Plio-Pleistocene facies environments from the KBS Member, Koobi Fora Formation: implications for climate controls on the development of lake-margin hominin habitats in the northeast Turkana Basin (northwest Kenya).

PubMed

Lepre, Christopher J; Quinn, Rhonda L; Joordens, Josephine C A; Swisher, Carl C; Feibel, Craig S

2007-11-01

Climate change is hypothesized as a cause of major events of Plio-Pleistocene East African hominin evolution, but the vertically discontinuous and laterally confined nature of the relevant geological records has led to difficulties with assessing probable links between the two. High-resolution sedimentary sequences from lacustrine settings can provide comprehensive data of environmental changes and detailed correlations with well-established orbital and marine records of climate. Hominin-bearing deposits from Koobi Fora Ridge localities in the northeast Turkana Basin of Kenya are an archive of Plio-Pleistocene lake-margin sedimentation though significant developmental junctures of northern African climates, East African environments, and hominin evolution. This study examines alluvial channel and floodplain, nearshore lacustrine, and offshore lacustrine facies environments for the approximately 136-m-thick KBS Member (Koobi Fora Formation) exposed at the Koobi Fora Ridge. Aspects of the facies environments record information on the changing hydrosedimentary dynamics of the lake margin and give insights into potential climatic controls. Seasonal/yearly climate changes are represented by the varve-like laminations in offshore mudstones and the slickensides, dish-shaped fractures, and other paleosol features overprinted on floodplain strata. Vertical shifts between facies environments, however, are interpreted to indicate lake-level fluctuations deriving from longer-term, dry-wet periods in monsoonal rainfall. Recurrence periods for the inferred lake-level changes range from about 10,000 to 50,000 years, and several are consistent with the average estimated timescales of orbital precession ( approximately 20,000 years) and obliquity ( approximately 40,000 years). KBS Member facies environments from the Koobi Fora Ridge document the development of lake-margin hominin habitats in the northeast Turkana Basin. Environmental changes in these habitats may be a result of

Oncorhynchus nerka population monitoring in the Sawtooth Valley Lakes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Teuscher, D.M.; Taki, D.; Ariwite, K.

1996-05-01

Critical habitat for endangered Snake River sockeye salmon includes five rearing lakes located in the Sawtooth Valley of central Idaho. Most of the lakes contain either introduced or endemic kokanee populations. Snake River sockeye occur naturally in Redfish Lake, and are being stocked in Redfish and Pettit Lakes. Because kokanee compete with sockeye for limited food resources, understanding population characteristics of both species such as spawn timing, egg-to-fry survival, distribution and abundance are important components of sockeye recovery. This chapter describes some of those characteristics. In 1995, hydroacoustic estimates of O. nerka densities in the Sawtooth Valley Lakes ranged frommore » 57 to 465 fish/ha. Densities were greatest in Pettit followed by Redfish (167), Alturas (95), and Stanley Lakes. O. nerka numbers increased from 1994 values in Pettit and Alturas Lakes, but declined in Redfish and Stanley. Despite a decline in total lake abundance, O. nerka biomass estimates in Redfish Lake increased. Approximately 144,000 kokanee fry recruited to Redfish Lake from Fishhook Creek. O. nerka fry recruitment to Stanley and Alturas lake was 5,000 and 30,000 fry, respectively. Egg-to-fry survival was 14% in Fishhook and 7% in Stanley Lake Creek. In Fishhook Creek, kokanee spawning escapement was estimated using stream surveys and a weir. Escapement estimates were 4,860 from weir counts, and 7,000 from stream surveys. As part of the kokanee reduction program, 385 of the spawning female kokanee were culled. Escapement for Stanley Lake Creek was only 60 fish, a ten fold decrease from 1994. In Alturas Lake, kokanee spawners dropped by 50% to 1,600.« less

Holocene evolution of the Tonle Sap Lake: valley network infill and rates of sedimentation in Cambodia's Great Lake

NASA Astrophysics Data System (ADS)

Best, J.; Darby, S. E.; Langdon, P. G.; Hackney, C. R.; Leyland, J.; Parsons, D. R.; Aalto, R. E.; Marti, M.

2017-12-01

Tonle Sap Lake, the largest freshwater lake in SE Asia (c. 120km long and 35 km wide), is a vital ecosystem that provides 40-60% of the protein for the population of Cambodia. The lake is fed by flow from the Mekong River that causes the lake rise in level by c. 8m during monsoonal and cyclone-related floods, with drainage of the lake following the monsoon. Hydropower dam construction on the Mekong River has raised concerns as to the fragility of the Tonle Sap habitat due to any changing water levels and sedimentation rates within the lake. This paper details results of sub-bottom profiling surveys of Tonle Sap Lake in October 2014 that detailed the stratigraphy of the lake and assessed rates of infill. An Innomar Parametric Echo Sounder (PES) was used to obtain c. 250 km of sub-bottom profiles, with penetration up to 15m below the lake bed at a vertical resolution of c. 0.20m. These PES profiles were linked to cores from the north of the lake and previous literature. The PES profiles reveal a network of valleys, likely LGM, with relief up to c. 15-20m, that have been infilled by a suite of Holocene sediments. The valley surface is picked out as a strong reflector throughout the lake, and displays a series of valleys that are up to c. 15m deep and commonly 50-200m wide, although some of the largest valleys are 1.2km in width. Modelling of channel network incision during LGM conditions generates landscapes consistent with our field observations. The Tonle Sap valley network is infilled by sediments that show firstly fluvial and/or subaerial slope sedimentation, and then by extensive, parallel-bedded, lacustrine sedimentation. Lastly, the top c. 1m of sedimentation is marked by a distinct basal erosional surface that can be traced over much of the Tonle Sap Lake, and that is overlain by a series of parallel PES reflections. This upper sediment layer is interpreted to represent sedimentation in the Tonle Sap lake due to sediment suspension settling but after a period

Thin, Conductive Permafrost Surrounding Lake Fryxell Indicates Salts From Past Lakes, McMurdo Dry Valleys, Antarctica

NASA Astrophysics Data System (ADS)

Foley, N.; Tulaczyk, S. M.; Gooseff, M. N.; Myers, K. F.; Doran, P. T.; Auken, E.; Dugan, H. A.; Mikucki, J.; Virginia, R. A.

