airborne laser swath mapping (ALSM) data, together with cosmogenic nuclide geochronology and field mapping to determine geologic slip rates over a variety of time scales on this section of the plate boundary. The scarcity of vegetation in the study area is ideal for acquisition of ALSM data to survey deformed geomorphic features; removal of data points related to returns from the top of plants does not reduce the point density of bare-earth shots, as it might in a heavily-canopied area. We have acquired 46 km2 of ALSM data from two locations along the northern DVFZ. In addition, approximately 100 km2 of ALSM data have been collected along the central Death Valley normal fault. The ALSM data highlight many dextral and normal fault offsets in alluvial fans along the western piedmonts of the Black and Grapevine Mountains. These data are particularly useful for active tectonic studies because the landscape can be artificially illuminated from any azimuth and sun angle to reveal subtle topographic features that may not otherwise be seen. The amount of mid-Pleistocene to Holocene displacement on the fault system can be determined by restoring alluvial channel offsets observed in the ALSM data along the DVFZ to their pre-faulting positions. Minimum fault offsets in surfaces of varying age range from < 5 m in the youngest offset surface to 390 m in the oldest deformed surface. We have also used the ALSM data to construct surficial geologic maps of offset fans on the basis of slope maps and surface roughness characteristics. Field mapping using the ALSM data as a base map will augment digital analyses of the topography. Cosmogenic nuclide geochronology (10Be) will constrain the ages of deformed surfaces, and generate precise intermediate- and long-term slip rates from the restored fault offsets. Comparison of these longer-term rate data with short-term geodetic data will allow us to determine whether strain storage and release have been constant over the Holocene-late Pleistocene time scales of interest. Of particular importance is whether the potential strain transient observed in the Mojave section of the ECSZ extends north of the Garlock fault and away from the zone of structural complexity associated with the Big Bend of the San Andreas fault.

Frankel, K. L.; Dolan, J. F.; Finkel, R. C.; Wasklewicz, T.

2005-12-01

129

Hydrologic reconnaissance of the Dugway Valley-Government Creek area, West-Central Utah  

USGS Publications Warehouse

The Dugway Valley-Government Creek area covers about 890 square miles (2,300 square kilometers) in west-central Utah. Total annual precipitation on the area averages about 380,000 acre-feet (470 cubic hectometers). Most streams are ephemeral except for a few in their upper reaches--all are ephemeral below the altitude of about 6,000 feet (1,830 meters). Surface-water development and use in the area are insignificant.

Stephens, Jerry C.; Sumsion, C. T.

1978-01-01

130

DISTRIBUTION AND ABUNDANCE OF LARGE SANDHILL CRANES, GRUS CANADENSIS, WINTERING IN CALIFORNIA'S CENTRAL VALLEY  

Microsoft Academic Search

Distribution and abundance of large sandhill cranes (Grus canadensis tabida, Greater Sandhill Crane, and Grus canadensis rowani, Canadian Sandhill Crane) were studied in California's Central Valley during October-February 1983-1984 and 1984-1985. We estimated that the population contained 6,000-6,800 cranes which were concentrated at eight geographic locations from Chico to Pixley National Wildlife Refuge (NWR) near Delano. Ninety-five percent of the

THOMAS H. POGSON; SUSAN M. LINDSTEDT

131

Fossil clavicle of a Middle Pleistocene hominid from the Central Narmada Valley, India  

Microsoft Academic Search

The discovery of a Middle Pleistocene hominid clavicle is reported here. This discovery is particularly important because clavicles are hitherto unrepresented in the fossil record of Asia. The Narmada clavicle comes from the Boulder Conglomerate horizon at Hathnora near Hoshangabad in the Central Narmada Valley. This is the same deposit that previously yielded theHomo erectus\\/archaicHomo sapienspartial cranium, which has recently

A. R. Sankhyan

1997-01-01

132

Wildlife Diversity in Valley-Foothill Riparian Habitat: North Central vs. Central Coast California1  

E-print Network

in July and average yearly precipitation on the study area totals about 65 cm (Barrett 1978). Little rain falls during summer--90 pct of the yearly total falls in the seven winter months from October to April. Snowfall is rare. Valley-foothill riparian habitat at Dye Creek is dominated by interior live oak (Quercus

Standiford, Richard B.

133

Research Spotlight: Groundwater is being depleted rapidly in California's Central Valley  

NASA Astrophysics Data System (ADS)

Groundwater is being depleted in California's Central Valley at a rapid rate, according to data from the Gravity Recovery and Climate Experiment (GRACE) satellite. Famiglietti et al. analyzed 78 months of GRACE data covering October 2003 to March 2010 to estimate water storage changes in California's Sacramento and San Joaquin river basins. They found that the basins are losing water at a rate of about 30 millimeters per year equivalent water height, or a total of about 30 cubic kilometers over the 78-month period. Furthermore, they found that two thirds of this loss, or a total of 20 cubic kilometers for the study period, came from groundwater depletion in the Central Valley. Quantifying groundwater depletion can be challenging in many areas because of a lack of monitoring infrastructure and reporting requirements; the study shows that satellite-based monitoring can be a useful way to track groundwater volumes. The authors warn that the current rate of groundwater depletion in the Central Valley may be unsustainable and could have “potentially dire consequences for the economic and food security of the United States.” (Geophysical Research Letters, doi:10.1029/2010GL046442, 2011)

Tretkoff, Ernie

2011-03-01

134

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

USGS Publications Warehouse

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.

Zabik, John M.; Seiber, James N.

1993-01-01

135

USDA Forest Service Gen.Tech. Rep. PSW-GTR-187. 2003. 159 V. The Central Valley Region  

E-print Network

/index.htm)]. Since the Central Valley is an economic rather than political region, its definition varies. It also Highway 99. Growth is driven by increased birth rates and continued immigration from around the Pacific

Standiford, Richard B.

136

Evaluation of multi-scale hyperspectral reflectance and emittance image data for remote mineral mapping in northeastern Death Valley National Park, California and Oasis Valley, Nevada  

NASA Astrophysics Data System (ADS)

This dissertation focuses upon the analyses of hyperspectral reflectance and thermal emission image data to remotely detect and map surficial mineralogy in an arid environment in southern Nevada and southeastern California. It includes four manuscripts prepared for submission to peer-reviewed journals, which are presented as single chapters. The research involves the use of longwave-infrared (LWIR) hyper- and multi-spectral measurements made from ground, aerial, and spaceborne perspectives of sedimentary and meta-sedimentary geologic units in northeastern Death Valley National Park, California and both shortwave-infrared (SWIR) and LWIR hyperspectral measurements in an area of diverse Paleozoic and Tertiary geology in Oasis Valley, Nevada. In Chapter 1, a brief overview of the dissertation is provided, including background on reflected and thermal-infrared mineral spectroscopy; remote sensing; the impacts of spatial and spectral resolution upon the ability to detect, identify, and map minerals using remote sensing image data; and the use of combined reflectance and emittance image data to better map minerals. In Chapter 2, ground-based SEBASS LWIR hyperspectral image data is analyzed in order to determine the utility of very high resolution remotely-sensed emittance measurements to delineate late-Proterozoic and Paleozoic sedimentary lithologies of an outcrop at Hell's Gate, Death Valley. In Chapter 3, airborne SEBASS image data over Boundary Canyon are analyzed in conjunction with moderate-scale geologic maps and laboratory measurements to map minerals associated with sedimentary and meta-sedimentary rocks and important in recognizing a detachment fault structure, as well as metamorphic facies. In Chapter 4, ground-based and aerial SEBASS, aerial MASTER, and spaceborne ASTER emittance measurements are compared over two study sites to determine what repercussions viewing perspective and spatial, spectral, and radiometric resolutions have upon remote identification and mapping of minerals associated with the Boundary Canyon detachment fault. In Chapter 5, a comparison of reflectance and emittance hyperspectral measurements made over Oasis Valley is used to determine whether certain minerals are optimally detected, identified, and mapped within a certain wavelength range. In Chapter 6, the presented research is summarized, repercussions of the results are analyzed, and future research possibilities are suggested. The research was successful in presenting: (1) new uses of imaging spectrometer data, (2) identifying mineralogic indicators of detachment faulting in the Boundary Canyon study area, (3) scale-based limitations upon detection of these mineral components associated with detachment faulting, and (4) limitations upon identifying particular minerals in specific wavelength segments, thereby constraining expectations of future VNIR/SWIR and LWIR image data mineral mapping surveys.

Aslett, Zan

137

Spatial Use by Wintering Greater White-Fronted Geese Relative to a Decade of Habitat Change in California's Central Valley  

Microsoft Academic Search

Abstract We investigated,the effect of recent,habitat changes,in California’s Central Valley on,wintering,Pacific greater,white-fronted,geese,(Anser albifrons frontalis) by comparing roost-to-feed distances, distributions, population range sizes, and habitat use during 1987–1990 and 1998– 2000. These habitat changes included wetland restoration and agricultural land enhancement,due to the 1990 implementation of the Central Valley Joint Venture, increased land area used for rice (Oryza sativa) production, and

JOSHUA T. ACKERMAN; JOHN Y. TAKEKAWA; DENNIS L. ORTHMEYER; JOSEPH P. FLESKES; JULIE L. YEE; KAMMIE L. KRUSE

2006-01-01

138

Financing the "Valley of Death" : an evaluation of incentive schemes for global health businesses  

E-print Network

Many early-stage biotech companies face a significant funding gap when trying to develop a new drug from preclinical development to a proof of concept clinical trial. This funding gap is sometimes referred to as the "valley ...

Miller, Brian L. K

2009-01-01

139

Surficial Geologic Mapping Using Digital Techniques Reveals Late-Phase Basin Evolution and Role of Paleoclimate, Death Valley Junction 30' × 60' Quadrangle, California and Nevada  

NASA Astrophysics Data System (ADS)

The recently released surficial geologic map of the Death Valley Junction 30' x 60' quadrangle at 1:100,000 scale (USGS SIM 3013) was simultaneously mapped and compiled using digital photogrammetric methods. The map area covers the central part of Death Valley and adjacent mountain ranges—the Panamint Range on the west and the Funeral Mountains on the east—as well as areas east of Death Valley including some of the Amargosa Desert, the Spring Mountains, and Pahrump Valley. We mapped six alluvial units, an eolian unit, three playa or playa-related units, lacustrine beach deposits, colluvium, and marl. Interpretation of surface morphology, tone, relative height, and map pattern in air photos enabled us to differentiate among the alluvial units, which make up about 80 percent of the surficial deposits in the map area. Systematic variations in alluvial surface morphology with age permit us to map and correlate geomorphic surfaces. Surface morphology is a product of depositional and post-depositional processes. Lithologic variations across the map area influence the tone of the alluvial units. Although young alluvial units are often light-toned due to an absence or paucity of rock varnish, they may appear dark where the source rocks are dark. Lithology also influences the development of rock varnish; fine-grained or aphanitic rocks, such as quartzite or basalt, tend to become varnished more quickly than rocks such as limestone or granite. Granite commonly disaggregates to grus before becoming varnished and limestone becomes etched. Relative height (topographic position) is useful for mapping in individual drainage basins near range fronts, but basinward, especially in tectonically inactive areas, most surfaces grade to the same base level, and relative height differs little among the alluvial units. Faulting, both the magnitude and location, also affects the map pattern of alluvial units. As faulting uplifts ranges relative to the basins, streams adjust to new base levels, abandoning and incising older alluvial units, thus preserving them on the footwall block of the fault. In tectonically inactive areas, streams continue to grade to the same level or aggrade, thus progressively burying older alluvial units. Therefore, map pattern of alluvial units is an important tool to evaluate late-phase basin evolution in the Basin and Range province. Determining the age of these alluvial units enables us to examine the role of paleoclimate during deposition. Six terrestrial cosmogenic-nuclide (TCN) 36Cl depth-profile dates of unit Qai fans along the west side of Death Valley range from about 40 ka to 100 ka (with a mean age of about 65 ka) and thus post-date the marine oxygen-isotope stage (MIS) 6 cycle of Pleistocene Lake Manly, but predate the lesser, MIS 2 successor. TCN 36Cl depth-profile dating establishes the age of a lacustrine bar complex at 30 m above sea level on the north side of Hanaupah Canyon to be 130 (+75/-39) ka and correlates with a deep lake at MIS 6. This bar predates units mapped as Qai and thus provides an important stratigraphic datum.

Slate, J.; Berry, M.; Menges, C. M.

2010-12-01

140

Hydrology of Prairie Dog Creek Valley, Norton Dam to state line, north-central Kansas  

USGS Publications Warehouse

Development of water resources has been a major factor in the economy of Prairie Dog Creek Valley in north-central Kansas. Releases from Norton Reservoir to the Almena Irrigation District averaged 6,900 acre-feet per year during 1967-76. The number of irrigation wells increased from 4 to 147 during 1947-78. Ground water in the valley is derived mostly from the alluvial aquifer. The effects of irrigation on the aquifer are indicated by water-level changes. The water in storage increased from 130,000 to 136,000 acre-feet during 1947-78 due to recharge from surface-water irrigation. A steady-state model of the aquifer prior to irrigation (1947) indicated that most recharge was from precipitation (88 percent) and most discharge was to streams (54 percent) and reparian transpiration (26 percent). Although aquifer storage increased in this area, storage generally decreased in other areas of western Kansas. (USGS)

Stullken, L.E.

1984-01-01

141

The role of Thurwieser rock avalanche in the geomorphological evolution of Zebrù Valley (Italian Central Alps)  

NASA Astrophysics Data System (ADS)

On September 18th, 2004 a rock avalanche with an estimated volume of 2.5 M m3 propagated from the southern flank of Punta Thurwieser, affecting the Marè Valley, a tributary located in upper part of Zebrù Valley, 30 Km East from Bormio, in the Italian Central Alps. The landslide event deposited a thick debris cover on the pre-landslide morphology up to 2.2 Km from the source area. In this contribution, we aim at studying the role of the rock avalanche on the geomorphological evolution of the valley and in particular in controlling the evolution of the drainage system, the sediment budget and the mass balance of Zebrù glacier. In fact, after ten years it is possible to appreciate and valuate how such an event could modify the landscape and the geomorphology of an alpine valley. First, the landslide body formed a robust obstacle splitting the original watershed into two different sub-units. This caused a different distribution of the sediment yield rate in the upper part of the valley. As a consequence, an extremely rapid excavation of a new channel took place, ending in a new debris fan along the Zebrù valley bottom. A consistent groundwater flow still occurs within the rock avalanche deposit along the old valley axis, excepted for periods characterized by intense precipitation and snow melting events, which are able to activate the recently developed drainage channel. Thus implies that the main transport of sediments will occur along the new channel, during periods of high discharge. In the middle part of the landslide deposit, a sediment trap formed, collecting the material eroded by the surrounding ridges and by the upper sector of the deposit itself, forming a small plain under constant accretion. From this temporary trap, it was possible to estimate the periglacial sediment transport yield of the basin. The Zebrù glacier, flowing from the Mt Zebrù peak, was partially interested from the landslide, which covered a portion of the ice tongue with a shallow layer of blocks and finer matrix. The Thurwieser debris acted as a thermal insulation, preserving a significant ice volume and building up a steep bound, in the order of 10 m high, between non-covered and covered glacier surface. Topographic data collected since 2004 are presented and analyzed in this contribution to study the evolution both at a large and small scale.

Riva, Federico; Frattini, Paolo; Greggio, Luca; Crosta, Giovanni B.

2014-05-01

142

Estimated Ground-Water Withdrawals from the Death Valley Regional Flow System, Nevada and California, 1913-98  

USGS Publications Warehouse

Ground-water withdrawals from 1913 through 1998 from the Death Valley regional flow system have been compiled to support a regional, three-dimensional, transient ground-water flow model. Withdrawal locations and depths of production intervals were estimated and associated errors were reported for 9,300 wells. Withdrawals were grouped into three categories: mining, public-supply, and commercial water use; domestic water use; and irrigation water use. In this report, groupings were based on the method used to estimate pumpage. Cumulative ground-water withdrawals from 1913 through 1998 totaled 3 million acre-feet, most of which was used to irrigate alfalfa. Annual withdrawal for irrigation ranged from 80 to almost 100 percent of the total pumpage. About 75,000 acre-feet was withdrawn for irrigation in 1998. Annual irrigation withdrawals generally were estimated as the product of irrigated acreage and application rate. About 320 fields totaling 11,000 acres were identified in six hydrographic areas. Annual application rates for high water-use crops ranged from 5 feet in Penoyer Valley to 9 feet in Pahrump Valley. The uncertainty in the estimates of ground-water withdrawals was attributed primarily to the uncertainty of application rate estimates. Annual ground-water withdrawal was estimated at about 90,000 acre-feet in 1998 with an assigned uncertainty bounded by 60,000 to 130,000 acre-feet.

Moreo, Michael T.; Halford, Keith J.; La Camera, Richard J.; Laczniak, Randell J.

2003-01-01

143

Estimated Ground-water Withdrawals From the Death Valley Regional Flow System, Nevada and California, 1913-98  

SciTech Connect

Ground-water withdrawals from 1913 through 1998 from the Death Valley regional flow system have been compiled to support a regional,three-dimensional, transient ground-water flow model. Withdrawal locations and depths of production intervals were estimated and associated errors were reported for 9,300 wells. Withdrawals were grouped into three categories: mining, public-supply, and commercial water use; domestic water use; and irrigation water use. In this report, groupings were based on the method used to estimate pumpage. Cumulative ground-water withdrawals from 1913 through 1998 totaled 3 million acre-feet, most of which was used to irrigate alfalfa. Annual withdrawal for irrigation ranged from 80 to almost 100 percent of the total pumpage. About 75,000 acre-feet was withdrawn for irrigation in 1998. Annual irrigation withdrawals generally were estimated as the product of irrigated acreage and application rate. About 320 fields totaling 11,000 acres were identified in six hydrographic areas. Annual application rates for high water-use crops ranged from 5 feet in Penoyer Valley to 9 feet in Pahrump Valley. The uncertainty in the estimates of ground-water withdrawals was attributed primarily to the uncertainty of application rate estimates. Annual ground-water withdrawal was estimated at about 90,000 acre-feet in 1998 with an assigned uncertainty bounded by 60,000 to 130,000 acre-feet.

M.T. Moreo; K.J. Halford; R.J. LaCamera; and R.J. Laczniak

2003-09-30

144

InSAR Reveals a Potpourri of Deformation Signals in the Yucca Mountain -- Amargosa Valley -- Death Valley Region, Southwestern Nevada/Southeastern California  

NASA Astrophysics Data System (ADS)

InSAR studies have revealed a variety of surface deformation signals attributed to several causes in the Yucca Mountain -- Amargosa Valley -- Death Valley region. This study utilizes 26 ERS 1 and 2 scenes to produce 34 interferometric pairs that cover the period of 1992 - 2000. Prominent signals that have been previously studied include the 1992 Little Skull Mountain Earthquake and groundwater subsidence in the Pahrump Valley (Lohman et al., 2002, and Utley, 2005). Several subsidence signals (2.5 -- 3.5 cm) present within Amargosa Valley represent aquifer response in close proximity to local groundwater withdrawal. Observed groundwater level declines in the vicinity of the subsidence bowls are also present. However, signals near Amargosa Flat and Ash Meadows National Wildlife Refuge appear to be a more complex regional aquifer response related either to distant groundwater use or other hydrologic processes related to the abundant spring activity in the area as groundwater levels have remained fairly steady in these regions. A subsidence signal at Frenchman Flat, within the Nevada Test Site, shows approximately 2 cm of subsidence with the majority occurring between 1998 and 2000. Groundwater use in this area was actually lower during this time period than during the previous six years covered by this study, and monitoring wells suggest a relatively constant depth to groundwater with no notable trend up or down. This suggests another mechanism behind the subsidence, including the possibility that three nuclear blast centers located within the subsidence bowl have altered groundwater recharge conditions in the area. The signal with the largest magnitude is related to mining activity at the Bullfrog Mine located west of Beatty, NV. At this location, as much as 8 cm of subsidence, occurring between 1995 and 2000, is centered on the eastern edge of the mine site and extends into the bedrock to the northeast. GPS data (Bennett et al, 2003 and Wernicke et al, 2004) suggest that a velocity contrast of approximately 3.5 mm/yr exists between the Yucca Mountain Block and the Furnace Creek Fault in eastern Death Valley. Unit vector values for the SAR data suggest that this velocity contrast translates to a line of sight (LOS) change of approximately 0.90 -- 0.95 mm/year. Therefore, over the eight year study period, a total LOS change of approximately 0.7 -- 0.8 cm is theorized. Although this LOS change is large enough to be detected using InSAR, this study was unable to detect and locate a signal that could be confidently attributed to this velocity contrast. This is likely due to the wide aperture over which the shear is acting, as well as topographic interference inherent in InSAR studies in regions of variable relief. This study was supported by NASA grant NAG 13 -- 02017.

Katzenstein, K. W.; Bell, J. W.

2005-12-01

145

Slip Rates, Recurrence Intervals and Earthquake Event Magnitudes for the southern Black Mountains Fault Zone, southern Death Valley, California  

NASA Astrophysics Data System (ADS)

The normal-oblique Black Mountain Fault zone (BMFZ) is part of the Death Valley fault system. Strong ground-motion generated by earthquakes on the BMFZ poses a serious threat to the Las Vegas, NV area (pop. ~1,428,690), the Death Valley National Park (max. pop. ~20,000) and Pahrump, NV (pop. 30,000). Fault scarps offset Holocene alluvial-fan deposits along most of the 80-km length of the BMFZ. However, slip rates, recurrence intervals, and event magnitudes for the BMFZ are poorly constrained due to a lack of age control. Also, Holocene scarp heights along the BMFZ range from <1 m to >6 m suggesting that geomorphic sections have different earthquake histories. Along the southernmost section, the BMFZ steps basinward preserving three post-late Pleistocene fault scarps. Surveys completed with a total station theodolite show scarp heights of 5.5, 5.0 and 2 meters offsetting the late Pleistocene, early to middle Holocene, to middle-late Holocene surfaces, respectively. Regression plots of vertical offset versus maximum scarp angle suggest event ages of <10 - 2 ka with a post-late Pleistocene slip rate of 0.1mm/yr to 0.3 mm/yr and recurrence of <3300 years/event. Regression equations for the estimated geomorphically constrained rupture length of the southernmost section and surveyed event displacements provides estimated moment magnitudes (Mw) between 6.6 and 7.3 for the BMFZ.

Fronterhouse Sohn, M.; Knott, J. R.; Bowman, D. D.

2005-12-01

146

A Guide for Using the Transient Ground-Water Flow Model of the Death Valley Regional Ground-Water Flow System, Nevada and California  

SciTech Connect

This report is a guide for executing numerical simulations with the transient ground-water flow model of the Death Valley regional ground-water flow system, Nevada and California using the U.S. Geological Survey modular finite-difference ground-water flow model, MODFLOW-2000. Model inputs, including observations of hydraulic head, discharge, and boundary flows, are summarized. Modification of the DVRFS transient ground-water model is discussed for two common uses of the Death Valley regional ground-water flow system model: predictive pumping scenarios that extend beyond the end of the model simulation period (1998), and model simulations with only steady-state conditions.

Joan B. Blainey; Claudia C. Faunt, and Mary C. Hill

2006-05-16

147

A guide for using the transient ground-water flow model of the Death Valley regional ground-water flow system, Nevada and California  

USGS Publications Warehouse

This report is a guide for executing numerical simulations with the transient ground-water flow model of the Death Valley regional ground-water flow system, Nevada and California using the U.S. Geological Survey modular finite-difference ground-water flow model, MODFLOW-2000. Model inputs, including observations of hydraulic head, discharge, and boundary flows, are summarized. Modification of the DVRFS transient ground-water model is discussed for two common uses of the Death Valley regional ground-water flow system model: predictive pumping scenarios that extend beyond the end of the model simulation period (1998), and model simulations with only steady-state conditions.

Blainey, Joan B.; Faunt, Claudia C.; Hill, Mary C.

2006-01-01

148

Paleoseismic results of the east strand of the Lower Tagus Valley Fault Zone, Central Portugal.  

NASA Astrophysics Data System (ADS)

The Lower Tagus Valley Fault Zone (LTVFZ) is a northeast-southwest trending tectonic structure located within the Lower Tagus Valley (LTV), in central Portugal associated with at least two historical events: the 1909 Mw 6.0-6.2 Benavente earthquake and the 1531 Mw 6.9 earthquake. Recent investigations indicate that the relatively linear valley associated with the Lower Tagus River is controlled by active faults in varying geometry and slip rates. Based on mapped traces, LTVFZ is about 80 kilometers long and transects Miocene to Holocene deposit. The east and west strands of the fault zone may have different level of activity based on the variable clarity of mapped morphological expressions. In recent studies new fault strands were identified using aerial photos and field survey on eastern side of LTV. These eastern faults have a trend that almost parallel those active traces previously mapped by Besana-Ostman et al., 2012 on the western side of the valley. Quaternary activity of this fault deforms fluvial terraces and produces morphological features related to left-lateral strike-slip movement like river offsets. In this work we present the results of the first paleoseismic analysis carried out on this strand of the fault. Trenching studies shows that surface rupture events have occurred affecting Tagus fluvial terraces. The geometry of faulting exposed in the trench provides valuable insights into the kinematics of the fault, and provides a preliminary minimum net slip rate. New relative ages of the deformation are established on preliminary trenching results, and recurrence intervals will be determined upon receipt of results of sample processing for C14 dating. The aim of this work is to contribute with new data to parameterize the paleoseismic activity of this active fault in order to be included in the future seismic hazard assessments. Further studies are proposed and underway to characterize the LTVFZ, including high-resolution LIDAR images analysis, more active fault mapping and paleoseismic excavations.

Canora, Carolina; Vilanova, Susana; Besana-Ostman, Glenda; Heleno, Sandra; Fonseca, Joao; Domingues, Ana; Pinheiro, Patricia; Pinto, Luis

2014-05-01

149

Late Cenozoic sedimentation and volcanism during transtensional deformation in Wingate Wash and the Owlshead Mountains, Death Valley  

NASA Astrophysics Data System (ADS)

New 1 : 24,000 scale mapping, geochemical analyses of volcanic rocks, and Ar/Ar and tephrochronology analyses of the Wingate Wash, northern Owlshead Mountain and Southern Panamint Mountain region document a complex structural history constrained by syntectonic volcanism and sedimentation. In this study, the region is divided into five structural domains with distinct, but related, histories: (1) The southern Panamint domain is a structurally intact, gently south-tilted block dominated by a middle Miocene volcanic center recognized as localized hypabyssal intrusives surrounded by proximal facies pyroclastic rocks. This Miocene volcanic sequence is an unusual alkaline volcanic assemblage ranging from trachybasalt to rhyolite, but dominated by trachyandesite. The volcanic rocks are overlain in the southwestern Panamint Mountains by a younger (Late Miocene?) fanglomerate sequence. (2) An upper Wingate Wash domain is characterized by large areas of Quaternary cover and complex overprinting of older structure by Quaternary deformation. Quaternary structures record ˜N-S shortening concurrent with ˜E-W extension accommodated by systems of strike-slip and thrust faults. (3) A central Wingate Wash domain contains a complex structural history that is closely tied to the stratigraphic evolution. In this domain, a middle Miocene volcanic package contains two distinct assemblages; a lower sequence dominated by alkaline pyroclastic rocks similar to the southern Panamint sequence and an upper basaltic sequence of alkaline basalt and basanites. This volcanic sequence is in turn overlain by a coarse clastic sedimentary sequence that records the unroofing of adjacent ranges and development of ˜N-S trending, west-tilted fault blocks. We refer to this sedimentary sequence as the Lost Lake assemblage. (4) The lower Wingate Wash/northern Owlshead domain is characterized by a gently north-dipping stratigraphic sequence with an irregular unconformity at the base developed on granitic basement. The unconformity is locally overlain by channelized deposits of older Tertiary(?) red conglomerate, some of which predate the onset of extensive volcanism, but in most of the area is overlain by a moderately thick package of Middle Miocene trachybasalt, trachyandesitic, ash flows, lithic tuff, basaltic cinder, basanites, and dacitic pyroclastic, debris, and lahar flows with localized exposures of sedimentary rocks. The upper part of the Miocene stratigraphic sequence in this domain is comprised of coarse grained-clastic sediments that are apparently middle Miocene based on Ar/Ar dating of interbedded volcanic rocks. This sedimentary sequence, however, is lithologically indistinguishable from the structurally adjacent Late Miocene Lost Lake assemblage and a stratigraphically overlying Plio-Pleistocene alluvial fan; a relationship that handicaps tracing structures through this domain. This domain is also structurally complex and deformed by a series of northwest-southeast-striking, east-dipping, high-angle oblique, sinistral, normal faults that are cut by left-lateral strike-slip faults. The contact between the southern Panamint domain and the adjacent domains is a complex fault system that we interpret as a zone of Late Miocene distributed sinistral slip that is variably overprinted in different portions of the mapped area. The net sinistral slip across the Wingate Wash fault system is estimated at 7-9 km, based on offset of Proterozoic Crystal Springs Formation beneath the middle Miocene unconformity to as much as 15 km based on offset volcanic facies in Middle Miocene rocks. To the south of Wingate Wash, the northern Owlshead Mountains are also cut by a sinistral, northwest-dipping, oblique normal fault, (referred to as the Filtonny Fault) with significant slip that separates the Lower Wingate Wash and central Owlshead domains. The Filtonny Fault may represent a young conjugate fault to the dextral Southern Death Valley fault system and may be the northwest-dipping fault imaged by COCORP studies. Similarly, younger deformation in upper Wingate Wash is

Luckow, Heather Golding; Pavlis, Terry L.; Serpa, Laura F.; Guest, Bernard; Wagner, David L.; Snee, Lawrence; Hensley, Tabitha M.; Korjenkov, Andrey

2005-12-01

150

Late Cenozoic sedimentation and volcanism during transtensional deformation in Wingate Wash and the Owlshead Mountains, Death Valley  

USGS Publications Warehouse

New 1:24,000 scale mapping, geochemical analyses of volcanic rocks, and Ar/Ar and tephrochronology analyses of the Wingate Wash, northern Owlshead Mountain and Southern Panamint Mountain region document a complex structural history constrained by syntectonic volcanism and sedimentation. In this study, the region is divided into five structural domains with distinct, but related, histories: (1) The southern Panamint domain is a structurally intact, gently south-tilted block dominated by a middle Miocene volcanic center recognized as localized hypabyssal intrusives surrounded by proximal facies pyroclastic rocks. This Miocene volcanic sequence is an unusual alkaline volcanic assemblage ranging from trachybasalt to rhyolite, but dominated by trachyandesite. The volcanic rocks are overlain in the southwestern Panamint Mountains by a younger (Late Miocene?) fanglomerate sequence. (2) An upper Wingate Wash domain is characterized by large areas of Quaternary cover and complex overprinting of older structure by Quaternary deformation. Quaternary structures record ???N-S shortening concurrent with ???E-W extension accommodated by systems of strike-slip and thrust faults. (3) A central Wingate Wash domain contains a complex structural history that is closely tied to the stratigraphic evolution. In this domain, a middle Miocene volcanic package contains two distinct assemblages; a lower sequence dominated by alkaline pyroclastic rocks similar to the southern Panamint sequence and an upper basaltic sequence of alkaline basalt and basanites. This volcanic sequence is in turn overlain by a coarse clastic sedimentary sequence that records the unroofing of adjacent ranges and development of ???N-S trending, west-tilted fault blocks. We refer to this sedimentary sequence as the Lost Lake assemblage. (4) The lower Wingate Wash/northern Owlshead domain is characterized by a gently north-dipping stratigraphic sequence with an irregular unconformity at the base developed on granitic basement. The unconformity is locally overlain by channelized deposits of older Tertiary(?) red conglomerate, some of which predate the onset of extensive volcanism, but in most of the area is overlain by a moderately thick package of Middle Miocene trachybasalt, trachyandesitic, ash flows, lithic tuff, basaltic cinder, basanites, and dacitic pyroclastic, debris, and lahar flows with localized exposures of sedimentary rocks. The upper part of the Miocene stratigraphic sequence in this domain is comprised of coarse grained-clastic sediments that are apparently middle Miocene based on Ar/Ar dating of interbedded volcanic rocks. This sedimentary sequence, however, is lithologically indistinguishable from the structurally adjacent Late Miocene Lost Lake assemblage and a stratigraphically overlying Plio-Pleistocene alluvial fan; a relationship that handicaps tracing structures through this domain. This domain is also structurally complex and deformed by a series of northwest-southeast-striking, east-dipping, high-angle oblique, sinistral, normal faults that are cut by left-lateral strike-slip faults. The contact between the southern Panamint domain and the adjacent domains is a complex fault system that we interpret as a zone of Late Miocene distributed sinistral slip that is variably overprinted in different portions of the mapped area. The net sinistral slip across the Wingate Wash fault system is estimated at 7-9 km, based on offset of Proterozoic Crystal Springs Formation beneath the middle Miocene unconformity to as much as 15 km based on offset volcanic facies in Middle Miocene rocks. To the south of Wingate Wash, the northern Owlshead Mountains are also cut by a sinistral, northwest-dipping, oblique normal fault, (referred to as the Filtonny Fault) with significant slip that separates the Lower Wingate Wash and central Owlshead domains. The Filtonny Fault may represent a young conjugate fault to the dextral Southern Death Valley fault system and may be the northwest

Luckow, H. G.; Pavlis, T. L.; Serpa, L. F.; Guest, B.; Wagner, D. L.; Snee, L.; Hensley, T. M.; Korjenkov, A.

2005-01-01

151

Lava flows vs. surface water: the geologic battle for the upper McKenzie valley, central Oregon Cascades  

Microsoft Academic Search

Over the past several thousand years, a battle for the upper McKenzie valley in the central Oregon Cascades has raged between, on one side, lava flows from the Sand Mountain volcanic chain and Belknap volcano, and on the other side, surface water fed by prolific springs. The north-south oriented upper McKenzie valley marks the boundary between the (old) western Cascades

N. I. Deligne; R. M. Conrey; K. V. Cashman; G. E. Grant; W. H. Amidon

2010-01-01

152

Hematology and plasma biochemistry values for the giant garter snake (Thamnophis gigas) and valley garter snake (Thamnophis sirtalis fitchi) in the Central Valley of California.  

PubMed

Hematology and plasma biochemistry parameters are useful in the assessment and management of threatened and endangered species. Although reference ranges are readily available for many mammalian species, reference ranges for snakes are lacking for most species. We determined hematology and plasma biochemistry reference ranges for giant garter snakes (Thamnophis gigas) and valley garter snakes (Thamnophis sirtalis fitchi) living in four management areas in the Central Valley of California. White blood cell, heterophil, lymphocyte, and azurophil counts in giant garter snakes were approximately twice the values of valley garter snakes. Statistically significant differences in aspartate aminotransferase, globulin, and potassium between the two species did not appear clinically significant. No significant differences were found in the measured parameters between male and female giant garter snakes. Some differences were found among collection sites. These reference ranges provide baseline data for comparisons over time and between collection sites. PMID:22493106

Wack, Raymund F; Hansen, Eric; Small, Marilyn; Poppenga, Robert; Bunn, David; Johnson, Christine K

2012-04-01

153

New observations of VOC emissions and concentrations in, above, and around the Central Valley of California  

NASA Astrophysics Data System (ADS)

Large portions of the Central Valley of California are out of compliance with current state and federal air quality standards for ozone and particulate matter, and the relative importance of biogenic and anthropogenic VOC emissions to their photochemical production in this region remains uncertain. In 2009-2011 multiple measurement campaigns were completed investigating the VOC emission inventory and concentration distributions. In 2009 BVOC emissions from more than 20 species of major agricultural crops in California were measured in a greenhouse using branch enclosures by both PTRMS and in-situ GC. Overall, crops were found to emit low amounts of BVOC compared to the natural forests surrounding the valley. Crops mainly emitted methanol and terpenes, with a broad array of other species emitted at lower levels, and all the measured crops showed negligible emissions of isoprene. Navel oranges were the largest crop BVOC emitters measured so a full year of flux measurements were made in an orange grove near Visalia in 2010 by eddy covariance(EC)-PTRMS with two multi-week periods of concentration measurements by hourly in-situ GC, and one month of high mass resolution flux measurements by EC-PTR-TOF-MS. The dominant BVOC emissions from the orange grove were methanol and terpenes, followed by acetone, acetaldehyde, and a low level of emissions for many other species. In 2011 aircraft eddy covariance measurements of BVOC fluxes were made by EC-PTRMS covering a large area of California as part of the California Airborne Bvoc Emission Research in Natural Ecosystem Transects (CABERNET) campaign aimed at improving BVOC emission models on regional scales, mainly profiling BVOC emissions from oak woodlands surrounding the Central Valley. In 2010, hourly in-situ VOC measurements were made via in-situ GC in Bakersfield, CA as part of the CalNex experiment. Additionally, in-situ measurements of fresh motor vehicle exhaust were made in Oakland's Caldecott tunnel. Measurements by in-situ GC included more than 200 anthropogenic and biogenic VOCs with a wide range of volatilities (up to 17 carbon atoms in size) and various functional groups (e.g. aldehydes, ketones, alcohols, halogens, sulfur, & nitrogen). Finally, in 2011 vertical profiles of VOC were made at 5 heights on a communication tower at Walnut Grove (~20 miles south of Sacramento) from 30' to 1550' by PTRMS. Results from all of these studies combined provide a novel overview of the distribution of VOC emissions and concentrations in, around, and above the Central Valley of California.

Goldstein, A. H.; Fares, S.; Gentner, D. R.; Park, J.; Weber, R.; Ormeno, E.; Holzinger, R.; Misztal, P. K.; Karl, T. R.; Guenther, A. B.; Fischer, M. L.; Harley, R. A.; Karlik, J. F.

2011-12-01

154

Preliminary estimates of spatially distributed net infiltration and recharge for the Death Valley region, Nevada-California  

USGS Publications Warehouse

A three-dimensional ground-water flow model has been developed to evaluate the Death Valley regional flow system, which includes ground water beneath the Nevada Test Site. Estimates of spatially distributed net infiltration and recharge are needed to define upper boundary conditions. This study presents a preliminary application of a conceptual and numerical model of net infiltration. The model was developed in studies at Yucca Mountain, Nevada, which is located in the approximate center of the Death Valley ground-water flow system. The conceptual model describes the effects of precipitation, runoff, evapotranspiration, and redistribution of water in the shallow unsaturated zone on predicted rates of net infiltration; precipitation and soil depth are the two most significant variables. The conceptual model was tested using a preliminary numerical model based on energy- and water-balance calculations. Daily precipitation for 1980 through 1995, averaging 202 millimeters per year over the 39,556 square kilometers area of the ground-water flow model, was input to the numerical model to simulate net infiltration ranging from zero for a soil thickness greater than 6 meters to over 350 millimeters per year for thin soils at high elevations in the Spring Mountains overlying permeable bedrock. Estimated average net infiltration over the entire ground-water flow model domain is 7.8 millimeters per year.To evaluate the application of the net-infiltration model developed on a local scale at Yucca Mountain, to net-infiltration estimates representing the magnitude and distribution of recharge on a regional scale, the net-infiltration results were compared with recharge estimates obtained using empirical methods. Comparison of model results with previous estimates of basinwide recharge suggests that the net-infiltration estimates obtained using this model may overestimate recharge because of uncertainty in modeled precipitation, bedrock permeability, and soil properties for locations such as the Spring Mountains. Although this model is preliminary and uncalibrated, it provides a first approximation of the spatial distribution of net infiltration for the Death Valley region under current climatic conditions.

Hevesi, J. A.; Flint, A. L.; Flint, L. E.

2002-01-01

155

Recent land-use/land-cover change in the Central California Valley  

USGS Publications Warehouse

Open access to Landsat satellite data has enabled annual analyses of modern land-use and land-cover change (LULCC) for the Central California Valley ecoregion between 2005 and 2010. Our annual LULCC estimates capture landscape-level responses to water policy changes, climate, and economic instability. From 2005 to 2010, agriculture in the region fluctuated along with regulatory-driven changes in water allocation as well as persistent drought conditions. Grasslands and shrublands declined, while developed lands increased in former agricultural and grassland/shrublands. Development rates stagnated in 2007, coinciding with the onset of the historic foreclosure crisis in California and the global economic downturn. We utilized annual LULCC estimates to generate interval-based LULCC estimates (2000–2005 and 2005–2010) and extend existing 27 year interval-based land change monitoring through 2010. Resulting change data provides insights into the drivers of landscape change in the Central California Valley ecoregion and represents the first, continuous, 37 year mapping effort of its kind.

Soulard, Christopher E.; Wilson, Tamara S.

2013-01-01

156

Hydrogeologic framework and occurrence, movement, and chemical characterization of groundwater in Dixie Valley, west-central Nevada  

USGS Publications Warehouse

Dixie Valley, a primarily undeveloped basin in west-central Nevada, is being considered for groundwater exportation. Proposed pumping would occur from the basin-fill aquifer. In response to proposed exportation, the U.S. Geological Survey, in cooperation with the Bureau of Reclamation and Churchill County, conducted a study to improve the understanding of groundwater resources in Dixie Valley. The objective of this report is to characterize the hydrogeologic framework, the occurrence and movement of groundwater, the general water quality of the basin-fill aquifer, and the potential mixing between basin-fill and geothermal aquifers in Dixie Valley. Various types of geologic, hydrologic, and geochemical data were compiled from previous studies and collected in support of this study. Hydrogeologic units in Dixie Valley were defined to characterize rocks and sediments with similar lithologies and hydraulic properties influencing groundwater flow. Hydraulic properties of the basin-fill deposits were characterized by transmissivity estimated from aquifer tests and specific-capacity tests. Groundwater-level measurements and hydrogeologic-unit data were combined to create a potentiometric surface map and to characterize groundwater occurrence and movement. Subsurface inflow from adjacent valleys into Dixie Valley through the basin-fill aquifer was evaluated using hydraulic gradients and Darcy flux computations. The chemical signature and groundwater quality of the Dixie Valley basin-fill aquifer, and potential mixing between basin-fill and geothermal aquifers, were evaluated using chemical data collected from wells and springs during the current study and from previous investigations. Dixie Valley is the terminus of the Dixie Valley flow system, which includes Pleasant, Jersey, Fairview, Stingaree, Cowkick, and Eastgate Valleys. The freshwater aquifer in the study area is composed of unconsolidated basin-fill deposits of Quaternary age. The basin-fill hydrogeologic unit can be several orders of magnitude more transmissive than surrounding and underlying consolidated rocks and Dixie Valley playa deposits. Transmissivity estimates in the basin fill throughout Dixie Valley ranged from 30 to 45,500 feet squared per day; however, a single transmissivity value of 0.1 foot squared per day was estimated for playa deposits. Groundwater generally flows from the mountain range uplands toward the central valley lowlands and eventually discharges near the playa edge. Potentiometric contours east and west of the playa indicate that groundwater is moving eastward from the Stillwater Range and westward from the Clan Alpine Mountains toward the playa. Similarly, groundwater flows from the southern and northern basin boundaries toward the basin center. Subsurface groundwater flow likely enters Dixie Valley from Fairview and Stingaree Valleys in the south and from Jersey and Pleasant Valleys in the north, but groundwater connections through basin-fill deposits were present only across the Fairview and Jersey Valley divides. Annual subsurface inflow from Fairview and Jersey Valleys ranges from 700 to 1,300 acre-feet per year and from 1,800 to 2,300 acre-feet per year, respectively. Groundwater flow between Dixie, Stingaree, and Pleasant Valleys could occur through less transmissive consolidated rocks, but only flow through basin fill was estimated in this study. Groundwater in the playa is distinct from the freshwater, basin-fill aquifer. Groundwater mixing between basin-fill and playa groundwater systems is physically limited by transmissivity contrasts of about four orders of magnitude. Total dissolved solids in playa deposit groundwater are nearly 440 times greater than total dissolved solids in the basin-fill groundwater. These distinctive physical and chemical flow restrictions indicate that groundwater interaction between the basin fill and playa sediments was minimal during this study period (water years 2009–11). Groundwater in Dixie Valley generally can be characterized as a sodium bicarbonate type, with greater proportions of chloride n

Huntington, Jena M.; Garcia, C. Amanda; Rosen, Michael R.