2017-12-01

In the McMurdo Dry Valleys (MDV), permafrost should be thick and liquid water rare. However, despite the well below zero mean annual temperature in this cryospheric desert, liquid water can be found in lakes, summer melt streams, subglacial outflow, and - recent work has shown - underneath anomalously thin permafrost. In part, this niche hydrosphere is maintained by the presence of salts, which depress the freezing point of water to perhaps as cold as -10° Celsius. We detected widespread salty water across the MDV in lakes and at depth using a helicopter-borne Time Domain Electromagnetic (TDEM) sensor. By using the presence of brines to mark the transition from frozen permafrost (near the surface) to unfrozen ground (at depth), we have created a map of permafrost thickness in Lower Taylor Valley (LTV), a large MDV with a complex history of glaciation and occupation by lakes. Our results show that permafrost is thinner ( 200m) than would be expected based on geothermal gradient measurements (up to 1000m), a result of the freezing point depression caused by salt and potentially enhanced by an unfinished transient freezing process. Near Lake Fryxell, a large, brackish lake in the center of LTV, permafrost is very thin (about 30-40m) and notably more electrically conductive than more distal permafrost. This thin ring of conductive permafrost surrounding the lake basin most likely reflects the high presence of salts in the subsurface, preventing complete freezing. These salts may be a remnant of the salty bottom waters of a historic larger lake (LGM glacially dammed Lake Washburn) or the remnant of salty basal water from a past advance of Taylor Glacier, which now sits many km up-valley but is known to contain brines which currently flow onto the surface and directly into the subsurface aquifer.

Home destruction examination: Grass Valley Fire, Lake Arrowhead, California

Treesearch

Jack D. Cohen; Richard D. Stratton

2008-01-01

The Grass Valley Fire started October 22, 2007 at approximately 0508, one-mile west of Lake Arrowhead in the San Bernardino Mountains. Fuel and weather conditions were extreme due to drought, dry Santa Ana winds, and chaparral and conifer vegetation on steep terrain. The fire proceeded south through the Grass Valley drainage one-mile before impacting an area of dense...

A leaf wax biomarker record of early Pleistocene hydroclimate from West Turkana, Kenya

NASA Astrophysics Data System (ADS)

Lupien, R. L.; Russell, J. M.; Feibel, C.; Beck, C.; Castañeda, I.; Deino, A.; Cohen, A. S.

2018-04-01

Climate is thought to play a critical role in human evolution; however, this hypothesis is difficult to test due to a lack of long, high-quality paleoclimate records from key hominin fossil locales. To address this issue, we analyzed organic geochemical indicators of climate in a drill core from West Turkana, Kenya that spans ∼1.9-1.4 Ma, an interval that includes several important hominin evolutionary transitions. We analyzed the hydrogen isotopic composition of terrestrial plant waxes (δDwax) to reconstruct orbital-timescale changes in regional hydrology and their relationship with global climate forcings and the hominin fossil record. Our data indicate little change in the long-term mean hydroclimate during this interval, in contrast to inferred changes in the level of Lake Turkana, suggesting that lake level may be responding dominantly to deltaic progradation or tectonically-driven changes in basin configuration as opposed to hydroclimate. Time-series spectral analyses of the isotopic data reveal strong precession-band (21 kyr) periodicity, indicating that regional hydroclimate was strongly affected by changes in insolation. We observe an interval of particularly high-amplitude hydrologic variation at ∼1.7 Ma, which occurs during a time of high orbital eccentricity hence large changes in processionally-driven insolation amplitude. This interval overlaps with multiple hominin species turnovers, the appearance of new stone tool technology, and hominin dispersal out of Africa, supporting the notion that climate variability played an important role in hominin evolution.

Climatic and morphological controls on post-glacial lake and river valley evolution in the Weichselian belt - an example from the Wda valley, Northern Poland

NASA Astrophysics Data System (ADS)

Kramkowski, M. A.; Błaszkiewicz, M.; Piotrowski, J. A.; Brauer, A.; Gierszewski, P.; Kordowski, J.; Lamparski, P.; Lorenz, S.; Noryśkiewicz, A. M.; Ott, F.; Slowinski, M. M.; Tyszkowski, S.

2014-12-01

The River Wda valley is a classical example of a polygenetic valley, consisting of former lake basins joined by erosive gap sections. In its middle section, which was the subject of our research, a fragment of an abandoned Lateglacial river valley is preserved, which is unique for the Weichselian moraine belt in the Central European Lowlands. The analysis of the relationship between the lacustrine and fluvial sediments and landforms enabled the authors to report many evolutionary connections between the initial period of the river system formation and the emergence of lakes during the Weichselian Lateglacial. The surface drainage essentially determined the progress of melting of dead ice blocks buried in the glacial depressions, which finally led to lake formation there. Most of the lake basins in the study area were formed during the Bølling-Allerød period. However, one section of the subglacial channel was not exposed to the thermokarst conditions and was therefore preserved with dead ice blocks throughout the entire Lateglacial. The dead ice decay at the beginning of the Holocene, as well as the emergence of another lake, created a lower base level of erosion in the close vicinity of the abandoned valley and induced a change of the river's course. Both fluvial and lacustrine deposits and landforms distributed in the central section of the River Wda valley indicate two processes, which proceeded simultaneously: (1) emergence of fluvially joined lake basins within a glacial channel, (2) degradation of the river bed in the gap sections interfering between the lakes. The processes described for the central section of the River Wda channel indicate a very dynamic river valley development during the Weichselian Lateglacial and the early Holocene. The valley formation was tightly interwoven with the morphogenesis of the primary basins within the valley, mainly with the melting of the buried blocks of dead ice and the development of lakes. This study is a contribution

Respiratory hospital admissions associated with PM10 pollution in Utah, Salt Lake, and Cache Valleys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pope CA, I.I.I.

This study assessed the association between respiratory hospital admissions and PM10 pollution in Utah, Salt Lake, and Cache valleys during April 1985 through March 1989. Utah and Salt Lake valleys had high levels of PM10 pollution that violated both the annual and 24-h standards issued by the Environmental Protection Agency (EPA). Much lower PM10 levels occurred in the Cache Valley. Utah Valley experienced the intermittent operation of its primary source of PM10 pollution: an integrated steel mill. Bronchitis and asthma admissions for preschool-age children were approximately twice as frequent in Utah Valley when the steel mill was operating versus whenmore » it was not. Similar differences were not observed in Salt Lake or Cache valleys. Even though Cache Valley had higher smoking rates and lower temperatures in winter than did Utah Valley, per capita bronchitis and asthma admissions for all ages were approximately twice as high in Utah Valley. During the period when the steel mill was closed, differences in per capita admissions between Utah and Cache valleys narrowed considerably. Regression analysis also demonstrated a statistical association between respiratory hospital admissions and PM10 pollution. The results suggest that PM10 pollution plays a role in the incidence and severity of respiratory disease.« less

Geology and geomorphology of Bear Lake Valley and upper Bear River, Utah and Idaho

USGS Publications Warehouse

Reheis, M.C.; Laabs, B.J.C.; Kaufman, D.S.

2009-01-01

Bear Lake, on the Idaho-Utah border, lies in a fault-bounded valley through which the Bear River flows en route to the Great Salt Lake. Surficial deposits in the Bear Lake drainage basin provide a geologic context for interpretation of cores from Bear Lake deposits. In addition to groundwater discharge, Bear Lake received water and sediment from its own small drainage basin and sometimes from the Bear River and its glaciated headwaters. The lake basin interacts with the river in complex ways that are modulated by climatically induced lake-level changes, by the distribution of active Quaternary faults, and by the migration of the river across its fluvial fan north of the present lake. The upper Bear River flows northward for ???150 km from its headwaters in the northwestern Uinta Mountains, generally following the strike of regional Laramide and late Cenozoic structures. These structures likely also control the flow paths of groundwater that feeds Bear Lake, and groundwater-fed streams are the largest source of water when the lake is isolated from the Bear River. The present configuration of the Bear River with respect to Bear Lake Valley may not have been established until the late Pliocene. The absence of Uinta Range-derived quartzites in fluvial gravel on the crest of the Bear Lake Plateau east of Bear Lake suggests that the present headwaters were not part of the drainage basin in the late Tertiary. Newly mapped glacial deposits in the Bear River Range west of Bear Lake indicate several advances of valley glaciers that were probably coeval with glaciations in the Uinta Mountains. Much of the meltwater from these glaciers may have reached Bear Lake via groundwater pathways through infiltration in the karst terrain of the Bear River Range. At times during the Pleistocene, the Bear River flowed into Bear Lake and water level rose to the valley threshold at Nounan narrows. This threshold has been modified by aggradation, downcutting, and tectonics. Maximum lake

Landslide susceptibility in the Tully Valley area, Finger Lakes region, New York

USGS Publications Warehouse

Jager, Stefan; Wieczorek, Gerald E.

1994-01-01

As a consequence of a large landslide in the Tully Valley, Onondaga County, New York, an investigation was undertaken to determine the factors responsible for the landslide in order to develop a model for regional landslide susceptibility. The April 27, 1993 Tully Valley landslide occurred within glacial lake clays overlain by till and colluvium on gentle slopes of 9-12 degrees. The landslide was triggered by extreme climatic events of prolonged heavy rainfall combined with rapid melting of a winter snowpack. A photoinventory and field checking of landslides within a 415 km2 study area, including the Tully Valley, revealed small recently-active landslides and other large dormant prehistoric landslides, probably Pleistocene in age. Similar to the larger Tully Valley landslide, the smaller recently-active landslides occurred in red, glacial lake clays very likely triggered by seasonal rainfall. The large dormant landslides have been stable for long periods as evidenced by slope denudational processes that have modified the landslides. These old and ancient landslides correspond with proglacial lake levels during the Pleistocene, suggesting that either inundation or rapid drainage was responsible for triggering these landslides. A logistic regression analysis was performed within a Geographic Information System (GIS) environment to develop a model of landslide susceptibility for the Tully Valley study area. Presence of glacial clays, slope angle, and glacial lake levels were used as explanatory variables for landslide incidence. The spatial probability of landsliding, categorized as low, moderate and high, is portrayed within 90-m square cells on the susceptibility map.

Late Pliocene and Early Pleistocene Temperature Reconstructions from Paleolakes of the West Turkana and North Awash Basins, East Africa

NASA Astrophysics Data System (ADS)

Castañeda, I. S.; Thompson-Munson, M.; Lupien, R.; Russell, J. M.

2015-12-01

The Hominin Sites and Paleolakes Drilling Project (HSPDP) aims to reconstruct past environments of the East African Rift Valley from locations in close proximity to some of the world's most important fossil hominin and artifact sites. In this study, we investigate sediments from the West Turkana and North Awash Basins, which were recently drilled as part of the HSPDP. The North Awash Basin contains abundant early hominin fossils and the lakebeds of the Hadar Formation (~3.6 to ~2.9 Ma) will provide a record of climate variability during the Pliocene, prior to the intensification of Northern Hemisphere glaciation at ~2.7 Ma. The lakebeds of the Turkana Basin are Early Pleistocene in age (~1.9 to ~1.45 Ma) and span the interval that includes some the earliest fossils of Homo rudolfensis and H. ergaster/erectus. Here we examine the organic geochemistry of West Turkana and North Awash Basin sediments and investigate the use of proxies based on isoprenoid and branched glycerol dialkyl glycerol tetraethers (GDGTs) to reconstruct temperature, including TEX86 and the methylation and cyclization (MBT and CBT) ratios and relative abundances of branched GDGTs. We also examine variability in the abundances and ratios of plant leaf waxes (n-alkanes) to provide insight into past vegetation changes on the East African landscape.

Late Pleistocene Hansel Valley basaltic ash, northern Lake Bonneville, Utah, USA

USGS Publications Warehouse

Miller, D.M.; Oviatt, Charles G.; Nash, B.P.

2008-01-01

The Hansel Valley ash bed lies within 5 cm of the base of deposits of Lake Bonneville (???28 ka) in the vicinity of Great Salt Lake and provides a useful stratigraphic marker for this area of the lake basin. However, it has not been matched to an eruptive edifice, presumably because such an edifice was eroded by waves of Lake Bonneville. We present data for the chemical composition of the tephra and for possible matching lavas and tephras of the region, as well as grain size data for the tephra in an attempt to identify the location of the eruption. Matches with other tephras are negative, but lavas near the coarsest ash deposits match well with the distinctive high values of TiO2 and P2O5 of the ash. Neither chemistry nor grain size data points uniquely to a source area, but an area near the northwest shore of Great Salt Lake and within Curlew Valley is most likely. The Hansel Valley ash is an example of an ash that has no direct numerical date from proximal deposits, despite considerable study, yet nonetheless is useful for stratigraphic studies by virtue of its known stratigraphic position and approximate age. Basaltic tephras commonly are not as widespread as their rhyolitic counterparts, and in some cases apparently are produced by eruptive sources that are short lived and whose edifices are not persistent. ?? 2007 Elsevier Ltd and INQUA.

The Pilot Valley shoreline: An early record of Lake Bonneville dynamics: Chapter 3

USGS Publications Warehouse

Miller, David; Phelps, Geoffrey

2016-01-01

The Pilot Valley shoreline is named for distinctive gravel beaches on the eastern, northern, and western sides of Pilot Valley playa, Utah. The shoreline has been identified across the Bonneville basin where it is characterized by one to three beach crests between ~ 1305 and 1309 m elevation, all overlain by deep-water marl of Lake Bonneville. It thus represents the lowest and earliest recognized shoreline of Lake Bonneville. Features of the shoreline indicate that both high wave energy and high stream sediment discharge contributed to shoreline development. Basin hypsometry did not play a role in the development of the shoreline, which must have been caused by a combination of climatically driven hydrologic and storm factors, such as reduced precipitation that stabilized lake level and increase in storm-driven wave energy. The Pilot Valley shoreline is poorly dated at about 30 ka. If it is somewhat older, correlation with Greenland Interstadial 5.1 at 30.8–30.6 ka could explain the stabilization of lake level.