2014-01-01

157

Chronology, sedimentology, and microfauna of groundwater discharge deposits in the central Mojave Desert, Valley Wells, California  

USGS Publications Warehouse

During the late Pleistocene, emergent groundwater supported persistent and long-lived desert wetlands in many broad valleys and basins in the American Southwest. When active, these systems provided important food and water sources for local fauna, supported hydrophilic and phreatophytic vegetation, and acted as catchments for eolian and alluvial sediments. Desert wetlands are represented in the geologic record by groundwater discharge deposits, which are also called spring or wetland deposits. Groundwater discharge deposits contain information on the timing and magnitude of past changes in water-table levels and, thus, are a source of paleohydrologic and paleoclimatic information. Here, we present the results of an investigation of extensive groundwater discharge deposits in the central Mojave Desert at Valley Wells, California. We used geologic mapping and stratigraphic relations to identify two distinct wetland sequences at Valley Wells, which we dated using radiocarbon, luminescence, and uranium-series techniques. We also analyzed the sediments and microfauna (ostracodes and gastropods) to reconstruct the specific environments in which they formed. Our results suggest that the earliest episode of high water-table conditions at Valley Wells began ca. 60 ka (thousands of calendar yr B.P.), and culminated in peak discharge between ca. 40 and 35 ka. During this time, cold (4–12 °C) emergent groundwater supported extensive wetlands that likely were composed of a wet, sedge-rush-tussock meadow mixed with mesic riparian forest. After ca. 35 ka, the water table dropped below the ground surface but was still shallow enough to support dense stands of phreatophytes through the Last Glacial Maximum (LGM). The water table dropped further after the LGM, and xeric conditions prevailed until modest wetlands returned briefly during the Younger Dryas cold event (13.0–11.6 ka). We did not observe any evidence of wet conditions during the Holocene at Valley Wells. The timing of these fluctuations is consistent with changes in other paleowetland systems in the Mojave Desert, the nearby Great Basin Desert, and in southeastern Arizona, near the border of the Sonoran and Chihuahuan Deserts. The similarities in hydrologic conditions between these disparate locations suggest that changes in groundwater levels during the late Pleistocene in desert wetlands scattered throughout the American Southwest were likely driven by synoptic-scale climate processes.

Pigati, Jeffrey S.; Miller, David M.; Bright, Jordon E.; Mahan, Shannon A.; Nekola, Jeffrey C.; Paces, James B.

2011-01-01

158

Chronology, sedimentology, and microfauna of groundwater discharge deposits in the central Mojave Desert, Valley Wells, California  

USGS Publications Warehouse

groundwater supported persistent and long-lived desert wetlands in many broad valleys and basins in the American Southwest. When active, these systems provided important food and water sources for local fauna, supported hydrophilic and phreatophytic vegetation, and acted as catchments for eolian and alluvial sediments. Desert wetlands are represented in the geologic record by groundwater discharge deposits, which are also called spring or wetland deposits. Groundwater discharge deposits contain information on the timing and magnitude of past changes in water-table levels and, thus, are a source of paleohydrologic and paleoclimatic information. Here, we present the results of an investigation of extensive groundwater discharge deposits in the central Mojave Desert at Valley Wells, California. We used geologic mapping and stratigraphic relations to identify two distinct wetland sequences at Valley Wells, which we dated using radiocarbon, luminescence, and uranium-series techniques. We also analyzed the sediments and microfauna (ostracodes and gastropods) to reconstruct the specific environments in which they formed. Our results suggest that the earliest episode of high water-table conditions at Valley Wells began ca. 60 ka (thousands of calendar yr B.P.), and culminated in peak discharge between ca. 40 and 35 ka. During this time, cold (4-12 ??C) emergent groundwater supported extensive wetlands that likely were composed of a wet, sedge-rush-tussock meadow mixed with mesic riparian forest. After ca. 35 ka, the water table dropped below the ground surface but was still shallow enough to support dense stands of phreatophytes through the Last Glacial Maximum (LGM). The water table dropped further after the LGM, and xeric conditions prevailed until modest wetlands returned briefly during the Younger Dryas cold event (13.0-11.6 ka). We did not observe any evidence of wet conditions during the Holocene at Valley Wells. The timing of these fluctuations is consistent with changes in other paleowetland systems in the Mojave Desert, the nearby Great Basin Desert, and in southeastern Arizona, near the border of the Sonoran and Chihuahuan Deserts. The similarities in hydrologic conditions between these disparate locations suggest that changes in groundwater levels during the late Pleistocene in desert wetlands scattered throughout the American Southwest were likely driven by synopticscale climate processes. ?? 2011 Geological Society of America.

Pigati, J.S.; Miller, D.M.; Bright, J.E.; Mahan, S.A.; Nekola, J.C.; Paces, J.B.

2011-01-01

159

Perspective: Transforming science into medicine: how clinician-scientists can build bridges across research's "valley of death".  

PubMed

Significant increases in National Institutes of Health (NIH) spending on medical research have not produced corresponding increases in new treatments and cures. Instead, laboratory discoveries remain in what has been termed the "valley of death," the gap between bench research and clinical application. Recently, there has been considerable discussion in the literature and scientific community about the causes of this phenomenon and how to bridge the abyss. In this article, the authors examine one possible explanation: Clinician-scientists' declining role in the medical research enterprise has had a dilatory effect on the successful translation of laboratory breakthroughs into new clinical applications. In recent decades, the percentage of MDs receiving NIH funding has drastically decreased compared with PhDs. The growing gap between the research and clinical enterprises has resulted in fewer scientists with a true understanding of clinical problems as well as scientists who are unable to or uninterested in gleaning new basic research hypotheses from failed clinical trials. The NIH and many U.S. medical schools have recognized the decline of the clinician-scientist as a major problem and adopted innovative programs to reverse the trend. However, more radical action may be required, including major changes to the NIH peer-review process, greater funding for translational research, and significantly more resources for the training, debt relief, and early career support of potential clinician-scientists. Such improvements are required for clinician-scientists to conduct translational research that bridges the valley of death and transforms biomedical research discoveries into tangible clinical treatments and technologies. PMID:22373616

Roberts, Scott F; Fischhoff, Martin A; Sakowski, Stacey A; Feldman, Eva L

2012-03-01

160

Hydraulic-property estimates for use with a transient ground-water flow model of the Death Valley regional ground-water flow system, Nevada and California  

SciTech Connect

The Death Valley regional ground-water flow system encompasses an area of about 43,500 square kilometers in southeastern California and southern Nevada. The study area is underlain by Quaternary to Tertiary basin-fill sediments and mafic-lava flows; Tertiary volcanic, volcaniclastic, and sedimentary rocks; Tertiary to Jurassic granitic rocks; Triassic to Middle Proterozoic carbonate and clastic sedimentary rocks; and Early Proterozoic igneous and metamorphic rocks. The rock assemblage in the Death Valley region is extensively faulted as a result of several episodes of tectonic activity. This study is comprised of published and unpublished estimates of transmissivity, hydraulic conductivity, storage coefficient, and anisotropy ratios for hydrogeologic units within the Death Valley region study area. Hydrogeologic units previously proposed for the Death Valley regional transient ground-water flow model, were recognized for the purpose of studying the distribution of hydraulic properties. Analyses of regression and covariance were used to assess if a relation existed between hydraulic conductivity and depth for most hydrogeologic units. Those analyses showed a weak, quantitatively indeterminate, relation between hydraulic conductivity and depth.

W.R. Belcher; P.E. Elliott; A.L. Geldon

2001-12-31

161

Cell death shapes embryonic lineages of the central complex in the grasshopper Schistocerca gregaria.  

PubMed

We have investigated cell death in identified lineages of the central complex in the embryonic brain of the grasshopper Schistocerca gregaria. Progeny from these lineages lie in the pars intercerebralis and direct projections to the protocerebral bridge and then the central body via the w, x, y, z tracts. Osmium-ethyl gallate staining reveals pycnotic cells exclusively in cortical regions, and concentrated specifically within the lineages of the W, X, Y, Z neuroblasts. Minimal cell death occurs in a sporadic, nonpatterned manner, in other protocerebral regions. Immunohistochemistry reveals pycnotic cells express the enzyme cleaved Caspase-3 in their cytoplasm and are therefore undergoing programmed cell death (apoptosis). The number of pycnotic bodies in lineages of the pars intercerebralis varies with age: small numbers are present in the Y, Z lineages early in embryogenesis (42%), the number peaks at 67-80%, and then declines and disappears late in embryogenesis. Cell death may encompass up to 20% of a lineage at mid-embryogenesis. Peak cell death occurs shortly after maximum neurogenesis in the Y, Z lineages, and is maintained after neurogenesis has ceased in these lineages. Cell death within a lineage is patterned. Apoptosis is more pronounced among older cells and almost absent among younger cells. This suggests that specific subsets of progeny will be culled from these lineages, and we speculate about the effect of apoptosis on the biochemical profile of such lineages. PMID:20623625

Boyan, George; Herbert, Zsofia; Williams, Leslie

2010-08-01

162

Reconstruction of Flooding Events for the Central Valley, California from Instrumental and Documentary Weather Records  

NASA Astrophysics Data System (ADS)

All available instrumental winter precipitation data for the Central Valley of California back to 1850 were digitized and analyzed to construct continuous time series. Many of these data, in paper or microfilm format, extend prior to modern National Weather Service Cooperative Data Program and Historical Climate Network data, and were recorded by volunteer observers from networks such as the US Army Surgeon General, Smithsonian Institution, and US Army Signal Service. Given incomplete individual records temporally, detailed documentary data from newspapers, personal diaries and journals, ship logbooks, and weather enthusiasts’ instrumental data, were used in conjunction with instrumental data to reconstruct precipitation frequency per month and season, continuous days of precipitation, and to identify anomalous precipitation events. Multilinear regression techniques, using surrounding stations and the relationships between modern and historical records, bridge timeframes lacking data and provided homogeneous nature of time series. The metadata for each station was carefully screened, and notes were made about any possible changes to the instrumentation, location of instruments, or an untrained observer to verify that anomalous events were not recorded incorrectly. Precipitation in the Central Valley varies throughout the entire region, but waterways link the differing elevations and latitudes. This study integrates the individual station data with additional accounts of flood descriptions through unique newspaper and journal data. River heights and flood extent inundating cities, agricultural lands, and individual homes are often recorded within unique documentary sources, which add to the understanding of flood occurrence within this area. Comparisons were also made between dam and levee construction through time and how waters are diverted through cities in natural and anthropogenically changed environments. Some precipitation that lead to flooding events that occur in the Central Valley in the mid-19th century through the early 20th century are more outstanding at some particular stations than the modern records include. Several years that are included in the study are 1850, 1862, 1868, 1878, 1881, 1890, and 1907. These flood years were compared to the modern record and reconstructed through time series and maps. Incorporating the extent and effects these anomalous events in future climate studies could improve models and preparedness for the future floods.

Dodds, S. F.; Mock, C. J.

2009-12-01

163

Tracking River Recharge in the Central Valley of California Using Chemical and Isotopic Tracers  

NASA Astrophysics Data System (ADS)

Recharge to alluvial aquifers along the major rivers of the Central Valley of California is influenced by human activity in adjacent urban areas and groundwater basins. Intense pumping of Central Valley aquifers may induce recharge, while slurry walls, emplaced for flood control in densely populated areas, are intended to protect levees by preventing shallow recharge. These large rivers carry distinct chemical and isotopic signatures that allow recent recharge to be traced in adjacent wells. In particular, stable isotopes of oxygen delineate areas where river water, carrying a depleted isotopic signature from Sierra Nevada precipitation (-11 to -15 per mil), is recharging groundwater aquifers where local precipitation is significantly heavier (-7 per mil). Trace anthropogenic compounds present in river water, such as MtBE (from precipitation and recreational boating on watershed reservoirs), are also useful for identifying areas where river water has recently infiltrated. Analysis of groundwater age, using the tritium-helium method allows estimation of the time since recharge, and evaluation of the effect of human activity on the natural groundwater recharge and flow patterns. Results from a detailed study along the American River in Sacramento, where a slurry wall is in place, show areas of recent recharge, as evidenced by relatively high MtBE concentrations (matching river concentrations) and young groundwater ages in shallow wells. In other wells, older ages and very low MtBE concentrations delineate areas where active recharge is not taking place. These results are interpreted in the context of basin-wide analyses for the Sacramento urban area, where most groundwater sampled from municipal wells is devoid of tritium, and therefore recharged more than about 50 years ago. These data are collected for the Ambient Groundwater Monitoring and Assessment (GAMA) program, sponsored by the CA State Water Resources Control Board. Oxygen isotopes indicate that American River water has recharged a large portion of this basin, with wells showing decreasing fractions of isotopically depleted water moving away from the river to the north. A similar pattern is observed in other areas of intense pumping in groundwater basins along the major rivers in the Central Valley. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-ENG-48.

Moran, J. E.; Hudson, B.; Evans, D.; Horner, T.; Leif, R.; Eaton, G. F.

2003-12-01

164

A plan to study the aquifer system of the Central Valley of California  

USGS Publications Warehouse

Unconsolidated Quaternary alluvial deposits comprise a large complex aquifer system in the Central Valley of California. Millions of acre-feet of water is pumped from the system annually to support a large and expanding agribusiness industry. Since the 1950's, water levels have been steadily declining in many areas of the valley and concern has been expressed about the ability of the entire ground-water system to support agribusiness at current levels, not to mention its ability to function at projected expansion levels. At current levels of ground-water use, an estimated 1.5 to 2 million acre-feet is withdrawn from storage each year; that is, 1.5 to 2 million acre-feet of water is pumped annually in excess of annual replenishment. The U.S. Geological Survey has initiated a 4-year study to develop geologic, hydrologic, and hydraulic information and to establish a valleywide ground-water data base that will be used to build computer models of the ground-water flow system. Subsequently, these models may be used to evaluate the system response to various ground-water management alternatives. This report describes current problems, objectives of the study, and outlines the general work to be accomplished in the study area. A bibliography of about 600 references is included. (Kosco-USGS)

Bertoldi, Gilbert L.

1979-01-01

165

Chemistry, mineralogy and origin of the clay-hill nitrate deposits, Amargosa River valley, Death Valley region, California, U.S.A.  

USGS Publications Warehouse

The clay-hill nitrate deposits of the Amargosa River valley, California, are caliche-type accumulations of water-soluble saline minerals in clay-rich soils on saline lake beds of Miocene, Pliocene(?) and Pleistocene age. The soils have a maximum thickness of ??? 50 cm, and commonly consist of three layers: (1) an upper 5-10 cm of saline-free soil; (2) an underlying 15-20 cm of rubbly saline soil; and (3) a hard nitrate-rich caliche, 10-20 cm thick, at the bottom of the soil profile. The saline constituents, which make up as much as 50% of the caliche, are chiefly Cl-, NO-3, SO2-4 and Na+. In addition are minor amounts of K+, Mg2+ and Ca2+, varying, though generally minor, amounts of B2O3 and CO2-3, and trace amounts of I (probably as IO-3), NO-2, CrO2-4 and Mo (probably as MoO2-4). The water-soluble saline materials have an I/Br ratio of ??? 1, which is much higher than nearly all other saline depostis. The principal saline minerals of the caliche are halite (NaCl), nitratite (NaNO3), darapskite (Na3(SO4)(NO3)??H2O), glauberite (Na2Ca(SO4)2), gypsum (CaSO4??2H2O) and anhydrite (CaSO4). Borax (Na2B4O5(OH)4??8H2O), tincalconite (Na2B4O5(OH)4??3H2O) and trona (Na3(CO3)(HCO3)??2H2O) are abundant locally. The clay-hill nitrate deposits are analogous to the well-known Chilean nitrate deposits, and probably are of similar origin. Whereas the Chilean deposits are in permeable soils of the nearly rainless Atacama Desert, the clay-hill deposits are in relatively impervious clay-rich soils that inhibited leaching by rain water. The annual rainfall in the Death Valley region of ??? 5 cm is sufficient to leach water-soluble minerals from the more permeable soils. The clay-hill deposits contain saline materials from the lake beds beneath the nitrate deposits are well as wind-transported materials from nearby clay-hill soils, playas and salt marshes. The nitrate is probably of organic origin, consisting of atmospheric nitrogen fixed as protein by photoautotrophic blue-green algae, which are thought to form crusts on soils at the sites of the deposits when moistened by rainfall. The protein is subsequently transformed to nitrate by autotophic bacteria. ?? 1988.

Ericksen, G.E.; Hosterman, J.W.; St., Amand, P.

1988-01-01

166

Buried paleoindian-age landscapes in stream valleys of the central plains, USA  

USGS Publications Warehouse

A systematic study of late-Quaternary landscape evolution in the Central Plains documented widespread, deeply buried paleosols that represent Paleoindian-age landscapes in terrace fills of large streams (> 5th order), in alluvial fans, and in draws in areas of western Kansas with a thick loess mantle. Alluvial stratigraphic sections were investigated along a steep bio-climatic gradient extending from the moist-subhumid forest-prairie border of the east-central Plains to the dry-subhumid and semi-arid shortgrass prairie of the west-central Plains. Radiocarbon ages indicate that most large streams were characterized by slow aggradation accompanied by cumulic soil development from ca. 11,500 to 10,000??14C yr B.P. In the valleys of some large streams, such as the Ninnescah and Saline rivers, these processes continued into the early Holocene. The soil-stratigraphic record in the draws of western Kansas indicates slow aggradation punctuated by episodes of landscape stability and pedogenesis beginning as early as ca. 13,300??14C yr B.P. and spanning the Pleistocene-Holocene boundary. The development record of alluvial fans in western Kansas is similar to the record in the draws; slow aggradation was punctuated by multiple episodes of soil development between ca. 13,000 and 9000??14C yr B.P. In eastern Kansas and Nebraska, development of alluvial fans was common during the early and middle Holocene, but evidence shows fan development as early as ca. 11,300??14C yr B.P. Buried soils dating between ca. 12,600 and 9000??14C yr B.P. were documented in fans throughout the region. In stream valleys across the Central Plains, rapid alluviation after ca. 9000??14C yr B.P. resulted in deeply buried soils that may harbor Paleoindian cultural deposits. Hence, the paucity of recorded stratified Paleoindian sites in the Central Plains is probably related to poor visibility (i.e., deep burial in alluvial deposits) instead of limited human occupation in the region during the terminal Pleistocene and early Holocene. The thick, dark, cumulic A horizons of soils, representing buried Paleoindian-age landscapes, are targets for future archaeological surveys. ?? 2008 Elsevier B.V. All rights reserved.

Mandel, R.D.

2008-01-01

167

Soil formation in Phobjikha Valley, Central Bhutan with special regard to the redistribution of loessic sediments  

NASA Astrophysics Data System (ADS)

Soil development and landscape evolution were studied in the basin-shaped Phobjikha Valley at 2900-3200 m a.s.l., to the west of the Black Mountain Range, West Central Bhutan. The local environmental setting with strong along-valley winds, frequent freeze-thaw cycles, extensive dry periods and sparse vegetation cover seems to encourage the generation and short-distance transport of silt-sized particles. The effects of this process are evidenced in the smooth valley morphology and in the nature of the examined pedons. Their involvement in continuing redistribution of local sediments is reflected by a homogeneous silty-clayey and stone-free texture, varying profile depths, buried topsoils and weakly developed recent A horizons. In protected locations, in situ weathering of metamorphic parent materials results in alu-andic features with bulk densities <0.9 g cm -3, (Al o + ½Fe o) > 2%, and phosphate retention >95%. Dominance by Al-hydroxy interlayered clay minerals and large amounts of well-crystallised iron oxides indicate an advanced stage of weathering. In areas of preferred eolian deposition, argic and ferralic features emerge, with clay contents of up to 60% and surface areas of >50 m 2 g -1. Under forest, umbric horizons can develop. CEC eff is below 10 cmol c kg -1 at all sites. Cluster and factor analyses of soil chemical and physical parameters confirm the redistribution of local sediments as a dominant factor behind the measured variables. No clear indication of glacial activities in the area was found, whereas the massive silty sediments in the lower parts of most profiles, the presence of debris slopes, and the asymmetric cross sections of the side valleys suggest periglacial conditions. Buried topsoils dated at about 2000 conventional 14C years BP indicate a weakening or absence of sediment influx under wetter conditions towards the end of the Holocene climate optimum. Charcoal on top of paleosols suggests that human activities of deforestation, grazing and arable agriculture may have contributed to the reactivation of local sediment redistribution until today.

Caspari, T.; Bäumler, R.; Norbu, C.; Tshering, K.; Baillie, I.

2009-03-01

168

Comparison of Summer and Winter California Central Valley Aerosol Distributions from Lidar and MODIS Measurements  

NASA Technical Reports Server (NTRS)

Aerosol distributions from two aircraft lidar campaigns conducted in the California Central Valley are compared in order to identify seasonal variations. Aircraft lidar flights were conducted in June 2003 and February 2008. While the PM2.5 concentration is highest in the winter, the aerosol optical depth measured from MODIS is highest in the summer. A seasonal comparison shows that PM2.5 in the winter can exceed summer PM2.5 by 55%, while summer AOD exceeds winter AOD by 43%. Higher temperatures wildfires in the summer produce elevated aerosol layers that are detected by satellite measurements, but not surface particulate matter monitors. Measurements of the boundary layer height from lidar instruments are necessary to incorporate satellite measurements with air quality measurements.

Lewis, Jasper R., Jr.; DeYoung, Russell J.; Chu, D. Allen

2010-01-01

169

The Dynamics of Social Indicator Research for California's Central Valley in Transition  

PubMed Central

How can social indicator research improve understanding of community health as well as inform stakeholders about the assets disadvantaged communities have for coping with disparities? This paper describes the development and evolution of the Partnership for Assessment of Communities (PAC) and its best practices for social indicator research. The PAC will be of interest to researchers across multiple disciplines for a number of reasons. First, PAC is a working model of best practices for multidisciplinary scholarly inquiry. Second, it has developed an integrated model of quantitative and qualitative methodology to define and measure community health as compared to traditional quality-of-life indicators. Third, it serves as an example of “action research,” in that the findings have the potential to make an impact on community stakeholders and policy outcomes in the greater Central San Joaquin Valley of California, a region characterized by deep social and economic disparities. PMID:21212814

Hernandez, Marcia D.; Sylvester, Dari E.; Weffer, Simon E.

2010-01-01

170

Chemical quality of ground water in the central Sacramento Valley, California  

USGS Publications Warehouse

The study area includes about 1,200 square miles in the central Sacramento Valley adjacent to the Sacramento River from Knights Landing to Los Molinos, Calif. With recent agricultural development in the area, additional land has been brought under irrigation from land which had been used primarily for dry farming and grazing. This report documents the chemical character of the ground water prior to water-level declines resulting from extensive pumping for irrigation or to changes caused by extensive use of imported surface water. Chemical analyses of samples from 209 wells show that most of the area is underlain by ground water of a quality suitable for most agricultural and domestic purposes. Most of the water sampled in the area has dissolved-solids concentrations ranging from 100 to 700 milligrams per liter. The general water types for the area are a calcium magnesium bicarbonate or magnesium calcium bicarbonate and there are negligible amounts of toxic trace elements. (Woodard-USGS)

Fogelman, Ronald P.

1978-01-01

171

MODELING THE CENTRAL VALLEY: Investigating the Effects of Irrigation on a Semi-Arid Hydrologic Cycle  

NASA Astrophysics Data System (ADS)

Growing populations and increased aridity in the Central Valley of California, USA has led to a renewed interest regarding the effects of population and anthropogenic irrigation on the region's hydrologic cycle. This model deviates from previous studies in that it utilizes a fully integrated hydrologic model to incorporate surface and subsurface systems on a finely discretized grid and includes an explicit treatment of the mountain systems. A model of the Southern portion of the Central Valley of California was undertaken using ParFlow, an integrated hydrologic model that includes surface, groundwater, land-surface vegetation and snow processes, coupled with the Common Land Model (a land-surface model). The goal of this study was to develop a model that incorporated complex subsurface hydrogeology as well as a complex surface discretization and to complete a comparison study on the effects irrigation on the land-energy and hydrology balances. The resulting model was composed of a matrix of approximately 60,000 sq. km (269 by 219 km) at a 1km resolution run over a period of 4 total model years using parallel processing. This study incorporated irrigation during the summer months (April through September) and no irrigation during wet months (October through March). This study highlights some of the potential impacts that anthropogenic irrigation has on this region including temperature, evapotranspiration and water flow as well techniques for subsurface discretizations (through geological simplifications) and land use variability via the incorporation of both general regional land use modeling as well as detailed county land use maps. The model domain is pictured here shown with a general schematic of flow within the ParFlow system.

Wolfenden, S. A.; Maxwell, R. M.; Lopez, S. R.

2012-12-01

172

The Effects of Mountaintop Mines and Valley Fills on Aquatic Ecosystems of the Central Appalachian Coalfields (External Review Draft)  

EPA Science Inventory

This report assesses the state of the science on the environmental impacts of mountaintop mines and valley fills (MTM-VF) on streams in the Central Appalachian Coalfields. Our review focused on the aquatic impacts of mountaintop removal coal mining, which, as its name suggests, ...

173

Analysis of microsatellite DNA resolves genetic structure and diversity of chinook salmon ( Oncorhynchus tshawytscha ) in California's Central Valley  

Microsoft Academic Search

We use 10 microsatellite DNA markers to assess genetic diversity within and among the four runs (winter, spring, fall, and late fall) of chinook salmon ( Oncorhynchus tshawytscha ) in California's Central Valley. Forty-one pop- ulation samples are studied, comprising naturally spawning and hatchery stocks collected from 1991 through 1997. Maximum likelihood methods are used to correct for kinship in

Michael A. Banks; Vanessa K. Rashbrook; Marco J. Calavetta; Cheryl A. Dean; Dennis Hedgecock

2000-01-01

174

Late quaternary geomorphology and geoarchaeology of a segment of the Central Mimbres River Valley, Grant County, New Mexico  

E-print Network

Two terraces, a modem floodplain, and alluvial fans were identified along a segment of the central Mimbres River Valley in Grant County, New Mexico. The oldest terrace, T2, is composed of one major depositional unit (1) and is capped by a...

Fitch, Michael Anthony

2012-06-07

175

Morphological variation and domestication of Escontria chiotilla (Cactaceae) under silvicultural management in the Tehuacán Valley, Central Mexico  

Microsoft Academic Search

People of the Tehuacán Valley, Central Mexico utilise the columnar cactus Escontria chiotilla for their edible fruits, gathering them in the wild and in silviculturally managed populations. Silvicultural management consists in sparing and enhancing selectively, in disturbed areas, individual trees producing fruits of the better quality for consumption and commercialisation. Fruits of trees in silviculturally managed populations are generally larger

Elizabeth Arellano; Alejandro Casas

2003-01-01

176

Paleohydrological fluctuations and steppe vegetation during the last glacial maximum in the central Ebro valley (NE Spain)  

Microsoft Academic Search

Combined analysis of sedimentary facies, geochemistry and pollen from lake sediment records, and sedimentological and palynological studies from slope deposits allow the characterization of vegetation and lake level status during the Last Glacial (LGM) in the central Ebro valley (NE Spain). These records show the presence of phases of increased effective moisture, while regional vegetation was dominated by steppe species.

Blas L. Valero-Garcés; Penélope González-Sampériz; Ana Navas; Javier Mach??n; Antonio Delgado-Huertas; Jose Luis Peña-Monné; Carlos Sancho-Marcén; Tony Stevenson; Basil Davis

2004-01-01

177

SEASONAL VARIATION IN PESTICIDE LOADS AND TRENDS IN THE CENTRAL VALLEY, CALIFORNIA: CALCULATED USING TWO PARAMETRIC METHODS  

Microsoft Academic Search

Mass loading and trends in concentration were calculated for four pesticides in two watersheds with different land uses in the Central Valley, California, by using two parametric models: (1) the Seasonal Wave model (SeaWave), in which a pulse signal is used to describe the annual cycle of pesticide occurrence in a stream; and, (2) the Sine Wave model (SineWave), in

D. Saleh; J. L. Domagalski; H. M. Johnson; D. J. Lorenz

2009-01-01

178

Fluid inclusion and Re–Os isotopic evidence for hot, Cenozoic mineralization in the central Pennsylvanian Valley and Ridge Province  

Microsoft Academic Search

Summary  Hypotheses concerning processes and timing of hydrothermal sulfide mineralization in the central Pennsylvanian Appalachians\\u000a utilize Mississippi Valley-type (MVT) models with Paleozoic ages. To examine this model, we studied sulfide-bearing veins\\u000a in the Skytop sulfide occurrence that contain pyritecentral Pennsylvania, USA. In this study,\\u000a we obtained Re–Os isotope compositions of hydrothermal pyrite and fluid inclusion data from

R. Mathur; L. Mutti; F. Barra; D. Gold; R. C. Smith; A. Doden; T. Detrie; J. Ruiz; A. McWilliams

2008-01-01

179

MICROBIAL FOSSILS FROM THE KHEINJUA FORMATION, MIDDLE PROTEROZOIC SEMRI GROUP (LOWER VINDHYAN)~ SON VALLEY AREA, CENTRAL INDIA  

Microsoft Academic Search

McMenamin, D.S., Kumar, S. and Awramik, S.M., 1983. Microbial fossils from the Khein- jua Formation, Middle Proterozoic Semri Group (Lower Vindhyan), Son Valley area, central India. Precambrian Res., 21: 247--271. Abundant coccoid and filamentous microfosslls are found in petrographic thin sections of stratiform stromatolitic cherts from the z1200 Ma-old Fawn Limestone of the Khein- jua Formation, lower Vindhyan Supergroup, central

SURENDRA KUMAR

180

Death Valley regional ground-water flow system, Nevada and California -- hydrogeologic framework and transient ground-water flow model  

USGS Publications Warehouse

A numerical three-dimensional (3D) transient ground-water flow model of the Death Valley region was developed by the U.S. Geological Survey for the U.S. Department of Energy programs at the Nevada Test Site and at Yucca Mountain, Nevada. Decades of study of aspects of the ground-water flow system and previous less extensive ground-water flow models were incorporated and reevaluated together with new data to provide greater detail for the complex, digital model. A 3D digital hydrogeologic framework model (HFM) was developed from digital elevation models, geologic maps, borehole information, geologic and hydrogeologic cross sections, and other 3D models to represent the geometry of the hydrogeologic units (HGUs). Structural features, such as faults and fractures, that affect ground-water flow also were added. The HFM represents Precambrian and Paleozoic crystalline and sedimentary rocks, Mesozoic sedimentary rocks, Mesozoic to Cenozoic intrusive rocks, Cenozoic volcanic tuffs and lavas, and late Cenozoic sedimentary deposits of the Death Valley Regional Ground-Water Flow System (DVRFS) region in 27 HGUs. Information from a series of investigations was compiled to conceptualize and quantify hydrologic components of the ground-water flow system within the DVRFS model domain and to provide hydraulic-property and head-observation data used in the calibration of the transient-flow model. These studies reevaluated natural ground-water discharge occurring through evapotranspiration and spring flow; the history of ground-water pumping from 1913 through 1998; ground-water recharge simulated as net infiltration; model boundary inflows and outflows based on regional hydraulic gradients and water budgets of surrounding areas; hydraulic conductivity and its relation to depth; and water levels appropriate for regional simulation of prepumped and pumped conditions within the DVRFS model domain. Simulation results appropriate for the regional extent and scale of the model were provided by acquiring additional data, by reevaluating existing data using current technology and concepts, and by refining earlier interpretations to reflect the current understanding of the regional ground-water flow system. Ground-water flow in the Death Valley region is composed of several interconnected, complex ground-water flow systems. Ground-water flow occurs in three subregions in relatively shallow and localized flow paths that are superimposed on deeper, regional flow paths. Regional ground-water flow is predominantly through a thick Paleozoic carbonate rock sequence affected by complex geologic structures from regional faulting and fracturing that can enhance or impede flow. Spring flow and evapotranspiration (ET) are the dominant natural ground-water discharge processes. Ground water also is withdrawn for agricultural, commercial, and domestic uses. Ground-water flow in the DVRFS was simulated using MODFLOW-2000, a 3D finite-difference modular ground-water flow modeling code that incorporates a nonlinear least-squares regression technique to estimate aquifer parameters. The DVRFS model has 16 layers of defined thickness, a finite-difference grid consisting of 194 rows and 160 columns, and uniform cells 1,500 m on each side. Prepumping conditions (before 1913) were used as the initial conditions for the transient-state calibration. The model uses annual stress periods with discrete recharge and discharge components. Recharge occurs mostly from infiltration of precipitation and runoff on high mountain ranges and from a small amount of underflow from adjacent basins. Discharge occurs primarily through ET and spring discharge (both simulated as drains) and water withdrawal by pumping and, to a lesser amount, by underflow to adjacent basins, also simulated by drains. All parameter values estimated by the regression are reasonable and within the range of expected values. The simulated hydraulic heads of the final calibrated transient model gener

: Belcher, Wayne R., (Edited By)

2004-01-01

181

Death Valley regional groundwater flow system, Nevada and California-Hydrogeologic framework and transient groundwater flow model  

USGS Publications Warehouse

A numerical three-dimensional (3D) transient groundwater flow model of the Death Valley region was developed by the U.S. Geological Survey for the U.S. Department of Energy programs at the Nevada Test Site and at Yucca Mountain, Nevada. Decades of study of aspects of the groundwater flow system and previous less extensive groundwater flow models were incorporated and reevaluated together with new data to provide greater detail for the complex, digital model. A 3D digital hydrogeologic framework model (HFM) was developed from digital elevation models, geologic maps, borehole information, geologic and hydrogeologic cross sections, and other 3D models to represent the geometry of the hydrogeologic units (HGUs). Structural features, such as faults and fractures, that affect groundwater flow also were added. The HFM represents Precambrian and Paleozoic crystalline and sedimentary rocks, Mesozoic sedimentary rocks, Mesozoic to Cenozoic intrusive rocks, Cenozoic volcanic tuffs and lavas, and late Cenozoic sedimentary deposits of the Death Valley regional groundwater flow system (DVRFS) region in 27 HGUs. Information from a series of investigations was compiled to conceptualize and quantify hydrologic components of the groundwater flow system within the DVRFS model domain and to provide hydraulic-property and head-observation data used in the calibration of the transient-flow model. These studies reevaluated natural groundwater discharge occurring through evapotranspiration (ET) and spring flow; the history of groundwater pumping from 1913 through 1998; groundwater recharge simulated as net infiltration; model boundary inflows and outflows based on regional hydraulic gradients and water budgets of surrounding areas; hydraulic conductivity and its relation to depth; and water levels appropriate for regional simulation of prepumped and pumped conditions within the DVRFS model domain. Simulation results appropriate for the regional extent and scale of the model were provided by acquiring additional data, by reevaluating existing data using current technology and concepts, and by refining earlier interpretations to reflect the current understanding of the regional groundwater flow system. Groundwater flow in the Death Valley region is composed of several interconnected, complex groundwater flow systems. Groundwater flow occurs in three subregions in relatively shallow and localized flow paths that are superimposed on deeper, regional flow paths. Regional groundwater flow is predominantly through a thick Paleozoic carbonate rock sequence affected by complex geologic structures from regional faulting and fracturing that can enhance or impede flow. Spring flow and ET are the dominant natural groundwater discharge processes. Groundwater also is withdrawn for agricultural, commercial, and domestic uses. Groundwater flow in the DVRFS was simulated using MODFLOW-2000, the U.S. Geological Survey 3D finitedifference modular groundwater flow modeling code that incorporates a nonlinear least-squares regression technique to estimate aquifer parameters. The DVRFS model has 16 layers of defined thickness, a finite-difference grid consisting of 194 rows and 160 columns, and uniform cells 1,500 meters (m) on each side. Prepumping conditions (before 1913) were used as the initial conditions for the transient-state calibration. The model uses annual stress periods with discrete recharge and discharge components. Recharge occurs mostly from infiltration of precipitation and runoff on high mountain ranges and from a small amount of underflow from adjacent basins. Discharge occurs primarily through ET and spring discharge (both simulated as drains) and water withdrawal by pumping and, to a lesser amount, by underflow to adjacent basins simulated by constant-head boundaries. All parameter values estimated by the regression are reasonable and within the range of expected values. The simulated hydraulic heads of the final calibrated transient mode

: Belcher, Wayne R., (Edited By); Sweetkind, Donald S.

2010-01-01

182

Geomorphology and Tectonics at the Intersection of Silurian and Death Valleys, Southern California - 2005 Guidebook Pacific Cell Friends of the Pleistocene  

USGS Publications Warehouse

This publication describes results from new regional and detailed surficial geologic mapping, combined with geomorphologic, geochronologic, and tectonic studies, in Silurian Valley and Death Valley, California. The studies address a long-standing problem, the tectonic and geomorphic evolution of the intersection between three regional tectonic provinces: the eastern California shear zone, the Basin and Range region of southern Nevada and adjacent California, and the eastern Mojave Desert region. The chapters represent work presented on the 2005 Friends of the Pleistocene field trip and meeting as well as the field trip road log.

Edited by Miller, David M.; Valin, Zenon C.

2007-01-01

183

Constraints on the post-middle-Pleistocene tectonic development of the Confidence Hills, southern Death Valley, California  

NASA Astrophysics Data System (ADS)

Our recent field mapping and tephrochronology offers new constraints on the style, timing, and rates of middle-Pleistocene-to-recent deformation in the Confidence Hills (CH), southern Death Valley. Movement on the active trace of the Southern Death Valley fault zone (SDVFZ) was preceded by earlier large-scale, northeast-vergent folding. This earlier folding involves several hundred meters of conformable late-Pliocene-to-middle-Pleistocene strata, which together form the common limb of a locally overturned fault-propagation fold pair. Geometric relations require that the blind thrust(s) responsible for earlier folding in the CH root well to the southwest of the active trace of the SDVFZ, which raises questions concerning previous flower structure models for earlier folding in the CH. Earlier folding began after deposition of Upper Glass Mountain tephra (1.1-0.9 Ma), which lies within the uppermost section of conformable, locally overturned Confidence Hills Formation(CHF), and ended prior to deposition of unconformably overlying fanglomerate, which contain tephra layers we tentatively correlate to the Bishop (0.76 Ma) and Lava Creek B (0.64 Ma) tephra. Earlier folding resulted in greater than 400 m structural relief and nearly 600 m of shortening in the span of 140-340 ka, yielding a middle-Pleistocene shortening rate of ~1.8-4.3 mm/yr. Dextral slip along the mappable traces of the SDVFZ began after earlier fault-propagation folding and also after deposition of the 0.76-0.64-Ma fanglomerates. Net right-lateral offset along the fault zone is well constrained ~4-km south of Shoreline Butte where a steeply-dipping contact marking the base of volcaniclastic conglomerate of the CHF is offset ~650 m. These relations yield a minimum post-middle-Pleistocene slip rate of ~1 mm/yr for the SDVFZ. Post-0.64-Ma shortening within the CH has been minor relative to earlier folding. The earlier fault-propagation folding in the CH appears to be related to a short-lived episode of northeast-directed motion of the Owlshead Mountains block, which was likely accommodated by left-lateral slip along the Wingate Wash fault.

Goodman, J. T.; Caskey, S. J.

2009-12-01

184

Using the Bidirectional Reflectance Distribution Function (BRDF) for remotely mapping surface roughness on alluvial fans: A comparison of Death Valley, CA to Mojave Crater on Mars  

NASA Astrophysics Data System (ADS)

The Bidirectional Reflectance Distribution Function (BRDF) describes how incoming light from a given direction is reflected from specific surfaces in response to different incoming solar radiation angles. The amount and directionality of reflected light is a function of surface roughness and orientation. The goal of this study is to assess whether a BRDF based approach may be applicable for creating surface roughness maps for Martian alluvial fans. Landsat 7 satellite imagery is used to make classifications of surfaces with different roughness and spectral properties for alluvial fan surfaces in Death Valley, California. The resulting classes have been interpreted to represent surfaces of different ages and also different deposit types. In Death Valley, older surfaces are classified based on the amount of shadowing due to gully formation, differences in the amount of surface smoothness from desert pavement formation, and desert varnish color variations. In contrast, the most recently formed surfaces have an assemblage of classes that represent surface deposits of different grain size and sorting, as well as different landform types - incised channels and elevated bars. Many Death Valley fans have a telescoping morphology where progressively younger surfaces reach basin-ward. This is more evident on some fans using a BRDF classification. A similar map was made for depositional landforms within Mojave Crater on Mars, identified as sub-kilometer alluvial fans by Williams and Malin (2008). These alluvial fans are the youngest found on Mars (Amazonian age) and have topographic similarities to fans in the southwestern US. Any geomorphic similarities between Death Valley fans and those within Mojave Crater can be assessed using surface roughness. Imagery from both the High Resolution Imaging Experiment (HiRISE) and Context Camera (CTX) onboard the Mars Reconnaissance Orbiter (MRO) were used to compare differences in spatial resolution on BRDF classifications. The resulting surface roughness maps are strikingly similar in classes and patterns to many fans within Death Valley. The surfaces interpreted by Williams and Malin (2008) to be evidence of multiple flow events are clearly classified using BRDF. In addition to age differences, possible locations of materials with different grain size and sorting are also identified. Since the BRDF classes of certain surface features on Earth and Mars fans largely overlap, field observations for each class type made for Death Valley fan surfaces may be useful for understanding the past fluvial processes on Mars and their similarities with fan forming processes in arid regions on Earth. This remote sensing approach has the potential to provide a tool for studying fans that may be inaccessible or too large for extensive fieldwork.

Doyle, S. L.; Wilkinson, M. J.; Scuderi, L. A.; Weissmann, G. S.; Scuderi, L. J.

2011-12-01

185

Paleoseismology of a possible fault scarp in Wenas Valley, central Washington  

USGS Publications Warehouse

In October 2009, two trenches excavated across an 11-kilometer-long scarp at Wenas Valley in central Washington exposed evidence for late Quaternary deformation. Lidar imagery of the Wenas Valley illuminated the west-northwest-trending, 2- to 8-meter-high scarp as it bisected alluvial fans developed at the mouths of canyons along the south side of Umtanum Ridge. The alignment of the scarp and aeromagnetic lineaments suggested that the scarp may be a product of and controlled by the same tectonic structure that produced the magnetic lineaments. Several large landslides mapped in the area demonstrated the potential for large mass-wasting events in the area. In order to test whether the scarp was the result of an earthquake-generated surface rupture or a landslide, trenches were excavated at Hessler Flats and McCabe Place. The profiles of bedrock and soil stratigraphy that underlie the scarp in each trench were photographed, mapped, and described, and a sequence of depositional and deformational events established for each trench. The McCabe Place trench exposed a sequence of volcaniclastic deposits overlain by soils and alluvial deposits separated by three unconformities. Six normal faults and two possible reverse faults deformed the exposed strata. Crosscutting relations indicated that up to five earthquakes occurred on a blind reverse fault, and a microprobe analysis of lapilli suggested that the earliest faulting occurred after 47,000 years before present. The Hessler Flat trench exposure revealed weathered bedrock that abuts loess and colluvium deposits and is overlain by soil, an upper sequence of loess, and colluvium. The latter two units bury a distinctive paloesol.

Sherrod, Brian L.; Barnett, Elizabeth A.; Knepprath, Nichole; Foit, Franklin F., Jr.

2013-01-01

186

Knowledge, transparency, and refutability in groundwater models, an example from the Death Valley regional groundwater flow system  

NASA Astrophysics Data System (ADS)

This work demonstrates how available knowledge can be used to build more transparent and refutable computer models of groundwater systems. The Death Valley regional groundwater flow system, which surrounds a proposed site for a high level nuclear waste repository of the United States of America, and the Nevada National Security Site (NNSS), where nuclear weapons were tested, is used to explore model adequacy, identify parameters important to (and informed by) observations, and identify existing old and potential new observations important to predictions. Model development is pursued using a set of fundamental questions addressed with carefully designed metrics. Critical methods include using a hydrogeologic model, managing model nonlinearity by designing models that are robust while maintaining realism, using error-based weighting to combine disparate types of data, and identifying important and unimportant parameters and observations and optimizing parameter values with computationally frugal schemes. The frugal schemes employed in this study require relatively few (10-1000 s), parallelizable model runs. This is beneficial because models able to approximate the complex site geology defensibly tend to have high computational cost. The issue of model defensibility is particularly important given the contentious political issues involved.

Hill, Mary C.; Faunt, Claudia C.; Belcher, Wayne R.; Sweetkind, Donald S.; Tiedeman, Claire R.; Kavetski, Dmitri

187

Trace Element Geochemistry of the Dolomite Member of the Neoproterozoic Ibex Formation, Death Valley National Park, CA  

NASA Astrophysics Data System (ADS)

This work examines the major and trace element geochemistry of the pink, laminated Dolomite Member of the Neoprotoerozic Ibex Formation, sampled at high resolution in the Ibex Hills of Death Valley, California. The Dolomite Member of the Ibex Formation directly overlies a basal conglomerate which has lead Corsetti and Kaufman (2005) to speculate that the juxtaposition of these units represents a diamictite - cap carbonate pair. Cap carbonates are inferred to represent deposition under high alkalinity conditions in the shallow ocean at the termination of low latitude glaciation. Increased alkalinity may be driven by the post glacial overturn of anoxic water masses. Here we infer paleoredox conditions during the deposition of the Dolomite Member of the Ibex Formation using trace metal enrichments. The Dolomite Member shows enrichments of Ni, Mo, Fe, Cu, V, Co, and Ba near the base of the unit, and also has a weak overall enrichment in Mn. The enrichment of these metals suggests a period of anoxia during the initial deposition of the Dolomite, and may signal the introduction of basin brines to the shallow ocean during marine transgression. These data are consistent with patterns observed in other cap carbonates worldwide, and support the speculation that the Dolomite Member is a cap carbonate. Alternatively, trace metal enrichments may reflect diagenetic alteration.