Influence of geomorphic setting on sedimentation of two adjacent alpine lakes, Triglav Lakes Valley (Julian Alps, NW Slovenia)

NASA Astrophysics Data System (ADS)

Smuc, Andrej; Skabene, Dragomir; Muri, Gregor; Vreča, Polona; Jaćimović, Radojko; Čermelj, Branko; Turšič, Janja

2013-04-01

The Triglav Lakes Valley is elongated, 7km long depression, located high (at places over 2000 m.a.s.l.) in the central part of the Julian Alps (NW Slovenia). It hosts 6 small isolated lakes that formed due to the combination of Neogene tectonic and Pleistocene glaciation. The study is focused on the 5th and 6th Triglav Valley Lakes that characterize lower part of the valley. The lakes are located so close to each other that they are even connected in times of high water. Thus, they share the same bedrock geology, are subjected to the same climatic forcing and share similar vegetation communities. Despite their proximity, the lakes differ in their hydrologic and geomorphic setting. The lakes have no permanent surface tributaries; however 5th is fed periodically, at times of high water level, by the Močivec spring, while additional water flows from the swamp area near its northern shore. An underground spring on the eastern side of 5th represents the lake's only permanent freshwater inflow, while drainage takes place to the west via a small ponor. 6th has only one weak underground spring on the eastern side of the lake. Water levels may fluctuate between 2 and 3 m. Additionally, the lakes have different configuration of lakes shores; the northern shores of the 5th lake are low-angle soil and debris covered plateau, while southern shores of the 5th lake and shores of the 6th lake are represented by heavily karstified carbonate base rock and covered partly by trees. The detailed sedimentary analysis of the lakes record showed some similarities, but also some significant differences. Sediments of both lakes are represented by fine-grained turbidity current deposits that are transported from lake shores during snow melt or storms. The grain-size and sedimentary rates of the lakes are however markedly different. The 5th lake has coarser grained sediments, with mean ranging from 46 to 60 µm and records higher sedimentation rates of ~0,57 cm/year, compared to the 6th lake

Tracing groundwater input into Lake Vanda, Wright Valley, Antarctica using major ions, stable isotopes and noble gas

NASA Astrophysics Data System (ADS)

Dowling, C. B.; Poreda, R. J.; Snyder, G. T.

2008-12-01

The McMurdo Dry Valleys (MDV), Antarctica, is the largest ice-free region on Antarctica. Lake Vanda, located in central Wright Valley, is the deepest lake among the MDV lakes. It has a relatively fresh water layer above 50 m with a hypersaline calcium-chloride brine below (50-72 m). The Onyx River is the only stream input into Lake Vanda. It flows westward from the coastal Lower Wright Glacier and discharges into Lake Vanda. Suggested by the published literature and this study, there has been and may still be groundwater input into Lake Vanda. Stable isotopes, major ions, and noble gas data from this study coupled with previously published data indicate that the bottom waters of Lake Vanda have had significant contributions from a deep groundwater system. The dissolved gas of the bottom waters of Lake Vanda display solubility concentrations rather than the Ar-enriched dissolved gas seen in the Taylor Valley lakes (such as Lake Bonney). The isotopic data indicate that the bottom calcium-chloride-brine of Lake Vanda has undergone very little evaporation. The calcium-chloride chemistry of the groundwater that discharges into Lake Vanda most likely results from the chemical weathering and dissolution of cryogenic evaporites (antarcticite and gypsum) within the glacial sediments of Wright Valley. The high calcium concentrations of the brine have caused gypsum to precipitate on the lake bottom. Our work also supports previous physical and chemical observations suggesting that the upper portion actively circulates and the hypersaline bottom layer does not. The helium and calcium chloride values are concentrated at the bottom, with a very narrow transition layer between it and the above fresh water. If the freshwater layer did not actively circulate, then diffusion over time would have caused the helium and calcium chloride to slowly permeate upwards through the water column.

The existence of Dracunculus medinensis (Linnaeus, 1758) in Turkana, Kenya.

PubMed

Macpherson, C N

1981-01-01

Dracontiasis has been previously reported in southern Sudan, northern Uganda and north-west Eritrea but this is the first report of autochthonous cases in Turkana, Kenya. Five Turkana tribesmen, three females from the same family, one young boy and an adult male were being treated for guinea-worm at the dispensary in Lokichogio, northern Turkana District. The three women had recently returned from southern Sudan, where the disease is endemic, but the two male tribesmen had only lived in and around the Lokichogio region. The methods used in obtaining water from water-holes dug in dry river beds provide an ideal situation for Dracunculus transmission amongst the tribesmen; this parasite may therefore become a problem in this remote impoverished area.

Subsurface Constraints on Late Cenozoic Basin Geometry in Northern Fish Lake Valley and Displacement Transfer Along the Northern Fish Lake Valley Fault Zone, Western Nevada

NASA Astrophysics Data System (ADS)

Mueller, N.; Kerstetter, S. R.; Katopody, D. T.; Oldow, J. S.

2016-12-01

The NW-striking, right-oblique Fish Lake Valley fault zone (FLVFZ) forms the northern segment of the longest active structure in the western Great Basin; the Death Valley - Furnace Creek - Fish Lake Valley fault system. Since the mid-Miocene, 50 km of right-lateral displacement is documented on the southern FLVFZ and much of that displacement was and is transferred east and north on active WNW left-lateral faults. Prior to the Pliocene, displacement was transferred east and north on a low-angle detachment. Displacement on the northern part of the FLVFZ continues and is transferred to a fanned array of splays striking (west to east) WNW, NNW, ENE and NNE. To determine the displacement budget on these structures, we conducted a gravity survey to determine subsurface basin morphology and its relation to active faults. Over 2450 stations were collected and combined with existing PACES and proprietary data for a total of 3388 stations. The data were terrain corrected and reduced to a 2.67 g/cm3 density to produce a residual complete Bouguer anomaly. The eastern part of northern Fish Lake Valley is underlain by several prominent gravity lows forming several sub-basins with maximum RCBA values ranging from -24 to -28 mGals. The RCBA was inverted for depth using Geosoft Oasis Montaj GM-SYS 3D modeling software. Density values for the inversion were constrained by lithologic and density logs from wells that penetrate the entire Cenozoic section into the Paleozoic basement. Best fitting gravity measurements taken at the wellheads yielded an effective density of 2.4 g/cm3 for the basin fill. Modeled basement depths range between 2.1 to 3 km. The sub-basins form an arc opening to the NW and are bounded by ENE and NNE faults in the south and NS to NNW in the north. At the northern end of the valley, the faults merge with ENE left-lateral strike slip faults of the Mina deflection, which carries displacement to NW dextral strike-slip faults of the central Walker Lane.

The distribution and relative abundance of ammonia-oxidizing bacteria in lakes of the McMurdo Dry Valley, Antarctica

USGS Publications Warehouse

Voytek, M.A.; Priscu, J.C.; Ward, B.B.

1999-01-01

Marked differences in the concentrations of major ions and cations, macronutrient chemistry and general trophic status exist among the lakes of the McMurdo dry valleys in Antarctica. These differences have been attributed to both variations in stream inputs and in situ lake processes (Priscu, 1995; Lizotte et al., 1996, Spigel and Priscu, 1996). This study examines the role of nitrifying bacteria in nitrogen transformations in these lakes. Applying two polymerase chain reaction (PCR) assays targeting the 16S rRNA genes of ammonia-oxidizing bacteria and the active site of the ammonia monooxygenase gene (amoA), the distribution of ammonia-oxidizers was examined in six Antarctic lakes: Lake Bonney, Lake Hoare, Lake Fryxell and Lake Joyce in the Taylor Valley, Lake Miers in the the Miers Valley and Lake Vanda in the Wright Valley. Using a two stage amplification procedure, ammonia-oxidizers from both the beta and gamma- subclasses of the Proteobacteria were detected and their relative abundances were determined in samples collected from all sites. Ammonia-oxidizers were detected in all lakes sampled. Members of the gamma subclass were only present in the saline lakes. In general, nitrifiers were most abundant at depths above the pycnocline and were usually associated with lower concentrations of NH4 and elevated concentrations of NO3 or NO2. The distribution of nitrifiers suggests that the primary N2O peak observed in most of the lakes was produced via nitrification. Preliminary data on the rate of nitrification (Priscu et al., 1996) support the occurrence of nitrification and the presence of nitrifiers at the depth intervals where nitrifiers were detected. In all lakes, except Lake Miers, the data indicate that nitrifying bacteria have an important role in the vertical distribution of nitrogen compounds in these systems.

Balancing lake ecological condition and agriculture irrigation needs in the Mississippi Alluvial Valley

USGS Publications Warehouse

Miranda, Leandro E.; Omer, A.R.; Killgore, K.J.

2017-01-01

The Mississippi Alluvial Valley includes hundreds of floodplain lakes that support unique fish assemblages and high biodiversity. Irrigation practices in the valley have lowered the water table, increasing the cost of pumping water, and necessitating the use of floodplain lakes as a source of water for irrigation. This development has prompted the need to regulate water withdrawals to protect aquatic resources, but it is unknown how much water can be withdrawn from lakes before ecological integrity is compromised. To estimate withdrawal limits, we examined descriptors of lake water quality (i.e., total nitrogen, total phosphorus, turbidity, Secchi visibility, chlorophyll-a) and fish assemblages (species richness, diversity, composition) relative to maximum depth in 59 floodplain lakes. Change-point regression analysis was applied to identify critical depths at which the relationships between depth and lake descriptors exhibited a rapid shift in slope, suggesting possible thresholds. All our water quality and fish assemblage descriptors showed rapid changes relative to depth near 1.2–2.0 m maximum depth. This threshold span may help inform regulatory decisions about water withdrawal limits. Alternatives to explain the triggers of the observed threshold span are considered.

Asynchronous ice lobe retreat and glacial Lake Bascom: Deglaciation of the Hoosic and Vermont valleys, southwestern Vermont

DOE Office of Scientific and Technical Information (OSTI.GOV)

Small, E.; Desimone, D.

Deglaciation of the Hoosic River drainage basin in southwestern Vermont was more complex than previously described. Detailed surficial mapping, stratigraphic relationships, and terrace levels/delta elevations reveal new details in the chronology of glacial Lake Bascom: (1) a pre-Wisconsinan proglacial lake was present in a similar position to Lake Bascom as ice advanced: (2) the northern margin of 275m (900 ft) glacial Lake Bascom extended 10 km up the Vermont Valley; (3) the 215m (705 ft) Bascom level was stable and long lived; (4) intermediate water planes existed between 215m and 190m (625 ft) levels; and (5) a separate ice tonguemore » existed in Shaftsbury Hollow damming a small glacial lake, here named glacial Lake Emmons. This information is used to correlate ice margins to different lake levels. Distance of ice margin retreat during a lake level can be measured. Lake levels are then used as control points on a Lake Bascom relative time line to compare rate of retreat of different ice tongues. Correlation of ice margins to Bascom levels indicates ice retreat was asynchronous between nearby tongues in southwestern Vermont. The Vermont Valley ice tongue retreated between two and four times faster than the Hoosic Valley tongue during the Bascom 275m level. Rate of retreat of the Vermont Valley tongue slowed to one-half of the Hoosic tongue during the 215m--190m lake levels. Factors responsible for varying rates of retreat are subglacial bedrock gradient, proximity to the Hudson-Champlain lobe, and the presence of absence of a calving margins. Asynchronous retreat produced splayed ice margins in southwestern Vermont. Findings from this study do not support the model of parallel, synchronous retreat proposed by many workers for this region.« less

Preliminary Study of the Effect of the Proposed Long Lake Valley Project Operation on the Transport of Larval Suckers in Upper Klamath Lake, Oregon

USGS Publications Warehouse

Wood, Tamara M.

2009-01-01

A hydrodynamic model of Upper Klamath and Agency Lakes, Oregon, was used to explore the effects of the operation of proposed offstream storage at Long Lake Valley on transport of larval suckers through the Upper Klamath and Agency Lakes system during May and June, when larval fish leave spawning sites in the Williamson River and springs along the eastern shoreline and become entrained in lake currents. A range in hydrologic conditions was considered, including historically high and low outflows and inflows, lake elevations, and the operation of pumps between Upper Klamath Lake and storage in Long Lake Valley. Two wind-forcing scenarios were considered: one dominated by moderate prevailing winds and another dominated by a strong reversal of winds from the prevailing direction. On the basis of 24 model simulations that used all combinations of hydrology and wind forcing, as well as With Project and No Action scenarios, it was determined that the biggest effect of project operations on larval transport was the result of alterations in project management of the elevation in Upper Klamath Lake and the outflow at the Link River and A Canal, rather than the result of pumping operations. This was because, during the spring time period of interest, the amount of water pumped between Upper Klamath Lake and Long Lake Valley was generally small. The dominant effect was that an increase in lake elevation would result in more larvae in the Williamson River delta and in Agency Lake, an effect that was enhanced under conditions of wind reversal. A decrease in lake elevation accompanied by an increase in the outflow at the Link River had the opposite effect on larval concentration and residence time.