Meyer, E. E.; Lanids, J. D.; Quicksall, A. N.; Ddamba, I.

2012-12-01

188

Evaluation of increases in dissolved solids in ground water, Stovepipe Wells Hotel, Death Valley National Monument, California  

USGS Publications Warehouse

Increases in dissolved solids have been monitored in two observation wells near Stovepipe Wells Hotel, Death Valley National Monument, California. One of the hotel 's supply wells delivers water to a reverse-osmosis treatment plant that produces the area 's potable water supply. Should water with increased dissolved solids reach the supply well, the costs of production of potable water will increase. The reverse-osmosis plant supply well is located about 0.4 mile south of one of the wells where increases have been monitored, and 0.8 mile southwest of the well where the most significant increases have been monitored. The direction of local ground-water movement is eastward, which reduces the probability of the supply well being affected. Honey mesquite, a phreatophyte located about 1.5 miles downgradient from the well where the most significant increases have been monitored, might be adversely affected should water with increased dissolved solids extend that far. Available data and data collected during this investigation do not indicate the source of the dissolved-solids increases. Continued ground-water-quality monitoring of existing wells and the installation of additional wells for water-quality monitoring would be necessary before the area affected by the increases, and the source and direction of movement of the water with increased dissolved solids, can be determined. (USGS)

Buono, Anthony; Packard, E.M.

1982-01-01

189

Simulated effects of climate change on the Death Valley regional ground-water flow system, Nevada and California  

SciTech Connect

The US Geological Survey, in cooperation with the US Department of Energy, is evaluating the geologic and hydrologic characteristics of the Death Valley regional flow system as part of the Yucca Mountain Project. As part of the hydrologic investigation, regional, three-dimensional conceptual and numerical ground-water-flow models have been developed to assess the potential effects of past and future climates on the regional flow system. A simulation that is based on climatic conditions 21,000 years ago was evaluated by comparing the simulated results to observation of paleodischarge sites. Following acceptable simulation of a past climate, a possible future ground-water-flow system, with climatic conditions that represent a doubling of atmospheric carbon dioxide, was simulated. The steady-state simulations were based on the present-day, steady-state, regional ground-water-flow model. The finite-difference model consisted of 163 rows, 153 columns, and 3 layers and was simulated using MODFLOWP. Climate changes were implemented in the regional ground-water-flow model by changing the distribution of ground-water recharge. Global-scale, average-annual, simulated precipitation for both past- and future-climate conditions developed elsewhere were resampled to the model-grid resolution. A polynomial function that represents the Maxey-Eakin method for estimating recharge from precipitation was used to develop recharge distributions for simulation.

D`Agnese, F.A.; O`Brien, G.M.; Faunt, C.C.; San Juan, C.A.

1999-04-01

190

Conservation Effects Assessment Project-Wetlands assessment in California's Central Valley and Upper Klamath River Basin  

USGS Publications Warehouse

Executive Summary-Ecosystem Services Derived from Wetlands Reserve Program Conservation Practices in California's Central Valley and Oregon's Upper Klamath River Basin. The Wetlands Reserve Program (WRP) is one of several programs implemented by the U.S. Department of Agriculture (USDA). Since the WRP's inception in 1990, it has resulted in the restoration of approximately 29,000 hectares in California's Central Valley (CCV) and roughly 12,300 hectares in Oregon's Upper Klamath River Basin (UKRB). Both the CCV and UKRB are agricultural dominated landscapes that have experienced extensive wetland losses and hydrological alteration. Restored habitats in the CCV and UKRB are thought to provide a variety of ecosystem services, but little is known about the actual benefits afforded. The U.S. Geological Survey (USGS) California Cooperative Fish and Wildlife Unit in collaboration with the USDA Natural Resources Conservation Service surveyed 70 WRP sites and 12 National Wildlife Refuge sites in the CCV, and 11 sites in the UKRB to estimate ecosystem services provided. In the CCV, sites were selected along three primary gradients; (1) restoration age, (2) management intensity, and (3) latitude (climate). Sites in the UKRB were assessed along restoration age and management intensity gradients where possible. The management intensity gradient included information about the type and frequency of conservation practices applied at each site, which was then ranked into three categories that differentiated sites primarily along a hydrological gradient. Information collected was used to estimate the following ecosystem services: Soil and vegetation nutrient content, soil loss reduction, floodwater storage as well as avian, amphibian, fish, and pollinator use and habitat availability. Prior to this study, very little was known about WRP habitat morphology in the CCV and UKRB. Therefore in this study, we described these habitats and related them to ecosystem services provided. Our results indicate that although WRP in the CCV and UKRB provide a number of benefits, there may be management mediated trade-offs among ecosystem services. In this report, we considered ecosystem services at the site-specific scale; however, future work will extend to include effects of WRP relative to surrounding cropland.

2011-01-01

191

Evidence for a Putative Impact Structure in Palm Valley, Central Australia  

NASA Astrophysics Data System (ADS)

Introduction: We present evidence supporting the impact origin of a circular structure located in Palm Valley, Central Australia (24° 03' 06'' S, 132° 42' 34'' E). The ~280 m wide structure was discovered using a combination of Google Maps and a local Arrernte Aboriginal oral tradition regarding a star that fell into a waterhole called Puka in Palm Valley, Northern Territory [1][2] (see [3] for details of the discovery). Geophysical Evidence: A survey of the structure in September 2009 collected magnetic, gravity and topographic data. Geophysical modeling of the data revealed the structure has a bowl-shaped subsurface morphology, as expected for a simple impact crater. Though the structure sits within the Finke Gorge system, the models do not support an erosional origin for the structure, as no buried channels are observed. Nor does the modeling fit a volcanic origin, as the density structure at depth is consistent with fractured sandstone/sediments. Geological Evidence: One channel runs out of the crater to the south, consistent with outflow from crater-filling events, but again not with an erosional origin for the structure itself. The microstructure of rock samples collected from the site revealed the presence of planar deformation features in the quartz grains. The coincident angle of the fractures is consistent with the crystallographic fracture directions under mild-end shocks. These grains probably represent local focusing of stress as the shock wave moved through the heterogeneous grain matrix, suggesting the conditions were right for the shock pressure to locally exceed the ~7.5 GPa required to form the features, even though the bulk of the shock pressure was much less. Conclusion: Based on the level of erosion and the absence of shatter cones and meteorite fragments, we estimate the structure's age to be in the millions of years. While the presence of shocked-quartz is a direct indicator of a cosmic impact, we cannot rule out that the quartz was transported from an older structure into the Hermannsburg sandstone as it was deposited. The ~22 km wide Gosse's Bluff impact structure, located ~40 km from Palm Valley, postdates the Hermannsburg sandstone, leaving a distal unidentified impact event as a possibility. However, the bowl shaped morphology of the Palm Valley structure, as well as the fractures on the structure's walls, support an impact origin. References: [1] Austin-Broos, D., 2009, "Arrernte Past, Arrernte Present", University of Chicago Press, pp. 37-38. [2] Róheim, G., 1945, "The Eternal Ones of the Dream: a psychoanalytic interpretation of Australian myth and ritual", International Universities Press, New York, p. 183. [3] Hamacher, D.W. & Norris, R.P., 2010, Using Aboriginal Oral Traditions to locate meteorite falls and impact craters. In Ilgarijiri - things belonging to the sky, edited by R.P. Norris, Proceedings of the symposium on Indigenous Astronomy held on 27 November 2009 at Australian Institute for Aboriginal and Torres Strait Islander Studies, Canberra, Australia (in press).

Hamacher, D. W.; O'Neill, C.; Buchel, A.; Britton, T. R.

2010-07-01

192

Hydraulic-property estimates for use with a transient ground-water flow model of the Death Valley regional ground-water flow system, Nevada and California  

Microsoft Academic Search

The Death Valley regional ground-water flow system encompasses an area of about 43,500 square kilometers in southeastern California and southern Nevada. The study area is underlain by Quaternary to Tertiary basin-fill sediments and mafic-lava flows; Tertiary volcanic, volcaniclastic, and sedimentary rocks; Tertiary to Jurassic granitic rocks; Triassic to Middle Proterozoic carbonate and clastic sedimentary rocks; and Early Proterozoic igneous and

W. R. Belcher; P. E. Elliott; A. L. Geldon

2001-01-01

193

Data on ground-water quality for the western Nevada part of the Death Valley 1 degree by 2 degree quadrangle  

USGS Publications Warehouse

Water quality data for groundwater has been compiled for the Nevada part of the Death Valley 1 degree x 2 degree quadrangle which covers a portion of western Nevada. Chemical characteristics of the water are shown on a map (at a scale of 1:250,000) and on trilinear diagrams for the major ions. The data for the area are also presented in a table. (USGS)

Welch, Alan H.; Williams, Rhea P.

1987-01-01

194

Using Gamma Spectrometry to Determine U, Th, and K Signatures in Cap Carbonates of the Death Valley Region and Their Relation to Other Carbonates  

Microsoft Academic Search

We collected spectral gamma data (K, U, Th) and measured sections in cap carbonates (Noonday dolomite) and cap-like carbonates (Beck Spring dolomite) of the Death Valley region in order to explore elemental changes in the post-snowball oceans. The Snowball Earth theory of Hoffman et al. (1998) proposes dramatic post-glacial chemical weathering as large concentrations of carbon were removed from the

M. Hannon; J. Lindberg; C. Barrie; T. Johnson; A. Donatelle; J. Goeden; S. Holter; T. Hickson; K. Theissen; M. Lamb

2004-01-01

195

Coastal, valley, and oasis interaction: Impact on the evolution of ancient populations in the South Central Andes.  

PubMed

The existing biocultural links are analyzed among ancient inhabitants of the Cochabamba valleys (Bolivia) from the Formative and Tiwanaku periods, coastal and inland Azapa region (Chile) from the Late Archaic to the Late periods, and the Atacama Desert oases (Chile) from the Formative period to the time of European contact. Craniometric information obtained from a sample of 565 individuals from different sites of the studied regions was evaluated using methods derived from quantitative genetics and multivariate statistical analysis techniques. It is shown that during the Formative and Tiwanaku periods inhabitants of the Cochabamba valleys maintained contact with the population of northern Chile. This contact was more fluid with the people from the interior valley of Azapa than it was with the settlers of San Pedro Atacama (SPA). An important biological affinity in the Late Period between the inhabitants of the Azapa valley and the late SPA groups is also examined. The Late-Inca Catarpe SPA sample shows a broad genetic variability shared with the majority of the groups studied. The results reaffirm the differences between the coastal and interior Azapa valley groups and strengthen the hypothesis of two pathways to populating the south central Andean area. The divergence observed among subpopulations can be explained by the spatiotemporal dispersion between them, genetic drift dispersion compensated by the action of gene flow, and cultural norms that regulate within group mating. Am J Phys Anthropol 155:591-599, 2014. © 2014 Wiley Periodicals, Inc. PMID:25234247

Varela, Héctor H; Cocilovo, Jose A; Fuchs, María L; O'Brien, Tyler G

2014-12-01

196

Are the stair case terraces in the Inylchek Valley (Central Tien Shan, Kyrgyzstan) of neotectonic or sedimentary origin?  

NASA Astrophysics Data System (ADS)

In 2011 we performed fieldwork at the Global Change Observatory "Gottfried Merzbacher" east of Gribkov Base. High-resolution satellite images show at least six ridges which can be traced on the northern slopes of the Inylchek Valley. These ridges parallel each other and are intersected by smaller erosional valleys. Detailed mapping of outcrops in the tributary valleys revealed intensively folded Paleozoic formations overlain by glacial and fluvioglacial deposits of a thickness of tens of meters. From the sedimentological point of view we differentiate between kame terraces (KT), which are defined as depositional terraces perched on valley sides, deposited by meltwater streams flowing between lateral glacier margins and the adjacent valley wall, and fluvial terraces (FT), deposited above the niveau of the present Inylchek River. In the investigated sector of the Inylchek Valley we mapped FT1 and FT2 above the recent valley floor of the braided Inylchek River. These terraces intersect with the debris fans of the tributary streams. Up the northern hill we mapped at least four higher ridges, which are interpreted as remnants of kame terraces. The first and second of these higher ridges do not differ significantly in altitude and are therefore considered remnants of KT1a & b, followed up by two higher kame terraces KT2 and KT3. Each kame terrace represents one distinct stage of deglaciation of the valley glacier in the Southern Inylchek Valley. When another lower kame terrace was deposited, the higher terrace partly eroded along the valley wall and finally turned into a ridge. The observation that former fluvioglacial terraces today form ridges between incised valleys provides an example for an inverted relief. From the morphology of six ridges on the northern slope of the Inylchek Valley we derive the following succession of glacial and periglacial processes: 1) The highest kame terrace 3 (KT3) was deposited between the glacier margin of the former Inylchek Glacier at 4000 m altitude and the adjacent valley wall. 2) The next lower kame terrace (KT2) at about 3920 m altitude documents the deglaciation of the Southern Inylchek Glacier by 80 metres. 3) The lowest kame terrace (KT1) is preserved at an altitude of 3850 m a.s.l., indicating that the Southern Inylchek Glacier melted down another 70 metres. 4) After the retreat of the Glacier at least two fluvial terraces document proglacial sedimentation in a braided river system of the Inylchek Valley (upper fluvial terrace FT2 and lower terrace FT1). 5) In the studied Gribkov sector the recent Inylchek River eroded FT1 by three meters. Despite the fact that many recent, historical and paleo-earthquakes have been recorded in the Northern and Central Tien Shan, and that many scarps and even terraces may have resulted either from slides or from neotectonic tilting, we do not interpret the set of multiple ridges on the northern slope of Inylchek Valley as of tectonic origin but present arguments for their fluvioglacial evolution.

Häusler, H.; Kopecny, A.; Leber, D.

2012-04-01

197

Rock avalanche deposits in Alai Valley, Central Asia: misinterpretation of glacial record  

NASA Astrophysics Data System (ADS)

The reconstruction of Quaternary glaciations has been restricted by conventional approaches with resulting contradictions in interpretation of the regional glacial record, that recently have been subjected to critical re-evaluation. Along with uncertainties in dating techniques and their applicability to particular landforms (Kirkbride and Winkler, 2012), it has recently been demonstrated that the presence of rock avalanche debris in a landform can be unequivocally detected; this allows for the first time definitive identification of and distinction between glacial moraines and landslide deposits. It also identifies moraines that have formed due to rock avalanche deposition on glaciers, possibly with no associated climatic signal (Reznichenko et al., 2012). Confusion between landslide deposits and moraines is evident for ranges in Central Asia (e.g., Hewitt, 1999) where the least-studied glacial record is selectively correlated with established glacial chronologies in Alpine ranges, which in turn masks the actual glacial extent and their responses to climate change, tectonics and landsliding activity. We describe examples in the glaciated Alai Valley, large intermountain depression between the Zaalay Range of the Northern Pamir and the Alay Range of the Southern Tien-Shan, showing that some large Quaternary deposits classically interpreted as moraines are of rock avalanche origin. Sediment from these deposits has been tested for the presence of agglomerates that are only produced under high stress conditions during rock avalanche motion, and are absent from glacial sediments (Reznichenko et al., 2012). This reveals that morphologically-similar deposits have radically different geneses: rock avalanche origin for a deposit in the Komansu river catchment and glacial origin for deposits in the Ashiktash and Kyzylart catchments. The enormous Komansu rock avalanche deposit, probably triggered by a rupture of the Main Pamir thrust, currently covers about 100 km2 with a minimum estimated volume more than 1 x 109 m3. Another smaller rock avalanche deposit rests on the Lenin Glacial sediment in the neighbour Ashiktash river catchment, which was previously suggested to originate from Mt. Lenin (7134 m). The revised origin of these deposits highlights the role of rock avalanches in glacial activity and in the resulting glacial record in this valley and other actively tectonic areas of Central Asia. Although further investigation is required to detail the geneses, magnitudes and ages for these and other landforms in the valley, this study contributes explicit evidence for contamination of palaeoclimate proxies with data from non-climatic events, and reinforces the urgent need for revised interpretation of the glacial chronologies. Hewitt, K., 1999. Quaternary moraines vs. catastrophic rock avalanches in the Karakoram Himalaya, Northern Pakistan. Quaternary Research, v. 51, p. 220-237. Kirkbride, M.P., and Winkler, S., 2012. Correlation of Late Quaternary moraines: impact of climate variability, glacier response, and chronological resolution: Quaternary Science Reviews, v. 46, p. 1-29. Reznichenko, N.V., Davies, T.R.H., Shulmeister, J. and Larsen S.H, 2012. A new technique for identifying rock-avalanche-sourced sediment in moraines and some paleoclimatic implications. Geology, v. 40, p. 319-322.

Reznichenko, Natalya; Davies, Tim; Robinson, Tom; De Pascale, Gregory

2013-04-01

198

Groundwater Age in Multi-Level Water Quality Monitor Wells on California Central Valley Dairies  

NASA Astrophysics Data System (ADS)

Dairy farming in California's Central Valley is a significant source of nitrate to underlying aquifers. One approach to mitigation is to implement farm-scale management plans that reduce nutrient loading to groundwater while sustaining crop yield. While the effect of different management practices on crop yield is easily measured, their effect on groundwater quality has only infrequently been evaluated. Documenting and predicting the impact of management on water quality requires a quantitative assessment of transport (including timescale and mixing) through the vadose and saturated zones. In this study, we measured tritium, helium isotopic composition, and noble gas concentrations in groundwater drawn from monitor wells on several dairies in the Lower San Joaquin Valley and Tulare Lake Basin of California's Central Valley in order to predict the timescales on which changes in management may produce observable changes in groundwater quality. These dairies differ in age (from <10 to >100 years old), thickness of the vadose zone (from <10 to 60 m), hydrogeologic setting, and primary source of irrigation water (surface or groundwater). All of the dairies use manure wastewater for irrigation and fertilization. Three of the dairies have implemented management changes designed to reduce nutrient loading and/or water usage. Monitor wells in the southern Tulare Lake Basin dairies were installed by UC-Davis as multi-level nested wells allowing depth profiling of tritium and noble gases at these sites. Tritium/helium-3 groundwater ages, calculated using a simple piston-flow model, range from <2 to >50 years. Initial tritium (the sum of measured tritium and tritiogenic helium-3) is close to or slightly above precipitation in the calculated recharge year for young samples; and significantly above the precipitation curve for older samples. This pattern is consistent with the use of 20-30 year old groundwater recharged before 1980 for irrigation, and illustrates how irrigation with groundwater can complicate the use of tritium alone for age dating. The presence of radiogenic helium-4 in several samples with measurable tritium provides evidence of mixing between pre-modern and younger groundwater. Groundwater age-depth relationships are complicated, consistent with transient flow patterns in shallow agricultural groundwaters affected by irrigation pumping and recharge. For the multi-level installations in the southern dairies, both depth profiles and re-sampling after significant changes in groundwater elevation emphasize the need to sample groundwater within 3 meters of the water table to obtain "first-encounter" groundwater with a tritium/helium-3 age of less than 5 years, and to use age tracers to identify wells and groundwater conditions suitable for monitoring and assessment of best management practice impacts on underlying groundwater quality. This work was carried out with funding from Sustainable Conservation and the California State Water Resources Control Board in collaboration with UC-Davis, and was performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344.

Esser, B. K.; Visser, A.; Hillegonds, D. J.; Singleton, M. J.; Moran, J. E.; Harter, T.

2011-12-01

199

Geochemistry of natural gas manifestions from the Upper Tiber Valley (central Italy)  

USGS Publications Warehouse

Six natural gas manifestions from the upper Tiber Valley at Caprese Michelangela and Pieve S. Stefano (Arezzo) and at Umbertide (Pertugia) localities have been analysed for major, minor, trace gas compositions, as well as for ??13C in CO2 and CH4, ??15N in N2 and 3He/4He isotopic ratios. All gas emissions are CO2-rich (???94%), with N2 contents of 4-5%. Those from Caprese and Pieve S. Stefano have very peculiar compsitions when compared to other gases from northern-central Apennines. Apart from CO2, these gases show relatively high contents of He (with crustal isotopic ratios) and medium to high temperature-related gases such as CO, H2 and C6H6. Although located quite far from the geothermal areas in Tuscany, the application of several gas geothermetric techniques suggest for these gases deep equilibrium tempratures of about 300??C. Moreover, the ??13C in CO2 and CH4 (~.4.0% and -38.0%, respectively) and the ??13N values in N2 (+0.064 to +0.84%) would seem to imply a multiple deep source for these gases.

Vaselli, O.; Tassi, F.; Minissale, A.; Capaccioni, B.; Macro, G.; Evans, W.C.

1997-01-01

200

High Resolution Monitoring of Algal Growth Dynamics in a Hypereutrophic River in the Central Valley, California  

NASA Astrophysics Data System (ADS)

The lower San Joaquin River in California's Central Valley experiences periods of hypoxia during the late summer and fall that is detrimental to aquatic organisms and migration of fall-run chinook salmon and steelhead trout. Hypoxia is attributable, in part, to excess nutrients from urban waste water and agricultural runoff, which contribute to growth of high concentrations of phytoplankton. This study examined spatial and temporal growth patterns that control algal loading using continuous fluorescence measurements at three sites along a 50 km section of the lower San Joaquin River between April and October. A strong diel fluorescence signal was observed and associated grab samples verified that fluorescence was an accurate measure of chlorophyll. Peak chlorophyll concentrations occurred between 18:00 and 20:00 and minimum concentrations between 10:00 and 12:00. Maximum concentrations were nearly two times greater than minimum concentrations although this ratio varied temporally and spatially. Although the mechanism for the diel chlorophyll signal is not very well understood several parameters including temperature, irradiance, turbidity, residence time, stream depth, and zooplankton grazing were considered within the scope of this study. This study highlights the importance of considering high resolution sampling on algal loading rates within heavily impacted riverine systems.

Henson, S. S.; Dahlgren, R.; van Nieuwenhuyse, E.; O'Geen, A. T.; Gallo, E. L.; Ahearn, D. S.

2005-05-01

201

Application of pesticide transport model for simulating diazinon runoff in California’s central valley  

NASA Astrophysics Data System (ADS)

Dormant spray application of pesticides to almond and other stone fruit orchards is the main source of diazinon during the winter in California's central valley. Understanding the pesticide transport and the tradeoffs associated with the various management practices is greatly facilitated by the use of physically-based contaminant transport models. In this study, performance of Joyce's et al. (2008) pesticide transport model was evaluated using experimental data collected from two ground treatments such as resident vegetation and bare soil. The model simulation results obtained in calibration and validation process were analyzed for pesticide concentration and total load. The pesticide transport model accurately predicted the pesticide concentrations and total load in the runoff from bare field and was capable of simulating chemical responses to rainfall-runoff events. In case of resident vegetation, the model results exhibited a larger range of variation than was observed in the bare soil simulations due to increased model parameterization with the addition of foliage and thatch compartments. Furthermore, the model was applied to study the effect of runoff lag time, extent of crop cover, organic content of soil and post-application irrigation on the pesticide peak concentration and total load. Based on the model results, recommendations were suggested to growers prior to implementing certain management decisions to mitigate diazinon transport in the orchard's spray runoff.

Joyce, Brian A.; Wallender, Wesley W.; Mailapalli, Damodhara R.

2010-12-01

202

Data for ground-water test hole near Zamora, Central Valley Aquifer Project, California  

USGS Publications Warehouse

Preliminary data are presented for the first of seven test holes drilled as a part of the Central Valley Aquifer Project which is part of the National Regional Aquifer Systems Analysis Program. The test hole was drilled in the SW 1/4 SE 1/4 sec. 34, T. 12 N. , R. 1 E., Yolo County, California, about 3 miles northeast of the town of Zamora. Drilled to a depth of 2,500 feet below land surface, the hole is cased to a depth of 190 feet and equipped with three piezometer tubes to depths of 947, 1,401, and 2,125 feet. A 5-foot well screen is at the bottom of each piezometer. Eighteen cores and 68 sidewall cores were recovered. Laboratory tests were made for mineralogy, hydraulic conductivity, porosity , consolidation, grain-size distribution, Atterberg limits, X-ray diffraction, diatom identification, thermal conductivity, and chemical analysis of water. Geophysical and thermal gradient logs were made. The hole is sampled periodically for chemical analysis and measured for water level in the three tapped zones. This report presents methods used to obtain field samples, laboratory procedures, and the data obtained. (USGS)

French, J. J.; Page, R. W.; Bertoldi, G. L.

1982-01-01

203

Data for ground-water test hole near Butte City, Central Valley aquifer project, California  

USGS Publications Warehouse

This report provides preliminary data for the third of seven test holes drilled as part of the Central Valley Aquifer Project which is part of the National Regional Aquifer Systems Analysis Program. The test hole was drilled in the SW 1/4 NE 1/4 sec. 32, T. 19 N., R. 1 W., Glenn County, California, about one-half mile south of the town of Butte City. Drilled to a depth of 1,432 feet below land surface, the hole is cased to a depth of 82 feet and equipped with three piezometer tubes to depths of 592 feet, 968 feet, and 1,330 feet. A 5-foot well screen is at the bottom of each piezometer. Each screened interval has a cement plug above and below it to isolate it from other parts of the aquifer , and the well bore is filled between the plugs with sediment. Nine cores and 49 sidewall cores were recovered. Laboratory tests were made for mineralogy, hydraulic conductivity, porosity , consolidation, grain-size distribution, Atterberg limits, X-ray diffraction, and chemical quality of water. Geophysical and thermal gradient logs were made. The hole is sampled periodically for chemical analysis and measured for water level in the three tapped zones. This report presents methods used to obtain field samples, laboratory procedures, and the data obtained. (USGS)

French, James J.; Page, R. W.; Bertoldi, G. L.

1983-01-01

204

Data for ground-water test hole near Nicolaus, Central Valley aquifer project, California  

USGS Publications Warehouse

Preliminary data are provided for the third of seven test holes drilled as a part of the Central Valley Aquifer Project which is part of the National Regional Aquifer Systems Analysis Program. The test hole was drilled in the SW 1/4 NE 1/4 sec. 2, T.12N., R.3E., Sutter County, California, about 1 1/2 miles northwest of the town of Nicolaus. Drilled to a depth of 1,150 feet below land surface, the hole is cased to a depth of 100 feet and equipped with three piezometer tubes to depths of 311, 711, and 1,071 feet. A 5-foot well screen is set in sand at the bottom of each piezometer. Each screened interval has a cement plug above and below it to isolate it from other parts of the aquifer, and the well bore is filled between the plugs with sediment. Thirty-one cores and 34 sidewall cores were recovered. Laboratory tests were made for minerology, consolidation, grain-size distribution, Atterberg limits, X-ray diffraction, thermal conductivity, and chemical analysis of water. Geophysical and thermal gradient logs were made. The hole is sampled periodically for chemical analysis of the three tapped zones and measured for water level. This report presents methods used to obtain field samples, laboratory procedures, and the data obtained. (USGS)

French, James J.; Page, R. W.; Bertoldi, Gilbert L.

1983-01-01

205

Drought resilience of the California Central Valley surface-groundwater-conveyance system  

SciTech Connect

A series of drought simulations were performed for the California Central Valley using computer applications developed by the California Department of Water Resources and historical datasets representing a range of droughts from mild to severe for time periods lasting up to 60 years. Land use, agricultural cropping patterns, and water demand were held fixed at the 2003 level and water supply was decreased by amounts ranging between 25 and 50%, representing light to severe drought types. Impacts were examined for four hydrologic subbasins, the Sacramento Basin, the San Joaquin Basin, the Tulare Basin, and the Eastside Drainage. Results suggest the greatest impacts are in the San Joaquin and Tulare Basins, regions that are heavily irrigated and are presently overdrafted in most years. Regional surface water diversions decrease by as much as 70%. Stream-to-aquifer flows and aquifer storage declines were proportional to drought severity. Most significant was the decline in ground water head for the severe drought cases, where results suggest that under these scenarios the water table is unlikely to recover within the 30-year model-simulated future. However, the overall response to such droughts is not as severe as anticipated and the Sacramento Basin may act as ground-water insurance to sustain California during extended dry periods.

Miller, N.L.; Dale, L.L.; Brush, C.; Vicuna, S.; Kadir, T.N.; Dogrul, E.C.; Chung, F.I.

2009-05-15

206

Modeling nitrate at domestic and public-supply well depths in the Central Valley, California  

USGS Publications Warehouse

Aquifer vulnerability models were developed to map groundwater nitrate concentration at domestic and public-supply well depths in the Central Valley, California. We compared three modeling methods for ability to predict nitrate concentration >4 mg/L: logistic regression (LR), random forest classification (RFC), and random forest regression (RFR). All three models indicated processes of nitrogen fertilizer input at the land surface, transmission through coarse-textured, well-drained soils, and transport in the aquifer to the well screen. The total percent correct predictions were similar among the three models (69–82%), but RFR had greater sensitivity (84% for shallow wells and 51% for deep wells). The results suggest that RFR can better identify areas with high nitrate concentration but that LR and RFC may better describe bulk conditions in the aquifer. A unique aspect of the modeling approach was inclusion of outputs from previous, physically based hydrologic and textural models as predictor variables, which were important to the models. Vertical water fluxes in the aquifer and percent coarse material above the well screen were ranked moderately high-to-high in the RFR models, and the average vertical water flux during the irrigation season was highly significant (p < 0.0001) in logistic regression.

Nolan, Bernard T.; Gronberg, JoAnn M.; Faunt, Claudia C.; Eberts, Sandra M.; Belitz, Ken

2014-01-01

207

Comparison of Summer and Winter California Central Valley Aerosol Distributions from Lidar and MODIS Measurements  

NASA Technical Reports Server (NTRS)

Aerosol distributions from two aircraft lidar campaigns conducted in the California Central Valley are compared in order to identify seasonal variations. Aircraft lidar flights were conducted in June 2003 and February 2007. While the ground PM(sub 2.5) concentration is highest in the winter, the aerosol optical depth measured from MODIS is highest in the summer. A seasonal comparison shows that PM(sub 2.5) in the winter can exceed summer PM(sub 2.5) by 55%, while summer AOD exceeds winter AOD by 43%. Higher temperatures and wildfires in the summer produce elevated aerosol layers that are detected by satellite measurements, but not surface particulate matter monitors. Temperature inversions, especially during the winter, contribute to higher PM(sub 2.5) measurements at the surface. Measurements of the boundary layer height from lidar instruments provide valuable information need to understand the relationship between satellite measurements of optical depth and in-situ measurements of PM(sub 2.5).

Lewis, Jasper; DeYoung, Russell; Ferrare, Richard; Chu, D. Allen

2010-01-01

208

Apoptotic cell death following traumatic injury to the central nervous system.  

PubMed

Apoptotic cell death is a fundamental and highly regulated biological process in which a cell is instructed to actively participate in its own demise. This process of cellular suicide is activated by developmental and environmental cues and normally plays an essential role in eliminating superfluous, damaged, and senescent cells of many tissue types. In recent years, a number of experimental studies have provided evidence of widespread neuronal and glial apoptosis following injury to the central nervous system (CNS). These studies indicate that injury-induced apoptosis can be detected from hours to days following injury and may contribute to neurological dysfunction. Given these findings, understanding the biochemical signaling events controlling apoptosis is a first step towards developing therapeutic agents that target this cell death process. This review will focus on molecular cell death pathways that are responsible for generating the apoptotic phenotype. It will also summarize what is currently known about the apoptotic signals that are activated in the injured CNS, and what potential strategies might be pursued to reduce this cell death process as a means to promote functional recovery. PMID:16248974

Springer, Joe E

2002-01-31

209

Knickpoint retreat and landscape disequilibrium on the James River from the Piedmont through the Valley and Ridge, central Virginia, USA  

NASA Astrophysics Data System (ADS)

Several lines of evidence indicate landscape disequilibrium in the James River basin in central Virginia. The river longitudinal profile possesses pronounced convexities and apparently migratory knickzones. Along much of its length, it flows in a narrow inner valley incised into a discontinuous, low-relief upland. In the inner Piedmont, the 150 m wide river channel occupies an incised valley that can be as little as 600 m wide and 75 m deep. Broad fluvial terraces are often found capping the high topography directly adjacent to the valleys, and we use these disconnected terraces to reconstruct paleo-river profiles spanning ~200 km in the Piedmont. These high, extensive terraces disappear in the James River Gap through the Blue Ridge, but reappear with less distinction in the carbonate rocks of the Great Valley. The river remains incised within the Great Valley, with prominent knickzones ~60-100 km above the Blue Ridge gap found on both the mainstem and tributaries. We dated terraces in the Piedmont with in-situ 10Be profiles and a depth integration technique. Dates from the highest terrace level at three locations along ~100 km of the river are ~1 m.yr., suggesting rapid river incision rates of ~55 m/m.yr. We also have documented exceptionally high incision rates along a tributary in the Great Valley. This dating suggests disequilibrium erosion was initiated and has persisted here during the late Quaternary. Assuming the incision is accomplished largely by knickpoint retreat, the dates suggest past retreat rates of up to one m/yr in the Piedmont and 250 m/m.yr. between the outer Piedmont and the Great Valley. We have two hypotheses for how this recent incision was triggered: 1) response to flexural-isostatic uplift generated by drainage basin capture and associated denudation and/or 2) the shift to more rapid climate fluctuations in the early Pleistocene. Additionally, we suggest two interpretations for the generation of the extensive high terrace surfaces. They may be valley floor remnants of a broad alluvial upland incised by a migrating knickpoint, or remnants of a broad valley floor developed at the base of knickpoints that have now migrated upstream along the profile.

Hancock, G.; Harbor, D.; Felis, J.

2003-12-01

210

Seasonal and diel patterns of total gaseous mercury concentration in the atmosphere of the Central Valley of Costa Rica  

Microsoft Academic Search

Monitoring of Hg in the atmosphere near volcanoes is limited with no previous data for Costa Rica. Seasonal and daily patterns of total gaseous mercury (TGM) were observed at the main sampling location at the Universidad Nacional, Heredia, Costa Rica. The area (lat. 10.000230 long. ?84.109499) is located in the Central Valley of Costa Rica and is 27km SE of

Aylin Castillo; Juan Valdes; Jose Sibaja; Ilena Vega; Rosa Alfaro; José Morales; Germain Esquivel; Elisa Barrantes; Paleah Black; David Lean

2011-01-01

211

The Mississippi Valley-type Zn-Pb deposit of San Vicente, Central Peru: an Andean syntectonic deposit  

Microsoft Academic Search

Ore-related structures at the Zn-Pb Mississippi Valley-type San Vicente deposit, Central Peru, display a systematic geometry with respect to bedding and a regional thrust, interpreted as Miocene in earlier studies. Sparry dolomite veins and breccia bodies have a constant NS direction, and are either perpendicular to bedding with dips ~70° to the east, or parallel to bedding, dipping ~25-30° westerly.

V. Badou; R. Moritz; L. Fontboté

212

Middle Pleistocene palaeoenvironments and the late Lower-Middle Palaeolithic of the Hrazdan valley, central Armenia  

NASA Astrophysics Data System (ADS)

The palaeogeographic importance of the southern Caucasus in the Pleistocene as a region of population expansion and contraction between Africa, the Levant and Eurasia is well established as a result of recent archaeological works in the Republics of Armenia and Georgia. Not only does the area have a unique Palaeolithic record, but the presence of volcanic layers in association with archaeological sites and off site sequences means that there is the potential for both high precision dating and correlation. The Hrazdan valley, central Armenia is a case in point. Late Lower to late Middle Palaeolithic sites found as a result of systematic survey and then explored in excavations in 2008-2011 are associated with various volcanogenic strata. 40K/40Ar and 40Ar/39Ar dating in the 1970-2000s demonstrates the onset of volcanism in the adjacent Gegham range in the period 700-500ky BP, while recent 40Ar/39Ar dates on the latest lava from the Gutanasar volcano shows the latest effusive eruption to have occurred at c. 200 ky BP. Nine Middle Pleistocene lavas from the intervening period have been mapped in the Hrazdan valley in a 15km-long study area 12km north-east of Yerevan. Several of the basalts seal terrestrial strata, and thereby bury and 'fossilize' earlier landscapes. The most significant of these is sandwiched between basalts dating to 200 and 440ky BP, where a 135m-long exposure contains a palaeosol developing in floodplain alluvium and in situ archaeological material (Nor Geghi 1). Morphological and micromorphological examination of site strata suggest that hominin activity took place during a temperate episode, which 40Ar/39Ar dating of interbedded crypotephra suggests was MIS 9e. However, strata at other locales buried beneath the same 200ky BP basalt suggest that the landscape occupied by these hominids was a mosaic of river channels, floodplains and lakes. The fossilized MIS 9 landscape is not unique as further lacustrine deposits are buried beneath earlier Middle Pleistocene basalts, although earlier archaeological sites have yet to be found.

Wilkinson, Keith; Adler, Daniel; Nahapetyan, Samvel; Smith, Victoria; Mark, Darren; Mallol, Carolina; Blockley, Simon; Gasparian, Boris

2014-05-01

213

Estimation of Evapotranspiration of Almond orchards using Remote Sensing based SEBAL model in Central Valley, California  

NASA Astrophysics Data System (ADS)

Evapotranspiration is one of the main components of the hydrologic cycle and its impact to hydrology, agriculture,forestry and environmental studies is very crucial. SEBAL (Surface Energy Balance Algorithm for Land) is an image-processing model comprised of twenty-five computational sub-models that computes actual evapotranspiration (ETa) and other energy exchanges as a component of energy balance which is used to derive the surface radiation balance equation for the net surface radiation flux (Rn) on a pixel-by-pixel basis. For this study, SEBAL method is applied to Level 1B dataset of visible, near-infrared and thermal infrared radiation channels of MASTER instrument on-board NASA-DC 8 flight. This paper uses the SEBAL method to (1) investigate the spatial distribution property of land surface temperature (Ls), NDVI, and ETa over the San Joaquin valley. (2) Estimate actual evapotranspiration of almond class on pixel-by-pixel basis in the Central valley, California. (3) Comparison of actual Evapotranspiration obtained from SEBAL model with reference evapotranspiration (Eto) using Penman Monteiths method based on the procedures and available data from California Irrigation Management Information System (CIMIS) stations. The results of the regression between extracted land surface temperature, NDVI and, evapotranspiration show negative (-) correlation. On the other hand Ls possessed a slightly stronger negative correlation with the ETa than with NDVI for Almond class. The correlation coefficient of actual ETa estimates from remote sensing with Reference ETo from Penmann Monteith are 0.8571. ETa estimated for almond crop from SEBAL were found to be almost same with the CIMIS_Penman Monteith method with bias of 0.77 mm and mean percentage difference is 0.10%. These results indicate that combination of MASTER data with surface meteorological data could provide an efficient tool for the estimation of regional actual ET used for water resources and irrigation scheduling and management. Keywords: Evapotranspiration, Hydrologic cycle, SEBAL, net surface radiation flux, MASTER, NDVI, Penman Monteith, CIMIS, Surface Temperature

Roy, S.; Ustin, S.; Kefauver, S. C.

2009-12-01

214

Mg- and K-bearing borates and associated evaporites at Eagle Borax spring, Death Valley, California: A spectroscopic exploration  

USGS Publications Warehouse

Efflorescent crusts at the Eagle Borax spring in Death Valley, California, contain an array of rare Mg and K borate minerals, several of which are only known from one or two other localities. The Mg- and/or K-bearing borates include aristarainite, hydroboracite, kaliborite, mcallisterite, pinnoite, rivadavite, and santite. Ulexite and probertite also occur in the area, although their distribution is different from that of the Mg and K borates. Other evaporite minerals in the spring vicinity include halite, thenardite, eugsterite, gypsum-anhydrite, hexahydrite, and bloedite. Whereas the first five of these minerals are found throughout Death Valley, the last two Mg sulfates are more restricted in occurrence and are indicative of Mg-enriched ground water. Mineral associations observed at the Eagle Borax spring, and at many other borate deposits worldwide, can be explained by the chemical fractionation of borate-precipitating waters during the course of evaporative concentration. The Mg sulfate and Mg borate minerals in the Eagle Borax efflorescent crusts point to the fractionation of Ca by the operation of a chemical divide involving Ca carbonate and Na-Ca borate precipitation in the subsurface sediments. At many other borate mining localities, the occurrence of ulexite in both Na borate (borax-kernite) and Ca borate (ulexite-colemanite) deposits similarly reflects ulexite's coprecipitation with Ca carbonate at an early concentration stage. Such ulexite may perhaps be converted to colemanite by later reaction with the coexisting Ca carbonate - the latter providing the additional Ca2+ ions needed for the conversion. Mg and Ca-Mg borates are the expected late-stage concentration products of waters forming ulexite-colemanite deposits and are therefore most likely to occur in the marginal zones or nearby mud facies of ulexite-colemanite orebodies. Under some circumstances, Mg and Ca-Mg borates might provide a useful prospecting guide for ulexite-colemanite deposits, although the high solubility of Mg borate minerals may prevent their formation in lacustrine settings and certainly inhibits their geologic preservation. The occurrence of Mg borates in borax-kernite deposits is also related to fractionation processes and points to the operation of an Mg borate chemical divide, characterized by Mg borate precipitation ahead of Mg carbonate. All of these considerations imply that Mg is a significant chemical component of many borate-depositing ground waters, even though Mg borate minerals may not be strongly evident in borate orebodies. The Eagle Borax spring borates and other evaporite minerals were studied using spectroscopic and X-ray powder diffraction methods, which were found to be highly complementary. Spectral reflectance measurements provide a sensitive means for detecting borates present in mixtures with other evaporites and can be used to screen samples rapidly for X-ray diffraction analysis. The apparently limited occurrence of Mg and K borate minerals compared to Ca and Na borates may stem partly from the inefficiency of X-ray diffraction methods for delineating the mineralogy of large and complex deposits. Spectral reflectance measurements can be made in the laboratory, in the field, on the mine face, and even remotely. Reflectance data should have an important role in studies of existing deposit mineralogy and related chemical fractionation processes, and perhaps in the discovery of new borate mineral resources.

Crowley, J. K.

1996-01-01

215

EFFECTIVE MODEL CALIBRATION OF THE GEOLOGICALLY COMPLEX DEATH VALLEY REGIONAL GROUND-WATER FLOW SYSTEM, NEVADA AND CALIFORNIA  

SciTech Connect

A numerical ground-water flow model is being constructed for the Death Valley regional ground-water system, an area that encompasses approximately 80,000 km{sup 2} in southern Nevada and southeastern California. Effective construction and calibration of the regional-scale steady-state flow model, developed using MODFLOW-2000, is dependent upon integration of hydrogeologic data and parameter-estimation techniques. A three-dimensional hydrogeologic-framework model of the region was initially constructed to provide a conceptual model of the geometry, composition, and hydraulic properties of the materials that control the regional ground-water flow system. This framework was resampled at the scale of the flow model to define the hydrogeologic units present in each of the 15 flow-model layers. In addition, there are non-traditional types of geologic data in the hydrogeologic-framework model that are used during flow-model calibration. For each hydrogeologic unit, the spatial distribution of geologic features important to the hydrologic system is defined. The volumetric cells can be populated by various hydrogeologic data such as the hydrogeologic unit, lithology, hydraulic conductivity, faulting, tectonic features, stratigraphic or lithologic facies, porosity, and derivative data calculated from these attributes. The approach for using this arsenal of geologic data is dependent on utilizing parameter-estimation techniques available within MODFLOW-2000. The principle of parsimony is used throughout the flow-modeling process so that a simple conceptual model is methodically made more complex. Initially, the most basic conceptual model that could reasonably define the flow system was constructed and geologic units were grouped into four major hydrogeologic units. Only major geologic structures were included; there was little structural or stratigraphic differentiation, and a minimum number of parameters were used. As the calibration process progresses, additional complexity is added to the flow model. Evaluation of the flow model is based on analysis of several MODFLOW-2000 functions such as composite scaled sensitivity, weighted and unweighted hydraulic-head and flow residuals, comparison of parameter estimates with reasonable values based on previous studies, and parameter correlations. These functions provide information on whether the available hydraulic-head and ground-water discharge data are likely to be sufficient to estimate parameter values and to subdivide parameters into more detailed units. If sufficient data are available then a parameter can be subdivided into several parameters that represent specific distinguishing hydrogeologic features. For example, in the Death Valley region the lower carbonate aquifer is widely distributed and although regionally uniform, areas with unique hydrologic characteristics exist. Although the lower carbonate aquifer was initially considered one hydrogeologic unit with one set of hydrologic properties, it has been progressively subdivided into different structural and stratigraphic regions with unique hydrologic properties. The best flow model consists of the fewest number of parameters that can adequately describe the flow system and meet the modeling objectives.

G.M. O'Brien; F.A. D'Agnese; C.C. Faunt; W.R. Belcher

2000-10-19

216

Do phreatomagmatic eruptions at Ubehebe Crater (Death Valley, California) relate to a wetter than present hydro-climate?  