Middle Pleistocene infill of Hinkley Valley by Mojave River sediment and associated lake sediment: Depositional architecture and deformation by strike-slip faults

USGS Publications Warehouse

Miller, David; Haddon, Elizabeth; Langenheim, Victoria; Cyr, Andrew J.; Wan, Elmira; Walkup, Laura; Starratt, Scott W.

2018-01-01

Hinkley Valley in the Mojave Desert, near Barstow about 140 km northeast of Los Angeles and midway between Victorville Valley and the Lake Manix basin, contains a thick sedimentary sequence delivered by the Mojave River. Our study of sediment cores drilled in the valley indicates that Hinkley Valley was probably a closed playa basin with stream inflow from four directions prior to Mojave River inflow. The Mojave River deposited thick and laterally extensive clastic wedges originating from the southern valley that rapidly filled much of Hinkley Valley. Sedimentary facies representing braided stream, wetland, delta, and lacustrine depositional environments all are found in the basin fill; in some places, the sequence is greater than 74 m (245 ft) thick. The sediment is dated in part by the presence of the ~631 ka Lava Creek B ash bed low in the section, and thus represents sediment deposition after Victorville basin was overtopped by sediment and before the Manix basin began to be filled. Evidently, upstream Victorville basin filled with sediment by about 650 ka, causing the ancestral Mojave River to spill to the Harper and Hinkley basins, and later to Manix basin.Initial river sediment overran wetland deposits in many places in southern Hinkley Valley, indicating a rapidly encroaching river system. These sediments were succeeded by a widespread lake (“blue” clay) that includes the Lava Creek B ash bed. Above the lake sediment lies a thick section of interlayered stream sediment, delta and nearshore lake sediment, mudflat and/or playa sediment, and minor lake sediment. This stratigraphic architecture is found throughout the valley, and positions of lake sediment layers indicate a successive northward progression in the closed basin. A thin overlapping sequence at the north end of the valley contains evidence for a younger late Pleistocene lake episode. This late lake episode, and bracketing braided stream deposits of the Mojave River, indicate that the river

Rhone River Valley & Lower Lake Geneva, Switzerland as seen from STS-60

NASA Image and Video Library

1994-02-09

STS060-90-007 (3-11 Feb 1994) --- Parts of the Swiss Cantons of Vaud and Valois and the French province of Chablais are shown. These mountains were created in the last great mountain-building episode in Europe around 50 million years ago. They have been reshaped by glaciers during the Pleistocene. The glaciers created the wide valley of the Rhone River by scouring a pre-existing stream. The fertile Swiss Plateau runs northwest from the shore of Lake Geneva and is visible in the upper right. The Franco-Swiss border is located in the center of the lake and follows a mountain divide east of the Rhone Valley. According to NASA geologists eutrofication is a problem in Lake Geneva. In 1971 a Swiss Commission was formed to try to slow the problem. Strong discharge laws were enacted, but they are hard to enforce due to the multi-national and multi-organizational parties contributing to the problem.

Grip strength and body composition in Turkana pastoralist children and adolescents.

PubMed

Little, Michael A

2017-03-01

In an earlier study, age changes and sex differences in grip strength were documented for adult Turkana pastoralists of Kenya (Little and Johnson, 1986). The objective here is to characterize age changes and sex differences in grip strength of Turkana children and adolescents in the context of arm lean tissue composition, and in comparison with other African, African-American, and non-Western populations. Anthropometric measurements, derived body composition values, and grip strength measures (maximum voluntary contraction) were taken on a sample of 232 nomadic Turkana pastoralist children (94 boys and 138 girls) aged 3 to 21 years. Relationships were tested between grip strength (in Newtons) and mid-upper arm (brachium) lean tissue cross-sectional areas. Comparisons were made among several different ethnic groups. Turkana children and adolescents had low arm muscle (derived lean tissue) and grip strength values when compared with U.S. NHANES percentile references. Girls' percentile rankings were greater than boys' percentile rankings for muscle and for grip strength. Both boys and girls were intermediate when compared with other non-Western populations and U.S. strength grip reference values. Correlations between grip strength and arm lean tissue areas were highly significant for both boys and girls. The greater relative muscle size and grip strength values of late adolescent girls compared to boys is consistent with an earlier study of adults. The difference is likely to result from greater physical subsistence activity and greater access to food in girls than in boys. Several suggestions are given to explain why Turkana youths have relatively small muscle sizes. © 2016 Wiley Periodicals, Inc.

Lateral spread hazard mapping of the northern Salt Lake Valley, Utah, for a M7.0 scenario earthquake

USGS Publications Warehouse

Olsen, M.J.; Bartlett, S.F.; Solomon, B.J.

2007-01-01

This paper describes the methodology used to develop a lateral spread-displacement hazard map for northern Salt Lake Valley, Utah, using a scenario M7.0 earthquake occurring on the Salt Lake City segment of the Wasatch fault. The mapping effort is supported by a substantial amount of geotechnical, geologic, and topographic data compiled for the Salt Lake Valley, Utah. ArcGIS?? routines created for the mapping project then input this information to perform site-specific lateral spread analyses using methods developed by Bartlett and Youd (1992) and Youd et al. (2002) at individual borehole locations. The distributions of predicted lateral spread displacements from the boreholes located spatially within a geologic unit were subsequently used to map the hazard for that particular unit. The mapped displacement zones consist of low hazard (0-0.1 m), moderate hazard (0.1-0.3 m), high hazard (0.3-1.0 m), and very high hazard (> 1.0 m). As expected, the produced map shows the highest hazard in the alluvial deposits at the center of the valley and in sandy deposits close to the fault. This mapping effort is currently being applied to the southern part of the Salt Lake Valley, Utah, and probabilistic maps are being developed for the entire valley. ?? 2007, Earthquake Engineering Research Institute.

Water quality of potential reference lakes in the Arkansas Valley and Ouachita Mountain ecoregions, Arkansas

USGS Publications Warehouse

Justus, B.G.; Meredith, Bradley J.

2014-01-01

This report describes a study to identify reference lakes in two lake classifications common to parts of two level III ecoregions in western Arkansas—the Arkansas Valley and Ouachita Mountains. Fifty-two lakes were considered. A screening process that relied on land-use data was followed by reconnaissance water-quality sampling, and two lakes from each ecoregion were selected for intensive water-quality sampling. Our data suggest that Spring Lake is a suitable reference lake for the Arkansas Valley and that Hot Springs Lake is a suitable reference lake for the Ouachita Mountains. Concentrations for five nutrient constituents—orthophosphorus, total phosphorus, total kjeldahl nitrogen, total nitrogen, and total organic carbon—were lower at Spring Lake on all nine sampling occasions and transparency measurements at Spring Lake were significantly deeper than measurements at Cove Lake. For the Ouachita Mountains ecoregion, water quality at Hot Springs Lake slightly exceeded that of Lake Winona. The most apparent water-quality differences for the two lakes were related to transparency and total organic carbon concentrations, which were deeper and lower at Hot Springs Lake, respectively. Our results indicate that when nutrient concentrations are low, transparency may be more valuable for differentiating between lake water quality than chemical constituents that have been useful for distinguishing between water-quality conditions in mesotrophic and eutrophic settings. For example, in this oligotrophic setting, concentrations for chlorophyll a can be less than 5 μg/L and diurnal variability that is typically associated with dissolved oxygen in more productive settings was not evident.