NASA Astrophysics Data System (ADS)

Phreatomagmatic eruptions occur when rising magma encounters groundwater and/or surface water, causing a steam explosion and the ejection of country rock and pyroclastic material. The predominance of this type of activity at the Ubehebe volcanic field in northern Death Valley, California, is enigmatic owing to the extremely arid climate of the region. A novel application of 10Be surface exposure dating is presented to determine the timing of phreatomagmatic eruptions at Ubehebe Crater and to test the idea that volcanism may relate to a wetter than present hydro-climate. Twelve of the fifteen ages obtained lie between 0.8 and 2.1 ka, while three samples give older, mid-Holocene ages. The cluster between 0.8 and 2.1 ka is interpreted as encompassing the interval of volcanic activity during which Ubehebe Crater was formed. The remaining older ages are inferred to date eruptions at the older neighboring craters. The main and most recent period of activity encompasses the Medieval Warm Period, an interval of prolonged drought in the American southwest, as well as slightly wetter conditions prior to the Medieval Warm Period. Phreatomagmatic activity under varied hydrologic conditions casts doubt on the idea that eruptive timing relates to a wetter hydro-climate. Instead, the presence of a relatively shallow modern water table suggests that sufficient groundwater was generally available for phreatomagmatic eruptions at the Ubehebe site, in spite of prevailing arid conditions. This and the youth of the most recent activity suggest that the Ubehebe volcanic field may constitute a more significant hazard than generally appreciated.

Sasnett, Peri; Goehring, Brent M.; Christie-Blick, Nicholas; Schaefer, Joerg M.

2012-01-01

217

Large-scale single incised valley from a small catchment basin on the western Adriatic margin (central Mediterranean Sea)  

NASA Astrophysics Data System (ADS)

The Manfredonia Incised Valley (MIV) is a huge erosional feature buried below the Apulian shelf, on the western side of the Adriatic margin. The incision extends more than 60 km eastward, from the Tavoliere Plain to the outer shelf, not reaching the shelf edge. High-resolution chirp sonar profiles allow reconstruction of the morphology of the incision and its correlation at regional scale. The MIV records a single episode of incision, induced by the last glacial-interglacial sea level fall that forced the rivers draining the Tavoliere Plain to advance basinward, reaching their maximum extent at the peak of the Last Glacial Maximum. The valley was filled during a relatively short interval of about 10,000 yr during the Late Pleistocene-Holocene sea level rise and almost leveled-off at the time of maximum marine ingression, possibly recording the short-term climatic fluctuations that occurred. The accommodation space generated by the lowstand incision was exploited during the following interval of sea level rise by very high rates of sediment supply that allowed the preservation of up to 45 m of valley fill. High-resolution chirp sonar profiles highlight stratal geometries that are consistent with a typical transgressive valley fill of an estuary environment, including bay-head deltas, central basin and distal barrier-island deposits, organized in a backstepping configuration. The highest complexity of the valley fill is reached in the shallowest and most proximal area, where a kilometric prograding wedge formed during a period dominated by riverine input, possibly connected to high precipitation rates. Based on the depth of the valley margins during this interval, the fill was likely isochronous with the formation of sapropel S1 in the Mediterranean region and may have recorded significant fluctuations within the hydrological cycle.

Maselli, Vittorio; Trincardi, Fabio

2013-01-01

218

Differential Hypermethylation of Death-Associated Protein Kinase Promoter in Central Neurocytoma and Oligodendroglioma  

PubMed Central

Background. Central neurocytoma and oligodendroglioma are rare tumors of the central nervous system. However, diagnosis between these two types of tumors is challenging due to their many cytological and histological similarities. Death-associated protein kinase (DAPK) is a calcium/calmodulin-regulated serine/threonine protein kinase involved in many apoptosis pathways, and repressed expression of DAPK by promoter hypermethylation has been found in a variety of human cancers. The purpose of this study was to assess DAPK protein expression and promoter hypermethylation in central neurocytoma and oligodendroglioma. Method. Central neurocytoma and oligodendroglioma samples were obtained from age- and sex-matched patients. DAPK protein expression was performed using immunohistochemical assays in formalin-fixed, paraffin-embedded sections. DAPK promoter hypermethylation was carried out using bisulfite-modified genomic DNA in methylation-specific PCR followed by separation in agarose gels. Findings. A statistically significant difference (P = 0.021) in DAPK promoter hypermethylation between central neurocytoma (76.9%) and oligodendroglioma (20%) was observed. High levels of DAPK protein expression were generally found in oligodendroglioma (90%), compared with 38.5% in central neurocytoma (P = 0.054; not statistically significant). There was an inverse correlation between DAPK protein expression and DAPK promoter hypermethylation in the cohort of 23 patients (P = 0.002). Conclusions. The results show that DAPK promoter hypermethylation and repressed expression of DAPK protein were more common in central neurocytoma than in oligodendroglioma. Thus, DAPK promoter hypermethylation could be useful for differential diagnosis between these two types of tumors, whereas DAPK protein expression might be less predictive. The role of DAPK promoter hypermethylation in the pathogenesis of central neurocytoma warrants further study. PMID:24877104

Chung, Chia-Li; Tsai, Hung Pei; Tsai, Cheng-Yu; Chen, Wan-Tzu; Lieu, Ann-Shung; Wang, Chih-Jen; Sheehan, Jason; Chai, Chee-Yin; Kwan, Aij-Lie

2014-01-01

219

Central Valley, California High Intensity Drug Trafficking Area, 2005 Annual Report. (Includes Fresno, Kern, Kings, Madera, Merced, Sacramento, San Joaquin, Stanislaus and Tulare Counties).  

National Technical Information Service (NTIS)

The Central Valley California HIDTA (CVC HIDTA) is one of the most prolific manufacturing regions for legitimate food crops as well as illegal drugs in the United States. Law enforcement agencies have battled the influences and activities of drug cartels ...

2006-01-01

220

Give Me Equity or Give Me Death - The Role of Competition and Compensation in Building Silicon Valley  

Microsoft Academic Search

In this essay, I argue that the preeminence of Silicon Valley as an incubator of technology companies is attributable to equity compensation. Ronald Gilson, relying on the work of AnnaLee Saxenian and others who have noted the tendency of Silicon Valley employees to job hop, has suggested that California law prohibiting the enforcement of non-compete agreements was a major factor

Richard A. Booth

2006-01-01

221

Land-Use and Land-Cover Dynamics in the Central Rift Valley of Ethiopia  

NASA Astrophysics Data System (ADS)

Understanding the complexity of land-use and land-cover (LULC) changes and their driving forces and impacts on human and environmental security is important for the planning of natural resource management and associated decision making. This study combines and compares participatory field point sampling (pfps) and remote sensing to explore local LULC dynamics. The study was conducted in two peasant associations located in the central Ethiopian Rift Valley, which is a dry-land mixed farming area exposed to rapid deforestation. From 1973-2006, the area of cropland doubled at the expense of woodland and wooded-grassland in both of the study sites. Major deforestation and forest degradation took place from 1973-1986; woodland cover declined from 40% to 9% in one of the study sites, while the other lost all of its original 54% woodland cover. Our study concludes that assessing LULC dynamics using a combination of remote sensing and pfps is a valuable approach. The two methods revealed similar LULC trends, while the pfps provided additional details on how farmers view the changes. This study documents dramatic trends in LULC over time, associated with rapid population growth, recurrent drought, rainfall variability and declining crop productivity. The alarming nature of these trends is reflected in a decrease in the livelihood security of local communities and in environmental degradation. Given these dry-land conditions, there are few opportunities to improve livelihoods and environmental security without external support. If negative changes are to be halted, action must be taken, including building asset bases, instituting family planning services, and creating opportunities outside these marginal environments.

Garedew, Efrem; Sandewall, Mats; Söderberg, Ulf; Campbell, Bruce M.

2009-10-01

222

Early Oligocene partial melting in the Main Central Thrust Zone (Arun valley, eastern Nepal Himalaya)  

NASA Astrophysics Data System (ADS)

The Main Central Thrust Zone (MCTZ) is a key tectonic feature in the architecture of the Himalayan chain. In the Arun valley of the eastern Nepal Himalaya, the MCTZ is a strongly deformed package of amphibolite- to granulite-facies metapelitic schist and granitic orthogneiss. This package is tectonically interposed between the underlying, low-grade, Lesser Himalaya sequences and the overlying, high-grade and locally anatectic, Higher Himalayan Crystallines (HHC). The MCTZ is characterized by a well documented inverted metamorphism from the Grt-Bt zone, across the Ky-in, St-in and -out, Kfs-in, Ms-out and Sil-in isograds. Partial melting with local occurrence of migmatitic segregations has been rarely reported from the highest structural levels of the MCTZ. While it is widely accepted that thrusting along the MCT occurred during the Miocene, geochronological data constraining the timing of crustal anatexis in the upper portion of the MCTZ are still lacking. In order to understand the link between partial melting in the MCTZ and the Miocene activation of the MCT, we present the P- T-time evolution of a kyanite-bearing anatectic gneiss occurring at the highest structural levels of the MCTZ, along the Arun-Makalu transect (eastern Nepal). Microstructural observations combined with P- T pseudosection analysis show that dehydration partial melting occurred in the kyanite-field. After reaching peak conditions at about 820 °C, 13 kbar, the studied sample experienced decompression accompanied by cooling down to 805 °C, 10 kbar, which caused in situ melt crystallization. SHRIMP monazite and zircon geochronology provides evidence that the anatexis affecting the upper portion of the MCTZ occurred during Early Oligocene (˜ 31 Ma). These results demonstrate that in the upper MCTZ, at least in the eastern Himalaya, crustal anatexis was earlier than, and not a consequence of, decompression linked to exhumation along the MCT.

Groppo, Chiara; Rubatto, Daniela; Rolfo, Franco; Lombardo, Bruno

2010-08-01

223

Rainwater harvesting for small-scale irrigation of maize in the Central Rift Valley, Ethiopia  

NASA Astrophysics Data System (ADS)

In the Central Rift Valley of Ethiopia, small scale farmers mostly rely on rainfall for crop production. The erratic nature of rainfall causes frequent crop failures and makes the region structurally dependent on food aid. Rainwater Harvesting (RWH) is a technique to collect and store runoff that could provide water for livestock, domestic use or small scale irrigation. Usually, such irrigation is promoted for high value crops, but in the light of regional food security it may become interesting to invest in irrigation of maize. In this research, two cemented RWH cisterns were investigated to determine their economic and social potential for supplemental irrigation of maize using drip irrigation. For this, data from test fields with irrigated maize and monitoring of water levels of the cisterns were used, as well as a survey under 30 farmers living close to the experimental site. The results show that catchment size and management should be in balance with the designed RWH system, to prevent too little runoff or flooding. An analysis with Cropwat 8.0 was used to investigate the possibility of irrigating maize with the observed amounts of water in the RWH cisterns. This would suffice for 0.3-0.8 ha of maize. For a RWH cistern with a drip irrigation system to be economically viable, the production on this acreage should become 3-4 ton/ha; 2.5 times higher than the current yield. But the biggest challenge would be to change the perception of respondents, who don't find it logical to spend precious water on a common crop like maize. Therefore, if the Ethiopian government considers the irrigation of maize to be important for regional food security, it is recommended to either subsidize the construction of RWH cisterns or provide credit on favourable terms.

Keesstra, Saskia; Hartog, Maaike; Muluneh, Alemayehu; Stroosnijder, Leo

2013-04-01

224

The role of cornice fall avalanche sedimentation in the valley Longyeardalen, Central Svalbard  

NASA Astrophysics Data System (ADS)

In arctic and alpine high relief landscapes snow avalanches are traditionally ranked behind rockfall in terms of their significance for mass wasting processes of rock slopes. Cornice fall avalanches are at present the most dominant snow avalanche type at two slope systems, called Nybyen and Larsbreen, in the valley Longyeardalen in Central Svalbard. Both slope systems are situated on NW-facing lee slopes underneath large summit plateau, where cornices form annually, and high frequency and magnitude cornice fall avalanching is observed by daily automatic time-lapse photography. In addition, rock debris sedimentation by these cornice fall avalanches was measured directly in either permanent sediment traps or by snow inventories. The results from a maximum of 7 yr of measurements in a total of 13 catchments show maximum avalanche sedimentation rates ranging from 8.2 to 38.7 kg m-2 at Nybyen and from 0.8 to 55.4 kg m-2 at Larsbreen. Correspondingly, the avalanche fan-surfaces accreted annually in a~maximum range from 3.7 to 13 mm yr-1 at Nybyen and from 0.3 to 21.4 mm yr-1 at Larsbreen. This comparably efficient rock slope mass wasting is due to collapsing cornices producing cornice fall avalanche with high rock debris content throughout the entire winter. The rock debris of different origin stems from the plateau crests, the adjacent free rock face and the transport pathway, accumulating distinct avalanche fans at both slope systems and contributing to the development of a rock glacier at the Larsbreen slope system.

Eckerstorfer, M.; Christiansen, H. H.; Rubensdotter, L.; Vogel, S.

2012-12-01

225

Identifying Key Vulnerabilities in Current Management of California Central Valley for the California Water Plan  

NASA Astrophysics Data System (ADS)

The California Department of Water Resources (DWR), for its 2013 Update of the California Water Plan (CWP), is building new analytic capabilities for developing and evaluating regional and state-wide water management strategies. These strategies are intended to address growing and diverse water needs coupled with uncertain future hydrologic conditions and available supplies. Recognizing the significant uncertainty about future water management conditions, DWR is utilizing new robust decision methods to identify robust and adaptive water management strategies. This talk will describe a recently completed application of Robust Decision Making (RDM) for long-term water planning as part of the 2013 CWP Update. This analysis utilizes a new hydrologic / water management model of the Sacramento River, San Joaquin River, and Tulare hydrologic regions, running the model under hundreds of potential futures. These futures consider potential variation in demographic growth, land-use patterns, drought length and timing, and other climate factors from projections generated by downscaled global circulation models. Cluster-finding "scenario discovery" algorithms, applied to the resulting database of simulation model results, identify the key characteristics of future conditions where current management fails to meet a wide range of policy objectives. These "vulnerabilities" provide the foundation for developing more robust and adaptive response packages and the considering tradeoffs between such response packages. This analysis will provide guidance for considering response packages to meet the challenges posed by future conditions in the California Central Valley and provides a widely applicable new approach for making water management plans more cognizant and responsive to a wide range of uncertainties.

Bloom, E.; Groves, D.; Joyce, B. A.; Juricich, R.

2012-12-01

226

Downscaling GRACE satellite data for sub-region groundwater storage estimates in California's Central Valley  

NASA Astrophysics Data System (ADS)

The Central Valley aquifer (CVA) is a vital economic and environmental resource for California and the United States, and supplies water for one of the most agriculturally productive regions in the world. Recent estimates of groundwater (GW) availability in California have indicated declines in GW levels that may pose a threat to sustainable groundwater use in this region. The Gravity Recovery and Climate Experiment (GRACE) can be used to estimate variations in total water storage (TWS) and are therefore used to estimate GW storage changes within the CVA. However, using GRACE data in the CVA is challenging due to the coarse spatial resolution and increased error. To compensate for this, we used a statistical downscaling approach applied to GRACE data at the sub-region level using GW storage estimates from the California Department of Water Resources' (DWR) C2VSim hydrological model. This method produced a spatially and temporally variable GW anomaly dataset for sub-region GW management and for analysis of GW changes influenced by spatial and temporal variability. An additional challenge for this region is the influence of natural climate variability, altering GW recharge and influencing pumping practices. Understanding the effects of climate variability on GW storage changes, may improve GRACE TWS and GW estimates during periods of increased rain or droughts. Thus, the GRACE TWS and GW storage estimates were compared to the El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) using singular spectral analysis (SSA). Results from SSA indicate that variations in GRACE TWS are moderately correlated to PDO (10-25 year cycle), although low correlations were observed when compared to ENSO (2-7 year cycle). The incorporation of these new methods for estimating variations in groundwater storage in highly productive aquifers may improve water management techniques in California.

Kuss, A. M.; Newcomer, M. E.; Hsu, W.; Bourai, A.; Puranam, A.; Landerer, F. W.; Schmidt, C.

2012-12-01

227

[Floristic composition and structure of a premontane moist forest in Central Valley of Costa Rica].  

PubMed

The floristic composition and structure of a premontane moist forest remnant were studied in the El Rodeo Protected Zone, Central Valley of Costa Rica. Three one-hectare plots were established in the non-disturbed forest, and all trees with a diameter at breast height (dbh) of 10 cm or greater were marked, measured and identified. The plots were located within a radius of 500 m from each other. A total of 106 tree species were recorded in the three plots. Average values: species richness 69.6 species ha-1, abundance 509 individuals ha-1, basal area 36.35 m2 ha-1. Total diversity was 3.54 (Shannon Index, H'), and the species similarity among the plots ranged between S = 0.68 and 0.70 (Sørensen Similarity Index). Most tree species are represented by few individuals (five or less). There is a lack of emergent trees and arborescent palms in the forest canopy. According to the Familial Importance Value, Moraceae, followed by Fabaceae, Lauraceae, and Sapotaceae, largely dominates this forest. Pseudolmedia oxyphillaria (Moraceae) is the dominant species (Importance Value Index), accounting for 25% of all the marked trees in the plots, followed by Clarisia racemosa (Moraceae), Heisteria concinna (Olacaceae), and Brosimum alicastrum (Moraceae). The size class distributions were similar among plots, and in general followed the expected J-inverted shape. Differences in tree abundance, floristic composition, and spatial distribution of some species among the plots suggest heterogeneity of this ecosystem's arborescent vegetation. Moreover, it is an important natural reservoir for the conservation of rare and endangered tree species in a national level. Using these results as a baseline, this study should start a long term monitoring of the structure and composition of this very reduced and fragmented ecosystem. PMID:11795150

Cascante, A; Estrada, A

2001-03-01

228

Geochemical evidence of hydrothermal recharge in Lake Baringo, central Kenya Rift Valley  

NASA Astrophysics Data System (ADS)

Lake Baringo, a freshwater lake in the central Kenya Rift Valley, is fed by perennial and ephemeral rivers, direct rainfall, and hot springs on Ol Kokwe Island near the centre of the lake. The lake has no surface outlet, but despite high evaporation rates it maintains dilute waters by subsurface seepage through permeable sediments and faulted lavas. New geochemical analyses (major ions, trace elements) of the river, lake, and hot spring waters and the suspended sediments have been made to determine the main controls of lake water quality. The results show that evaporative concentration and the binary mixing between two end members (rivers and thermal waters) can explain the hydrochemistry of the lake waters.Two zones are recognized from water composition. The southern part of the lake near sites of perennial river inflow is weakly influenced by evaporation, has low total dissolved species (TDS), and has a seasonally variable load of mainly detrital suspended sediments. In contrast, waters of the northern part of the lake show evidence for strong evaporation (TDS of up to eight times inflow). Authigenic clay minerals and calcite may be precipitating from those more concentrated fluids.The subaerial hot-spring waters have a distinctive chemistry and are enriched in some elements that are also present in the lake water. Comparison of the chemical composition of the inflowing surface waters and lake water shows (1) an enrichment of some species (HCO3-, Cl, SO42-, F, Na, B, V, Cr, As, Mo, Ba and U) in the lake, (2) a depletion in SiO2 in the lake, and (3) a possible hydrothermal origin for most F. The rare earth element distribution and the F/Cl and Na/Cl ratios give valuable information on the rate of mixing of the river and hydrothermal fluids in the lake water. Calculations imply that thermal fluids may be seeping upward locally into the lake through grid-faulted lavas, particularly south of Ol Kokwe Island.

Tarits, Corinne; Renaut, Robin W.; Tiercelin, Jean-Jacques; Le Hérissé, Alain; Cotten, Jo; Cabon, Jean-Yves

2006-06-01

229

Soil chemical changes under irrigated mango production in the Central São Francisco River Valley, Brazil.  

PubMed

Irrigated areas in Brazil's Central São Francisco River Valley have experienced declines in productivity, which may be a reflection of changes in soil chemical properties due to management. This study was conducted to compare the chemical composition of soil solutions and cation exchange complexes in a five-year-old grove of irrigated mango (Mangifera indica L. cv. Tommy Atkins) with that of an adjacent clearing in the native caatinga vegetation. A detailed physiographic characterization of the area revealed a subsurface rock layer, which was more undulating than the current land surface, and identified the presence of a very saline and sodic (1045 microS cm(-1), sodium adsorption ratio [SAR] = 5.19) ground water table. While changes in concentrations of Ca, Mg, and K could be attributed to direct management inputs (fertilization and liming with dolomite), increases in Na suggested average annual capillary rise from the ground water table of 28 L m(-2). Accordingly, soil salinity levels appeared to be more dependent on surface elevation than the elevation of the rock layer or sediment thickness. The apparent influence of land surface curvature on water redistribution and the solution chemistry was more pronounced under irrigated mango production. In general, salinity levels had doubled in the mango grove and nearly tripled under the canopies, after only five years of irrigation. Though critical saline or sodic conditions were not encountered, the changes observed indicate a need for more adequate monitoring and management of water and salt inputs despite the excellent water quality of the São Francisco River. PMID:12931897

Heck, R J; Tiessen, H; Salcedo, I H; Santos, M C

2003-01-01

230

Interpretation of the Last Chance thrust, Death Valley region, California, as an Early Permian de??collement in a previously undeformed shale basin  

USGS Publications Warehouse

The Last Chance thrust, discontinuously exposed over an area of at least 2500 km2 near the south end of the Cordilleran foreland thrust belt in the Death Valley region of east-central California, is controversial because of its poorly constrained age and its uncertain original geometry and extent. We interpret this thrust to be Early Permian in age, to extend throughout a sedimentary basin in which deep-water Mississippian shale overlain by Pennsylvanian and earliest Permian limestone turbidites accumulated, to represent about 30 km of eastward displacement, and to be related to convergence on a northeast-trending segment of the Early Permian continental margin. Last Chance deformation occurred between the times of the Antler and Sonoma orogenies of Late Devonian-Early Mississippian and Late Permian ages, respectively, and followed Early to Middle Pennsylvanian truncation of the continental margin by transform faulting. In the western part of the Mississippian shale basin in east-central California, the originally recognized exposures of the Last Chance thrust show Neoproterozoic and early Paleozoic strata above lower-plate Mississippian shale. Farther east, faults subparallel to bedding above, below, and within the Mississippian shale are interpreted to mark the thrust zone and to represent a regional de??collement. At the eastern margin of the basin, upper-plate thrust slices of deep-water, late Paleozoic strata are interpreted to have piled up against the margin of the Mississippian carbonate shelf to form a large antiformal stack above the Lee Flat thrust, which we regard as the easternmost exposure of the Last Chance thrust. Thrust loading depressed the western part of the shelf, creating a new sedimentary basin in which about 3.5 km of younger Early Permian deep-water strata were deposited against the antiformal stack. Later, probably in the Late Permian, other thrusts, including the Inyo Crest thrust, which was subsequently overlapped by Early to Middle(?) Triassic marine strata, cut across the Last Chance thrust. We interpret the Last Chance thrust as similar in many ways to Appalachian-type de??collements in which the zone of thrusting is localized along a shale interval. The Last Chance thrust, however, has been dismembered during later geologic events so that its original geometry has been obscured. Our model may have unrecognized analogs in other structurally complex shale basins in which the initial deformation was along a major shale unit. ?? 2005 Elsevier B.V. All rights reserved.

Stevens, C. H.; Stone, P.

2005-01-01

231

COMMUNITY AND EDAPHIC ANALYSIS OF MIXED OAK FORESTS IN RIDGE AND VALLEY PROVINCE OF CENTRAL PENNSYLVANIA  

E-print Network

rubrum L. and Prunus serotina Ehrh. dominated the understories. _e importance of Quercus prinus L saccharum Marsh. and Fraxinus americana L. on mesic toe slopes, indented stream bank and valley floor sites

Abrams, Marc David

232

A detailed lithologic study of glacially buried valley in central Champaign County, Ohio  

SciTech Connect

Previous subsurface mapping in this area has identified a bedrock valley (Teays), which trends southeast to northwest and has a maximum depth of 135 m and width of 7 km. The valley is largely filled with outwash and is flanked on the east by moraines. This study focuses on the details of the sedimentary fill in the valley; it was spurred by proposed highway construction and its possible effects on a nearby fen. In addition to the surficial geology map of the county, lithologic interpretations were based on logs of water wells, and lithologic logs of 43 wells drilled by Wright State University to evaluate the stratigraphy of the valley, together with 26 gamma logs of these holes. The well logs were interpreted in terms of seven standardized lithologies and then correlated as depositional units on cross sections.

Schilling, D.J.; Dominic, D.F. (Wright State Univ., Dayton, OH (United States). Dept. of Geological Sciences)

1994-04-01

233

Data network, collection, and analysis in the Diamond Valley flow system, central Nevada  

USGS Publications Warehouse

Future groundwater development and its effect on future municipal, irrigation, and alternative energy uses in the Diamond Valley flow system are of concern for officials in Eureka County, Nevada. To provide a better understanding of the groundwater resources, the U.S. Geological Survey, in cooperation with Eureka County, commenced a multi-phase study of the Diamond Valley flow system in 2005. Groundwater development primarily in southern Diamond Valley has resulted in water-level declines since the 1960s ranging from less than 5 to 100 feet. Groundwater resources in the Diamond Valley flow system outside of southern Diamond Valley have been relatively undeveloped. Data collected during phase 2 of the study (2006-09) included micrometeorological data at 4 evapotranspiration stations, 3 located in natural vegetation and 1 located in an agricultural field; groundwater levels in 95 wells; water-quality constituents in aquifers and springs at 21 locations; lithologic information from 7 recently drilled wells; and geophysical logs from 3 well sites. This report describes what was accomplished during phase 2 of the study, provides the data collected, and presents the approaches to strengthen relations between evapotranspiration rates measured at micrometeorological stations and spatially distributed groundwater discharge. This report also presents the approach to improve delineation of areas of groundwater discharge and describes the current methodology used to improve the accuracy of spatially distributed groundwater discharge rates in the Diamond Valley flow system.

Knochenmus, Lari A.; Berger, David L.; Moreo, Michael T.; Smith, J. LaRue

2011-01-01

234

Evolution of Late Miocene to Contemporary Displacement Transfer Between the Northern Furnace Creek and Southern Fish Lake Valley Fault Zones and the Central Walker Lane, Western Great Basin, Nevada  

NASA Astrophysics Data System (ADS)

Late Miocene to contemporary displacement transfer from the north Furnace Creek (FCF) and southern Fish Lake Valley (FLVF) faults to structures in the central Walker Lane was and continues to be accommodated by a belt of WNW-striking left-oblique fault zones in the northern part of the southern Walker Lane. The WNW fault zones are 2-9 km wide belts of anastomosing fault strands that intersect the NNW-striking FCF and southern FLVF in northern Death Valley and southern Fish Lake Valley, respectively. The WNW fault zones extend east for over 60 km where they merge with a 5-10 km wide belt of N10W striking faults that marks the eastern boundary of the southern Walker Lane. Left-oblique displacement on WNW faults progressively decreases to the east, as motion is successively transferred northeast on NNE-striking faults. NNE faults localize and internally deform extensional basins that each record cumulative net vertical displacements of between 3.0 and 5.2 km. The transcurrent faults and associated basins decrease in age from south to north. In the south, the WNW Sylvania Mountain fault system initiated left-oblique motion after 7 Ma but does not have evidence of contemporary displacement. Farther north, the left-oblique motion on the Palmetto Mountain fault system initiated after 6.0 to 4.0 Ma and has well-developed scarps in Quaternary deposits. Cumulative left-lateral displacement for the Sylvania Mountain fault system is 10-15 km, and is 8-12 km for the Palmetto fault system. The NNE-striking faults that emanate from the left-oblique faults merge with NNW transcurrent faults farther north in the eastern part of the Mina deflection, which links the Owens Valley fault of eastern California to the central Walker Lane. Left-oblique displacement on the Sylvania Mountain and Palmetto Mountain fault zones deformed the Furnace Creek and Fish Lake Valley faults. Left-oblique motion on Sylvania Mountain fault deflected the FCF into the 15 km wide Cucomungo Canyon restraining bend, segmented the >3.0 km deep basin underlying southern Fish Lake Valley, and formed a 2 km wide restraining bend in the FLVF. Part of the left-oblique motion on the Palmetto Mountain fault zone crosses Fish Lake Valley and offsets the FLVF in a 3 km wide restraining bend with the remainder being taken-up by NNW structures along the eastern side of southern Fish Lake Valley.

Oldow, J. S.; Geissman, J. W.

2013-12-01

235

Fjord-valley fill stratigraphy from onshore high-resolution shear-wave seismics, Trondheim harbour area, central Norway  

NASA Astrophysics Data System (ADS)

To obtain information on the stratigraphic variability within the underlying fjord-valley fill, a shallow, shear-wave reflection seismic survey was successfully carried out on land in the Trondheim harbor area, central Norway. Since the last deglaciation, the region has been subjected to a fall of relative sea level of totally 175 m due to glacioisostatic rebound. The relative sea-level fall was accompanied by river erosion of emerging (glacio) marine deposits, several, large landslides, and delta progradation into the fjord. The infilled harbour area is located on the submerged part of a delta plain, and land reclamation is still going on. Historic and older submarine landslides are known to have taken place along the shoreline and an improved understanding of the ground conditions is therefore valuable for engineering purposes. In addition, the unique, S-wave seismic record gives insight into the overall architecture and long-term development of a fjord-valley filling influenced by relative sea level fall accompanied by occasional major mass-wasting events. Shear-wave reflection seismics was applied using a land streamer of 120 channels combined with a newly developed shear-wave vibrator from LIAG. Overall, 4.2 profile-km were acquired in a 2.5-D grid along paved roads and parking lots during night to minimize environmental noise. The investigations achieved a highly resolved image of the fjord-valley fill and clear bedrock detection. Vertical resolution is within a few meters over the entire profile whereas horizontal resolution decreases with depth. The entire fjord-valley fill is up to 160 m thick and five main stratigraphic units have been identified including bedrock. The fjord-valley fill is interpreted as consisting of glaciomarine deposits overlain by marine fjord sediments grading upwards into deltaic deposits. The change from continuous to more discontinuous or irregular reflection patterns reflects a progressive influence of delta-derived processes and mass-wasting during progradation of the shoreline. The seismic sections also indicate the presence of erosional surfaces such as scours or slide scars, and localized sediment accumulations such as landslide debris or the deposits of more diluted flows. The fjord-valley succession is draped by anthropogenic fill. Existing drill-hole data and seismic data offshore help to constrain the interpretation of the shear-wave seismic data. However, deeper and more targeted cores are needed to validate the geophysical and geological model. It is shown that the S-wave method has a great potential for the investigation of a fjord-valley stratigraphy even on man-made fills.

Hansen, L.; Polom, U.; L'Heureux, J.; Sauvin, G.; Lecomte, I.; Krawczyk, C. M.; Longva, O.

2009-12-01

236

Tilt and rotation of the footwall of a major normal fault system: Paleomagnetism of the Black Mountains, Death Valley extended terrane, California  

SciTech Connect

Paleomagnetic data have been obtained from Miocene intrusions, Proterozoic Paleomagnetic data have been obtained from Miocene intrusions, Proterozoic crystalline rocks and cross-cutting mafic to felsic dikes to evaluate footwall deformation during extension and unroofing of the crystalline core of the Black Mountains, Death Valley, California. Synrift intrusions contain a well-defined and, at the site level, well-grouped magnetization, interpreted to be of dual polarity, whose in situ direction is discordant in declination and inclination with an expected late Cenozoic reference direction. In situ site mean directions of this magnetization are directed towards the west and west-northwest with moderate to shallow positive and negative inclinations. The variation in magnetization direction, particularly inclination, with site locality around the turtleback structures along the western flank of the Black Mountains suggests folding of the intrusion after remanence acquisition. Two populations of in situ site means are identified: one with southwest declination and negative inclination, the other with northward declination and positive inclination. A preferred interpretation for footwall deformation involves, from oldest to youngest: (1) northeast-side up tilting of 20--40[degree] and local folding of the crystalline rocks associated with early structures (the Death Valley turtlebacks) between 11.6 and 8.7 Ma, (2) progressive east to west footwall unroofing between 8.7 and [approximately]6.5 Ma, and (3) large-scale clockwise rotation (50--80[degree]) after the core detached from stable terrane to the west. The authors interpret late rotation as oroflexure related to right-lateral shear along the Death Valley fault zone.

Holm, D.K. (Kent State Univ., OH (United States). Dept. of Geology); Geissman, J.W. (Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Geology and Planetary Sciences); Wernicke, B. (California Inst. of Tech., Pasadena, CA (United States). Dept. of Geology and Planetary Sciences)

1993-04-01

237

Annual ground-water discharge by evapotranspiration from areas of spring-fed riparian vegetation along the eastern margin of Death Valley, 2000-02  

USGS Publications Warehouse

Flow from major springs and seeps along the eastern margin of Death Valley serves as the primary local water supply and sustains much of the unique habitat in Death Valley National Park. Together, these major spring complexes constitute the terminus of the Death Valley Regional Ground-Water Flow System--one of the larger flow systems in the Southwestern United States. The Grapevine Springs complex is the least exploited for water supply and consequently contains the largest area of undisturbed riparian habitat in the park. Because few estimates exist that quantify ground-water discharge from these spring complexes, a study was initiated to better estimate the amount of ground water being discharged annually from these sensitive, spring-fed riparian areas. Results of this study can be used to establish a basis for estimating water rights and as a baseline from which to assess any future changes in ground-water discharge in the park. Evapotranspiration (ET) is estimated volumetrically as the product of ET-unit (general vegetation type) acreage and a representative ET rate. ET-unit acreage is determined from high-resolution multi-spectral imagery; and a representative ET rate is computed from data collected in the Grapevine Springs area using the Bowen-ratio solution to the energy budget, or from rates given in other ET studies in the Death Valley area. The ground-water component of ET is computed by removing the local precipitation component from the ET rate. Two different procedures, a modified soil-adjusted vegetation index using the percent reflectance of the red and near-infrared wavelengths and land-cover classification using multi-spectral imagery were used to delineate the ET units within each major spring-discharge area. On the basis of the more accurate procedure that uses the vegetation index, ET-unit acreage for the Grapevine Springs discharge area totaled about 192 acres--of which 80 acres were moderate-density vegetation and 112 acres were high-density vegetation. ET-unit acreage for two other discharge areas delineated in the Grapevine Springs area (Surprise Springs and Staininger Spring) totaled about 6 and 43 acres, respectively; and for the discharge areas delineated in the Furnace Creek area (Nevares Springs, Cow Creek-Salt Springs, Texas Spring, and Travertine Springs) totaled about 29, 13, 11, and 21 acres, respectively. In discharge areas other than Grapevine Springs, watering and spring diversions have altered the natural distribution of the vegetation. More...

Laczniak, Randell J.; Smith, J. LaRue; DeMeo, Guy A.

2006-01-01

238

Ecohydrology of Wetlands Occurring on Perched Seasonally Saturated Water Tables in the Central Valley of California  

NASA Astrophysics Data System (ADS)

The Central Valley, California has extensive areas of shallow perched groundwater systems associated with geomorphic terraces. Early season water supply is derived from precipitation (PPT) that has infiltrated into soils underlain by a near surface aquitard, typically at less than 2 m depth. Early season water input is regulated by the hydraulic conductivity of the (clay-) loamy soils and by surface and aquitard slope of the local catchments associated with these old alluvial landforms. Research on these landforms and shallow aquifers has identified a complex PPT and evapotranspiration (ET) sensitive system that includes shallow depressions that seasonally produce water table derived wetlands (“vernal pools”). These wetlands have been recognized for a very high level of plant and invertebrate species diversity including endangered species. Our work on these seasonal perched systems shows that as much as 80 percent of the soil column above the aquitard is saturated, during average to high rainfall years, for up to 90 to 120 days. Soil surface topographic depressions reduce the soil depth to the aquitard. Where the water table of this perched system intercepts the land surface, vernal pools develop. The perched groundwater drains into seasonal surface drainages that ultimately supply the Sacramento and San Joaquin rivers. At the end of the rainy season, both the vernal pools and the perched aquifer rapidly and synchronously disappear. Once the soil is unsaturated, water flow is vertically upward due to ET. Aquatic and wetland adapted plant species develop within the basins along a depth gradient. Variably saturated modeling of this system was conducted using HYDRUS 2D/3D. Climate inputs were from local and regional weather stations that measure and calculate daily PPT and ET, respectively. Initial conditions and calibration of the domain were based on field measurements using pressure transducers and soil moisture sensors. Soil pressure flux was measured using a matric potential soil sensor. Field measurements were taken throughout the local catchment and discharge points. The HYDRUS modeling has revealed a high level of sensitivity of the perched system to PPT and ET, with the first major seasonal PPT event generally establishing initial moisture saturation immediately above the aquitard. Plant species adapted to vernal pools were found to occur within narrow (5 to 10 cm) elevation zones in the pool basins and are correlated with specific hydroperiods of surface inundation. Annual variation in the amount and distribution of rainfall can cause a change the plant community composition. Longer term climate changes could result in regional shifts in plant community structure.

McCarten, N. F.; Harter, T.

2010-12-01

239

Paleomagnetic and structural evidence for middle Tertiary counterclockwise block rotation in the Dixie Valley region, west-central Nevada  

SciTech Connect

Paleomagnetic data from late Oligocene to early Miocene ash-flow tuffs at four localities in the northern Dixie Valley region, west-central Nevada, indicate that parts of the crust have rotated counterclockwise by at least 25/sup 0/ and perhaps significantly more in late Cenozoic time. Field relations in White Rock Canyon, Stillwater Range, suggest that rotation (1) was accommodated by right-lateral slip on northwest-trending faults, (2) spanned ash-flow tuff emplacement, and (3) probably ceased before eruption of overlying middle Miocene basalts. Accurate estimates of Cenozoic extension, as well as evaluation of earlier Mesozoic structures, must include the strain partitioned into rotation in the area.

Hudson, M.R.; Geissman, J.W.

1987-07-01

240

Spatial use by wintering greater white-fronted geese relative to a decade of habitat change in California's Central Valley  

USGS Publications Warehouse

We investigated the effect of recent habitat changes in California's Central Valley on wintering Pacific greater white-fronted geese (Anser albifrons frontalis) by comparing roost-to-feed distances, distributions, population range sizes, and habitat use during 1987-1990 and 1998-2000. These habitat changes included wetland restoration and agricultural land enhancement due to the 1990 implementation of the Central Valley Joint Venture, increased land area used for rice (Oryza sativa) production, and the practice of flooding, rather than burning, rice straw residues for decomposition because of burning restrictions enacted in 1991. Using radiotelemetry, we tracked 192 female geese and recorded 4,516 locations. Geese traveled shorter distances between roosting and feeding sites during 1998-2000 (24.2 ?? 2.2 km) than during 1987-1990 (32.5 ?? 3.4 km); distance traveled tended to decline throughout winter during both decades and varied among watershed basins. Population range size was smaller during 1998-2000 (3,367 km2) than during 1987-1990 (5,145 km2), despite a 2.2-fold increase in the size of the Pacific Flyway population of white-fronted geese during the same time period. The population range size also tended to increase throughout winter during both decades. Feeding and roosting distributions of geese also differed between decades; geese shifted into basins that had the greatest increases in the amount of area in rice production (i.e., American Basin) and out of other basins (i.e., Delta Basin). The use of rice habitat for roosting (1987-1990: 40%, 1998-2000: 54%) and feeding (1987-1990: 57%, 1998-2000: 72%) increased between decades, whereas use of wetlands declined for roosting (1987-1990: 36%, 1998-2000: 31%) and feeding (1987-1990: 22%, 1998-2000: 12%). Within postharvested rice habitats, geese roosted and fed primarily in burned rice fields during 1987-1990 (roost: 43%, feed: 34%), whereas they used flooded rice fields during 1998-2000 (roost: 78%, feed: 64%). Our results suggest that white-fronted geese have altered their spatial use of California's Central Valley during the past decade in response to changing agricultural practices and the implementation of the Central Valley Joint Venture.

Ackerman, J.T.; Takekawa, J.Y.; Orthmeyer, D.L.; Fleskes, J.P.; Yee, J.L.; Kruse, K.L.

2006-01-01

241

Geologic map and upper Paleozoic stratigraphy of the Marble Canyon area, Cottonwood Canyon quadrangle, Death Valley National Park, Inyo County, California  

USGS Publications Warehouse

This geologic map and pamphlet focus on the stratigraphy, depositional history, and paleogeographic significance of upper Paleozoic rocks exposed in the Marble Canyon area in Death Valley National Park, California. Bedrock exposed in this area is composed of Mississippian to lower Permian (Cisuralian) marine sedimentary rocks and the Jurassic Hunter Mountain Quartz Monzonite. These units are overlain by Tertiary and Quaternary nonmarine sedimentary deposits that include a previously unrecognized tuff to which we tentatively assign an age of late middle Miocene (~12 Ma) based on tephrochronologic analysis, in addition to the previously recognized Pliocene tuff of Mesquite Spring. Mississippian and Pennsylvanian rocks in the Marble Canyon area represent deposition on the western continental shelf of North America. Mississippian limestone units in the area (Tin Mountain, Stone Canyon, and Santa Rosa Hills Limestones) accumulated on the outer part of a broad carbonate platform that extended southwest across Nevada into east-central California. Carbonate sedimentation was interrupted by a major eustatic sea-level fall that has been interpreted to record the onset of late Paleozoic glaciation in southern Gondwana. Following a brief period of Late Mississippian clastic sedimentation (Indian Springs Formation), a rise in eustatic sea level led to establishment of a new carbonate platform that covered most of the area previously occupied by the Mississippian platform. The Pennsylvanian Bird Spring Formation at Marble Canyon makes up the outer platform component of ten third-order (1 to 5 m.y. duration) stratigraphic sequences recently defined for the regional platform succession. The regional paleogeography was fundamentally changed by major tectonic activity along the continental margin beginning in middle early Permian time. As a result, the Pennsylvanian carbonate shelf at Marble Canyon subsided and was disconformably overlain by lower Permian units (Osborne Canyon and Darwin Canyon Formations) representing part of a deep-water turbidite basin filled primarily by fine-grained siliciclastic sediment derived from cratonal sources to the east. Deformation and sedimentation along the western part of this basin continued into late Permian time. The culminating phase was part of a regionally extensive late Permian thrust system that included the Marble Canyon thrust fault just west of the present map area.

Stone, Paul; Stevens, Calvin H.; Belasky, Paul; Montañez, Isabel P.; Martin, Lauren G.; Wardlaw, Bruce R.; Sandberg, Charles A.; Wan, Elmira; Olson, Holly A.; Priest, Susan S.

2014-01-01

242

Cell Death, Neuronal Plasticity and Functional Loading in the Development of the Central Nervous System  

NASA Technical Reports Server (NTRS)

Research on the precise timing and regulation of neuron production and maturation in the vestibular and visual systems of Wistar rats and several inbred strains of mice (C57B16 and Pallid mutant) concentrated upon establishing a timing baseline for mitotic development of the neurons of the vestibular nuclei and the peripheral vestibular sensory structures (maculae, cristae). This involved studies of the timing and site of neuronal cell birth and preliminary studies of neuronal cell death in both central and peripheral elements of the mammalian vestibular system. Studies on neuronal generation and maturation in the retina were recently added to provide a mechanism for more properly defining the in utero' developmental age of the individual fetal subject and to closely monitor potential transplacental effects of environmentally stressed maternal systems. Information is given on current efforts concentrating upon the (1) perinatal period of development (E18 thru P14) and (2) the role of cell death in response to variation in the functional loading of the vestibular and proprioreceptive systems in developing mammalian organisms.

Keefe, J. R.

1985-01-01

243

Lava flows vs. surface water: the geologic battle for the upper McKenzie valley, central Oregon Cascades  

NASA Astrophysics Data System (ADS)

Over the past several thousand years, a battle for the upper McKenzie valley in the central Oregon Cascades has raged between, on one side, lava flows from the Sand Mountain volcanic chain and Belknap volcano, and on the other side, surface water fed by prolific springs. The north-south oriented upper McKenzie valley marks the boundary between the (old) western Cascades and the (active) high Cascades. The McKenzie valley hosted a glacier in the Pleistocene. In the Holocene, the valley has become a natural destination and conduit for both lava flows and surface water: it is downhill from volcanic vents, and as it follows the boundary between low (west) and high (east) porosity terrains, groundwater sourced from the high Cascades is forced to emerge in the valley. New surface age exposure dates, in conjunction with 14C dating, indicate that about 3000 years ago multiple lava flows from the Sand Mountain volcanic chain entered the valley from the east. The entire eruptive episode lasted several hundred years and caused massive disturbances to the ancestral McKenzie river. In the early stages of the eruptive episode, a lava flow dammed the McKenzie river, forming Clear Lake (modern source of the McKenzie river) and drowning a Douglas Fir forest. Relic drowned trees suggest that Clear Lake formed in two stages, as trees tops in the deepest part of the lake are consistently rotted off at a depth of 20 meters below water level, while trees in the shallower parts of the lake are rotted off at the surface. This suggests a paleo-lake level 20 meters below modern levels; lake levels are suspected to have reached modern levels later in the course of the eruptive episode when subsequent Sand Mountain lava flows entered the lake. In the years since the Sand Mountain eruptive episode, the McKenzie river re-established itself by adopting a lava channel. Considerable water also flows through the lava flows, emerging as springs along the river channel. The river also hosts two spectacular waterfalls at two lava flow fronts; these waterfalls appear to have retreated at least 50 meters since the lava flows were emplaced. In two unrelated volcanic episodes, lava flows from Belknap volcano entered the valley south of the Sand Mountain flows. A Belknap lava flow which predates the Sand Mountain lavas buried the river; today, the McKenzie river still disappears into the lava and reemerges at a spring several kilometers south. Younger Belknap lava flows did not reach the valley floor but resurface a considerable portion of the watershed. Thus, the upper McKenzie valley showcases strategic maneuvers by two great geologic fluids in the battle for domination: lava flows conquer by overwhelming the system, and water reaches a truce by adopting the enemy’s turf and flowing over and through it.

Deligne, N. I.; Conrey, R. M.; Cashman, K. V.; Grant, G. E.; Amidon, W. H.

2010-12-01

244

Facies analysis of Tertiary basin-filling rocks of the Death Valley regional ground-water system and surrounding areas, Nevada and California  

USGS Publications Warehouse

Existing hydrologic models of the Death Valley region typically have defined the Cenozoic basins as those areas that are covered by recent surficial deposits, and have treated the basin-fill deposits that are concealed under alluvium as a single unit with uniform hydrologic properties throughout the region, and with depth. Although this latter generalization was known to be flawed, it evidently was made because available geologic syntheses did not provide the basis for a more detailed characterization. As an initial attempt to address this problem, this report presents a compilation and synthesis of existing and new surface and subsurface data on the lithologic variations between and within the Cenozoic basin fills of this region. The most permeable lithologies in the Cenozoic basin fills are freshwater limestones, unaltered densely welded tuffs, and little-consolidated coarse alluvium. The least permeable lithologies are playa claystones, altered nonwelded tuffs, and tuffaceous and clay-matrix sediments of several types. In all but the youngest of the basin fills, permeability probably decreases strongly with depth owing to a typically increasing abundance of volcanic ash or clay in the matrices of the clastic sediments with increasing age (and therefore with increasing depth in general), and to increasing consolidation and alteration (both hydrothermal and diagenetic) with increasing depth and age. This report concludes with a categorization of the Cenozoic basins of the Death Valley region according to the predominant lithologies in the different basin fills and presents qualitative constraints on the hydrologic properties of these major lithologic categories.

Sweetkind, Donald S.; Fridrich, Christopher J.; Taylor, Emily

2001-01-01

245

Facies Analysis of Tertiary Basin-Filling Rocks of the Death Valley Regional Ground-Water System and Surrounding Areas, Nevada and California  

SciTech Connect

Existing hydrologic models of the Death Valley region typically have defined the Cenozoic basins as those areas that are covered by recent surficial deposits, and have treated the basin-fill deposits that are concealed under alluvium as a single unit with uniform hydrologic properties throughout the region, and with depth. Although this latter generalization was known to be flawed, it evidently was made because available geologic syntheses did not provide the basis for a more detailed characterization. As an initial attempt to address this problem, this report presents a compilation and synthesis of existing and new surface and subsurface data on the lithologic variations between and within the Cenozoic basin fills of this region. The most permeable lithologies in the Cenozoic basin fills are freshwater limestones, unaltered densely welded tuffs, and little-consolidated coarse alluvium. The least permeable lithologies are playa claystones, altered nonwelded tuffs, and tuffaceous and cl ay-matrix sediments of several types. In all but the youngest of the basin fills, permeability probably decreases strongly with depth owing to a typically increasing abundance of volcanic ash or clay in the matrices of the clastic sediments with increasing age (and therefore with increasing depth in general), and to increasing consolidation and alteration (both hydrothermal and diagenetic) with increasing depth and age. This report concludes with a categorization of the Cenozoic basins of the Death Valley region according to the predominant lithologies in the different basin fills and presents qualitative constraints on the hydrologic properties of these major lithologic categories.

Sweetkind, D.S.; Fridrich, C.J.; Taylor, Emily

2002-04-04

246

Update to the Ground-Water Withdrawals Database for the Death Valley REgional Ground-Water Flow System, Nevada and California, 1913-2003  

SciTech Connect

Ground-water withdrawal estimates from 1913 through 2003 for the Death Valley regional ground-water flow system are compiled in an electronic database to support a regional, three-dimensional, transient ground-water flow model. This database updates a previously published database that compiled estimates of ground-water withdrawals for 1913–1998. The same methodology is used to construct each database. Primary differences between the 2 databases are an additional 5 years of ground-water withdrawal data, well locations in the updated database are restricted to Death Valley regional ground-water flow system model boundary, and application rates are from 0 to 1.5 feet per year lower than original estimates. The lower application rates result from revised estimates of crop consumptive use, which are based on updated estimates of potential evapotranspiration. In 2003, about 55,700 acre-feet of ground water was pumped in the DVRFS, of which 69 percent was used for irrigation, 13 percent for domestic, and 18 percent for public supply, commercial, and mining activities.

Michael T. Moreo; and Leigh Justet

2008-07-02

247

Significance of orthogonal flow in the Funeral Mountains metamorphic core complex, Death Valley, California: Insights from geochronology and microstructural analysis  

NASA Astrophysics Data System (ADS)

The Funeral Mountains metamorphic core complex (FMMCC) in Death Valley, California, exposes middle to lower crustal rocks of the Sevier-Laramide orogen in the footwall of the Boundary Canyon detachment (BCD). Monarch Canyon, located in the northwest section of the Funeral Mountains, exposes the structurally deepest rocks in the FMMCC. These Mesoproterozoic to Neoproterozoic metasedimentary rocks record upper amphibolite facies metamorphism with migmatites developed at the deepest levels. The Monarch Spring fault (MSF) juxtaposes migmatitic paragneisses below against pelitic schists, calcsilicate schists, and marbles above, and represents a deformed anatectic front. In the footwall of the BCD above the MSF, distributed ductile deformation and stratigraphically localized high-strain zones, termed intracore shear zones, are responsible for attenuation and local stratigraphic omission during top-northwest non-coaxial deformation. The relative contributions of Late Cretaceous-early Tertiary and Miocene extensional strains which manifest in the top-northwest fabrics remains unclear, and is being addressed by ongoing and combined thermochronologic, microstructural, and EBSD studies. Our working hypothesis is a polystage extensional history in the FMMCC, with Late Cretaceous extensional intracore shear zones locally reactivated during the Miocene. Below the MSF, migmatitic paragneisses lack similar greenschist to lower amphibolite facies top-northwest fabrics. These rocks instead exhibit heterogeneous strain and a weak to moderately developed northeast-trending mineral lineation, and a local, strong fabric asymmetry indicative of a top-southwest sense of shear. We propose that the anatectic front is an apparent zone of structural decoupling between top-southwest shear below and top-northwest shear above the MSF. Structural and geochronologic studies are currently underway to establish whether the orthogonally directed flow above and below the anatectic front were coeval or developed in sequence with a progressive change in kinematics. Preliminary zircon U-Pb geochronology on leucogranite dikes and sills provide constraints on the timing of top-southwest shearing in paragneisses below the MSF. In lower Monarch Canyon, a strongly deformed pegmatitic muscovite granite sill that is folded with the surrounding rock provides an age of 68.1 × 0.3 Ma. A weakly deformed leucogranite dike in upper Monarch Canyon yields an age of 61.1 × 0.8 Ma, and an undeformed leucogranite dike that cross cuts the top-southwest fabric as well as the folded sills in lower Monarch Canyon yields an age of 57.2 × 0.9 Ma. These ages suggest that this phase of deformation below the MSF began after ~68 Ma, was in its waning stages at ~61 Ma, and had ceased by ~57 Ma. Currently, there are few constraints on the timing of top-northwest shearing above the MSF. If the top-northwest and top-southwest fabrics are determined to be coeval, we will test if the contact represents a distributed zone of decoupling or an attachment zone.

Sauer, K. M.; Wells, M. L.; Hoisch, T. D.

2013-12-01

248

Cyclicity in the Irish Valley Member of the Catskill Formation, central Pennsylvania  

SciTech Connect

The Upper Devonian Irish Valley Member of the Catskill Formation was deposited on a muddy coastline along the Catskill Delta margin. The Irish Valley contains cycles of varying duration caused by lateral shifting of facies during fluctuations of relative seal level. Approximately 400m of the Irish Valley Member at a newly exposed highway cut south of Selinsgrove, Pa. were described in terms of depth-diagnostic lithofacies: (A) Red siltstone and mudstone containing pedogenic features and root traces--Exposed coastal margin; (B) Heterolithic sand-dominated facies containing hummocky cross-stratification--Upper shoreface; (C) Wave-generated sand-dominated facies containing predominant flaser bedding--Middle Shoreface; (D) Wave-generated mud-dominated facies containing lenticular to wavy bedding--Lower shoreface; (E) Heterolithic mud-dominated facies containing parallel, thin laminations and thin (< 1 m) sandstone storm beds, which often have HCS--Offshore, between fair weather and storm wave bases--likely an offshore extension of Facies B. Approximately 30 shallowing-upward sequences occur throughout the section, and these sequences may be analyzed for patterns of cyclicity. It appears that smaller-scale (possibly fifth-order) cycles are superimposed on a higher order pattern (possibly fourth-order cycles). The Irish Valley Member was deposited over the course of 2.0--2.5 million years, thus each cycle likely represents 50,000--100,000 years. This figure fits nicely with the idea that the cycles of the Irish Valley Member were formed by eustatic sea-level fluctuations caused by Milankovitch-type orbital variations.

Terry, J.M. (Bucknell Univ., Lewisburg, PA (United States). Dept. of Geology)

1993-03-01

249

Runoff simulation in the Ferghana Valley (Central Asia) using conceptual hydrological HBV-light model  

NASA Astrophysics Data System (ADS)

Glaciers and permafrost on the ranges of the Tien Shan mountain system are primary sources of water in the Ferghana Valley. The water artery of the valley is the Syr Darya River that is formed by confluence of the Naryn and Kara Darya rivers, which originate from the mountain glaciers of the Ak-Shyrak and the Ferghana ranges accordingly. The Ferghana Valley is densely populated and main activity of population is agriculture that heavily depends on irrigation especially in such arid region. The runoff reduction is projected in future due to global temperature rise and glacier shrinkage as a consequence. Therefore, it is essential to study climate change impact on water resources in the area both for ecological and economic aspects. The evaluation of comparative contribution of small upper catchments (n=24) with precipitation predominance in discharge and the large Naryn and Karadarya River basins, which are fed by glacial melt water, to the Fergana Valley water balance under current and future climatic conditions is general aim of the study. Appropriate understanding of the hydrological cycle under current climatic conditions is significant for prognosis of water resource availability in the future. Thus, conceptual hydrological HBV-light model was used for analysing of the water balance of the small upper catchments that surround the Ferghana Valley. Three trial catchments (the Kugart River basin, 1010 km²; the Kurshab River basin, 2010 km2; the Akbura River basin, 2260 km²) with relatively good temporal quality data were chosen to setup the model. Due to limitation of daily temperature data the MODAWEC weather generator, which converts monthly temperature data into daily based on correlation with rainfall, was tested and applied for the HBV-light model.

Radchenko, Iuliia; Breuer, Lutz; Forkutsa, Irina; Frede, Hans-Georg

2013-04-01

250

A three-dimensional numerical model of predevelopment conditions in the Death Valley regional ground-water flow system, Nevada and California  

USGS Publications Warehouse

In the early 1990's, two numerical models of the Death Valley regional ground-water flow system were developed by the U.S. Department of Energy. In general, the two models were based on the same basic hydrogeologic data set. In 1998, the U.S. Department of Energy requested that the U.S. Geological Survey develop and maintain a ground-water flow model of the Death Valley region in support of U.S. Department of Energy programs at the Nevada Test Site. The purpose of developing this 'second-generation' regional model was to enhance the knowledge an understanding of the ground-water flow system as new information and tools are developed. The U.S. Geological Survey also was encouraged by the U.S. Department of Energy to cooperate to the fullest extent with other Federal, State, and local entities in the region to take advantage of the benefits of their knowledge and expertise. The short-term objective of the Death Valley regional ground-water flow system project was to develop a steady-state representation of the predevelopment conditions of the ground-water flow system utilizing the two geologic interpretations used to develop the previous numerical models. The long-term objective of this project was to construct and calibrate a transient model that simulates the ground-water conditions of the study area over the historical record that utilizes a newly interpreted hydrogeologic conceptual model. This report describes the result of the predevelopment steady-state model construction and calibration. The Death Valley regional ground-water flow system is situated within the southern Great Basin, a subprovince of the Basin and Range physiographic province, bounded by latitudes 35 degrees north and 38 degrees 15 minutes north and by longitudes 115 and 118 degrees west. Hydrology in the region is a result of both the arid climatic conditions and the complex geology. Ground-water flow generally can be described as dominated by interbasinal flow and may be conceptualized as having two main components: a series of relatively shallow and localized flow paths that are superimposed on deeper regional flow paths. A significant component of the regional ground-water flow is through a thick Paleozoic carbonate rock sequence. Throughout the flow system, ground water flows through zones of high transmissivity that have resulted from regional faulting and fracturing. The conceptual model of the Death Valley regional ground-water flow system used for this study is adapted from the two previous ground-water modeling studies. The three-dimensional digital hydrogeologic framework model developed for the region also contains elements of both of the hydrogeologic framework models used in the previous investigations. As dictated by project scope, very little reinterpretation and refinement were made where these two framework models disagree; therefore, limitations in the hydrogeologic representation of the flow system exist. Despite limitations, the framework model provides the best representation to date of the hydrogeologic units and structures that control regional ground-water flow and serves as an important information source used to construct and calibrate the predevelopment, steady-state flow model. In addition to the hydrogeologic framework, a complex array of mechanisms accounts for flow into, through, and out of the regional ground-water flow system. Natural discharges from the regional ground-water flow system occur by evapotranspiration, springs, and subsurface outflow. In this study, evapotranspiration rates were adapted from a related investigation that developed maps of evapotranspiration areas and computed rates from micrometeorological data collected within the local area over a multiyear period. In some cases, historical spring flow records were used to derive ground-water discharge rates for isolated regional springs. For this investigation, a process-based, numerical model was developed to estimat

D'Agnese, Frank A.; O'Brien, G. M.; Faunt, C. C.; Belcher, W. R.; San Juan, C.

2002-01-01

251

Assessment of regional change in nitrate concentrations in groundwater in the Central Valley, California, USA, 1950s-2000s  

USGS Publications Warehouse

A regional assessment of multi-decadal changes in nitrate concentrations was done using historical data and a spatially stratified non-biased approach. Data were stratified into physiographic subregions on the basis of geomorphology and soils data to represent zones of historical recharge and discharge patterns in the basin. Data were also stratified by depth to represent a shallow zone generally representing domestic drinking-water supplies and a deep zone generally representing public drinking-water supplies. These stratifications were designed to characterize the regional extent of groundwater with common redox and age characteristics, two factors expected to influence changes in nitrate concentrations over time. Overall, increasing trends in nitrate concentrations and the proportion of nitrate concentrations above 5 mg/L were observed in the east fans subregion of the Central Valley. Whereas the west fans subregion has elevated nitrate concentrations, temporal trends were not detected, likely due to the heterogeneous nature of the water quality in this area and geologic sources of nitrate, combined with sparse and uneven data coverage. Generally low nitrate concentrations in the basin subregion are consistent with reduced geochemical conditions resulting from low permeability soils and higher organic content, reflecting the distal portions of alluvial fans and historical groundwater discharge areas. Very small increases in the shallow aquifer in the basin subregion may reflect downgradient movement of high nitrate groundwater from adjacent areas or overlying intensive agricultural inputs. Because of the general lack of regionally extensive long-term monitoring networks, the results from this study highlight the importance of placing studies of trends in water quality into regional context. Earlier work concluded that nitrate concentrations were steadily increasing over time in the eastern San Joaquin Valley, but clearly those trends do not apply to other physiographic subregions within the Central Valley, even where land use and climate are similar.

Burow, Karen R.; Jurgens, Bryant C.; Belitz, Kenneth; Dubrovsky, Neil M.

2013-01-01

252

Epigenetic and deep-burial dolomitization of Middle Ordovician Antelope Valley Limestone (Pogonip Group), Central Nevada  

Microsoft Academic Search

Pervasive dolomitization of strata in the Antelope Valley Limestone (AVL) is chiefly related to faulting and burial depth. At Clear Creek Canyon and Keystone Canyon, north-south and northeast-southwest-trending parallel extension faults juxtapose entirely dolomitized sections of the AVL and shaly units of Cambrian, Ordovician and Silurian age. Magmatic intrusives and related quartz veins that cut this formation are post-dolomitic and

A. Kaya; G. M. Friedman

1988-01-01

253

Linear-Patterned Slopes in the Discontinuous Permafrost Zone of the Central Mackenzie River Valley  

Microsoft Academic Search

In the Mackenzie River Valley between Norman Wells and Fort Simpson a study of the character, dlstribution and orientation of gently-inclined, linear-patterned slopes revealed that most northeast-facing, lichen-covered slopes have permafrost within about 10-25 inches of the surface, and display evidence that cryoturbation was once operative in the active layer. Most lineated slopes without near-surface permafrost face southwest, are surficially

C. B. CRAMPTON

254

Wild food plants and wild edible fungi in two valleys of the Qinling Mountains (Shaanxi, central China)  

PubMed Central

Background The aim of the study was to investigate knowledge and use of wild food plants in two mountain valleys separated by Mount Taibai – the highest peak of northern China and one of its biodiversity hotspots, each adjacent to species-rich temperate forest vegetation. Methods Seventy two free lists were collected among the inhabitants of two mountain valleys (36 in each). All the studied households are within walking distance of primary forest vegetation, however the valleys differed in access to urban centers: Houzhenzi is very isolated, and the Dali valley has easier access to the cities of central Shaanxi. Results Altogether, 185 wild food plant species and 17 fungi folk taxa were mentioned. The mean number of freelisted wild foods was very high in Houzhenzi (mean 25) and slightly lower in Dali (mean 18). An average respondent listed many species of wild vegetables, a few wild fruits and very few fungi. Age and male gender had a positive but very low effect on the number of taxa listed. Twelve taxa of wild vegetables (Allium spp., Amaranthus spp., Caryopteris divaricata, Helwingia japonica, Matteucia struthiopteris, Pteridium aquilinum, Toona sinensis, Cardamine macrophylla, Celastrus orbiculatus, Chenopodium album, Pimpinella sp., Staphylea bumalda &S. holocarpa), two species of edible fruits (Akebia trifoliata, Schisandra sphenanthera) and none of the mushrooms were freelisted by at least half of the respondents in one or two of the valleys. Conclusion The high number of wild vegetables listed is due to the high cultural position of this type of food in China compared to other parts of the world, as well as the high biodiversity of the village surroundings. A very high proportion of woodland species (42%, double the number of the ruderal species used) among the listed taxa is contrary to the general stereotype that wild vegetables in Asia are mainly ruderal species. The very low interest in wild mushroom collecting is noteworthy and is difficult to explain. It may arise from the easy access to the cultivated Auricularia and Lentinula mushrooms and very steep terrain, making foraging for fungi difficult. PMID:23587149

2013-01-01

255

Central California Valley Ecoregion: Chapter 17 in Status and trends of land change in the Western United States--1973 to 2000  

USGS Publications Warehouse

The Central California Valley Ecoregion, which covers approximately 45,983 km2 (17,754 mi2), is an elongated basin extending approximately 650 km north to south through central California (fig. 1) (Omernik, 1987; U.S. Environmental Protection Agency, 1997). The ecoregion is surrounded entirely by the Southern and Central California Chaparral and Oak Woodlands Ecoregion, which includes parts of the Coast Ranges to the west and which is bounded by the Sierra Nevada to the east. The Central California Valley Ecoregion accounts for more than half of California’s agricultural production value and is one of the most important agricultural regions in the country, with flat terrain, fertile soils, a favorable climate, and nearly 70 percent of its land in cultivation (Kuminoff and others, 2000; Sumner and others, 2003). Commodities produced in the region include milk and dairy, cattle and calves, cotton, almonds, citrus, and grapes, among others (U.S. Department of Agriculture, 2004; Johnston and McCalla, 2004; Kuminoff and others, 2000) (figs. 2A,B,C). Six of the top eight agricultural-producing counties in California are located at least partly within the Central California Valley Ecoregion (Kuminoff and others, 2000) (table 1). The Central California Valley Ecoregion is also home to nearly 5 million people spread throughout the region, including the major cities of Sacramento (state capital), Fresno, Bakersfield, and Stockton, California (U.S. Census Bureau, 2000) (fig. 1).

Sleeter, Benjamin M.

2012-01-01

256

Climate change impact on future water resources availability for a semi-arid area (Ferghana Valley, Central Asia)  

NASA Astrophysics Data System (ADS)

Considering increasing temperatures and glacier recession during the last decades, it is of high interest to study the climate change impact on water resources availability in semi-arid regions of Central Asia. The Ferghana Valley is surrounded by the Tien-Shan and Pamiro-Alay mountain systems that store big amounts of water in snowpacks and glaciers. In the valley the agricultural activity of local people strongly depends on available water from the Syrdarya River. The river is formed by the confluence of the Naryn and Karadarya Rivers, which are mainly fed by the glacier and snow melt from the Akshiirak and Ferghana ridges of the aforementioned mountain systems. The small upper river basins of the valley also contribute with runoff (~34 %) to the Syrdarya River. These small rivers are mainly fed by precipitation and seasonal snow melt. Thus, because of climate change and glacier decline, it is necessary to investigate the comparative contribution of the small catchments versus two big river basins to the Syrdarya River system, as these small upper catchments could become more important for future water consumption. In this study the conceptual hydrological HBV-light model has been calibrated and validated for the period 1980-1985 over 18 upper catchments that feed the Syrdarya River from the surrounding mountain ridges. Dynamically downscaled climate change scenarios were then applied up to the year 2100 for these basins. The scenarios were generated by means of Global Circulation Model (ECHAM5) and Regional Climate Model (REMO) with a baseline period from 1971 till 2000. We will present modelling results of water resources, the contribution of small rivers to the Syrdarya River and to what extent this contribution is likely to change in the future. Moreover, the results of simulated potential runoff will be used to develop future climate change adaptation strategies regarding socio-economic and environmental sustainable water use.

Radchenko, Iuliia; Breuer, Lutz; Mannig, Birgit; Frede, Hans-Georg

2014-05-01

257

Heat flow in Railroad Valley, Nevada and implications for geothermal resources in the south-central Great Basin  

USGS Publications Warehouse

The Great Basin is a province of high average heat flow (approximately 90 mW m-2), with higher values characteristic of some areas and relatively low heat flow (<60 mW m-2) characteristic of an area in south-central Nevada known as the Eureka Low. There is hydrologie and thermal evidence that the Eureka Low results from a relatively shallow, hydrologically controlled heat sink associated with interbasin water flow in the Paleozoic carbonate aquifers. Evaluating this hypothesis and investigating the thermal state of the Eureka Low at depth is a high priority for the US Geological Survey as it prepares a new national geothermal resource assessment. Part of this investigation is focused on Railroad Valley, the site of the largest petroleum reservoirs in Nevada and one of the few locations within the Eureka Low with a known geothermal system. Temperature and thermal conductivity data have been acquired from wells in Railroad Valley in order to determine heat flow in the basin. The results reveal a complex interaction of cooling due to shallow ground-water flow, relatively low (49 to 76 mW m-2) conductive heat flow at depth in most of the basin, and high (up to 234 mW m-2) heat flow associated with the 125??C geothermal system that encompasses the Bacon Flat and Grant Canyon oil fields. The presence of the Railroad Valley geothermal resource within the Eureka Low may be reflect the absence of deep ground-water flow sweeping heat out of the basin. If true, this suggests that other areas in the carbonate aquifer province may contain deep geothermal resources that are masked by ground-water flow.

Williams, C.F.; Sass, J.H.

2006-01-01

258

Comparison of sediment supply to San Francisco Bay from watersheds draining the Bay Area and the Central Valley of California  

USGS Publications Warehouse

Quantifying suspended sediment loads is important for managing the world's estuaries in the context of navigation, pollutant transport, wetland restoration, and coastal erosion. To address these needs, a comprehensive analysis was completed on sediment supply to San Francisco Bay from fluvial sources. Suspended sediment, optical backscatter, velocity data near the head of the estuary, and discharge data obtained from the output of a water balance model were used to generate continuous suspended sediment concentration records and compute loads to the Bay from the large Central Valley watershed. Sediment loads from small tributary watersheds around the Bay were determined using 235 station-years of suspended sediment data from 38 watershed locations, regression analysis, and simple modeling. Over 16 years, net annual suspended sediment load to the head of the estuary from its 154,000 km2 Central Valley watershed varied from 0.13 to 2.58 (mean = 0.89) million metric t of suspended sediment, or an average yield of 11 metric t/km2/yr. Small tributaries, totaling 8145 km2, in the nine-county Bay Area discharged between 0.081 and 4.27 (mean = 1.39) million metric t with a mean yield of 212 metric t/km2/yr. The results indicate that the hundreds of urbanized and tectonically active tributaries adjacent to the Bay, which together account for just 5% of the total watershed area draining to the Bay and provide just 7% of the annual average fluvial flow, supply 61% of the suspended sediment. The small tributary loads are more variable (53-fold between years compared to 21-fold for the inland Central Valley rivers) and dominated fluvial sediment supply to the Bay during 10 out of 16 yr. If San Francisco Bay is typical of other estuaries in active tectonic or climatically variable coastal regimes, managers responsible for water quality, dredging and reusing sediment accumulating in shipping channels, or restoring wetlands in the world's estuaries may need to more carefully account for proximal small urbanized watersheds that may dominate sediment supply.

McKee, L.J.; Lewicki, M.; Schoellhamer, D.H.; Ganju, N.K.

2013-01-01

259

Pliocene and Pleistocene geologic and climatic evolution in the San Luis Valley of south-central Colorado  

USGS Publications Warehouse

Sediments of the Alamosa Formation spanning the upper part of the Gauss and most of the Matuyama Chrons were recovered by coring in the high (2300 m) San Luis Valley of south-central Colorado. The study site is located at the northern end of the Rio Grande rift. Lithologic changes in the core sediments provide evidence of events leading to integration of the San Luis drainage basin into the Rio Grande. The section, which includes the Huckleberry Ridge Ash (2.02 Ma) and spans the entire Matuyama Chron, contains pollen, and invertebrate and vertebrate fossils. Stable isotope analyses of inorganic and biogenic carbonate taken over most of the core indicate substantially warmer temperatures than occur today in the San Luis Valley. At the end of the Olduvai Subchron, summer precipitation decreased, summer pan evaporation increased, and temperatures increased slightly compared to the earlier climate represented in the core. By the end of the Jaramillo Subchron, however, cold/wet and warm/dry cycles become evident and continue into the cold/wet regime associated with the deep-sea oxygen-isotope Stage 22 glaciation previously determined from outcrops at the same locality. Correspondence between the Hansen Bluff climatic record and the deep-sea oxygen-isotope record (oxygen-isotope stages from about 110-18) is apparent, indicating that climate at Hansen Bluff was responding to global climatic changes. ?? 1992.

Rogers, K. L.; Larson, E. E.; Smith, G.; Katzman, D.; Smith, G. R.; Cerling, T.; Wang, Y.; Baker, R. G.; Lohmann, K. C.; Repenning, C. A.; Patterson, P.; Mackie, G.

1992-01-01

260

Vivid valleys, pallid peaks? Hypsometric variations and rural-urban land change in the Central Peruvian Andes  

PubMed Central

What happens to the land cover within the hinterland's altitudinal belts while Central Andean cities are undergoing globalization and urban restructuring? What conclusions can be drawn about changes in human land use? By incorporating a regional altitudinal zonation model, direct field observations and GIS analyses of remotely sensed long term data, the present study examines these questions using the example of Huancayo Metropolitano – an emerging Peruvian mountain city of 420,000 inhabitants, situated at 3260 m asl in the Mantaro Valley. The study's results indicate that rapid urban growth during the late 1980s and early 1990s was followed by the agricultural intensification and peri-urban condominization at the valley floor (quechua) – since the beginning of Peru's neoliberal era. Moreover, regarding the adjoining steep slopes (suni) and subsequent grassland ecosystems (puna), the research output presents land cover change trajectories that clearly show an expansion of human land use, such as reforestation for wood production and range burning for livestock grazing, even at high altitudes – despite rural–urban migration trends and contrary to several results of extra-Andean studies. Consequently, rural–urban planners and policy makers are challenged to focus on the manifold impacts of globalization on human land use – at all altitudinal belts of the Andean city's hinterland: toward sustainable mountain development that bridges the social and physical gaps – from the bottom up. PMID:23564987

Haller, Andreas

2012-01-01

261

Cardiospecificity of the 3 rd generation cardiac troponin T assay during and after a 216 km ultra-endurance marathon run in Death Valley  

Microsoft Academic Search

Background\\u000a   The reasons\\u000a for the appearance of cardiacspecific\\u000a troponin (cTnT) after\\u000a strenuous exercise are unclear. The\\u000a aim of the present study was to\\u000a evaluate the cardiospecificity of the\\u000a 3rd generation cardiac cTnT assay\\u000a during and after an ultra-endurance\\u000a race of 216 km at extreme\\u000a environmental conditions in Death\\u000a Valley.\\u000a \\u000a \\u000a \\u000a \\u000a Study design and methods\\u000a   We measured serially cTnT, creatine\\u000a kinase (CK),

H. J. Roth; R. M. Leithäuser; H. Doppelmayr; M. Doppelmayr; H. Finkernagel; S. P. von Duvillard; S. Korff; H. A. Katus; Evangelos Giannitsis; R. Beneke

2007-01-01

262

Nd isotopic composition of cratonic rocks in the southern Death Valley region: Evidence for a substantial Archean source component in Mojavia  

USGS Publications Warehouse

Thirty Early Proterozoic intermediate to silicic metasedimentary and metaigneous rocks in the southern Death Valley region and vicinity show ??(Nd) values of -1.6 to -6.3 at 1.7 Ga and Nd model ages of 2.1 to 2.6 Ga. These cratonic rocks thus reveal an older signature than so far reported for Nd province 1 of the western United States; as much as 30%-40% of their mass may be Archean crustal material. The Archean component was introduced in the form of sedimentary detritus that was probably subducted and mixed with juvenile material at a convergent margin. Three younger Precambrian rocks associated with the cratonic rocks also have a Nd isotopic composition of province 1 type.

Calzia, J. P.

1998-01-01

263

Kinematics at the intersection of the Garlock and Death Valley fault zones, California: Integration of TM data and field studies. LANDSAT TM investigation proposal TM-019  

NASA Technical Reports Server (NTRS)

Processing and interpretation of Thematic Mapper (TM) data, extensive field work, and processing of SPOT data were continued. Results of these analyses led to the testing and rejecting of several of the geologic/tectonic hypotheses concerning the continuation of the Garlock Fault Zone (GFZ). It was determined that the Death Valley Fault Zone (DVFZ) is the major through-going feature, extending at least 60 km SW of the Avawatz Mountains. Two 5 km wide fault zones were identified and characterized in the Soda and Bristol Mountains, forming a continuous zone of NW trending faulting. Geophysical measurements indicate a buried connection between the Avawatz and the Soda Mountains Fault Zone. Future work will involve continued field work and mapping at key locations, further analyses of TM data, and conclusion of the project.

Abrams, Michael; Verosub, Ken

1987-01-01

264

Rise and tilt of metamorphic rocks in the lower plate of a detachment fault in the Funeral Mountains, Death Valley, California  

SciTech Connect

The authors attempt to integrate new and old observations on the Funeral Mountains, in Death Valley, California, into an integrated model of the evolution of the lower plate in this region. This area consists of a detachment fault. Much effort has been directed toward explaining the development of detachment faults. Extensive petrologic, geochronologic and mapping evidence had been developed. The authors combine thermobarometric data on unsheared metamorphic rock in this region, kinematic analysis of folding in the area, and new geochronologic data from fission track measurements, K-Ar and [sup 40]Ar/[sup 39]Ar dating measurements. Their conclusion is that the data supports the feature of models for detachment faulting which claim that a fault surface dips and undergoes a rotation to a horizontal orientation, accompanied by a comparable tilt of the lower plate. 64 refs., 19 figs., 4 tabs.

Hoisch, T.D. (Northern Arizona Univ., Flagstaff (United States)); Simpson, C. (Johns Hopkins Univ., Baltimore, MD (United States))

1993-04-10

265

Scenario earthquake hazards for the Long Valley Caldera-Mono Lake area, east-central California  

USGS Publications Warehouse

As part of the U.S. Geological Survey’s (USGS) multi-hazards project in the Long Valley Caldera-Mono Lake area, the California Geological Survey (CGS) developed several earthquake scenarios and evaluated potential seismic hazards, including ground shaking, surface fault rupture, liquefaction, and landslide hazards associated with these earthquake scenarios. The results of these analyses can be useful in estimating the extent of potential damage and economic losses because of potential earthquakes and in preparing emergency response plans. The Long Valley Caldera-Mono Lake area has numerous active faults. Five of these faults or fault zones are considered capable of producing magnitude ?6.7 earthquakes according to the Uniform California Earthquake Rupture Forecast, Version 2 (UCERF 2) developed by the 2007 Working Group of California Earthquake Probabilities (WGCEP) and the USGS National Seismic Hazard Mapping (NSHM) Program. These five faults are the Fish Slough, Hartley Springs, Hilton Creek, Mono Lake, and Round Valley Faults. CGS developed earthquake scenarios for these five faults in the study area and for the White Mountains Fault to the east of the study area. Earthquake scenarios are intended to depict the potential consequences of significant earthquakes. They are not necessarily the largest or most damaging earthquakes possible. Earthquake scenarios are both large enough and likely enough that emergency planners should consider them in regional emergency response plans. Earthquake scenarios presented here are based on fault geometry and activity data developed by the WGCEP, and are consistent with the 2008 Update of the United States National Seismic Hazard Maps (NSHM).For the Hilton Creek Fault, two alternative scenarios were developed in addition to the NSHM scenario to account for different opinions in how far north the fault extends into the Long Valley Caldera. For each scenario, ground motions were calculated using the current standard practice: USGS deterministic seismic hazard analysis program and three Next Generation Ground Motion Attenuation (NGA) models. Ground motion calculations incorporated the potential amplification of seismic shaking by near-surface soils defined by a map of the average shear wave velocity in the uppermost 30 m (VS30) developed by CGS. In addition to ground shaking, earthquakes cause ground failure, which can cause severe damage to buildings and lifelines. Ground failure includes surface fault rupture, liquefaction, and seismically induced landslides. For each earthquake scenario, potential surface fault displacements are estimated using deterministic and probabilistic approaches. Liquefaction occurs when saturated sediments lose their strength because of ground shaking. Zones of potential liquefaction are mapped by incorporating areas where loose sandy sediments, shallow groundwater, and strong earthquake shaking coincide in the earthquake scenario. The process for defining zones of potential landslide and rockfall incorporates rock strength, surface slope, existing landslides, with ground motions caused by the earthquake scenario. Each scenario is illustrated with maps of seismic shaking potential and fault displacement, liquefaction, and landslide potential. Seismic shaking is depicted by the distribution of shaking intensity, peak ground acceleration, and 1.0-second spectral acceleration. One-second spectral acceleration correlates well with structural damage to surface facilities. Acceleration greater than 0.2 g is often associated with strong to violent perceived ground shaking and may cause moderate to heavy damage. The extent of strong shaking is influenced by subsurface fault dip and near surface materials. Strong shaking is more widespread in the hanging wall regions of a normal fault. Larger ground motions also occur where young alluvial sediments amplify the shaking. Both of these effects can lead to strong shaking that extends farther from the fault on the valley side than on the hill side. The effect of fault rupture displacements may be localized along the s

Chen, Rui; Branum, David M.; Wills, Chris J.; Hill, David P.

2014-01-01

266

Adapting to Climate Variability and Change: Experiences from Cereal-Based Farming in the Central Rift and Kobo Valleys, Ethiopia  

NASA Astrophysics Data System (ADS)

Small-holder farmers in Ethiopia are facing several climate related hazards, in particular highly variable rainfall with severe droughts which can have devastating effects on their livelihoods. Projected changes in climate are expected to aggravate the existing challenges. This study examines farmer perceptions on current climate variability and long-term changes, current adaptive strategies, and potential barriers for successful further adaptation in two case study regions—the Central Rift Valley (CRV) and Kobo Valley. The study was based on a household questionnaire, interviews with key stakeholders, and focus group discussions. The result revealed that about 99 % of the respondents at the CRV and 96 % at the Kobo Valley perceived an increase in temperature and 94 % at CRV and 91 % at the Kobo Valley perceived a decrease in rainfall over the last 20-30 years. Inter-annual and intraseasonal rainfall variability also has increased according to the farmers. The observed climate data (1977-2009) also showed an increasing trend in temperature and high inter-annual and intra-seasonal rainfall variability. In contrast to farmers’ perceptions of a decrease in rainfall totals, observed rainfall data showed no statistically significant decline. The interaction among various bio-physical and socio-economic factors, changes in rainfall intensity and reduced water available to crops due to increased hot spells, may have influenced the perception of farmers with respect to rainfall trends. In recent decades, farmers in both the CRV and Kobo have changed farming practices to adapt to perceived climate change and variability, for example, through crop and variety choice, adjustment of cropping calendar, and in situ moisture conservation. These relatively low-cost changes in farm practices were within the limited adaptation capacity of farmers, which may be insufficient to deal with the impacts of future climate change. Anticipated climate change is expected to impose new risks outside the range of current experiences. To enable farmers to adapt to these impacts critical technological, institutional, and market-access constraints need to be removed. Inconsistencies between farmers’ perceptions and observed climate trends (e.g., decrease in annual rainfall) could lead to sub-optimal or counterproductive adaptations, and therefore must be removed by better communication and capacity building, for example through Climate Field Schools. Enabling strategies, which are among others targeted at agricultural inputs, credit supply, market access, and strengthening of local knowledge and information services need to become integral part of government policies to assist farmers to adapt to the impacts of current and future climate change.

Kassie, Belay Tseganeh; Hengsdijk, Huib; Rötter, Reimund; Kahiluoto, Helena; Asseng, Senthold; Van Ittersum, Martin

2013-11-01

267

Central Avra Valley Storage and Recovery Project (CAVSARP) Site, Tucson, Arizona: Floodwater and Soil Moisture Investigations with Extraterrestrial Applications  

NASA Technical Reports Server (NTRS)

Planetary geologists, geomorphologists, and hydrologists have hypothesized that Mars is a dynamic, water-enriched planet since the Mariner and Viking missions based on geologic, geomorphic, and topographic information. Recent acquisition of Gamma Ray and Neutron Spectrometer information has added further credence to this hypothesis. A unique investigation is underway to work towards being able to successfully map the extent and depth of water on Mars. Researchers from the University of Arizona and members of the Autonomous Sciencecraft Experiment (ASE) have been compiling multiple layers of information in time and space at the Central Avra Valley Storage and Recovery Project (CAVSARP) site, Tucson, Arizona, for eventual comparative analysis. This information has been acquired from a variety of observational/scientific platforms in controlled conditions. CAVSARP facility:

Rucker, D. F.; Dohm, J. M.; Ferre, T. P. A.; Ip, Felipe; Baker, V. R.; Davies, A. G.; Castano, R.; Chien, S.; Doggett, T. C.

2004-01-01

268

Crustal shear-wave anisotropy in the New Madrid and Wabash Valley seismic regions of the Central US  

NASA Astrophysics Data System (ADS)

Local and regional earthquakes recorded by the US Array , the New Madrid and GSN - IRIS/USGS network of stations are analyzed to study crustal shear-wave anisotropy of the New Madrid and Wabash Valley seismic zones of the Central United States. The N-S and E-W components of the ground motion are cross-correlated to obtain the polarization angle of the fast shear-wave, and delay time of the slow shear-wave. Data with high signal to noise ratio, and incidence angle at a station less than 35 degrees are selected for further analysis. Preliminary results from data recorded by select stations show that the fast shear-wave is polarized in the direction of regional maximum horizontal compressional stress. Time delays over 100 ms are observed between the fast and the slow shear-waves.

Jemberie, A. L.

2012-12-01

269

Using remote sensing and GIS techniques to estimate discharge and recharge fluxes for the Death Valley regional groundwater flow system, USA  

USGS Publications Warehouse

The recharge and discharge components of the Death Valley regional groundwater flow system were defined by techniques that integrated disparate data types to develop a spatially complex representation of near-surface hydrological processes. Image classification methods were applied to multispectral satellite data to produce a vegetation map. The vegetation map was combined with ancillary data in a GIS to delineate different types of wetlands, phreatophytes and wet playa areas. Existing evapotranspiration-rate estimates were used to calculate discharge volumes for these area. An empirical method of groundwater recharge estimation was modified to incorporate data describing soil-moisture conditions, and a recharge potential map was produced. These discharge and recharge maps were readily converted to data arrays for numerical modelling codes. Inverse parameter estimation techniques also used these data to evaluate the reliability and sensitivity of estimated values.The recharge and discharge components of the Death Valley regional groundwater flow system were defined by remote sensing and GIS techniques that integrated disparate data types to develop a spatially complex representation of near-surface hydrological processes. Image classification methods were applied to multispectral satellite data to produce a vegetation map. This map provided a basis for subsequent evapotranspiration and infiltration estimations. The vegetation map was combined with ancillary data in a GIS to delineate different types of wetlands, phreatophytes and wet playa areas. Existing evapotranspiration-rate estimates were then used to calculate discharge volumes for these areas. A previously used empirical method of groundwater recharge estimation was modified by GIS methods to incorporate data describing soil-moisture conditions, and a recharge potential map was produced. These discharge and recharge maps were readily converted to data arrays for numerical modelling codes. Inverse parameter estimation techniques also used these data to evaluate the reliability and sensitivity of estimated values.

D'Agnese, F. A.; Faunt, C.C.; Turner, A.K.

1996-01-01

270

Luminescence ages for alluvial-fan deposits in Southern Death Valley: Implications for climate-driven sedimentation along a tectonically active mountain front  

USGS Publications Warehouse

Controversy exists over whether alluvial-fan sedimentation along tectonically active mountain fronts is driven by climatic changes or tectonics. Knowing the age of sedimentation is the key to understanding the relationship between sedimentation and its cause. Alluvial-fan deposits in Death Valley and throughout the arid southwestern United States have long been the subjects of study, but their ages have generally eluded researchers until recently. Most mapping efforts have recognized at least four major relative-age groupings (Q1 (oldest), Q2, Q3, and Q4 (youngest)), using observed changes in surface soils and morphology, relation to the drainage net, and development of desert pavement. Obtaining numerical age determinations for these morphologic stages has proven challenging. We report the first optically stimulated luminescence (OSL) ages for three of these four stages deposited within alluvial-fans along the tectonically active Black Mountains of Death Valley. Deposits showing distinct, remnant bar and swale topography (Q3b) have OSL ages from 7 to 4 ka., whereas those with moderate to poorly developed desert pavement and located farther above the active channel (Q3a) have OSL ages from 17 to 11 ka. Geomorphically older deposits with well-developed desert pavement (Q2d) have OSL ages ???25 ka. Using this OSL-based chronology, we note that alluvial-fan deposition along this tectonically active mountain front corresponds to both wet-to-dry and dry-to-wet climate changes recorded globally and regionally. These findings underscore the influence of climate change on alluvial fan deposition in arid and semi-arid regions. ?? 2007 Elsevier Ltd and INQUA.

Sohn, M. F.; Mahan, S. A.; Knott, J. R.; Bowman, D. D.

2007-01-01

271

Facies analysis of Late Proterozoic through Lower Cambrian rocks of the Death Valley regional ground-water system and surrounding areas, Nevada and California  

SciTech Connect

Late Proterozoic through Lower Cambrian rocks in the southern Great Basin form a westward-thickening wedge of predominantly clastic deposits that record deposition on the early western shelf edge of western North America (Stewart and Poole, 1974; Poole and others, 1992). Regional analyses of geologic controls on ground-water flow in the southern Great Basin typically combined lithostratigraphic units into more general hydrogeologic units that have considerable lateral extent and distinct hydrologic properties. The Late Proterozoic through Lower Cambrian rocks have been treated as a single hydrogeologic unit, named the lower clastic aquitard (Winograd and Thordarson, 1975) or the quartzite confining unit (Laczniak and others, 1996), that serves as the hydrologic basement to the flow system. Although accurate in a general sense, this classification ignores well-established facies relations within these rocks that might increase bedrock permeability and locally influence ground-water flow . This report presents a facies analysis of Late Proterozoic through Lower Cambrian rocks (hereafter called the study interval) in the Death Valley regional ground-water flow system - that portion of the southern Great Basin that includes Death Valley, the Nevada Test Site, and the potential high-level nuclear waste underground repository at Yucca Mountain (fig. 1). The region discussed in this report, hereafter called the study area, covers approximately 100,000 km2 (lat 35 degrees-38 degrees 15'N., long 115 degrees-118 degrees W.). The purpose of this analysis is to provide a general documentation of facies transitions within the Late Proterozoic through Lower Cambrian rocks in order to provide an estimate of material properties (via rock type, grain size, and bedding characteristics) for specific hydrogeologic units to be included in a regional ground-water flow model.