An Early Pleistocene high-resolution paleoclimate reconstruction from the West Turkana (Kenya) HSPDP drill site

NASA Astrophysics Data System (ADS)

Stockhecke, Mona; Beck, Catherine; Brown, Erik T.; Cohen, Andrew; Deocampo, Daniel M.; Feibel, Craig S.; Pelletier, Jon D.; Rabideaux, Nathane M.; Sier, Mark

2016-04-01

The Hominin Sites and Paleolakes Drilling Project (HSPDP), and the related Olorgesailie Drilling Project (ODP), recovered ~2 km of drill core since 2012. At the HSPDP West Turkana Kaitio (WTK) site a 216 m-long core that covers the Early Pleistocene time window (1.3 to 1.87 Ma) during which hominids first expanded out of Africa and marine records document reorganization of tropical climate and the development of the strong Walker circulation. WTK carries particular interest for paleoclimate and paleoenvironmental reconstructions as it is located only 2.5 km from the location of one of the most complete hominin skeletons ever recovered (Nariokotome Boy). XRF core scanning data provide a means of evaluating records of past environmental conditions continuously and at high resolution. However, the record contains complex lithologies reflecting repeated episodes of inundation and desiccation along a dynamic lake margin. Here we present a methodological approach to address the highly variable lithostratigraphy of the East African records to establish comprehensive paleoclimate timeseries. The power spectrum of the presented hydroclimate record peaks at Milankovitch cycles, qualifying HSPDP drill cores from the Turkana Basin to be used as high-resolution Early Pleistocene paleoclimate archive. Comparing these data with marine climate reconstructions sheds light into athmospheric processes and continental climate dynamics.

Regional assessment of lake ecological states using Landsat: A classification scheme for alkaline-saline, flamingo lakes in the East African Rift Valley

NASA Astrophysics Data System (ADS)

Tebbs, E. J.; Remedios, J. J.; Avery, S. T.; Rowland, C. S.; Harper, D. M.

2015-08-01

In situ reflectance measurements and Landsat satellite imagery were combined to develop an optical classification scheme for alkaline-saline lakes in the Eastern Rift Valley. The classification allows the ecological state and consequent value, in this case to Lesser Flamingos, to be determined using Landsat satellite imagery. Lesser Flamingos depend on a network of 15 alkaline-saline lakes in East African Rift Valley, where they feed by filtering cyanobacteria and benthic diatoms from the lakes' waters. The classification developed here was based on a decision tree which used the reflectance in Landsat ETM+ bands 2-4 to assign one of six classes: low phytoplankton biomass; suspended sediment-dominated; microphytobenthos; high cyanobacterial biomass; cyanobacterial scum and bleached cyanobacterial scum. The classification accuracy was 77% when verified against in situ measurements. Classified imagery and timeseries were produced for selected lakes, which show the different ecological behaviours of these complex systems. The results have highlighted the importance to flamingos of the food resources offered by the extremely remote Lake Logipi. This study has demonstrated the potential of high spatial resolution, low spectral resolution sensors for providing ecologically valuable information at a regional scale, for alkaline-saline lakes and similar hypereutrophic inland waters.

The Response of Eastern African Terrestrial Environments to the Mid-Pleistocene Climate Transition: Paleosol Isotopic Evidence from the Turkana Basin, Kenya

NASA Astrophysics Data System (ADS)

Quinn, R.; Lepre, C. J.

2017-12-01

Heightened aridity and C4 grass expansion are recorded in Africa during the Mid-Pleistocene Climate Transition (MPCT, 1.3-0.7 Ma), potentially as consequences of decreasing atmospheric CO2. Whether all of Africa responded to the MPCT in the same manner is unclear. Recent studies of a Malawi Basin lake core and paleosols show abundant C3 flora across the MPCT. African climate change is often suggested as a primary cause of hominin speciation, extinction, and technological innovations. Competing environmental-based evolutionary hypotheses propose increased aridity, humidity pulses, and climatic variability as influences of water availability and vegetation structure in Plio-Pleistocene hominin habitats. The Turkana Basin in northern Kenya preserves a rich fossil record of hominins from 4.3-0.7 Ma and offers high-resolution age control via paleomagnetic stratigraphy, isotopic geochronology, and tephrostratigraphy. Turkana's large paleosol isotopic database demonstrates a gradual increase in C4 grass abundance and aridity from 4-1 Ma. Faunal evidence for increasing abundances of C4 grazers corroborates the spread of C4 grasslands from 2-1 Ma. However, there is a dearth of terrestrial environmental records after 1.5 Ma and through the MPCT at Turkana, during which time eastern Africa witnessed the extinction of Paranthropus and the disperal of genus Homo. Here we report a stable isotopic (δ13C, δ18O) record of paleosol carbonates from the Turkana Basin from 1.4 to 0.7 Ma. Based on our findings and comparisons with comparable datasets from other hominin locales, we suggest that eastern African environments responded to the MPCT in a phased shift from south to north, possibly as a consequence of the compression of the ITCZ during glacial maxima and/or to changes to the Indian Ocean Dipole.

Determinism in fish assemblages of floodplain lakes of the vastly disturbed Mississippi Alluvial Valley

USGS Publications Warehouse

Miranda, L.E.; Lucas, G.M.

2004-01-01

The Mississippi Alluvial Valley between southern Illinois and southern Louisiana contains hundreds of floodplain lakes, most of which have been adversely affected by landscape modifications used to control flooding and support agriculture. We examined fish assemblages in lakes of this region to determine whether deterministic patterns developed in relation to prominent abiotic lake characteristics and to explore whether relevant abiotic factors could be linked to specific assemblage structuring mechanisms. The distributions of 14 taxa in 29 lakes were governed primarily by two gradients that contrasted assemblages in terms of lake area, lake elongation, and water clarity. The knowledge of whether a lake was clear or turbid, large or small, and long or short helped determine fish assemblage characteristics. Abiotic factors influenced fish assemblage structures, plausibly through limitations on foraging and physiological tolerances. Determinism in assemblage organization of floodplain lakes relative to recurrence in physicochemical features has been documented for unaltered rivers. Whereas the Mississippi Alluvial Valley has been subjected to vast anthropogenic disturbances and is not a fully functional floodplain river, fish assemblages in its floodplain lakes remain deterministic and organized by the underlying factors that also dictate assemblages in unaltered rivers. In advanced stages of lake aging, fish assemblages in these lakes are expected to largely include species that thrive in turbid, shallow systems with few predators and low oxygen concentrations. The observed patterns related to physical characteristics of these lakes suggest three general conservation foci, including (1) watershed management to control erosion, (2) removal of sediments or increases in water level to alleviate depth reductions and derived detriments to water physicochemistry, and (3) management of fish populations through stockings, removals, and harvest regulations.