Sweetkind, D.S.; White, D.K.

2002-03-15

272

Dissolved Pesticide and Organic Carbon Concentrations Detected in Surface Waters, Northern Central Valley, California, 2001-2002  

USGS Publications Warehouse

Field and laboratory studies were conducted to determine the effects of pesticide mixtures on Chinook salmon under various environmental conditions in surface waters of the northern Central Valley of California. This project was a collaborative effort between the U.S. Geological Survey (USGS) and the University of California. The project focused on understanding the environmental factors that influence the toxicity of pesticides to juvenile salmon and their prey. During the periods January through March 2001 and January through May 2002, water samples were collected at eight surface water sites in the northern Central Valley of California and analyzed by the USGS for dissolved pesticide and dissolved organic carbon concentrations. Water samples were also collected by the USGS at the same sites for aquatic toxicity testing by the Aquatic Toxicity Laboratory at the University of California Davis; however, presentation of the results of these toxicity tests is beyond the scope of this report. Samples were collected to characterize dissolved pesticide and dissolved organic carbon concentrations, and aquatic toxicity, associated with winter storm runoff concurrent with winter run Chinook salmon out-migration. Sites were selected that represented the primary habitat of juvenile Chinook salmon and included major tributaries within the Sacramento and San Joaquin River Basins and the Sacramento?San Joaquin Delta. Water samples were collected daily for a period of seven days during two winter storm events in each year. Additional samples were collected weekly during January through April or May in both years. Concentrations of 31 currently used pesticides were measured in filtered water samples using solid-phase extraction and gas chromatography-mass spectrometry at the U.S. Geological Survey's organic chemistry laboratory in Sacramento, California. Dissolved organic carbon concentrations were analyzed in filtered water samples using a Shimadzu TOC-5000A total organic carbon analyzer.

Orlando, James L.; Jacobson, Lisa A.; Kuivila, Kathryn M.

2004-01-01

273

Evidence for Late-Paleozoic brine migration in Cambrian carbonate rocks of the central and southern Appalachians: Implications for Mississippi Valley-type sulfide mineralization  

Microsoft Academic Search

Many Lower Paleozoic limestones and dolostones in the Valley and Ridge province of the central and southern Appalachians contain 10 to 25 weight percent authigenic potassium feldspar. This was considered to be a product of early diagenesis, however, 40 Ar \\/ 39 Ar analyses of overgrowths on detrital K-feldspar in Cambrian carbonate rocks from Pennsylvania, Maryland, Virginia, and Tennessee yield

Paul P. Hearn Jr.; John F. Sutter; Harvey E. Belkin

1987-01-01

274

Socioeconomic effects of power marketing alternatives for the Central Valley and Washoe Projects: 2005 regional econmic impact analysis using IMPLAN  

SciTech Connect

The Western Area Power Administration (Western) was founded by the Department of Energy Organization Act of 1977 to market and transmit federal hydroelectric power in 15 western states outside the Pacific Northwest, which is served by the Bonneville Power Administration. Western is divided into four independent Customer Service Regions including the Sierra Nevada Region (Sierra Nevada), the focus of this report. The Central Valley Project (CVP) and the Washoe Project provide the primary power resources marketed by Sierra Nevada. Sierra Nevada also purchases and markets power generated by the Bonneville Power Administration, Pacific Gas and Electric (PG&E), and various power pools. Sierra Nevada currently markets approximately 1,480 megawatts of power to 77 customers in northern and central California. These customers include investor-owned utilities, public utilities, government agencies, military bases, and irrigation districts. Methods and conclusions from an economic analysis are summarized concerning distributional effects of alternative actions that Sierra Nevada could take with it`s new marketing plan.

Anderson, D.M.; Godoy-Kain, P.; Gu, A.Y.; Ulibarri, C.A.

1996-11-01

275

Epigenetic and deep-burial dolomitization of Middle Ordovician Antelope Valley Limestone (Pogonip Group), Central Nevada  

SciTech Connect

Pervasive dolomitization of strata in the Antelope Valley Limestone (AVL) is chiefly related to faulting and burial depth. At Clear Creek Canyon and Keystone Canyon, north-south and northeast-southwest-trending parallel extension faults juxtapose entirely dolomitized sections of the AVL and shaly units of Cambrian, Ordovician and Silurian age. Magmatic intrusives and related quartz veins that cut this formation are post-dolomitic and not responsible for dolomitization. At Martin Rigbe, dolomitization gradually decreases with increasing distance from the fault zones. At Lone Mountain, dolomitized strata are conformable with non-dolomitic units and their associations with faulting have not been observed. Petrographic study indicates that xenotopic mosaics of dolomite crystals with curved and penetrative boundaries and undulose extinction are the dominant kinds of crystals in pervasively dolomitized strata. These mosaics postdate stylolites, and replaced calcite-filled veins as well as idiotopic dolomite crystals in selectively dolomitized particles. These mosaics are postdated by saddle dolomite, and by quartz and calcite veins of probably hydrothermal origin. Most of the dolomites are uniformly dull or nonluminescent, indicating a possible high iron content typical of burial dolomite. Homogenization temperatures (T/sub h/) of two-phase fluid inclusions range from 105/sup 0/ to 285/sup 0/C. Thermal alteration indices (2.7 - 3.1) and vitrinite reflectance data (R = 0.93 - 1.13) are consistent with high T/sub h/.

Kaya, A.; Friedman, G.M.

1988-01-01

276

Geohydrology of the central Mesilla Valley, Dona Ana County, New Mexico  

USGS Publications Warehouse

Five large-capacity irrigation wells, with depths ranging from 370 to 686 feet, were drilled by the Elephant Butte Irrigation District between 1973 and 1975, in the Mesilla Valley about 7 miles south of Las Cruces, New Mexico. These were the first deep wells in the area, and their installation provided an opportunity to conduct extensive aquifer tests under relatively undisturbed conditions. The deep irrigation wells are perforated in the Santa Fe Group of Miocene to Pleistocene Age. The Santa Fe Group is composed of interfingering and alternating beds of clay, silt, sand, and small gravel. In the area of these wells, the upper part of the saturated zone contains slightly saline water to a depth of about 100 to 175 feet below the water table, underlain by a freshwater zone extending to depths greater than 1,200 feet. As water is pumped from the freshwater zone, leakage occurs from above and below the perforated interval. At one of the irrigation district wells, slightly saline water moved downward because of a lack of confining layers in the aquifer. At three other wells, the surface casing was not set deep enough and slightly saline water moved into the top of the perforations , downward in the casing, and into the freshwater part of the aquifer. (USGS)

Wilson, Clyde A.; White, Robert R.

1984-01-01

277

Genetic population structure of Chinook salmon (Oncorhynchus tshawytscha) in California's Central Valley.  

E-print Network

i Genetic population structure of Chinook salmon (Oncorhynchus tshawytscha) in California's Central assignment matrices by population sample #12;1 Abstract An understanding of genetic population structure ESUs. We use genetic data from 20 microsatellite loci, and compare population samples of adult Chinook

278

Deep-currents along a rift valley of Central Indian Ridge observed by AUV "r2D4"  

NASA Astrophysics Data System (ADS)

In December 2006, the Institute of Industrial Science made geological and chemical investigation along rift valleys off the Rodriguez Island in the Central Indian Ridge with an AUV "gr2D4"h and found hydrothermal activities in one of the valleys, named the Great Dodo Lava Plain (water depth of approximately 2700m). In this present study, based on the AUV"fs navigation data taken from the investigation, we figured out the distribution of deep-currents in the Great Dodo Lava Plain and analyzed those currents and their relations with the tidal current and water-mass property. For current velocity, we used water-tracking velocity data measured by the Doppler Velocity Log (DVL) at a layer under the AUV. When the AUV was close to the sea bed, the velocity was adjusted to the absolute current velocity with bottom-tracking velocity measured by the DVL. When the bottom-tracking velocity was not available, the velocity was adjusted with AUV"fs velocity measured by the Inertial Navigation System. The adjusted current velocity data in the Great Dodo Lava Plain were observed for 6.5-hours in the range of 18.32°S-18.45°S, 65.28°E-65.37°E, and most of them reached 20 cm s-1 or more. The direction of the currents is between northwest and northeast, which almost corresponds to the direction of the valley"fs extension (north-northwest). The observed current speed is much higher than the tidal current speed predicted from a barotropic tidal model (< 3 cm s-1), but its meridional velocity component is stronger than the zonal component as well as the observed velocity. The predicted tidal current velocity shows semi-diurnal period, and that is also the case in the observed meridional velocity component. Thus, it is expected that the deep-currents and tidal currents are influenced by the bottom topography extending north-northwestward. For error consideration, we compared near-surface current velocities measured by the AUV and by the shipboard acoustic Doppler velocity profiler of the parent vessel. Then, the directions roughly correspond although the current speed measured by the AUV is rather low. This might be because bottom-tracking data measured by the DVL were not available at near-surface. In our presentation, we will also show the analysis in terms of water-mass properties and the other results from the data measured in the Mariana Trough in May 2004 and in the Izu-Ogasawara Island Arc in August 2005.

Komaki, K.; Ura, T.; Nagahashi, K.; Tamaki, K.

2008-12-01

279

Fluid inclusion and Re-Os isotopic evidence for hot, Cenozoic mineralization in the central Pennsylvanian Valley and Ridge Province  

NASA Astrophysics Data System (ADS)

Hypotheses concerning processes and timing of hydrothermal sulfide mineralization in the central Pennsylvanian Appalachians utilize Mississippi Valley-type (MVT) models with Paleozoic ages. To examine this model, we studied sulfide-bearing veins in the Skytop sulfide occurrence that contain pyritecentral Pennsylvania, USA. In this study, we obtained Re-Os isotope compositions of hydrothermal pyrite and fluid inclusion data from hydrothermal quartz intergrown with these pyrites. Pyrite occurs in two separate structural domains as thin vein fillings and in a younger cross cutting fault breccia. Pyrite in both domains is intergrown with quartz and forms micron sized needles and whisker overgrowths on cubic and octahedral pyrite. The fault breccia pyrite contains more Re and Os, on average (6 ppb and 41 ppt) than the vein pyrite (2 ppb and 20 ppt). A seven point Re-Os isochron from the fault breccia pyrite yielded an age of 33.8 ± 4.8 Ma and an 187Os/188Os initial ratio of 0.18 ± 0.05. None of the vein pyrite samples lie on this isochron. Fluid inclusion homogenization temperatures from quartz sampled near the fault range from 140 to >375 °C. The high temperature fluid inclusions occur within 5 feet of the fault. The Re-Os isotope and fluid inclusion data do not fit current models for sulfide generation in central Pennsylvania that invoke MVT hydrothermal processes. These MVT models imply that mineralization in the area formed in the late Paleozoic at relatively low temperatures (120 ± 40 °C) with metals originating from surrounding sedimentary rocks. The data from the present study indicates that a younger, high temperature (>200 °C) mineralization event (represented by the fault breccia pyrite) overprinted the MVT type mineralization (represented by the vein pyrite). The timing of the younger mineralization event coincides with two Cenozoic events in the Appalachian Basin: the Chesapeake Bay impact and Eocene volcanism in the southern portion of the Nittany anticlinorium.

Mathur, R.; Mutti, L.; Barra, F.; Gold, D.; Smith, R. C.; Doden, A.; Detrie, T.; Ruiz, J.; McWilliams, A.

2008-07-01

280

Long-term impacts on macroinvertebrates downstream of reclaimed mountaintop mining valley fills in Central Appalachia.  

PubMed

Recent studies have documented adverse effects to biological communities downstream of mountaintop coal mining and valley fills (VF), but few data exist on the longevity of these impacts. We sampled 15 headwater streams with VFs reclaimed 11-33 years prior to 2011 and sampled seven local reference sites that had no VFs. We collected chemical, habitat, and benthic macroinvertebrate data in April 2011; additional chemical samples were collected in September 2011. To assess ecological condition, we compared VF and reference abiotic and biotic data using: (1) ordination to detect multivariate differences, (2) benthic indices (a multimetric index and an observed/expected predictive model) calibrated to state reference conditions to detect impairment, and (3) correlation and regression analysis to detect relationships between biotic and abiotic data. Although VF sites had good instream habitat, nearly 90 % of these streams exhibited biological impairment. VF sites with higher index scores were co-located near unaffected tributaries; we suggest that these tributaries were sources of sensitive taxa as drifting colonists. There were clear losses of expected taxa across most VF sites and two functional feeding groups (% scrapers and %shredders) were significantly altered. Percent VF and forested area were related to biological quality but varied more than individual ions and specific conductance. Within the subset of VF sites, other descriptors (e.g., VF age, site distance from VF, the presence of impoundments, % forest) had no detectable relationships with biological condition. Although these VFs were constructed pursuant to permits and regulatory programs that have as their stated goals that (1) mined land be reclaimed and restored to its original use or a use of higher value, and (2) mining does not cause or contribute to violations of water quality standards, we found sustained ecological damage in headwaters streams draining VFs long after reclamation was completed. PMID:24990807

Pond, Gregory J; Passmore, Margaret E; Pointon, Nancy D; Felbinger, John K; Walker, Craig A; Krock, Kelly J G; Fulton, Jennifer B; Nash, Whitney L

2014-10-01

281

Long-Term Impacts on Macroinvertebrates Downstream of Reclaimed Mountaintop Mining Valley Fills in Central Appalachia  

NASA Astrophysics Data System (ADS)

Recent studies have documented adverse effects to biological communities downstream of mountaintop coal mining and valley fills (VF), but few data exist on the longevity of these impacts. We sampled 15 headwater streams with VFs reclaimed 11-33 years prior to 2011 and sampled seven local reference sites that had no VFs. We collected chemical, habitat, and benthic macroinvertebrate data in April 2011; additional chemical samples were collected in September 2011. To assess ecological condition, we compared VF and reference abiotic and biotic data using: (1) ordination to detect multivariate differences, (2) benthic indices (a multimetric index and an observed/expected predictive model) calibrated to state reference conditions to detect impairment, and (3) correlation and regression analysis to detect relationships between biotic and abiotic data. Although VF sites had good instream habitat, nearly 90 % of these streams exhibited biological impairment. VF sites with higher index scores were co-located near unaffected tributaries; we suggest that these tributaries were sources of sensitive taxa as drifting colonists. There were clear losses of expected taxa across most VF sites and two functional feeding groups (% scrapers and %shredders) were significantly altered. Percent VF and forested area were related to biological quality but varied more than individual ions and specific conductance. Within the subset of VF sites, other descriptors (e.g., VF age, site distance from VF, the presence of impoundments, % forest) had no detectable relationships with biological condition. Although these VFs were constructed pursuant to permits and regulatory programs that have as their stated goals that (1) mined land be reclaimed and restored to its original use or a use of higher value, and (2) mining does not cause or contribute to violations of water quality standards, we found sustained ecological damage in headwaters streams draining VFs long after reclamation was completed.

Pond, Gregory J.; Passmore, Margaret E.; Pointon, Nancy D.; Felbinger, John K.; Walker, Craig A.; Krock, Kelly J. G.; Fulton, Jennifer B.; Nash, Whitney L.

2014-10-01

282

Analysis of consumer lending problems of the banks in the central Texas Brazos Valley area  

E-print Network

AHALXSIS QF CONSUMER LENDING PROBLEMS OF THE BANKS Ih THE CENTRAL TEXAS BRAEOS VALLEf AREA A Thesis rillisa Doasld Old, II Subaitted to the Graduate School of the Agricultural esd Mechanical College of Tease ia yertisl fulfillaent... ArauabDity of Neliablo Credit Infoxaation Section 7 Advertising and Consnnor Xdneation CHAPTSN 7 SUNWANX AND CONCLUSIONS APPSNDIZ A 70 79 Personal Interior Cnoetionnaire Personal Interview Qnestionnaire Resnlts Consuner Loan Perfornanee for Ares...

Old, William Donald

2012-06-07

283

SEASONAL VARIATION IN PESTICIDE LOADS AND TRENDS IN THE CENTRAL VALLEY, CALIFORNIA: CALCULATED USING TWO PARAMETRIC METHODS  

NASA Astrophysics Data System (ADS)

Mass loading and trends in concentration were calculated for four pesticides in two watersheds with different land uses in the Central Valley, California, by using two parametric models: (1) the Seasonal Wave model (SeaWave), in which a pulse signal is used to describe the annual cycle of pesticide occurrence in a stream; and, (2) the Sine Wave model (SineWave), in which first-order Fourier series sine and cosine terms are used to simulate seasonal loading patterns. The models were applied to data for water years 1997 through 2005 provided by the National Water Quality Assessment Program (NAWQA). The pesticides considered in this study were carbaryl, diazinon, metolachlor, and molinate. Data were analyzed for two seasons: precipitation season (October through March), and the irrigation season (April through September). Results from the two models show that the ability to capture seasonal variations in pesticide concentrations was affected by pesticide use patterns and the methods by which pesticides are transported to streams. When compared with results from previous studies, both models well estimated seasonal loads and trends in concentrations. It is important to point out that loads estimated by the two models did not differ substantially from each other, with the exceptions of carbaryl and molinate during the precipitation season, where loads were affected by application patterns and precipitation. At the same time, trends in pesticide concentrations over time, as estimated by both models, were nearly identical indicating that either model can be used equally for calculating trends in concentrations. However, in watersheds where pesticides are applied in specific patterns— involving multiple applications of various amounts—the SeaWave model might be a better model to use due to its robust capability to describe seasonal variations in pesticide concentrations. As a case study, trends in pesticide concentrations for streams in the Central Valley were estimated using SeaWave. Timing of peak concentrations for individual compounds varied greatly across this geographic gradient because of different application periods and the effects of local rainfall patterns, irrigation, and soil drainage. Pesticides that have been the target of numerous regulatory actions, such as diazinon and chlorpyrifos, tended to have negative trends at most of the sampling locations as agriculturists shifted to the use of alternative pesticides and urban users faced mandatory sales restrictions. In general, herbicides, which have not been the target of regulatory restrictions, generally showed no significant changes in concentrations. However, in a few cases the model indicated increasing trends resulting from land-use changes or decreasing trends due to shifts in herbicide product use (like diazinon) in the watersheds.

Saleh, D.; Domagalski, J. L.; Johnson, H. M.; Lorenz, D. J.

2009-12-01

284

Mammal Inventory of the Mojave Network Parks-Death Valley and Joshua Tree National Parks, Lake Mead National Recreation Area, Manzanar National Historic Site, and Mojave National Preserve  

USGS Publications Warehouse

This report describes the results of a mammal inventory study of National Park Service units in the Mojave Desert Network, including Death Valley National Park, Joshua Tree National Park, Lake Mead National Recreation Area, Manzanar National Historic Site, and Mojave National Preserve. Fieldwork for the inventory focused on small mammals, primarily rodents and bats. Fieldwork for terrestrial small mammals used trapping with Sherman and Tomahawk small- and medium-sized mammal traps, along with visual surveys for diurnal species. The majority of sampling for terrestrial small mammals was carried out in 2002 and 2003. Methods used in field surveys for bats included mist-netting at tanks and other water bodies, along with acoustic surveys using Anabat. Most of the bat survey work was conducted in 2003. Because of extremely dry conditions in the first two survey years (and associated low mammal numbers), we extended field sampling into 2004, following a relatively wet winter. In addition to field sampling, we also reviewed, evaluated, and summarized museum and literature records of mammal species for all of the Park units. We documented a total of 59 mammal species as present at Death Valley National Park, with an additional five species that we consider of probable occurrence. At Joshua Tree, we also documented 50 species, and an additional four 'probable' species. At Lake Mead National Recreation Area, 57 mammal species have been positively documented, with 10 additional probable species. Manzanar National Historic Site had not been previously surveyed. We documented 19 mammal species at Manzanar, with an additional 11 probable species. Mojave National Preserve had not had a comprehensive list previously, either. There are now a total of 50 mammal species documented at Mojave, with three additional probable species. Of these totals, 23 occurrences are new at individual park units (positively documented for the first time), with most of these being at Manzanar. Noteworthy additions include western mastiff bat at Joshua Tree, house mouse at a number of wildland sites at Lake Mead, and San Diego pocket mouse at Mojave National Preserve. There are also species that have been lost from the Mojave Network parks. We discuss remaining questions, including the possible occurrence of additional species at each park area (most of these are marginal species whose distributional range may or may not edge into the boundaries of the area). Taxonomic changes are also discussed, along with potential erroneous species records.

Drost, Charles A.; Hart, Jan

2008-01-01

285

Characterization of inland fog zone in the Chilean Central Valley (35-38 S, 71W)  

NASA Astrophysics Data System (ADS)

In this work we document the frequency and distribution of an almost permanent fog layer that occurs in South Central Chile between the latitudes of 35 and 38 S. This phenomenon is popularly known by local people, but hardly studied before. The absence of previous work motivates the challenge to document the main observed characteristics of the phenomenon, and also try to understand its development. Using GOES data for years 2009 and 2010, in channels IR2, IR4 and visible, we document the spatial and and temporal variability of this fog. We find that topography influences the extent of the fog region that tends to be constrained below the 280 m.a.m.s.l. We will discuss the seasonal variations of this fog in relation to the seasonal cycle of clear sky solar radiation on top of the fog layer over the region. Also we will validate the satellite observations using available surface observations of dew point and relative humidity over the region. monthly frequency of fog during non-upper clouds days in June of 2010, for 23 local time (UTC-4) monthly frequency of low clouds during non-upper clouds for 10 local time (UTC-4) for June of 2010. Within the central area of this patter of low cloudiness, topographic contour of 285 m.a.s.l. is well adjusted (black contour).

Pizarro Andía, P. I.; Molina, A.; Rondanelli, R. F.

2012-12-01

286

Mixed carbonate-siliciclastic infilling of a Neogene carbonate shelf-valley system: Tampa Bay, West-Central Florida  

Microsoft Academic Search

The shelf-valley system underlying Tampa Bay, Florida’s largest estuary, is situated in the middle of the Neogene carbonate Florida Platform. Compared to well-studied fluvially incised coastal plain valley systems, this shelf-valley system is unique in its karstic origin and its alternating carbonate-siliciclastic infill. A complex record of sea-level changes, paleo-fluvial variability and marine processes have controlled the timing and mechanisms

David S. Duncan; Stanley D. Locker; Gregg R. Brooks; Albert C. Hine; Larry J. Doyle

2003-01-01

287

Water transfer and major environmental provisions of the Central Valley Project Improvement Act: A preliminary economic evaluation  

NASA Astrophysics Data System (ADS)

Increasing block water pricing, water transfer, and wildlife refuge water supply provisions of the Central Valley Project (CVP) Improvement Act are analyzed in terms of likely farmer response and economic efficiency of these provisions. Based on a simplified partial equilibrium analysis, we estimate small, but significant water conservation savings due to pricing reform, the potential for substantial water transfers to non-CVP customers in severe drought years when the water price exceeds 110 per acre foot (1 acre foot equals 1.234 × 103 m3) and positive net benefits for implementation of the wildlife refuge water supply provisions. The high threshold water price is partly a result of requiring farmers to pay full cost on transferred water plus a surcharge of 25 per acre foot if the water is transferred to a non-CVP user. The act also sets an important precedent for water pricing reform, water transfer provisions, and environmental surcharges on water users that may find their way to other Bureau of Reclamation projects.

Loomis, John B.

1994-06-01

288

Evidence for Alleghenian brine migration in the central and southern Appalachians: implications for Mississippi valley-type sulfide mineralization  

SciTech Connect

Authigenic K-feldspar has been found in rocks near Mississippi Valley-Type (MVT) sulfide mineralization in lower Paleozoic carbonate rocks of Pennsylvania, Maryland, Virginia, and Tennessee. Synthetic /sup 40/Ar//sup 39/Ar age spectra for the authigenic K-feldspar yield Carboniferous ages. Mass balance calculations indicate that the formation of the K-feldspar involved the flux of multiple pore volumes of fluid through the rocks. Estimates of vapor-liquid ratios and microthermometric homogenization temperatures of primary fluid inclusions in K-feldspar overgrowths, the presence of halite daughter crystals in some associated carbonate-hosted inclusions, and low whole-rock Cl/Br ratios indicate the K-feldspar formed by the interaction of connate brines with siliciclastic debris at temperatures between 100/sup 0/ and 200/sup 0/C. The common occurrence of feldspathized rocks stratigraphically below mineralized zones and the similarity of primary fluid inclusions in K-feldspar overgrowths to those observed in ore and qanque minerals suggest the authigenic K-feldspar and mineralization are coeval. The Carboniferous age suggested by /sup 40/Ar//sup 39/Ar age spectra is consistent with estimates based on (1) paleomagnetic studies and (2) analyses of sphalerite deformation fabrics. Accordingly, the authors suggest that MVT sulfide deposits in the central and southern Appalachians were emplaced by the migration of heated connate brines along structural pathways developed during the Alleghenian Orogeny.

Hearn, P.P.; Sutter, J.F.; Kunk, M.J.; Belkin, H.E.

1985-01-01

289

Parkinson's Disease and Residential Exposure to Maneb and Paraquat From Agricultural Applications in the Central Valley of California  

PubMed Central

Evidence from animal and cell models suggests that pesticides cause a neurodegenerative process leading to Parkinson's disease (PD). Human data are insufficient to support this claim for any specific pesticide, largely because of challenges in exposure assessment. The authors developed and validated an exposure assessment tool based on geographic information systems that integrated information from California Pesticide Use Reports and land-use maps to estimate historical exposure to agricultural pesticides in the residential environment. In 1998–2007, the authors enrolled 368 incident PD cases and 341 population controls from the Central Valley of California in a case-control study. They generated estimates for maneb and paraquat exposures incurred between 1974 and 1999. Exposure to both pesticides within 500 m of the home increased PD risk by 75% (95% confidence interval (CI): 1.13, 2.73). Persons aged ?60 years at the time of diagnosis were at much higher risk when exposed to either maneb or paraquat alone (odds ratio?=?2.27, 95% CI: 0.91, 5.70) or to both pesticides in combination (odds ratio?=?4.17, 95% CI: 1.15, 15.16) in 1974–1989. This study provides evidence that exposure to a combination of maneb and paraquat increases PD risk, particularly in younger subjects and/or when exposure occurs at younger ages. PMID:19270050

Cockburn, Myles; Bronstein, Jeff; Zhang, Xinbo; Ritz, Beate

2009-01-01

290

An estimated potentiometric surface of the Death Valley region, Nevada and California, developed using geographic information system and automated interpolation techniques  

SciTech Connect

An estimated potentiometric surface was constructed for the Death Valley region, Nevada and California, from numerous, disparate data sets. The potentiometric surface was required for conceptualization of the ground-water flow system and for construction of a numerical model to aid in the regional characterization for the Yucca Mountain repository. Because accurate, manual extrapolation of potentiometric levels over large distances is difficult, a geographic-information-system method was developed to incorporate available data and apply hydrogeologic rules during contour construction. Altitudes of lakes, springs, and wetlands, interpreted as areas where the potentiometric surface intercepts the land surface, were combined with water levels from well data. Because interpreted ground-water recharge and discharge areas commonly coincide with groundwater basin boundaries, these areas also were used to constrain a gridding algorithm and to appropriately place local maxima and minima in the potentiometric-surface map. The resulting initial potentiometric surface was examined to define areas where the algorithm incorrectly extrapolated the potentiometric surface above the land surface. A map of low-permeability rocks overlaid on the potentiometric surface also indicated areas that required editing based on hydrogeologic reasoning. An interactive editor was used to adjust generated contours to better represent the natural water table conditions, such as large hydraulic gradients and troughs, or ``vees``. The resulting estimated potentiometric-surface map agreed well with previously constructed maps. Potentiometric-surface characteristics including potentiometric-surface mounds and depressions, surface troughs, and large hydraulic gradients were described.

D`Agnese, F.A.; Faunt, C.C.; Turner, A.K.

1998-07-01

291

Methods for Using Ground-Water Model Predictions to Guide Hydrogeologic Data Collection, with Applications to the Death Valley Regional Ground-Water Flow System  

SciTech Connect

Calibrated models of ground-water systems can provide substantial information for guiding data collection. This work considers using such models to guide hydrogeologic data collection for improving model predictions, by identifying model parameters that are most important to the predictions. Identification of these important parameters can help guide collection of field data about parameter values and associated flow-system features that can lead to improved predictions. Methods for identifying parameters important to predictions include prediction scaled sensitivities (PSS), which account for uncertainty on individual parameters as well as prediction sensitivity to parameters, and a new ''value of improved information'' (VOII) method, which includes the effects of parameter correlation in addition to individual parameter uncertainty and prediction sensitivity. The PSS and VOII methods are demonstrated using a model of the Death Valley regional ground-water flow system. The predictions of interest are advective-transport paths originating at sites of past underground nuclear testing. Results show that for two paths evaluated, the most important parameters include a subset of five or six of the 23 defined model parameters. Some of the parameters identified as most important are associated with flow-system attributes that do not lie in the immediate vicinity of the paths. Results also indicate that the PSS and VOII methods can identify different important parameters. Because the methods emphasize somewhat different criteria for parameter importance, it is suggested that parameters identified by both methods be carefully considered in subsequent data collection efforts aimed at improving model predictions.

Claire R. Tiedeman; M.C. Hill; F.A. D'Agnese; C.C. Faunt

2001-07-31

292

Methods for using groundwater model predictions to guide hydrogeologic data collection, with application to the Death Valley regional groundwater flow system  

USGS Publications Warehouse

Calibrated models of groundwater systems can provide substantial information for guiding data collection. This work considers using such models to guide hydrogeologic data collection for improving model predictions by identifying model parameters that are most important to the predictions. Identification of these important parameters can help guide collection of field data about parameter values and associated flow system features and can lead to improved predictions. Methods for identifying parameters important to predictions include prediction scaled sensitivities (PSS), which account for uncertainty on individual parameters as well as prediction sensitivity to parameters, and a new "value of improved information" (VOII) method presented here, which includes the effects of parameter correlation in addition to individual parameter uncertainty and prediction sensitivity. In this work, the PSS and VOII methods are demonstrated and evaluated using a model of the Death Valley regional groundwater flow system. The predictions of interest are advective transport paths originating at sites of past underground nuclear testing. Results show that for two paths evaluated the most important parameters include a subset of five or six of the 23 defined model parameters. Some of the parameters identified as most important are associated with flow system attributes that do not lie in the immediate vicinity of the paths. Results also indicate that the PSS and VOII methods can identify different important parameters. Because the methods emphasize somewhat different criteria for parameter importance, it is suggested that parameters identified by both methods be carefully considered in subsequent data collection efforts aimed at improving model predictions.

Tiedeman, C.R.; Hill, M.C.; D'Agnese, F. A.; Faunt, C.C.

2003-01-01

293

Probability distributions of hydraulic conductivity for the hydrogeologic units of the Death Valley regional ground-water flow system, Nevada and California  

SciTech Connect

The use of geologic information such as lithology and rock properties is important to constrain conceptual and numerical hydrogeologic models. This geologic information is difficult to apply explicitly to numerical modeling and analyses because it tends to be qualitative rather than quantitative. This study uses a compilation of hydraulic-conductivity measurements to derive estimates of the probability distributions for several hydrogeologic units within the Death Valley regional ground-water flow system, a geologically and hydrologicaly complex region underlain by basin-fill sediments, volcanic, intrusive, sedimentary, and metamorphic rocks. Probability distributions of hydraulic conductivity for general rock types have been studied previously; however, this study provides more detailed definition of hydrogeologic units based on lithostratigraphy, lithology, alteration, and fracturing and compares the probability distributions to the aquifer test data. Results suggest that these probability distributions can be used for studies involving, for example, numerical flow modeling, recharge, evapotranspiration, and rainfall runoff. These probability distributions can be used for such studies involving the hydrogeologic units in the region, as well as for similar rock types elsewhere. Within the study area, fracturing appears to have the greatest influence on the hydraulic conductivity of carbonate bedrock hydrogeologic units. Similar to earlier studies, we find that alteration and welding in the Tertiary volcanic rocks greatly influence conductivity. As alteration increases, hydraulic conductivity tends to decrease. Increasing degrees of welding appears to increase hydraulic conductivity because welding increases the brittleness of the volcanic rocks, thus increasing the amount of fracturing.

Belcher, W.R.; Sweetkind, D.S.; Elliott, P.E.

2002-11-19

294

Preliminary evaluation of the importance of existing hydraulic-head observation locations to advective-transport predictions, Death Valley regional flow system, California and Nevada  

SciTech Connect

When a model is calibrated by nonlinear regression, calculated diagnostic statistics and measures of uncertainty provide a wealth of information about many aspects of the system. This report presents a method of ranking the likely importance of existing observation locations using measures of prediction uncertainty. It is suggested that continued monitoring is warranted at more important locations, and unwarranted or less warranted at less important locations. The report develops the methodology and then demonstrates it using the hydraulic-head observation locations of a three-layer model of the Death Valley regional flow system (DVRFS). The predictions of interest are subsurface transport from beneath Yucca Mountain and 14 underground Test Area (UGTA) sites. The advective component of transport is considered because it is the component most affected by the system dynamics represented by the regional-scale model being used. The problem is addressed using the capabilities of the U.S. Geological Survey computer program MODFLOW-2000, with its ADVective-Travel Observation (ADV) Package, and an additional computer program developed for this work.

Hill, M.C.; Ely, D.M.; Tiedeman, C.R.; O'Brien, G.M.; D'Agnese, F.A.; Faunt, C.C.

2001-08-01

295

Effects of the 1997 flood on the transport and storage of sediment and mercury within the Carson River Valley, west-central Nevada  

SciTech Connect

Intense, warm rains falling on a heavy snowpack in the Sierra Nevada at the end of December 1996 produced some of the largest floods on record in west-central Nevada. Within the Carson River basin, a peak discharge of 632 cm was recorded at the Fort Churchill gaging station on January 3, 1997, a flow exceeding the 100-yr event. Geomorphic impacts of the event, and the redistribution of mercury (Hg) released to the Carson River valley by Comstock mining operations during the mid- to late-1800s, were assessed by combining field data with the interpretation of aerial photographs. Geomorphic impacts included significant increases in channel width, measuring up to 280% of preflood conditions, and large-scale shifts in channel position, ranging from < 10 to 110 m. Both changes in channel width and position vary as a function of valley morphometry (width and slope) and differ from the long-term trends measured from 1965 to 1991. The 1997 flood also produced widespread overbank deposits that vary morphologically and sedimentologically according to distance from the channel and the nature of the vegetation on the valley floor. Within the overbank deposits, Hg is primarily associated with the fine-grained (< 63 {micro}m) sediment fraction, which makes up a larger percentage of the deposits immediately adjacent to the channel and at the extremities of overbank deposition. Mass balance calculations demonstrate that, along reaches with narrow valleys (< 450 m), approximately 10%--65% of the sediment eroded from the channel banks was stored in overbank deposits, whereas more than 90% of the sediment eroded along reaches with wider valleys was stored on the valley floor. Locally, however, storage exceeded 650% where meander cutoff was extensive. The above data indicate that the erosion, redeposition, and storage of sediment and sediment-bound Hg were greater along reaches characterized by low gradients and wide valley floors. Downstream trends in Hg concentration within the channel bed did not change following the 1997 flood and are presumably controlled by the overall structure of the system, including valley morphometry, the location of tributaries that deliver clean sediment to the channel, and the distribution of Hg within the valley fill.

Miller, J.; Barr, R.; Grow, D.; Richardson, D.; Waltman, K. [Indiana Univ.-Purdue Univ., Indianapolis, IN (United States). Dept. of Geology] [Indiana Univ.-Purdue Univ., Indianapolis, IN (United States). Dept. of Geology; Lechler, P.; Warwick, J. [Univ. of Nevada, Reno, NV (United States)] [Univ. of Nevada, Reno, NV (United States)

1999-05-01

296

Evidence for late-paleozoic brine migration in Cambrian carbonate rocks of the central and southern Appalachians: implications for Mississippi Valley-type sulfide mineralization  

Microsoft Academic Search

Many Lower Paleozoic limestones and dolostones in the Valley and Ridge province of the central and southern Appalachians contain 10 to 25 weight percent authigenic potassium feldspar. This was considered to be a product of early diagenesis, however, ⁴°Ar\\/³⁹Ar analyses of overgrowths on detrital K-feldspar in Cambrian carbonate rocks from Pennsylvania, Maryland, Virginia, and Tennessee yield Late Carboniferous-Early Permian ages

P. P. Jr Hearn; J. F. Sutter; H. E. Belkin

1987-01-01

297

Inferences on the hydrothermal system beneath the resurgent dome in Long Valley Caldera, east-central California, USA, from recent pumping tests and geochemical sampling  

Microsoft Academic Search

Quaternary volcanic unrest has provided heat for episodic hydrothermal circulation in the Long Valley caldera, including the present-day hydrothermal system, which has been active over the past 40 kyr. The most recent period of crustal unrest in this region of east-central California began around 1980 and has included periods of intense seismicity and ground deformation. Uplift totaling more than 0.7

Christopher D. Farrar; Michael L. Sorey; Evelyn Roeloffs; Devin L. Galloway; James F. Howle; Ronald Jacobson

2003-01-01

298

Digital Elevation Model (DEM) file of topographic elevations for the Death Valley region of southern Nevada and southeastern California processed from US Geological Survey 1-degree Digital Elevation Model data files  

SciTech Connect

Elevation data have been compiled into a digital data base for an {approx}100,000-km{sup 2} area of the southern Great Basin, the Death Valley region of southern Nevada, and SE Calif., located between lat 35{degree}N, long 115{degree}W, and lat 38{degree}N, long 118{degree}W. This region includes the Nevada Test Site, Yucca Mountain, and adjacent parts of southern Nevada and eastern California and encompasses the Death Valley regional ground-water system. Because digital maps are often useful for applications other than that for which they were originally intended, and because the area corresponds to a region under continuing investigation by several groups, these digital files are being released by USGS.

Turner, A.K.; D`Agnese, F.A.; Faunt, C.C.

1996-04-01

299

Late Pleistocene and Holocene environmental history of the Iguala Valley, Central Balsas Watershed of Mexico  

PubMed Central

The origin of agriculture was a signal development in human affairs and as such has occupied the attention of scholars from the natural and social sciences for well over a century. Historical studies of climate and vegetation are closely associated with crop plant evolution because they can reveal the ecological contexts of plant domestication together with the antiquity and effects of agricultural practices on the environment. In this article, we present paleoecological evidence from three lakes and a swamp located in the Central Balsas watershed of tropical southwestern Mexico that date from 14,000 B.P. to the modern era. [Dates expressed in B.P. years are radiocarbon ages. Calibrated (calendar) ages, expressed as cal B.P., are provided for dates in the text.] Previous molecular studies suggest that maize (Zea mays L.) and other important crops such as squashes (Cucurbita spp.) were domesticated in the region. Our combined pollen, phytolith, charcoal, and sedimentary studies indicate that during the late glacial period (14,000–10,000 B.P.), lake beds were dry, the climate was cooler and drier, and open vegetational communities were more widespread than after the Pleistocene ended. Zea was a continuous part of the vegetation since at least the terminal Pleistocene. During the Holocene, lakes became important foci of human activity, and cultural interference with a species-diverse tropical forest is indicated. Maize and squash were grown at lake edges starting between 10,000 and 5,000 B.P., most likely sometime during the first half of that period. Significant episodes of climatic drying evidenced between 1,800 B.P. and 900 B.P. appear to be coeval with those documented in the Classic Maya region and elsewhere, showing widespread instability in the late Holocene climate. PMID:17537917

Piperno, D. R.; Moreno, J. E.; Iriarte, J.; Holst, I.; Lachniet, M.; Jones, J. G.; Ranere, A. J.; Castanzo, R.

2007-01-01

300

Modeling vadose zone processes during land application of food-processing waste water in California's Central Valley.  

PubMed

Land application of food-processing waste water occurs throughout California's Central Valley and may be degrading local ground water quality, primarily by increasing salinity and nitrogen levels. Natural attenuation is considered a treatment strategy for the waste, which often contains elevated levels of easily degradable organic carbon. Several key biogeochemical processes in the vadose zone alter the characteristics of the waste water before it reaches the ground water table, including microbial degradation, crop nutrient uptake, mineral precipitation, and ion exchange. This study used a process-based, multi-component reactive flow and transport model (MIN3P) to numerically simulate waste water migration in the vadose zone and to estimate its attenuation capacity. To address the high variability in site conditions and waste-stream characteristics, four food-processing industries were coupled with three site scenarios to simulate a range of land application outcomes. The simulations estimated that typically between 30 and 150% of the salt loading to the land surface reaches the ground water, resulting in dissolved solids concentrations up to sixteen times larger than the 500 mg L(-1) water quality objective. Site conditions, namely the ratio of hydraulic conductivity to the application rate, strongly influenced the amount of nitrate reaching the ground water, which ranged from zero to nine times the total loading applied. Rock-water interaction and nitrification explain salt and nitrate concentrations that exceed the levels present in the waste water. While source control remains the only method to prevent ground water degradation from saline wastes, proper site selection and waste application methods can reduce the risk of ground water degradation from nitrogen compounds. PMID:18765777

Miller, Gretchen R; Rubin, Yoram; Mayer, K Ulrich; Benito, Pascual H

2008-01-01

301

Monitoring unrest in a large silicic caldera, the long Valley-inyo craters volcanic complex in east-central California  

USGS Publications Warehouse

Recent patterns of geologic unrest in long Valley caldera in east-central California emphasize that this large, silicic volcanic system and the adjacent, geologically youthful Inyo-Mono Craters volcanic chain are still active and capable of producing locally hazardous volcanic eruptions. A series of four magnitude -6 earthquakes in May 1980 called attention to this current episode of unrest, and subsequent activity has included numerous earthquake swarms in the south moat of the caldera accompanied by inflation of the resurgent dome by more than 50 cm over the last five years. The seismicity associated with this unrest is currently monitored by a network of 31 telemetered seismic stations with an automatic processing system that yelds hypocentral locations and earthquake magnitudes in near-real time. Deformation of the ground is monitored by a) a series of overlapping trilateration networks that provide coverage ranging from annual measurements of regional deformation to daily measurements of deformation local to the active, southern section of the caldera, b) a regional network of level lines surveyed annually, c) a regional network of precise gravity stations occupied annually, d) local, L-shaped level figures surveyed every few months, and e) a network of fourteen borehole tiltmeter clusters (two instruments in each cluster) and a borehole dilatometer, the telemetered signals from which provide continuous data on deformation rates. Additional telemetered data provide continuous information on fluctuations in the local magnetic field, hydrogen gas emission rates at three sites, and water level and temperatures in three wells. Continuous data on disharge rates and temperatures from hot springs and fumaroles are collected by several on-site recorders within the caldera, and samples for liquid and gas chemistry are collected several times per year from selected hot springs and fumaroles. ?? 1984 Intern. Association of Volcanology and Chemistry of the Earth's Interior.

Hill, D. P.

1984-01-01

302

Methods, quality assurance, and data for assessing atmospheric deposition of pesticides in the Central Valley of California  

USGS Publications Warehouse

The U.S. Geological Survey monitored atmospheric deposition of pesticides in the Central Valley of California during two studies in 2001 and 2002–04. The 2001 study sampled wet deposition (rain) and storm-drain runoff in the Modesto, California, area during the orchard dormant-spray season to examine the contribution of pesticide concentrations to storm runoff from rainfall. In the 2002–04 study, the number and extent of collection sites in the Central Valley were increased to determine the areal distribution of organophosphate insecticides and other pesticides, and also five more sample types were collected. These were dry deposition, bulk deposition, and three sample types collected from a soil box: aqueous phase in runoff, suspended sediment in runoff, and surficial-soil samples. This report provides concentration data and describes methods and quality assurance of sample collection and laboratory analysis for pesticide compounds in all samples collected from 16 sites. Each sample was analyzed for 41 currently used pesticides and 23 pesticide degradates, including oxygen analogs (oxons) of 9 organophosphate insecticides. Analytical results are presented by sample type and study period. The median concentrations of both chloryprifos and diazinon sampled at four urban (0.067 micrograms per liter [?g/L] and 0.515 ?g/L, respectively) and four agricultural sites (0.079 ?g/L and 0.583 ?g/L, respectively) during a January 2001 storm event in and around Modesto, Calif., were nearly identical, indicating that the overall atmospheric burden in the region appeared to be fairly similar during the sampling event. Comparisons of median concentrations in the rainfall to those in the McHenry storm-drain runoff showed that, for some compounds, rainfall contributed a substantial percentage of the concentration in the runoff; for other compounds, the concentrations in rainfall were much greater than in the runoff. For example, diazinon concentrations in rainfall were about 70 percent of the diazinon concentration in the runoff, whereas the chlorpyrifos concentration in the rain was 1.8 times greater than in the runoff. The more water-soluble pesticides—carbaryl, metolachlor, napropamide, and simazine—followed the same pattern as diazinon and had lower concentrations in rain compared to runoff. Similar to chlorpyrifos,compounds with low water solubilities and higher soil-organic carbon partition coefficients, including dacthal, pendimethalin, and trifluralin, were found to have higher concentrations in rain than in runoff water and were presumed to partition to the suspended sediments and organic matter on the ground. During the 2002–04 study period, the herbicide dacthal had the highest detection frequencies for all sample types collected from the Central Valley sites (67–100 percent). The most frequently detected compounds in the wet-deposition samples were dacthal, diazinon, chlorpyrifos, and simazine (greater than 90 percent). The median wet-deposition amounts for these compounds were 0.044 micrograms per square meter per day (?g/m2/day), 0.209 ?g/m2/day, 0.079 ?g/m2/day, and 0.172 ?g/m2/day, respectively. For the dry-deposition samples, detection frequencies were greater than 73 percent for the compounds dacthal, metolachor, and chlorpyrifos, and median deposition amounts were an order of magnitude less than for wet deposition. The differences between wet deposition and dry deposition appeared to be closely related to the Henry’s Law (H) constant of each compound, although the mass deposited by dry deposition takes place over a much longer time frame. Pesticides detected in rainfall usually were detected in the aqueous phase of the soil-box runoff water, and the runoff concentrations were generally similar to those in the rainfall. For compounds detected in the aqueous phase and suspended-sediment samples of soil-box runoff, concentrations of pesticides in the aqueous phase generally were detected in low concentrations and had few corresponding detections in the suspended- sediment samples. Dacthal, diazinon, c

Zamora, Celia; Majewski, Michael S.; Foreman, William T.

2013-01-01

303

Contrasting Oligocene and Miocene thermal histories from the hanging wall and footwall of the South Tibetan detachment in the central Himalaya from 40Ar\\/39Ar thermochronology, Marsyandi Valley, central Nepal  

Microsoft Academic Search

In the Marsyandi valley of central Nepal, a major strand of the South Tibetan detachment system, the 18–22 Ma Chame detachment, places epidote-amphibolite to amphibolite facies calc-silicate rocks and marbles of the Tibetan sedimentary sequence on amphibolite facies pelitic gneisses and calc-silicate rocks of the Greater Himalayan sequence. Although the resulting metamorphic discontinuity is minor and sometimes cryptic, 40Ar\\/39Ar thermochronologic

Margaret E. Coleman; Kip V. Hodges

1998-01-01

304

Late Holocene glacial history of the Copper River Delta, coastal south-central Alaska, and controls on valley glacier fluctuations  

E-print Network

on valley glacier fluctuations David J. Barclay a,*, Elowyn M. Yager b , Jason Graves a , Michael Kloczko to be reconstructed with very high spatial and temporal detail (e.g. Luckman, 1995; Holzhauser et al., 2005; Barclay

Barclay, David J.

305

Tectonic problems revisited: The eastern terminus of the Miocene Garlock fault and the amount of slip on the southern Death Valley fault zone  

SciTech Connect

Prior to 1973, the eastern end of the sinistral Garlock fault (GF) was generally assumed to lie at its junction with the southern Death Valley fault zone (SDVFZ). Although there seems little doubt that the Quaternary GF ends there in a complicated zone of interaction with the dextral SDVFZ, the location of the eastern terminus of a late Miocene GF has been more controversial. Davis and Burchfiel (1973) analyzed the geometry of geologic terranes and features offset > 50 km along the eastern half of the present GF (several within 15 km of the SDVFZ), that it had been offset dextrally [approximately] 8 km along the younger zone, and that the GF was an intracontinental transform structure separating a more extended northern terrane (Basin-and-Range) from a less extended southern terrane (Mojave Desert). USC field studies in areas east of the SDVFZ/GF intersection support the original contention of Davis and Burchfiel that the Miocene GF lies beneath alluvial deposits of Kingston Wash. A left-slip fault with a displacement of [approximately]3 km has been identified beneath upper reaches of the Wash north of Kingston Spring. It lies above the older (and coeval ) west-rooting, mid- to Late Miocene Kingston Range detachment fault, and it appears to bound the southern margin of a distributed breakaway zone of N-S-striking normal faults that distends the Kingston Peak pluton (ca 12.5 Ma). The authors believe that the cumulative effects of pre- and post-12.5 Ma east-west extension north of this buried fault may explain the geometry of offset terranes along the GF in areas west of the SDVFZ. If so, total dextral slip on the younger, cross-cutting SDVFZ must be 10 km or less.

Davis, G.A. (Univ. of Southern California, Los Angeles, CA (United States). Dept. of Geological Sciences); Burchfiel, B.C. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Earth, Atmospheric, and Planetary Science)

1993-04-01

306

A method for evaluating the importance of system state observations to model predictions, with application to the Death Valley regional groundwater flow system  

NASA Astrophysics Data System (ADS)

We develop a new observation-prediction (OPR) statistic for evaluating the importance of system state observations to model predictions. The OPR statistic measures the change in prediction uncertainty produced when an observation is added to or removed from an existing monitoring network, and it can be used to guide refinement and enhancement of the network. Prediction uncertainty is approximated using a first-order second-moment method. We apply the OPR statistic to a model of the Death Valley regional groundwater flow system (DVRFS) to evaluate the importance of existing and potential hydraulic head observations to predicted advective transport paths in the saturated zone underlying Yucca Mountain and underground testing areas on the Nevada Test Site. Important existing observations tend to be far from the predicted paths, and many unimportant observations are in areas of high observation density. These results can be used to select locations at which increased observation accuracy would be beneficial and locations that could be removed from the network. Important potential observations are mostly in areas of high hydraulic gradient far from the paths. Results for both existing and potential observations are related to the flow system dynamics and coarse parameter zonation in the DVRFS model. If system properties in different locations are as similar as the zonation assumes, then the OPR results illustrate a data collection opportunity whereby observations in distant, high-gradient areas can provide information about properties in flatter-gradient areas near the paths. If this similarity is suspect, then the analysis produces a different type of data collection opportunity involving testing of model assumptions critical to the OPR results.

Tiedeman, Claire R.; Ely, D. Matthew; Hill, Mary C.; O'Brien, Grady M.

2004-12-01

307

A method for evaluating the importance of system state observations to model predictions, with application to the Death Valley regional groundwater flow system  

USGS Publications Warehouse

We develop a new observation-prediction (OPR) statistic for evaluating the importance of system state observations to model predictions. The OPR statistic measures the change in prediction uncertainty produced when an observation is added to or removed from an existing monitoring network, and it can be used to guide refinement and enhancement of the network. Prediction uncertainty is approximated using a first-order second-moment method. We apply the OPR statistic to a model of the Death Valley regional groundwater flow system (DVRFS) to evaluate the importance of existing and potential hydraulic head observations to predicted advective transport paths in the saturated zone underlying Yucca Mountain and underground testing areas on the Nevada Test Site. Important existing observations tend to be far from the predicted paths, and many unimportant observations are in areas of high observation density. These results can be used to select locations at which increased observation accuracy would be beneficial and locations that could be removed from the network. Important potential observations are mostly in areas of high hydraulic gradient far from the paths. Results for both existing and potential observations are related to the flow system dynamics and coarse parameter zonation in the DVRFS model. If system properties in different locations are as similar as the zonation assumes, then the OPR results illustrate a data collection opportunity whereby observations in distant, high-gradient areas can provide information about properties in flatter-gradient areas near the paths. If this similarity is suspect, then the analysis produces a different type of data collection opportunity involving testing of model assumptions critical to the OPR results.

Tiedeman, C.R.; Ely, D.M.; Hill, M.C.; O'Brien, G. M.

2004-01-01

308

Trace element distribution in the cainozoic lavas of Nevado Coropuna and Andagua Valley, Central Andes of Southern Peru  

Microsoft Academic Search

Major and minor elements have been determined on 26 samples of andesitie to rhyolitic lavas from Nevado Coropuna and Andagua\\u000a valley in Southern Peru. Nevado Coropuna dating back since late Miocene is the highest stratovolcano of Peru. It is located\\u000a at 150 km NW of Arequipa and at 110 km E of the Pacific coast. Andagua valley is situated at

G. Venturelli; M. Fragipane; M. Weibel; D. Antiga

1978-01-01

309

Holocene activity of the Subequana Valley-Middle Aterno Valley normal fault system, south of the epicentral area of the April 6, 2009 "L'Aquila" earthquake (Mw 6.3): Implications for seismic hazard in central Italy  

NASA Astrophysics Data System (ADS)

Geological and paleoseismological analyses led along the 10 km long Subequana Valley fault, in central Apennines, located about 40 km S of the epicentre of the earthquake that struck central Italy in April 6, 2009 (Mw 6.3), indicate that this structure ruptured twice during the late Holocene, resulting in surface displacement with a slip per event of about 70-80 cm. The last activation occurred after the IV-II century b.C. and before the past millennium (perhaps during the II century b.C.), while the penultimate event occurred between 6381±30BP and 3511±37 PB. The presence of transtensive faults connecting the SVF with the 15 km long (at least) Middle Aterno Valley fault indicate that these structures belong to the same fault system, ?26 km long, that probably ruptures during M?6.7 earthquakes. Lastly, we analyse the possible influence of the Coulomb stress diffusion induced by the April 6 seismic event on the earthquake probability related to the analysed fault system.

Falcucci, Emanuela; Gori, Stefano; Moro, Marco; Galadini, Fabrizio; Pisani, Anna Rita; Fredi, Paola

2010-05-01

310

Providing care and facing death: nursing during Ebola outbreaks in central Africa.  

PubMed

Few studies have focused on describing the experiences of health care workers during rapid killing epidemics. In this article, the views and experiences of nurses during three outbreaks of Ebola hemorrhagic fever (EHF) in Central Africa are examined. These three outbreaks occurred in Kikwit, Democratic Republic of Congo (DRC, 1995); Gulu, Uganda (2000-2001); and Republic of Congo (ROC, 2003). Open-ended and semistructured interviews with individuals and small groups were conducted during the outbreaks in Uganda and ROC; data from DRC are extracted from published sources. Three key themes emerged from the interviews: (a) lack of protective gear, basic equipment, and other resources necessary to provide care, especially during the early phases of the outbreaks; (b) stigmatization by family, coworkers, and community; and (c) exceptional commitment to the nursing profession in a context where the lives of the health care workers were in jeopardy. PMID:16160191

Hewlett, Bonnie L; Hewlett, Barry S

2005-10-01

311

Aquifer-test evaluation and potential effects of increased ground-water pumpage at the Stovepipe Wells Hotel area, Death Valley National Monument, California  

USGS Publications Warehouse

Ground-water use in the Stovepipe Wells Hotel area in Death Valley National Monument is expected to increase significantly if the nonpotable, as well as potable, water supply is treated by reverse osmosis. During the peak tourist season, October through March, ground-water pumpage could increase by 37,500 gallons per day, or 76%. The effects of this additional pumpage on water levels in the area, particularly near a strand of phreatophytes about 10,000 feet east of the well field, are of concern. In order to evaluate the effects of increased pumpage on water levels in the Stovepipe Wells Hotel area well field, two aquifer tests were performed at the well field to determine the transmissivity and storage coefficients of the aquifer. Analysis of the aquifer test determined that a transmissivity of 1,360 feet squared per day was representative of the aquifer. The estimated value of transmissivity and the storage-coefficient values that are representative of confined (1.2 x .0004) and unconfined (0.25) conditions were used in the Theis equation to calculate the additional drawdown that might occur after 1, 10, and 50 years of increased pumpage. The drawdown calculated by using the lower storage-coefficient value represents the maximum additional drawdown that might be expected from the assumed increase in pumpage; the drawdown calculated by using the higher storage-coefficient value represents the minimum additional drawdown. Calculated additional drawdowns after 50 years of pumping range from 7.8 feet near the pumped well to 2.4 feet at the phreatophyte stand assuming confined conditions, and from 5.7 feet near the pumped well to 0.3 foot at the phreatophyte stand assuming unconfined conditions. Actual drawdowns probably will be somewhere between these values. Drawdowns measured in observation wells during 1973-85, in response to an average pumpage of 34,200 gallons per day at the Stovepipe Wells Hotel well field, are similar to the drawdowns calculated by the Theis equation for the assumed increase in pumpage. (Author 's abstract)

Woolfenden, L. R.; Martin, Peter; Baharie, Brian

1988-01-01

312

Inflammation and programmed cell death in Alzheimer's disease: comparison of the central nervous system and peripheral blood.  

PubMed

Although the central nervous system (CNS) has been defined as a privileged site in Alzheimer's disease (AD), periphery can be more than simply witness of events leading to neurodegeneration. The CNS and peripheral blood can mutually communicate through cells and factors trafficking from the circulation into the brain and vice versa. A number of articles have reviewed inflammatory profiles and programmed cell death (PCD) in AD, separately in the CNS and at the peripheral level. This review does not provide an exhaustive account of what has been published on inflammation and PCD in AD. Rather, the aim of this review is to focus on possible linkages between the central and the peripheral compartments during AD progression, by critically analyzing, in a comparative manner, phenomena occurring in the CNS as well as the peripheral blood. In fact, growing evidence suggests that CNS and peripheral inflammation might present common features in the disease. Microarrays and metabolomics revealed that dysfunction of the glycolytic and oxidative pathways is similar in the brain and in the periphery. Moreover, dysregulated autophagosome/lysosomal molecular machinery, both at the CNS and the peripheral level, in AD-related cell damage, has been observed. Possible implications of these observations have been discussed. PMID:24445952

Macchi, Beatrice; Marino-Merlo, Francesca; Frezza, Caterina; Cuzzocrea, Salvatore; Mastino, Antonio

2014-10-01

313

Potential of public lands in California's central valley as habitat for the endangered San Joaquin kit fox. [Vulpes macrotis mutica  

SciTech Connect

As part of an assessment of the impacts of their activities on the endangered San Joaquin kit fox and its essential habitat, the Department of Energy and Bureau of Land Management investigated the potential of public lands in the San Joaquin Valley as suitable habitat for the San Joaquin kit fox. (ACR)

O'Farrell, T.P.; McCue, P.; Sauls, M.L.; Kato, T.

1982-01-01

314

Numerical simulation of ground-water flow in the central part of the western San Joaquin Valley, California  

USGS Publications Warehouse

The occurrence of selenium in agricultural drain water in the central part of the western San Joaquin Valley, California, has focused concern on strategies for managing shallow, saline ground water. To assess alternatives to agricultural drains, a three-dimensional, finite-difference numerical model of the regional groundwater flow system was developed. This report documents the mathematical approach used to model the flow system, the data base on which the model is based, and the methods used to calibrate the model. The 550-square-mile study area includes parts of the Panoche Creek alluvial fan and parts of the Little Panoche Creek and Cantua Creek alluvial fans. The model simulates transient flow in the semiconfined and confined zones above and below the Corcoran Clay Member of the Tulare Formation of Pleistocene age. The model incorporates areally distributed ground-water recharge, areally and vertically distributed pumping, regional-collector drains in the Wesdands Water District (operative from 1980 to 1985), on-farm drains in parts of the Panoche, Broadview, and Firebaugh Water Districts, and bare-soil evaporation (which occurs if the water table is within 7 feet of land surface). The model also incorporates texture-based estimates of hydraulic conductivity, where texture is defined as the fraction of coarse-grained deposits present in a given subsurface interval. The numerical model was developed using hydrologic data from 1972 to 1988. Most of the parameters incorporated into the model were evaluated independently of the model, including system geometry, the distribution of texture, the altitudes of the water table and potentiometric surface of the confined zone in 1972 (initial condition), the hydraulic conductivity of coarse-grained deposits derived from the Coast Ranges, the hydraulic conductivity of coarse-grained deposits derived from the Sierra Nevada, specific storage, recharge, pumping, and parameters needed to incorporate drains and bare-soil evaporation. Four parameters were calibration variables: the hydraulic conductivity of fine-grained deposits in the semiconfined zone, the hydraulic conductivity of the Corcoran Clay Member, specific yield, and the transmissivity of the confined zone. The model was calibrated in two phases. In the first phase, a steady-state model of the ground-water flow system in 1984 was used to constrain the relation between the hydraulic conductivity of fine-grained deposits in the semiconfined zone and the hydraulic conductivity of the Corcoran Clay Member, thus reducing the number of independent variables from four to three. In the second phase of calibration, the change in altitude of the water table from 1972 to 1984, the change in altitude of the potentiometric surface of the confined zone from 1972 to 1984, and the number of model cells subject to bare-soil evaporation from 1972 to 1988 were used to evaluate the remaining three variables. The calibrated model reproduces the average change in water-table altitude (1972-84) to within 0.4 foot (average measured change 11.5 feet) and the average change in confined zone head (1972- 84) to within 19 feet (average measured change 120 feet). The simulated time-series record of the total number of model cells subject to bare-soil evaporation (each cell is 1 mile square) is within the range of the measured data. The measured values are at a minimum in October and a maximum in July. The October values ranged from 103 in 1972 to 132 in 1984 (the drains were closed in 1985) to 151 in 1988. The July values ranged from 144 in 1973 to 198 in 1984, to 204 in 1988. The simulated values ranged from 103 in 1972 to 161 in 1984, to 208 in 1988.

Belitz, Kenneth; Phillips, Steven P.; Gronberg, Jo Ann M.

1993-01-01

315

Assessing the Vulnerability of Public-Supply Wells to Contamination: Central Valley Aquifer System near Modesto, California  

USGS Publications Warehouse

This fact sheet highlights findings from the vulnerability study of a public-supply well in Modesto, California. The well selected for study pumps on average about 1,600 gallons per minute from the Central Valley aquifer system during peak summer demand. Water samples were collected at the public-supply well and at monitoring wells installed in the Modesto vicinity. Samples from the public-supply wellhead contained the undesirable constituents uranium, nitrate, arsenic, volatile organic compounds (VOCs), and pesticides, although none were present at concentrations exceeding drinking-water standards. Of these contaminants, uranium and nitrate pose the most significant water-quality risk to the public-supply well because human activities have caused concentrations in groundwater to increase over time. Overall, study findings point to four primary factors that affect the movement and (or) fate of contaminants and the vulnerability of the public-supply well in Modesto: (1) groundwater age (how long ago water entered, or recharged, the aquifer); (2) irrigation and agricultural and municipal pumping that drives contaminants downward into the primary production zone of the aquifer; (3) short-circuiting of contaminated water down the public-supply well during the low-pumping season; and (4) natural geochemical conditions of the aquifer. A local-scale computer model of groundwater flow and transport to the public-supply well was constructed to simulate long-term nitrate and uranium concentrations reaching the well. With regard to nitrate, two conflicting processes influence concentrations in the area contributing recharge to the well: (1) Beneath land that is being farmed or has recently been farmed (within the last 10 to 20 years), downward-moving irrigation waters contain elevated nitrate concentrations; yet (2) the proportion of agricultural land has decreased and the proportion of urban land has increased since 1960. Urban land use is associated with low nitrate concentrations in recharge (3.1 milligrams per liter). Results of the simulation indicate that nitrate concentrations in the public-supply well peaked in the late 1990s and will decrease slightly from the current level of 5.5 milligrams per liter during the next 100 years. A lag time of 20 to 30 years between peak nitrate concentrations in recharge and peak concentrations in the well is the result of the wide range of ages of water reaching the public-supply well combined with changing nitrogen input concentrations over time. As for uranium, simulation results show that concentrations in the public-supply well will likely approach the Maximum Contaminant Level of 30 micrograms per liter over time; however, it will take more than 100 years because of the contribution of old water at depth in the public-supply well that dilutes uranium concentrations in shallower water entering the well. This allows time to evaluate management strategies and to alter well-construction or pumping strategies to prevent uranium concentrations from exceeding the drinking-water standard.

Jagucki, Martha L.; Jurgens, Bryant C.; Burow, Karen R.; Eberts, Sandra M.

2009-01-01

316

Linking groundwater use and stress to specific crops using the groundwater footprint in the Central Valley and High Plains aquifer systems, U.S.  

NASA Astrophysics Data System (ADS)

number of aquifers worldwide are being depleted, mainly by agricultural activities, yet groundwater stress has not been explicitly linked to specific agricultural crops. Using the newly developed concept of the groundwater footprint (the area required to sustain groundwater use and groundwater-dependent ecosystem services), we develop a methodology to derive crop-specific groundwater footprints. We illustrate this method by calculating high-resolution groundwater footprint estimates of crops in two heavily used aquifer systems: the Central Valley and High Plains, U.S. In both aquifer systems, hay and haylage, corn, and cotton have the largest groundwater footprints, which highlights that most of the groundwater stress is induced by crops meant for cattle feed. Our results are coherent with other studies in the High Plains but suggest lower groundwater stress in the Central Valley, likely due to artificial recharge from surface water diversions which were not taken into account in previous estimates. Uncertainties of recharge and irrigation application efficiency contribute the most to the total relative uncertainty of the groundwater footprint to aquifer area ratios. Our results and methodology will be useful for hydrologists, water resource managers, and policy makers concerned with which crops are causing the well-documented groundwater stress in semiarid to arid agricultural regions around the world.

Esnault, Laurent; Gleeson, Tom; Wada, Yoshihide; Heinke, Jens; Gerten, Dieter; Flanary, Elizabeth; Bierkens, Marc F. P.; van Beek, Ludovicus P. H.

2014-06-01

317

Evidence for Alleghenian brine migration in the central and southern Appalachians: implications for Mississippi valley-type sulfide mineralization  

Microsoft Academic Search

Authigenic K-feldspar has been found in rocks near Mississippi Valley-Type (MVT) sulfide mineralization in lower Paleozoic carbonate rocks of Pennsylvania, Maryland, Virginia, and Tennessee. Synthetic ⁴°Ar\\/³⁹Ar age spectra for the authigenic K-feldspar yield Carboniferous ages. Mass balance calculations indicate that the formation of the K-feldspar involved the flux of multiple pore volumes of fluid through the rocks. Estimates of vapor-liquid

P. P. Hearn; J. F. Sutter; M. J. Kunk; H. E. Belkin

1985-01-01

318

Stratigraphy of the Arriaga Palaeolithic sites. Implications for the geomorphological evolution recorded by thickened fluvial sequences within the Manzanares River valley (Madrid Neogene Basin, Central Spain)  

NASA Astrophysics Data System (ADS)

The Arriaga Palaeolithic sites, located within the Middle-Late Pleistocene thickened terrace (TCMZ: + 18-22 m) of the Manzanares River valley (Madrid, Central Spain), were subject to intensive archaeological and palaeontological prospecting during the 1980s. Compilation of documents from these old excavations, together with new geoarchaeological, sedimentological, pedological and geophysical data, allow us to locate the morpho-stratigraphic position of the analysed sites within the overall stratigraphy of the TCMZ. This thickened terrace comprises two main fluvial sequences (Lower and Upper) topped by a thick (2.5-5 m) alluvial-colluvial formation. The fluvial sequences are stacked in the study site located in the lowermost reach of the valley, but display complex inset relationships upstream, where they are individualized in two different terrace levels at + 18-22 and + 12-15 m. Terrace thickening was primarily controlled by synsedimentary subsidence caused by dissolution of the evaporitic substratum and locally influenced and backfed by tectonic activity. The regional analysis of the dated (TL and OSL) fluvial sequences containing Palaeolithic sites within the TCMZ, together with new TL dates provided in this study, indicate that the three sedimentary sequences in the TCMZ are time-transgressive valley-fill bodies. Terrace thickening started before the Last Interglacial Period (MIS 6 or older) and continued during whole MIS 5 (lower fluvial sequence) and MIS 4 (upper fluvial sequence) reaching the MIS 3 (top alluvial formation), the latter characterized by the accumulation of alluvial-colluvial sequences derived from the main tributaries and valley slopes. The TCMZ records the Middle-Late Pleistocene boundary, but also the transition between the Lower and Middle Palaeolithic periods during the Late MIS 5 (ca. 96 to 74 ka). The studied Arriaga sites contain evolved Lower Palaeolithic industry (evolved Acheulean techno-complexes) and warm faunal assemblages located within the Lower fluvial sequence, but apparently well constrained Middle Palaeolithic sites are placed within the Upper fluvial sequence at other upstream locations. Deposition of the thickened alluvium was mainly controlled by the upstream advance of dissolution-induced subsidence phenomena, blurring the impact of Late Pleistocene climatic cycles and producing time-transgressive longitudinal valley-fill bodies (i.e. sedimentary sequences). Late Quaternary climatic changes only seem to control the incision/aggradation cycles after the termination of the TCMZ from the Late MIS 3. Dates related to the development of younger inset terraces indicate that they are apparently linked with cold Heinrich events H4 to H1. These younger inset terraces yield cold faunal assemblages and abundant Middle Palaeolithic "Mousterian" assemblages.

Silva, P. G.; López-Recio, M.; Tapias, F.; Roquero, E.; Morín, J.; Rus, I.; Carrasco-García, P.; Giner-Robles, J. L.; Rodríguez-Pascua, M. A.; Pérez-López, R.

2013-08-01

319

Natural heat storage in a brine-filled solar pond in the Tully Valley of central New York  

USGS Publications Warehouse

The Tully Valley, located in southern Onondaga County, New York, has a long history of unusual natural hydrogeologic phenomena including mudboils (Kappel, 2009), landslides (Tamulonis and others, 2009; Pair and others, 2000), landsurface subsidence (Hackett and others, 2009; Kappel, 2009), and a brine-filled sinkhole or “Solar pond” (fig. 1), which is documented in this report. A solar pond is a pool of salty water (brine) which stores the sun’s energy in the form of heat. The saltwater naturally forms distinct layers with increasing density between transitional zones (haloclines) of rapidly changing specific conductance with depth. In a typical solar pond, the top layer has a low salt content and is often times referred to as the upper convective zone (Lu and others, 2002). The bottom layer is a concentrated brine that is either convective or temperature stratified dependent on the surrounding environment. Solar insolation is absorbed and stored in the lower, denser brine while the overlying halocline acts as an insulating layer and prevents heat from moving upwards from the lower zone (Lu and others, 2002). In the case of the Tully Valley solar pond, water within the pond can be over 90 degrees Fahrenheit (°F) in late summer and early fall. The purpose of this report is to summarize observations at the Tully Valley brine-filled sinkhole and provide supplemental climate data which might affect the pond salinity gradients insolation (solar energy).

Hayhurst, Brett; Kappel, William M.

2014-01-01

320

Boundary of the Eagle River Watershed Valley-Fill Aquifer, Eagle County, North-Central Colorado, 2006-2007  

USGS Publications Warehouse

This vector data set delineates the approximate boundary of the Eagle River watershed valley-fill aquifer (ERWVFA). This data set was developed by a cooperative project between the U.S. Geological Survey, Eagle County, the Eagle River Water and Sanitation District, the Town of Eagle, the Town of Gypsum, and the Upper Eagle Regional Water Authority. This project was designed to evaluate potential land-development effects on groundwater and surface-water resources so that informed land-use and water management decisions can be made. The boundary of the ERWVFA was developed by combining information from two data sources. The first data source was a 1:250,000-scale geologic map of the Leadville quadrangle developed by Day and others (1999). The location of Quaternary sediments was used as a first approximation of the ERWVFA. The boundary of the ERWVFA was further refined by overlaying the geologic map with Digital Raster Graphic (DRG) scanned images of 1:24,000 topographic maps (U.S. Geological Survey, 2001). Where appropriate, the boundary of the ERWVFA was remapped to correspond with the edge of the valley-fill aquifer marked by an abrupt change in topography at the edge of the valley floor throughout the Eagle River watershed. The boundary of the ERWVFA more closely resembles a hydrogeomorphic region presented by Rupert (2003, p. 8) because it is based upon general geographic extents of geologic materials and not on an actual aquifer location as would be determined through a rigorous hydrogeologic investigation.

Rupert, Michael G.; Plummer, L. Niel

2009-01-01

321

Earthquake recurrence and fault behavior on the Homestead Valley fault -- Central segment of the 1992 Landers surface rupture sequence  

SciTech Connect

The 1992 M 7.5 Landers earthquake produced complex surface rupture on sections of the previously mapped Johnson Valley, Homestead Valley, and Emerson faults. The earthquake has raised questions about new faulting, characteristic earthquakes, and fault segmentation. To address these issues the authors initiated a study of both ruptured and unruptured fault segments, and report initial observations on the Homestead Valley fault (HVF). The authors site is located at the distal end of a large alluvial fan where 1992 right slip was 3 m, vertical slip was 40 cm, and the rupture followed pre-existing NE-facing scarps. Two trenches provide clear evidence of the two most recent pre-1992 surface faulting events. The trenches exposed alluvial fan and scarp derived colluvial deposits that are displaced and locally warped by both vertical strike-slip and low angle reverse-oblique( )-slip faults. At the main fault trace two pre-1992 colluvial wedges overlie a distinctive Bt soil horizon of late( ) Pleistocene age. Colluvium from the penultimate event has weak soil development, indicating a Holocene age for this faulting; apparent vertical displacement from this event is 35 cm, essentially the same as 1992. Preliminary observations indicate that recurrence of large magnitude earthquakes on faults of the Eastern California Shear Zone is one to two orders of magnitude longer than on major faults of the San Andreas system. The length of the HVF is short for this amount of offset, which suggests prior events may have also involved the rupture of multiple fault segments.

Cinti, F.R. (ING, Rome (Italy)); Fumal, T.E.; Garvin, C.D.; Hamilton, J.C.; Powers, T.J.; Schwartz, D.P. (Geological Survey, Menlo Park, CA (United States))

1993-04-01

322

Map of water table in Solomon River valley, Waconda Lake to Solomon, north-central Kansas, May 1980  

USGS Publications Warehouse

A map of the water table in the Solomon River valley from Waconda Lake to Solomon presents current (1980) data on water levels in the unconsolidated deposits. The Solomon River, which originates in western Kansas, flows southeastward from Waconda Lake to its confluence with the Smoky Hill River at Solomon. In the study area, its valley is incised into consolidated rocks that are composed mostly of shale and limestone. The unconsolidated deposits in the valley underlie the flood plain and the terrace. The alluvial deposits generally consist of gravel and sand, grading upward to sand and silt, with clay lenses interbedded throughout. Thickness of the deposits may be as much as 70 feet. Ground water in the unconsolidated deposits is a principal source of supply for domestic, stock, and irrigation use. Water-table contours indicate that ground water moves from the alluvial deposits to the stream. Thus, the Solomon River gains in flow through most of the reach. Water-level measurements for this study were made during the spring of 1980, prior to the irrigation season. (USGS)

Reed, Thomas B.

1983-01-01

323

Mortality survey on HIV\\/AIDS-related deaths in HIV epidemic regions caused by contaminated plasma donation in central China  

Microsoft Academic Search

The objective of our study was to understand the trend of AIDS deaths and the impact of AIDS-related deaths on the local mortality rate in seven villages in Shangcai County, Henan Province. A retrospective study survey among all deaths was conducted through household visits from 1 January 1995 to 31 October 2007 in seven administrative villages in Shangcai County of

Dongmin Li; Helen Chen; Xin Gao; Lu Wang; Zhe Wang; Zhaolin Cui; Luping Song; Wensheng He; Shuiwang Wang; Changkuan Chen; Ning Wang

2010-01-01

324

Regional soil geochemistry in the Ojailen Valley: a realm dominated by the industrial and mining city of Puertollano (South Central Spain)  

NASA Astrophysics Data System (ADS)

Regional soil geochemistry in the Ojailén Valley: a realm dominated by the industrial and mining city of Puertollano (South Central Spain). Authors: Miguel A. López-Berdonces¹; Sergio Fernández Calderón¹; Pablo Higueras¹; José María Esbrí¹; Beatriz González-Corrochano¹; Eva Mª García-Noguero¹; Alba Martínez-Coronado¹; Carolina García Noguero¹ ¹Instituto de Geología Aplicada, Universidad de Castilla La Mancha, Almadén 13400 (Spain). Ojailén Valley is situated in South Central of Spain, an area where livestock, agriculture, mining and industry coexist. This work tries to assess the relationships between these activities and local environmental compartments: water, soils and heavy metal contents, and establish the most appropriate methodology of sample treatment and analytical techniques that can be employed on this kind of studies. For soil geochemistry, 152 samples were taken at two different depths, one at surface layer and another at 20 cm depth, and establish relationships between them and the possible sources. For this purpose, we determine soil parameters (pH, conductivity and organic matter) and total metal contents by Energy Dispersion of X Ray Fluorescence (EDXRF). Samples with higher nickel contents were analyzed with Inductive Coupled Plasma Spectroscopy (ICP-OES) after acid digestion. The study of surface waters includes 18 samples along the river and tributaries near mining and industrial areas. Water analysis was performed by ICP-OES. Soil samples shows pH between 6 and 8.5, highest located near on the east part of the valley, in the vicinity of petrochemical complex. Conductivity values show higher levels (1600 µS cm¯¹) in the vicinity of Puertollano and the industrial sites. Local reference value (LRV) for contaminated soils were determined according to the methodology proposed by Jimenez-Ballesta et al. (2010), using the equation: LRV=GM + 2SD, where LRV: Local Reference Value, GM: Geometric Mean, SD: Standard Deviation. Trace metals values are significantly higher than calculated LRV, especially for Zn, Pb, (Average content: 230 mg kg¯¹ and 249.9 mg kg¯¹ respectively), probable due to Pb-Zn mining in the nearest Alcudia valley. Other elements seem to be influenced by petrochemical industry (Ni, V, and Cu) with LRV: 199.9 mg kg¯¹, 39.2 mg kg¯¹ and 184.2 mg kg¯¹ respectively. Most water samples have metal contents higher than levels for drinking water (WHO, 2006), especially Fe and Pb with 20 µg l¯¹ and 10 µg l¯¹ respectively. Higher metal contents were located on three different sites: downstream an open-pit coal mine, in stagnant water where we can find an old sewage treatment plant, and downstream a photovoltaic plant built in 2008. We can consider that Ojailén Valley is not an area with high contents in heavy metals in the environment, but Puertollano and its petrochemical complex have contents in Pb, Zn, Cu, As, Ni above the LRV. A comparison of results obtained by ICP-MS and XRF related to Pb, Zn, Cr, Ni in thirty-four selected samples, we can conclude that both techniques are qualitatively agree, although XRF cannot be considered suitable for establishing reference legal limits. References Jiménez-Ballesta, R; Conde-Bueno,P; Martin-Rubí,J.A.; García-Jímenez,R. 2010. Geochemical baseline contents levels and soil quality reference values of trace elements in soils from the Mediterranean (Castilla-La Mancha, Spain). Central European Journal of Geosciences 2, 441-454. WHO2006. Guidelines for drinking- water quality, Vol.1, 3rd edition incorporating 1st and 2nd addenda. (http//www.who.int/entity/water_sanitation_health/dwq/fulltext.pdf) Geneve, Suiza.

López-Berdonces, Miguel; Fernandez-Calderón, Sergio; Higueras, Pablo; María Esbrí, Jose; Gonzalez-Corrochano, Beatríz; García-Noguero, Eva Mª; Martínez-Coronado, Alba; García-Noguero, Carolina

2013-04-01

325

Digital tabulation of stratigraphic data from oil and gas wells in Cuyama Valley and surrounding areas, central California  

USGS Publications Warehouse

Stratigraphic information from 391 oil and gas exploration wells from Cuyama Valley, California, and surrounding areas are herein compiled in digital form from reports that were released originally in paper form. The Cuyama Basin is located within the southeasternmost part of the Coast Ranges and north of the western Transverse Ranges, west of the San Andreas fault. Knowledge of the location and elevation of stratigraphic tops of formations throughout the basin is a first step toward understanding depositional trends and the structural evolution of the basin through time, and helps in understanding the slip history and partitioning of slip on San Andreas and related faults.

Sweetkind, Donald S.; Bova, Shiera C.; Langenheim, Victoria E.; Shumaker, Lauren E.; Scheirer, Daniel S.

2013-01-01

326

Comagmatic contact relationships between the Rock Creek Gabbro and Round Valley Peak granodiorite, central Sierra Nevada, CA  

SciTech Connect

The Rock Creek Gabbro (RCG) in Little Lakes Valley, near Tom's Place, CA abuts three granodiorites with distinctive contact characteristics. Against within a cm in most places. The contact with Round Valley Peak (RVP) on the north, however, is a zone at least 3 km wide and records a mode of mafic magmatic enclave formation. A northward traverse of the zone begins 300--400 m within the RCG with progressively lighter, though still uniform rock. Next is a 100--200m wide jumble of sharp-edged angular 10--30m gabbroic xenoliths, variable in grainsize and plastic deformation and interspersed with stretched partially disaggregated enclaves in normal RVP granodiorite. Xenoliths are essentially absent from the RVP from here north; stretched enclaves with very consistent strikes paralleling (within 20[degree]) the mapped RCG-RVP contact and high angle dips (70--90[degree]), occur singly and in dense swarms and fall from 4% to 0.5% of outcrop area in the remaining traverse. Rock Creek gabbros including xenoliths at the contact cluster chemically with RVP enclaves on all major and trace element plots, suggesting a common parentage; some of each group show evidence of plagioclase flotation. Trace element data (esp. Zr/Nb) suggests that fractional crystallization dominates mixing in the evolution of the gabbroic/enclave magma.

Christensen, C.C.; Bown, C.J. (Hampshire College, Amherst, MA (United States). School of Natural Science)

1993-03-01

327

A regression model for the temporal development of soil pipes and associated gullies in the alluvial-fill valley of the Rio Puerco, central New Mexico  

NASA Technical Reports Server (NTRS)

On Mars, the association of gullied escarpments and chaotic terrain is evidence for failure and scarp retreat of poorly consolidated materials. Some martian gullies have no surface outlets and may have drained through subterranean channels. Similar features, though on a much smaller scale, can be seen in alluvium along terrestrial river banks in semiarid regions, such as the Rio Puerco Valley of central New Mexico. Many of the escarpments along the Rio Puerco are developing through formation of collapse gullies, which drain through soil pipes. Gully development can be monitored on aerial photographs taken in 1935, 1962, and 1980. A regression model was developed to quantify gully evolution over a known time span. Soil pipes and their associated collapse gullies make recognizable signatures on the air photos. The areal extent of this signature can be normalized to the scarp length of each pipe-gully system, which makes comparisons between systems possible.

Condit, C. D.; Elston, W. E.

1984-01-01

328

Late Pleistocene Terraces in River Valleys of the Central Russian Plain: Morphology, Structure and History of Development  

NASA Astrophysics Data System (ADS)

Morphology and sedimentary composition of low terraces of the Seim (the middle Dnieper catchment) and Khoper (the middle Don catchment) rivers were studied in the field (DGPS topographic profiling, hand and mechanical coring, examination of natural exposures) and in laboratory (grain size analysis, spore-pollen composition, 14C and OSL dating, microscopic study of quartz grains). Archaeological data have also been taken into account. It was found that Late Pleistocene river terraces were subject to complex reworking after the alluvial sedimentation had finished. Terraces may therefore contain sediments of different origin and terrace levels may vary according to the post-alluvial reworking. To establish terrace sedimentation mechanisms we supplemented lithological data collected in the field with quartz grains morphoscopy technique - microscopic study of quartz grains surfaces. The results exhibit wide participation of aeolian and slope wash sediments in terrace deposits, deep aeolian reworking of terrace alluvium during LGM that could be possible due to ground water lowering because of deep pre-LGM incision of rivers. The main difficulty in interpretation of morphoscopic results is that aeolian signals are sometimes not clear due to short duration of wind action over alluvial sands. River incision was detected within the interval since 50-60 to 25-30 ka BP (cal). High runoff increase is proposed as the reason of this incision, which is illustrated by formation of "big meanders" (macromeanders) in river valleys. There were probably several time spans of high runoff divided by low runoff intervals. By the time of LGM rivers had already been incised down to the modern river levels or deeper. The cryoaridic LGM time (20-23 ka BP cal) makes the most pronounced low runoff interval. After LGM, the last high runoff epoch started, which is dated to 13-18(19) ka BP (cal). Numerous now relict macromeanders were formed in river valleys at that time and considerable portions of modern floodplains were established. So the morphology of river valleys indicates contrasting runoff variations being the characteristic feature of the Valdai (Weichselian) cold stage.

Matlakhova, Ekaterina; Panin, Andrey

2014-05-01

329

Three-dimensional hydrogeologic framework model for use with a steady-state numerical ground-water flow model of the Death Valley regional flow system, Nevada and California  

USGS Publications Warehouse

The U.S. Geological Survey, in cooperation with the Department of Energy and other Federal, State, and local agencies, is evaluating the hydrogeologic characteristics of the Death Valley regional ground-water flow system. The ground-water flow system covers an area of about 100,000 square kilometers from latitude 35? to 38?15' North to longitude 115? to 118? West, with the flow system proper comprising about 45,000 square kilometers. The Death Valley regional ground-water flow system is one of the larger flow systems within the Southwestern United States and includes in its boundaries the Nevada Test Site, Yucca Mountain, and much of Death Valley. Part of this study includes the construction of a three-dimensional hydrogeologic framework model to serve as the foundation for the development of a steady-state regional ground-water flow model. The digital framework model provides a computer-based description of the geometry and composition of the hydrogeologic units that control regional flow. The framework model of the region was constructed by merging two previous framework models constructed for the Yucca Mountain Project and the Environmental Restoration Program Underground Test Area studies at the Nevada Test Site. The hydrologic characteristics of the region result from a currently arid climate and complex geology. Interbasinal regional ground-water flow occurs through a thick carbonate-rock sequence of Paleozoic age, a locally thick volcanic-rock sequence of Tertiary age, and basin-fill alluvium of Tertiary and Quaternary age. Throughout the system, deep and shallow ground-water flow may be controlled by extensive and pervasive regional and local faults and fractures. The framework model was constructed using data from several sources to define the geometry of the regional hydrogeologic units. These data sources include (1) a 1:250,000-scale hydrogeologic-map compilation of the region; (2) regional-scale geologic cross sections; (3) borehole information, and (4) gridded surfaces from a previous three-dimensional geologic model. In addition, digital elevation model data were used in conjunction with these data to define ground-surface altitudes. These data, properly oriented in three dimensions by using geographic information systems, were combined and gridded to produce the upper surfaces of the hydrogeologic units used in the flow model. The final geometry of the framework model is constructed as a volumetric model by incorporating the intersections of these gridded surfaces and by applying fault truncation rules to structural features from the geologic map and cross sections. The cells defining the geometry of the hydrogeologic framework model can be assigned several attributes such as lithology, hydrogeologic unit, thickness, and top and bottom altitudes.

Belcher, Wayne R.; Faunt, Claudia C.; D'Agnese, Frank A.

2002-01-01

330

An 11 000-year-long record of fire and vegetation history at Beaver Lake, Oregon, central Willamette Valley  

NASA Astrophysics Data System (ADS)

High-resolution macroscopic charcoal and pollen analysis were used to reconstruct an 11 000-year-long record of fire and vegetation history from Beaver Lake, Oregon, the first complete Holocene paleoecological record from the floor of the Willamette Valley. In the early Holocene (ca 11 000-7500 calendar years before present [cal yr BP]), warmer, drier summers than at present led to the establishment of xeric woodland of Quercus, Corylus, and Pseudotsuga near the site. Disturbances (i.e., floods, fires) were common at this time and as a result Alnus rubra grew nearby. High fire frequency occurred in the early Holocene from ca 11 200-9300 cal yr BP. Riparian forest and wet prairie developed in the middle Holocene (ca 7500 cal yr BP), likely the result of a decrease in the frequency of flooding and a shift to effectively cooler, wetter conditions than before. The vegetation at Beaver Lake remained generally unchanged into the late Holocene (from 4000 cal yr BP to present), with the exception of land clearance associated with Euro-American settlement of the valley (ca 160 cal yr BP). Middle-to-late Holocene increases in fire frequency, coupled with abrupt shifts in fire-episode magnitude and charcoal composition, likely indicate the influence anthropogenic burning near the site. The paleoecological record from Beaver Lake, and in particular the general increase in fire frequency over the last 8500 years, differs significantly from other low-elevation sites in the Pacific Northwest, which suggests that local controls (e.g., shifts in vegetation structure, intensification of human land-use), rather than regional climatic controls, more strongly influenced its environmental history.

Walsh, Megan K.; Pearl, Christopher A.; Whitlock, Cathy; Bartlein, Patrick J.; Worona, Marc A.

2010-05-01

331

An 11??000-year-long record of fire and vegetation history at Beaver Lake, Oregon, central Willamette Valley  

USGS Publications Warehouse

High-resolution macroscopic charcoal and pollen analysis were used to reconstruct an 11??000-year-long record of fire and vegetation history from Beaver Lake, Oregon, the first complete Holocene paleoecological record from the floor of the Willamette Valley. In the early Holocene (ca 11??000-7500 calendar years before present [cal??yr??BP]), warmer, drier summers than at present led to the establishment of xeric woodland of Quercus, Corylus, and Pseudotsuga near the site. Disturbances (i.e., floods, fires) were common at this time and as a result Alnus rubra grew nearby. High fire frequency occurred in the early Holocene from ca 11??200-9300??cal??yr??BP. Riparian forest and wet prairie developed in the middle Holocene (ca 7500??cal??yr??BP), likely the result of a decrease in the frequency of flooding and a shift to effectively cooler, wetter conditions than before. The vegetation at Beaver Lake remained generally unchanged into the late Holocene (from 4000??cal??yr??BP to present), with the exception of land clearance associated with Euro-American settlement of the valley (ca 160??cal??yr BP). Middle-to-late Holocene increases in fire frequency, coupled with abrupt shifts in fire-episode magnitude and charcoal composition, likely indicate the influence anthropogenic burning near the site. The paleoecological record from Beaver Lake, and in particular the general increase in fire frequency over the last 8500??years, differs significantly from other low-elevation sites in the Pacific Northwest, which suggests that local controls (e.g., shifts in vegetation structure, intensification of human land-use), rather than regional climatic controls, more strongly influenced its environmental history. ?? 2010 Elsevier Ltd.

Walsh, M.K.; Pearl, C.A.; Whitlock, C.; Bartlein, P.J.; Worona, M.A.

2010-01-01

332

THE SLOW DEATH (OR REBIRTH?) OF EXTENDED STAR FORMATION IN z {approx} 0.1 GREEN VALLEY EARLY-TYPE GALAXIES  

SciTech Connect

UV observations in the local universe have uncovered a population of early-type galaxies with UV flux consistent with low-level recent or ongoing star formation. Understanding the origin of such star formation remains an open issue. We present resolved UV-optical photometry of a sample of 19 Sloan Digital Sky Survey (SDSS) early-type galaxies at z {approx} 0.1 drawn from the sample originally selected by Salim and Rich to lie in the bluer part of the green valley in the UV-optical color-magnitude diagram as measured by the Galaxy Evolution Explorer (GALEX). Utilizing high-resolution Hubble Space Telescope (HST) far-UV imaging provides unique insight into the distribution of UV light in these galaxies, which we call ''extended star-forming early-type galaxies'' (ESF-ETGs) because of extended UV emission that is indicative of recent star formation. The UV-optical color profiles of all ESF-ETGs show red centers and blue outer parts. Their outer colors require the existence of a significant underlying population of older stars in the UV-bright regions. An analysis of stacked SDSS spectra reveals weak LINER-like emission in their centers. Using a cross-matched SDSS DR7/GALEX GR6 catalog, we search for other green valley galaxies with similar properties to these ESF-ETGs and estimate that Almost-Equal-To 13% of dust-corrected green valley galaxies of similar stellar mass and UV-optical color are likely ESF-candidates, i.e., ESF-ETGs are not rare. Our results are consistent with star formation that is gradually declining in existing disks, i.e., the ESF-ETGs are evolving onto the red sequence for the first time, or with rejuvenated star formation due to accreted gas in older disks provided that the gas does not disrupt the structure of the galaxy and the resulting star formation is not too recent and bursty. ESF-ETGs may typify an important subpopulation of galaxies that can linger in the green valley for up to several Gyrs, based on their resemblance to nearby gas-rich green valley galaxies with low-level ongoing star formation.

Fang, Jerome J.; Faber, S. M. [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Salim, Samir [Department of Astronomy, Indiana University, Bloomington, IN 47404 (United States); Graves, Genevieve J. [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); Rich, R. Michael, E-mail: jjfang@ucolick.org [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)

2012-12-10

333

Hydrologic and geologic characteristics of the Yucca Mountain site relevant to the performance of a potential repository: Day 1, Las Vegas, Nevada to Pahrump, Nevada: Stop 6A. Keane Wonder Spring and regional groundwater flow in the Death Valley region  

USGS Publications Warehouse

Yucca Mountain, located ~100 mi northwest of Las Vegas, Nevada, has been designated by Congress as a site to be characterized for a potential mined geologic repository for high-level radioactive waste. This field trip will examine the regional geologic and hydrologic setting for Yucca Mountain, as well as specific results of the site characterization program, The first day focuses on the regional seeing with emphasis on current and paleo hydrology, which are both of critical concern for predicting future performance of a potential repository. Morning stops will be in southern Nevada and afternoon stops will be in Death Valley. The second day will be spent at Yucca Mountain. The filed trip will visit the underground testing sites in the "Exploratory Studies Facility" and the "Busted Butte Unsaturated Zone Transport Field Test" plus several surface-based testing sites. Much of the work at the site has concentrated on studies of the unsaturated zone, and element of the hydrologic system that historically has received little attention. Discussions during the second day will comprise selected topics of Yucca Mountain geology, mic hazard in the Yucca Mountain area. Evening discussions will address modeling of regional groundwater flow, the geology and hydrology of Yucca Mountain to the performance of a potential repository. Day 3 will examine the geologic framework and hydrology of the Pahute Mesa-Oasis Valley Groundwater Basin and then will continue to Reno via Hawthorne, Nevada and the Walker Lake area.

Steinkampf, W.C.

2000-01-01

334

Hydrology and model of North Fork Solomon River Valley, Kirwin Dam to Waconda Lake, north-central Kansas  

USGS Publications Warehouse

The alluvial valley of the North Fork Solomon River is an important agricultural area. Reservoir releases diverted below Kirwin Dam are the principal source of irrigation water. During the 1970'S, severe water shortages occurred in Kirwin Reservoir and other nearby reservoirs as a result of an extended drought. Some evidence indicates that surface-water shortages may have been the result of a change in the rainfall-runoff relationship. Examination of the rainfall-runoff relationship shows no apparent trend from 1951 to 1968, but annual records from 1969 to 1976 indicate that deficient rainfall occurred during 6 of the 8 years. Ground water from the alluvial aquifer underlying the river valley also is used extensively for irrigation. Utilization of ground water for irrigation greatly increased from about 200 acre-feet in 1955 to about 12,300 acre-feet in 1976. Part of the surface water diverted for irrigation has percolated downward into the aquifer raising the ground-water level. Ground-water storage in the aquifer increased from 230,000 acre-feet in 1946 to 275,000 acre-feet in 1976-77. A digital model was used to simulate the steady-state conditions in the aquifer prior to closure of Kirwin Dam. Model results indicated that precipitation was the major source of recharge to the aquifer. The effective recharge, or gain from precipitation minus evapotranspiration, was about 11,700 acre-feet per year. The major element of discharge from the aquifer was leakage to the river. The simulated net leakage (leakage to the river minus leakage from the river) was about 11,500 acre-feet per year. The simulated value is consistent with the estimated gain in base flow of the river within the area modeled. Measurements of seepage used to determine gain and loss to the stream were made twice during 1976. Based on these measurements and on base-flow periods identified from hydrographs, it was estimated that the ground-water discharge to the stream has increased about 4,000 acre-feet per year from 1946 to 1976. During the same period, ground water withdrawn from the aquifer increased 12,100 acre-feet per year. Hydrographs of water levels in wells indicate some withdrawal from aquifer storage during 1976, possibly as a combined result of below-normal rainfall and greatly increased pumpage. The analysis of data is inconclusive as to whether the aquifer can sustain increased groundwater development. However, the analysis does indicate that the aquifer could sustain withdrawals at the 1976 rate for several consecutive years of drought similar to the 1976 conditions.

Jorgensen, Donald G.; Stullken, Lloyd E.

1981-01-01

335

Sedimentology and permeability architecture of Atokan Valley-Fill natural gas reservoirs, Boonsville Field, North-Central Texas  

SciTech Connect

The Boonsville {open_quotes}Bend Conglomerate{close_quotes} gas field in Jack and Wise Counties comprises numerous thin (10-20 ft) conglomeratic sandstone reservoirs within an approximately 1,000-ft-thick section of Atokan strata. Reservoir sandstone bodies commonly overlie sequence-boundary unconformities and exhibit overall upward-fining grain-size trends. Many represent incised valley-fill deposits that accumulated during postunconformity base-level rise. This stratal architectures is repeated at several levels throughout the Bend Conglomerate, suggesting that sediment accumulation occurred in a moderate- to low-accommodation setting and that base level fluctuated frequently. The reservoir units were deposited by low-sinuosity fluvial processes, causing a hierarchy of bed forms and grain-avalanche bar-front processes to produce complex grain-size variations. Permeability distribution is primarily controlled by depositional factors but may also be affected by secondary porosity created by the selective dissolution of chert clasts. High-permeability zones ({approximately}2.8 darcys) are characterized by macroscopic vugs composed of clast-shaped moldic voids ({approximately}5 mm in diameter). Tight (low-permeability) zones are heavily cemented by silica, calcite, dolomite, and ankerite and siderate cements. Minipermeameter, x-radiography, and petrographic studies and facies analysis conducted on cores from two Bend Conglomerate reservoirs (Threshold Development Company, I.G. Yates 33, and OXY U.S.A. Sealy {open_quotes}C{close_quotes} 2) illustrate the hierarchy of sedimentological and diagenetic controls on permeability architecture.

Burn, M.J.; Carr, D.L. [Univ. of Texas, Austin, TX (United States); Stuede, J. [Scientific Measurement Systems, Inc., Austin, TX (United States)

1994-12-31

336

Thrust faults of southern Diamond Mountains, central Nevada: Implications for hydrocarbons in Diamond Valley and at Yucca Mountain  

SciTech Connect

Overmature Mississippian hydrocarbon source rocks in the southern Diamond Mountains have been interpreted to be a klippe overlying less mature source rocks and represented as an analogy to similar conditions near Yucca Mountain (Chamberlain, 1991). Geologic evidence indicates an alternative interpretation. Paleogeologic mapping indicates the presence of a thrust fault, referred to here as the Moritz Nager Thrust Fault, with Devonian rocks emplaced over Permian to Mississippian strata folded into an upright to overturned syncline, and that the overmature rocks of the Diamond Mountains are in the footwall of this thrust. The upper plate has been eroded from most of the Diamond Mountains but remnants are present at the head of Moritz Nager Canyon and at Sentinel Mountain. Devonian rocks of the upper plate comprised the earliest landslide megabreccia. Later, megabreccias of Pennsylvanian and Permian rocks of the overturned syncline of the lower plate were deposited. By this interpretation the maturity of lower-plate source rocks in the southern Diamond Mountains, which have been increased by tectonic burial, is not indicative of conditions in Diamond Valley, adjacent to the west, where upper-plate source rocks might be present in generating conditions. The interpretation that overmature source rocks of the Diamond Mountains are in a lower plate rather than in a klippe means that this area is an inappropriate model for the Eleana Range near Yucca Mountain.

French, D.E.

1993-04-01

337

Measurement of evapotranspiration in phreatophyte areas, Smith Creek Valley and Carson Desert, west-central Nevada, 1983  

USGS Publications Warehouse

Evaporation from bare soils and evapotranspiration from phreatophyte areas are major sources of natural groundwater loss in the Great Basin region of Nevada, Utah, and adjacent states. This study evaluated three methods for determining evapotrans- piration under natural conditions and provides quantitative estimates of evapotranspiration. Two of the methods used, the eddy-correlation and the Bowen ratio methods, measure actual evapotrans- piration under natural conditions, whereas the Penman method measures potential evapotranspiration. Phreatophytes at the Smith Creek Valley site (near Austin, Nev.) consist mainly of rabbitbrush. Actual evapotranspiration for 1983 at this site, estimated by the eddy-correlation method, was about 0.32 m/yr, compared with a calculated potential evapotrans- piration (measured by the Penman method) of about 2.0 m/yr. Phreatophytes at the Carson Desert site (near Fallon, Nev.) consist predominantly of greasewood. Estimated actual evapotranspiration at this site for 1983 (eddy-correlation method) was 0.18 m/yr, compared with a calculated potential evapotranspiration (Penman method) of 1.8 m/yr.

Carman, R. L.

1993-01-01

338

Evidence for Late-Paleozoic brine migration in Cambrian carbonate rocks of the central and southern Appalachians: Implications for Mississippi Valley-type sulfide mineralization  

NASA Astrophysics Data System (ADS)

Many Lower Paleozoic limestones and dolostones in the Valley and Ridge province of the central and southern Appalachians contain 10 to 25 weight percent authigenic potassium feldspar. This was considered to be a product of early diagenesis, however, 40Ar /39Ar analyses of overgrowths on detrital K-feldspar in Cambrian carbonate rocks from Pennsylvania, Maryland, Virginia, and Tennessee yield Late Carboniferous-Early Permian ages (278-322 Ma). Simple mass balance calculations suggest that the feldspar could not have formed isochemically, but required the flux of multiple pore volumes of fluid through the rocks, reflecting regional fluid migration events during the Late-Paleozoic Alleghanian orogeny. Microthermometric measurements of fluid inclusions in overgrowths on detrital K-feldspar and quartz grains from unmineralized rocks throughout the study area indicate homogenization temperatures from 100° to 200°C and freezing point depressions of -14° to -18.5°C (18-21 wt.% NaCl equiv). The apparent similarity of these fluids to fluid inclusions in ore and gangue minerals of nearby Mississippi Valley-type (MVT) deposits suggests that the regional occurrences of authigenic K-feldspar and MVT mineralization may be genetically related. This hypothesis is supported by the discovery of authigenic K-feldspar intergrown with sphalerite in several mines of the Mascot-Jefferson City District, E. Tennessee. Regional potassic alteration in unmineralized carbonate rocks and localized occurrences of MVT mineralization are both explainable by a gravity-driven flow model, in which deep brines migrate towards the basin margin under a hydraulic gradient established during the Alleghanian orogeny. The authigenic K-feldspar may reflect the loss of K during disequilibrium cooling of the ascending brines. MVT deposits are probably localized manifestations of the same migrating fluids, occurring where the necessary physical and chemical traps are present.

Hearn, Paul P., Jr.; Sutter, John F.; Belkin, Harvey E.

1987-05-01

339

Groundwater Quality, Age, and Probability of Contamination, Eagle River Watershed Valley-Fill Aquifer, North-Central Colorado, 2006-2007  

USGS Publications Warehouse

The Eagle River watershed is located near the destination resort town of Vail, Colorado. The area has a fastgrowing permanent population, and the resort industry is rapidly expanding. A large percentage of the land undergoing development to support that growth overlies the Eagle River watershed valley-fill aquifer (ERWVFA), which likely has a high predisposition to groundwater contamination. As development continues, local organizations need tools to evaluate potential land-development effects on ground- and surface-water resources so that informed land-use and water management decisions can be made. To help develop these tools, the U.S. Geological Survey (USGS), in cooperation with Eagle County, the Eagle River Water and Sanitation District, the Town of Eagle, the Town of Gypsum, and the Upper Eagle Regional Water Authority, conducted a study in 2006-2007 of the groundwater quality, age, and probability of contamination in the ERWVFA, north-central Colorado. Ground- and surface-water quality samples were analyzed for major ions, nutrients, stable isotopes of hydrogen and oxygen in water, tritium, dissolved gases, chlorofluorocarbons (CFCs), and volatile organic compounds (VOCs) determined with very low-level laboratory methods. The major-ion data indicate that groundwaters in the ERWVFA can be classified into two major groups: groundwater that was recharged by infiltration of surface water, and groundwater that had less immediate recharge from surface water and had elevated sulfate concentrations. Sulfate concentrations exceeded the USEPA National Secondary Drinking Water Regulations (250 milligrams per liter) in many wells near Eagle, Gypsum, and Dotsero. The predominant source of sulfate to groundwater in the Eagle River watershed is the Eagle Valley Evaporite, which is a gypsum deposit of Pennsylvanian age located predominantly in the western one-half of Eagle County.

Rupert, Michael G.; Plummer, L. Niel

2009-01-01

340

Evidence for late-paleozoic brine migration in Cambrian carbonate rocks of the central and southern Appalachians: implications for Mississippi Valley-type sulfide mineralization  

SciTech Connect

Many Lower Paleozoic limestones and dolostones in the Valley and Ridge province of the central and southern Appalachians contain 10 to 25 weight percent authigenic potassium feldspar. This was considered to be a product of early diagenesis, however, /sup 40/Ar//sup 39/Ar analyses of overgrowths on detrital K-feldspar in Cambrian carbonate rocks from Pennsylvania, Maryland, Virginia, and Tennessee yield Late Carboniferous-Early Permian ages (278-322 Ma). Simple mass balance calculations suggest the feldspar could not have formed isochemically, but required the flux of multiple pore volumes of fluid through the rocks, reflecting regional fluid migration events during the Late-Paleozoic Alleghanian orogeny. Microthermometric measurements of fluid inclusions in overgrowths on detrital K-feldspar and quartz grains from unmineralized rocks throughout the study area indicate homogenization temperatures from 100/sup 0/ to 200/sup 0/C and freezing point depressions of -14/sup 0/ to -18.5/sup 0/C. The apparent similarity of these fluids to fluid inclusions in ore and gangue minerals of nearby Mississippi Valley-type (MVT) deposits suggests that the regional occurrences of authigenic K-feldspar and MVT mineralization may be genetically related. This hypothesis is supported by the discovery of authigenic K-feldspar intergrown with sphalerite in several mines of the Mascot-Jefferson City District, E. Tennessee. Regional potassic alteration in unmineralized carbonate rocks and localized occurrences of MVT mineralization are both explainable by a gravity-driven flow model, in which deep brines migrate towards the basin margin under a hydraulic gradient established during the Alleghanian orogeny.

Hearn, P.P. Jr; Sutter, J.F.; Belkin, H.E.

1987-05-01

341

Evidence for Late-Paleozoic brine migration in Cambrian carbonate rocks of the central and southern Appalachians: Implications for Mississippi Valley-type sulfide mineralization  

USGS Publications Warehouse

Many Lower Paleozoic limestones and dolostones in the Valley and Ridge province of the central and southern Appalachians contain 10 to 25 weight percent authigenic potassium feldspar. This was considered to be a product of early diagenesis, however, 40Ar 39Ar analyses of overgrowths on detrital K-feldspar in Cambrian carbonate rocks from Pennsylvania, Maryland, Virginia, and Tennessee yield Late Carboniferous-Early Permian ages (278-322 Ma). Simple mass balance calculations suggest that the feldspar could not have formed isochemically, but required the flux of multiple pore volumes of fluid through the rocks, reflecting regional fluid migration events during the Late-Paleozoic Alleghanian orogeny. Microthermometric measurements of fluid inclusions in overgrowths on detrital K-feldspar and quartz grains from unmineralized rocks throughout the study area indicate homogenization temperatures from 100?? to 200??C and freezing point depressions of -14?? to -18.5??C (18-21 wt.% NaCl equiv). The apparent similarity of these fluids to fluid inclusions in ore and gangue minerals of nearby Mississippi Valley-type (MVT) deposits suggests that the regional occurrences of authigenic K-feldspar and MVT mineralization may be genetically related. This hypothesis is supported by the discovery of authigenic K-feldspar intergrown with sphalerite in several mines of the Mascot-Jefferson City District, E. Tennessee. Regional potassic alteration in unmineralized carbonate rocks and localized occurrences of MVT mineralization are both explainable by a gravity-driven flow model, in which deep brines migrate towards the basin margin under a hydraulic gradient established during the Alleghanian orogeny. The authigenic K-feldspar may reflect the loss of K during disequilibrium cooling of the ascending brines. MVT deposits are probably localized manifestations of the same migrating fluids, occurring where the necessary physical and chemical traps are present. ?? 1987.

Hearn, Jr. , P. P.; Sutter, J. F.; Belkin, H. E.

1987-01-01

342

Critical controlling of PRED system of oasis ecology in the arid region of central Asia: a case study of Keriya River Valley oases, Xinjiang  

NASA Astrophysics Data System (ADS)

Oases is a special ecosystem formed in arid climate and hungriness environment, in which resident, water and soil are the principal factor and exchanges of materials, energy and information are the main functional characteristics. The oases regions in central Asia are not only the basilic cradle of civilization of human beings, but also the important strategic places in world growing awareness of the potential benefits. We choose Keriya River Basin oases in south of Xinjiang as a case to study critical controlling of Oases Evolution, Based on the theories and methods used for environmental geology, physical geography, land resource research, and oases ecology. This study try to indicate the essential factors driving the oases ecosystem and the interactional dynamic mechanism in different scales and levels, confirm the optimal equilibrium aggregate of harmonious development between Population, Resources, Environment and Development, and establish the critical controlling pattern of sustainable development. We advance the indicator system to research the evolution of the PRED System of oases in Keriya River valley oases, in basis of the information derived from the field investigation and local materials. According to inquisitional result based on technical support of Geographic Information System (GIS) and Remote Sense (RS), the comparisons and analyses are carried out in land use at the upper reaches, vegetation change in the middle reaches, and desertification at the lower reaches, which narrates the regulations of Keriya River Valley oases land cover dynamic change. The main land cover types represent distinct characteristics of the local place. On the basis of field survey and statistical data, we use ARCINFO software to preprocess these data and the 2 TM satellite images. Through analyzing these images resulting from post-classification compare, we sums up the concrete quantificational dynamic distributed data of 13 land types covering a span of 15 years and regulation of the local ecological environment system. It finally points out that the trend of Keriya River Valley oases desertification expansion is mainly related to two important reasons: impact of natural environment and impact of human activities. In order to improve the local ecological environment, people inhabited this

Chen, Rui; Liu, Jiaqi; Niu, Wenyuan; Deng, Xiangzheng; Mu, Guijin; Wagner, Mayke; Geldmacher, Karl

2003-07-01

343

Inferences on the hydrothermal system beneath the resurgent dome in Long Valley Caldera, east-central California, USA, from recent pumping tests and geochemical sampling  

USGS Publications Warehouse

Quaternary volcanic unrest has provided heat for episodic hydrothermal circulation in the Long Valley caldera, including the present-day hydrothermal system, which has been active over the past 40 kyr. The most recent period of crustal unrest in this region of east-central California began around 1980 and has included periods of intense seismicity and ground deformation. Uplift totaling more than 0.7 m has been centered on the caldera's resurgent dome, and is best modeled by a near-vertical ellipsoidal source centered at depths of 6-7 km. Modeling of both deformation and microgravity data now suggests that (1) there are two inflation sources beneath the caldera, a shallower source 7-10 km beneath the resurgent dome and a deeper source ???15 km beneath the caldera's south moat and (2) the shallower source may contain components of magmatic brine and gas. The Long Valley Exploration Well (LVEW), completed in 1998 on the resurgent dome, penetrates to a depth of 3 km directly above this shallower source, but bottoms in a zone of 100??C fluid with zero vertical thermal gradient. Although these results preclude extrapolations of temperatures at depths below 3 km, other information obtained from flow tests and fluid sampling at this well indicates the presence of magmatic volatiles and fault-related permeability within the metamorphic basement rocks underlying the volcanic fill. In this paper, we present recently acquired data from LVEW and compare them with information from other drill holes and thermal springs in Long Valley to delineate the likely flow paths and fluid system properties under the resurgent dome. Additional information from mineralogical assemblages in core obtained from fracture zones in LVEW documents a previous period of more vigorous and energetic fluid circulation beneath the resurgent dome. Although this system apparently died off as a result of mineral deposition and cooling (and/or deepening) of magmatic heat sources, flow testing and tidal analyses of LVEW water level data show that relatively high permeability and strain sensitivity still exist in the steeply dipping principal fracture zone penetrated at a depth of 2.6 km. The hydraulic properties of this zone would allow a pressure change induced at distances of several kilometers below the well to be observable within a matter of days. This indicates that continuous fluid pressure monitoring in the well could provide direct evidence of future intrusions of magma or high-temperature fluids at depths of 5-7 km. ?? 2003 Elsevier B.V. All rights reserved.

Farrar, C. D.; Sorey, M. L.; Roeloffs, E.; Galloway, D. L.; Howle, J. F.; Jacobson, R.

2003-01-01

344

Inferences on the hydrothermal system beneath the resurgent dome in Long Valley Caldera, east-central California, USA, from recent pumping tests and geochemical sampling  

NASA Astrophysics Data System (ADS)

Quaternary volcanic unrest has provided heat for episodic hydrothermal circulation in the Long Valley caldera, including the present-day hydrothermal system, which has been active over the past 40 kyr. The most recent period of crustal unrest in this region of east-central California began around 1980 and has included periods of intense seismicity and ground deformation. Uplift totaling more than 0.7 m has been centered on the caldera's resurgent dome, and is best modeled by a near-vertical ellipsoidal source centered at depths of 6-7 km. Modeling of both deformation and microgravity data now suggests that (1) there are two inflation sources beneath the caldera, a shallower source 7-10 km beneath the resurgent dome and a deeper source ˜15 km beneath the caldera's south moat and (2) the shallower source may contain components of magmatic brine and gas. The Long Valley Exploration Well (LVEW), completed in 1998 on the resurgent dome, penetrates to a depth of 3 km directly above this shallower source, but bottoms in a zone of 100°C fluid with zero vertical thermal gradient. Although these results preclude extrapolations of temperatures at depths below 3 km, other information obtained from flow tests and fluid sampling at this well indicates the presence of magmatic volatiles and fault-related permeability within the metamorphic basement rocks underlying the volcanic fill. In this paper, we present recently acquired data from LVEW and compare them with information from other drill holes and thermal springs in Long Valley to delineate the likely flow paths and fluid system properties under the resurgent dome. Additional information from mineralogical assemblages in core obtained from fracture zones in LVEW documents a previous period of more vigorous and energetic fluid circulation beneath the resurgent dome. Although this system apparently died off as a result of mineral deposition and cooling (and/or deepening) of magmatic heat sources, flow testing and tidal analyses of LVEW water level data show that relatively high permeability and strain sensitivity still exist in the steeply dipping principal fracture zone penetrated at a depth of 2.6 km. The hydraulic properties of this zone would allow a pressure change induced at distances of several kilometers below the well to be observable within a matter of days. This indicates that continuous fluid pressure monitoring in the well could provide direct evidence of future intrusions of magma or high-temperature fluids at depths of 5-7 km.

Farrar, Christopher D.; Sorey, Michael L.; Roeloffs, Evelyn; Galloway, Devin L.; Howle, James F.; Jacobson, Ronald

2003-10-01

345

Stable isotopes as indicators of sources and processes influencing nitrate distributions in dairy monitoring wells and domestic supply wells in the Central Valley, California  

NASA Astrophysics Data System (ADS)

Nitrate concentrations above the 10 mg/L NO3-N maximum contaminant level (MCL) have been found in many wells throughout the Central Valley, California. This area contains many possible anthropogenic nitrate sources including current and historic agriculture, private septic systems, municipal waste water, and confined animal feeding operations (primarily dairies). In order to better understand the potential contributions of dairy manure derived nitrate to both shallow and deep groundwater, we used a combined chemical, stable isotope, and age-dating approach for water samples collected from a network of shallow groundwater monitoring wells located on seven different dairies, and from a survey of approximately 200 deeper domestic supply wells (used for drinking water and dairy operations). Groundwater from shallow monitoring wells and deep supply wells was collected in two geographic regions. In the northern region, the lower San Joaquin Valley, the water table is shallow (2- 5 m below surface) and therefore considered highly vulnerable to contamination, while in the southern region, the Tulare Lake Basin, the water table is much deeper (20 - 30 m). Mean ?15N of nitrate in dairy monitoring wells in both the north and south regions was significantly higher than the mean ?15N measured in the deeper supply wells, and also showed greater variability. Mean ?15N and ?18O values measured in the deep supply wells were not significantly different between the north and south regions. Mean nitrate concentrations, ?15N, and ?18O were significantly higher in the northern (lower San Joaquin Valley) monitoring wells in comparison to the southern (Tulare Lake Basin) monitoring wells. Nitrate isotope measurements indicated that many of the northern monitoring wells had consistently high contributions of manure-derived nitrate to the shallow groundwater during the 16 month study. Monitoring wells located in relatively new dairies in the south region showed little evidence of manure-derived nitrate, while those located in much older dairies in the south region showed a very wide range of nitrate isotope values, indicating significant nitrate contributions from multiple sources including manure and industrial fertilizer and biological processing effects. Combined nitrate concentration and isotopic data from all the monitoring wells showed very little evidence of significant saturated-zone denitrification. Monitoring well networks within individual dairies showed wide ranges of nitrate concentrations, nitrate isotopic compositions, and geochemical compositions, confirming the heterogeneity of the nitrate loading across dairy facilities and indicating that measurements from any single monitoring well may not be representative of general groundwater quality downgradient of an individual dairy.

Young, M. B.; Harter, T.; Kendall, C.; Silva, S. R.; Esser, B. K.; Singleton, M. J.; Holstege, D.; Lockhart, K.; Applegate, O.

2011-12-01

346

Structural imprints at the front of the Chocó-Panamá indenter: Field data from the North Cauca Valley Basin, Central Colombia  

NASA Astrophysics Data System (ADS)

The northern Andes are a complex area where tectonics is dominated by the interaction between three major plates and accessory blocks, in particular, the Chocó-Panamá and Northern Andes Blocks. The studied Cauca Valley Basin is located at the front of the Chocó-Panamá Indenter, where the major Romeral Fault System, active since the Cretaceous, changes its kinematics from right-lateral in the south to left-lateral in the north. Structural studies were performed at various scales: DEM observations in the Central Cordillera between 4 and 5.7°N, aerial photograph analyses, and field work in the folded Oligo-Miocene rocks of the Serranía de Santa Barbara and in the flat-lying, Pleistocene Quindío-Risaralda volcaniclastic sediments interfingering with the lacustrine to fluviatile sediments of the Zarzal Formation. The data acquired allowed the detection of structures with a similar orientation at every scale and in all lithologies. These families of structures are arranged similarly to Riedel shears in a right-lateral shear zone and are superimposed on the Cretaceous Romeral suture. They appear in the Central Cordillera north of 4.5°N, and define a broad zone where 060-oriented right-lateral distributed shear strain affects the continental crust. The Romeral Fault System stays active and strain partitioning occurs among both systems. The southern limit of the distributed shear strain affecting the Central Cordillera corresponds to the E-W trending Garrapatas-Ibagué shear zone, constituted by several right-stepping, en-échelon, right-lateral, active faults and some lineaments. North of this shear zone, the Romeral Fault System strike changes from NNE to N. Paleostress calculations gave a WNW-ESE trending, maximum horizontal stress, and 69% of compressive tensors. The orientation of ?1 is consistent with the orientation of the right-lateral distributed shear strain and the compressive state characterizing the Romeral Fault System in the area: it bisects the synthetic and antithetic Riedels and is (sub)-perpendicular to the active Romeral Fault System. It is proposed that the continued movement of the Chocó-Panamá Indenter may be responsible for the 060-oriented right-lateral distributed shear strain, and may have closed the northern part of the Cauca Valley, thereby forming the Cauca Valley Basin. Conjugate extensional faults observed at surface in the flat-lying sediments of the Zarzal Formation and Quindío-Risaralda volcaniclastic Fan are associatedwith soft-sediment deformations. These faults are attributed to lateral spreading of the superficial layers during earthquakes and testify to the continuous tectonic activity from Pleistocene to Present. Finally, results presented here bring newinformation about the understanding of the seismic hazard in this area: whereas the Romeral Fault Systemwas so far thought to be themost likely source of earthquakes, themore recent cross-cutting fault systems described herein are another potential hazard to be considered.

Suter, F.; Sartori, M.; Neuwerth, R.; Gorin, G.

2008-11-01

347

Developmental and hypoxia-induced cell death share common ultrastructural and biochemical apoptotic features in the central nervous system.  

PubMed

Hypoxic insults during the perinatal period lead to motor and cognitive impairments that later appear during childhood. In the adult brain, hypoxic events often lead to necrotic neuronal death, depending on the region and intensity of the event. During development an active apoptotic cell death occurs and could be an important variable affecting the hypoxic insult outcome. In the present work we performed a comparative study, in a chick embryo model, of the phenotypes and molecular markers exhibited during developmental and hypoxic cell death (HxCD). Ultrastructural analysis of optic tectum cells of embryos subjected to hypoxia (8% O2, 60 min) revealed a clear apoptotic morphology that did not differ from the one exhibited during developmental cell death. Integrity of plasma membrane, condensation of chromatin in round well-defined bodies, and gradual shrinkage of the cell are all hallmarks of the apoptotic process and were present in both control and hypoxic cells. To elucidate if hypoxic and developmental cell deaths share a common mechanism we evaluated the activation of both intrinsic and extrinsic apoptotic pathways. A basal cleavage of caspase-9 and cytochrome c release was observed by co-immunofluorescence in control embryos, but hypoxic insult significantly increased the incidence of this colocalization. Caspase-8 cleavage remained unchanged after the hypoxic insult, suggesting that the extrinsic pathway would not be involved in hypoxic death. We also observed a significant decrease of Akt activation immediately after hypoxia, possibly facilitating the later release of cytochrome c. In addition we analyzed the influence of retinal ganglion cells (RGC) in neuronal survival. Transection of RGC fibers at embryonic day (ED) 3 did not induce any change in developmental and HxCD at ED12. In conclusion, our findings demonstrate that a hypoxic insult in the developing brain triggers the same apoptotic pathway as the active developmental death. PMID:23933309

Pozo Devoto, V M; Bogetti, M E; Fiszer de Plazas, S

2013-11-12

348

Farmers' Perceptions of Land Degradation and Their Investments in Land Management: A Case Study in the Central Rift Valley of Ethiopia  

NASA Astrophysics Data System (ADS)

To combat land degradation in the Central Rift Valley (CRV) of Ethiopia, farmers are of crucial importance. If farmers perceive land degradation as a problem, the chance that they invest in land management measures will be enhanced. This study presents farmers' perceptions of land degradation and their investments in land management, and to what extent the latter are influenced by these perceptions. Water erosion and fertility depletion are taken as main indicators of land degradation, and the results show that farmers perceive an increase in both indicators over the last decade. They are aware of it and consider it as a problem. Nevertheless, farmers' investments to control water erosion and soil fertility depletion are very limited in the CRV. Results also show that farmers' awareness of both water erosion and soil fertility decline as a problem is not significantly associated with their investments in land management. Hence, even farmers who perceive land degradation on their fields and are concerned about its increase over the last decade do not significantly invest more in water erosion and soil fertility control measures than farmers who do not perceive these phenomena. Further research is needed to assess which other factors might influence farmers' investments in land management, especially factors related to socioeconomic characteristics of farm households and plot characteristics which were not addressed by this study.

Adimassu, Zenebe; Kessler, Aad; Yirga, Chilot; Stroosnijder, Leo

2013-05-01

349

Combination of multi-sensor PSI monitoring data with a landslide damage inventory: the Tena Valley case study (Central Spanish Pyrenees) (Invited)  

NASA Astrophysics Data System (ADS)

This work illustrates the usefulness of integrating multi-sensor DInSAR monitoring data and landslide damage inventories for risk analysis. The approach has been applied in the Tena Valley (Central Spanish Pyrenees), where active landslides have caused significant damage on human structures over the last decade. Slope instability in this glacial trough is mainly related to very slow deep-seated slide-flows developed in Paleozoic slates. The PSI processing of ascending orbit ALOS PALSAR images (2006-2010), and descending orbit ERS & Envisat (2001-2007) and TerraSAR-X (2008) datasets, has provided heterogeneous displacement velocity measurements. The geometrical differences introduced by each satellite have been homogenized through the projection of the LOS displacements along the steepest slope gradient. Additionally, conventional DInSAR analysis of ALOS PALSAR images has permitted the detection of faster movements (up to 145cm yr-1) from 46 day interferograms (, increasing the number of detected landslides. Overall, the number of monitored landslides increased from 4% and 19%, using C- and X- band data, to 38% of the total (294) using L-band. In a subsequent phase, the multi-sensor velocities measured for the landslides are classified with respect to the magnitude of the road damage occurred in the 2008-2010 period. According to available measurements, minor or no damages are produced for landslide velocities smaller than 21 mm yr-1, moderate damages occurred between 21 and 160 mm yr-1, and major damages between 160 and 1450 mm yr-1.

Herrera, G.; Gutierrez, F.; García-Davalillo, J.; Galve, J.; Fernández-Merodo, J.; Cooksley, G.; Guerrero, J.; Duro, J.

2013-12-01

350

Predictive simulation of alternatives for managing the water resources of North Fork Solomon River Valley between Kirwin Dam and Waconda Lake, north-central Kansas  

USGS Publications Warehouse

Since 1974 water levels in the alluvial aquifer of the North Fork Solomon River Valley in north-central Kansas have decreased due to increases in ground-water pumpage, decreases in availability of surface water for irrigation, and below-average precipitation. A finite-element model was developed in cooperation with the U.S. Bureau of Reclamation to simulate changing conditions between 1970-79. Model results indicate that annual recharge to the aquifer due to precipitation, applcation of water for irrigation, and canal leakage averaged about 22,825 acre-feet and that annual ground-wate discharge to the river averaged about 16,590 acre-feet. Predictive simulations for 1980-2000 were made using management alternatives that involved clay-lining of irrigation ditches, reduction of surface-water availability with and without an increase in ground-water pumping, and continuation of 1979 pumping conditions. The simulations indicated that as much as 5.5 feet of additional average water-level drawdown in wells would occur by 2000 if surface-water supply were reduced 100 percent and ground-water pumpage increased. The simulations also indicated that a decrease in average drawdown of 0.55 foot would occur by 2000 and that base flow to the river would decrease to 12,300 acre-feet per year if 1979 conditions remained constant. (USGS)

Burnett, R. D.

1984-01-01

351

Post-Closure Inspection and Monitoring Report for Corrective Action Unit 417: Central Nevada Test Area Surface, Hot Creek Valley, Nevada For Calendar Year 2006  

SciTech Connect

Corrective Action Unit (CAU) 417, Central Nevada Test Area - Surface, is located in Hot Creek Valley in northern Nye County, Nevada, and consists of three areas commonly referred to as UC-1, UC-3, and UC-4. CAU 417 consists of 34 Corrective Action Sites (CASs) which were closed in 2000 (U.S. Department of Energy, National Nuclear Security Administration Nevada Operations Office, 2001). Three CASs at UC-1 were closed in place with administrative controls. At CAS 58-09-01, Central Mud Pit (CMP), a vegetated soil cover was constructed over the mud pit. At the remaining two sites, CAS 58-09-02, Mud Pit, and CAS 58-09-05, Mud Pits (3), aboveground monuments and warning signs were installed to mark the CAS boundaries. Three CASs at UC-3 were closed in place with administrative controls. Aboveground monuments and warning signs were installed to mark the site boundaries at CAS 58-09-06, Mud Pits (5), CAS 58-25-01, Spill, and CAS 58-10-01, Shaker Pad Area. Two CASs that consist of five sites at UC-4 were closed in place with administrative controls. At CAS 58-09-03, Mud Pits (5), an engineered soil cover was constructed over Mud Pit C. At the remaining three sites in CAS 58-09-03 and at CAS 58-10-05, Shaker Pad Area, aboveground monuments and warning signs were installed to mark the site boundaries. The remaining 26 CASs at CAU 417 were either clean-closed or closed by taking no further action.

None

2007-06-01

352

State-dependent life history models in a changing (and regulated) environment: steelhead in the California Central Valley  

PubMed Central

We use a state dependent life history model to predict the life history strategies of female steelhead trout (Oncorhynchus mykiss) in altered environments. As a case study of a broadly applicable approach, we applied this model to the American and Mokelumne Rivers in central California, where steelhead are listed as threatened. Both rivers have been drastically altered, with highly regulated flows and translocations that may have diluted local adaptation. Nevertheless, evolutionary optimization models could successfully predict the life history displayed by fish on the American River (all anadromous, with young smolts) and on the Mokelumne River (a mix of anadromy and residency). The similar fitness of the two strategies for the Mokelumne suggested that a mixed strategy could be favored in a variable environment. We advance the management utility of this framework by explicitly modeling growth as a function of environmental conditions and using sensitivity analyses to predict likely evolutionary endpoints under changed environments. We conclude that the greatest management concern with respect to preserving anadromy is reduced survival of emigrating smolts, although large changes in freshwater survival or growth rates are potentially also important. We also demonstrate the importance of considering asymptotic size along with maximum growth rate.

Satterthwaite, William H; Beakes, Michael P; Collins, Erin M; Swank, David R; Merz, Joseph E; Titus, Robert G; Sogard, Susan M; Mangel, Marc

2010-01-01

353

Contrasting Oligocene and Miocene thermal histories from the hanging wall and footwall of the South Tibetan detachment in the central Himalaya from 40Ar/39Ar thermochronology, Marsyandi Valley, central Nepal  

NASA Astrophysics Data System (ADS)

In the Marsyandi valley of central Nepal, a major strand of the South Tibetan detachment system, the 18-22 Ma Chame detachment, places epidote-amphibolite to amphibolite facies calc-silicate rocks and marbles of the Tibetan sedimentary sequence on amphibolite facies pelitic gneisses and calc-silicate rocks of the Greater Himalayan sequence. Although the resulting metamorphic discontinuity is minor and sometimes cryptic, 40Ar/39Ar thermochronologic results from the area reveal that the hanging wall and footwall of the detachment had distinctive thermal histories. Hanging wall phlogopites and biotites yield cooling ages of 27.1 - 29.9 Ma, compared with footwall biotite ages of 14.1 - 16.6 Ma. U-Pb monazite thermochronology demonstrates that the Greater Himalayan sequence experienced peak amphibolite facies conditions at approximately 22 Ma, but the 40Ar/39Ar results require hanging wall metamorphism to be an Oligocene (or older) phenomenon. These events are interpreted as representing the "Neohimalayan" and "Eohimalayan" metamorphic phases proposed by previous workers in the central Himalaya. Some of the dated hanging wall phlogopites grew synchronously with development of SW vergent macroscopic folds in the Tibetan sedimentary sequence, implying that Eohimalayan metamorphism was associated with an important phase of crustal shortening in this sector of the Himalaya. Despite the intensity of Neohimalayan metamorphism below the Chame detachment, evidence for Eohimalayan metamorphism and igneous activity is preserved in the footwall rocks of the Marsyandi drainage. Inherited approximately 35 Ma monazites of either metamorphic or igneous origin have been found in the upper Greater Himalayan sequence in this area, and one hornblende separate from the uppermost footwall yields a 40Ar/39Ar age of 30.0 ± 3.0 Ma. This hornblende date and a similar result from the same structural level in the nearby Kali Gandaki valley, if robust, suggest that the duration of the Neohimalayan event was extremely short, probably less than 1 million years and that peak temperatures in the upper part of the Greater Himalayan sequence were not substantially greater than about 900 K.

Coleman, Margaret E.; Hodges, Kip V.

1998-10-01

354

Digital hydrographic, land use/land cover, and hydrologic unit boundary files for the Death Valley region of southern Nevada and southeastern California processed from US Geological Survey 1:100,000- and 1:250,000-scale digital data files  

SciTech Connect

Digital hydrographic and land-use/land-cover data have been compiled into a digital geographic data base for an {approx}100,000-km{sup 2} area of the Southern Great Basin, the Death Valley region of southern Nevada and SE California, located between lat 35{degree}N, long 115{degree}W and lat 38{degree}N, long 118{degree}W. This region includes the Nevada Test Site at Yucca Mountain and adjacent parts of southern Nevada and eastern California. The data base was compiled from USGS data files distributed by the USGS Earth Scinece Information Center. The data files were converted into six thematic ARC/INFO map coverages representing the Death Valley region.

Turner, A.K.; D`Agnese, F.A.; Faunt, C.C.

1996-04-01

355

Development of regional skews for selected flood durations for the Central Valley Region, California, based on data through water year 2008  

USGS Publications Warehouse

Flood-frequency information is important in the Central Valley region of California because of the high risk of catastrophic flooding. Most traditional flood-frequency studies focus on peak flows, but for the assessment of the adequacy of reservoirs, levees, other flood control structures, sustained flood flow (flood duration) frequency data are needed. This study focuses on rainfall or rain-on-snow floods, rather than the annual maximum, because rain events produce the largest floods in the region. A key to estimating flood-duration frequency is determining the regional skew for such data. Of the 50 sites used in this study to determine regional skew, 28 sites were considered to have little to no significant regulated flows, and for the 22 sites considered significantly regulated, unregulated daily flow data were synthesized by using reservoir storage changes and diversion records. The unregulated, annual maximum rainfall flood flows for selected durations (1-day, 3-day, 7-day, 15-day, and 30-day) for all 50 sites were furnished by the U.S. Army Corps of Engineers. Station skew was determined by using the expected moments algorithm program for fitting the Pearson Type 3 flood-frequency distribution to the logarithms of annual flood-duration data. Bayesian generalized least squares regression procedures used in earlier studies were modified to address problems caused by large cross correlations among concurrent rainfall floods in California and to address the extensive censoring of low outliers at some sites, by using the new expected moments algorithm for fitting the LP3 distribution to rainfall flood-duration data. To properly account for these problems and to develop suitable regional-skew regression models and regression diagnostics, a combination of ordinary least squares, weighted least squares, and Bayesian generalized least squares regressions were adopted. This new methodology determined that a nonlinear model relating regional skew to mean basin elevation was the best model for each flood duration. The regional-skew values ranged from -0.74 for a flood duration of 1-day and a mean basin elevation less than 2,500 feet to values near 0 for a flood duration of 7-days and a mean basin elevation greater than 4,500 feet. This relation between skew and elevation reflects the interaction of snow and rain, which increases with increased elevation. The regional skews are more accurate, and the mean squared errors are less than in the