Wind-driven Water Bodies : a new paradigm for lake geology

NASA Astrophysics Data System (ADS)

Nutz, A.; Schuster, M.; Ghienne, J. F.; Roquin, C.; Bouchette, F. A.

2015-12-01

In this contribution we emphasize the importance in some lakes of wind-related hydrodynamic processes (fair weather waves, storm waves, and longshore, cross-shore and bottom currents) as a first order forcing for clastics remobilization and basin infill. This alternative view contrasts with more classical depositional models for lakes where fluvial-driven sedimentation and settling dominates. Here we consider three large lakes/paleo-lakes that are located in different climatic and geodynamic settings: Megalake Chad (north-central Africa), Lake Saint-Jean (Québec, Canada), and Lake Turkana (Kenya, East African Rift System). All of these three lake systems exhibit well developed modern and ancient high-energy littoral morphosedimentary structures which directly derive from wind-related hydrodynamics. The extensive paleo-shorelines of Megalake Chad are composed of beach-foredune ridges, spits, wave-dominated deltas, barriers, and wave-ravinment surface. For Lake Saint-Jean the influence of wind is also identified below the wave-base at lake bottom from erosional surfaces, and sediment drifts. In the Lake Turkana Basin, littoral landforms and deposits are identified for three different time intervals (today, Holocene, Plio-Pleistocene) evidencing that wind-driven hydrodynamics can be preserved in the geological record. Moreover, a preliminary global survey suggests that numerous modern lakes (remote sensing) and paleo-lakes (bibliographic review) behave as such. We thus coin the term "Wind-driven Water Bodies" (WWB) to refer to those lake systems where sedimentation (erosion, transport, deposition) is dominated by wind-induced hydrodynamics at any depth, as it is the case in the marine realm for shallow seas. Integrating wind forcing in lake models has strong implications for basin analysis (paleoenvironments and paleoclimates restitutions, resources exploration), but also for coastal engineering, wildlife and reservoirs management, or leisure activities.

Comparison of effects of breast-feeding practices on birth-spacing in three societies: nomadic Turkana, Gainj, and Quechua.

PubMed

Gray, S J

1994-01-01

Variation in the duration and pattern of breast-feeding contributes significantly to inter-population differences in fertility. In this paper, measures of suckling frequency and intensity are used to compare the effects of breast-feeding practices on the duration of lactational amenorrhoea, and on the length of the birth interval in three prospective studies undertaken during the 1980s, among Quechua Indians of Peru, Turkana nomads of Kenya, and Gainj of Papua New Guinea. In all three societies, lactation is prolonged well into the second year postpartum, and frequent, on-demand breast-feeding is the norm. However, the duration of lactational amenorrhoea and the length of birth intervals vary considerably. Breast-feeding patterns among Gainj and Turkana are similar, but Turkana women resume menses some 3 months earlier than do the Gainj. The average birth interval among the Gainj exceeds that of nomadic Turkana by over 15 months. Suckling activity decreases significantly with increasing age of nurslings among both Gainj and Quechua, but not among Turkana. Earlier resumption of menses among Turkana women may be linked to the unpredictable demands of the pastoral system, which increase day-to-day variation in the number of periods of on-demand breast-feeding, although not in suckling patterns. This effect is independent of the age of infants. The short birth intervals of Turkana women, relative to those of the Gainj, may be related to early supplementation of Turkana nurslings with butterfat and animals' milk, which reduces energetic demands on lactating women at risk of negative energy balance.

Childhood disability in Turkana, Kenya: Understanding how carers cope in a complex humanitarian setting

PubMed Central

Nyapera, Velma; Mwenda, Victoria; Kisia, James; Rono, Hilary; Palmer, Jennifer

2016-01-01

Background Although the consequences of disability are magnified in humanitarian contexts, research into the difficulties of caring for children with a disability in such settings has received limited attention. Methods Based on in-depth interviews with 31 families, key informants and focus group discussions in Turkana, Kenya, this article explores the lives of families caring for children with a range of impairments (hearing, vision, physical and intellectual) in a complex humanitarian context characterised by drought, flooding, armed conflict, poverty and historical marginalisation. Results The challenging environmental and social conditions of Turkana magnified not only the impact of impairment on children, but also the burden of caregiving. The remoteness of Turkana, along with the paucity and fragmentation of health, rehabilitation and social services, posed major challenges and created opportunity costs for families. Disability-related stigma isolated mothers of children with disabilities, especially, increasing their burden of care and further limiting their access to services and humanitarian programmes. In a context where social systems are already stressed, the combination of these factors compounded the vulnerabilities faced by children with disabilities and their families. Conclusion The needs of children with disabilities and their carers in Turkana are not being met by either community social support systems or humanitarian aid programmes. There is an urgent need to mainstream disability into Turkana services and programmes. PMID:28730061

Niche specialization of bacteria in permanently ice-covered lakes of the McMurdo Dry Valleys, Antarctica.

PubMed

Kwon, Miye; Kim, Mincheol; Takacs-Vesbach, Cristina; Lee, Jaejin; Hong, Soon Gyu; Kim, Sang Jong; Priscu, John C; Kim, Ok-Sun

2017-06-01

Perennially ice-covered lakes in the McMurdo Dry Valleys, Antarctica, are chemically stratified with depth and have distinct biological gradients. Despite long-term research on these unique environments, data on the structure of the microbial communities in the water columns of these lakes are scarce. Here, we examined bacterial diversity in five ice-covered Antarctic lakes by 16S rRNA gene-based pyrosequencing. Distinct communities were present in each lake, reflecting the unique biogeochemical characteristics of these environments. Further, certain bacterial lineages were confined exclusively to specific depths within each lake. For example, candidate division WM88 occurred solely at a depth of 15 m in Lake Fryxell, whereas unknown lineages of Chlorobi were found only at a depth of 18 m in Lake Miers, and two distinct classes of Firmicutes inhabited East and West Lobe Bonney at depths of 30 m. Redundancy analysis revealed that community variation of bacterioplankton could be explained by the distinct conditions of each lake and depth; in particular, assemblages from layers beneath the chemocline had biogeochemical associations that differed from those in the upper layers. These patterns of community composition may represent bacterial adaptations to the extreme and unique biogeochemical gradients of ice-covered lakes in the McMurdo Dry Valleys. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

A Comparison of the Seasonal Change of Albedo across Glaciers and Ice-Covered Lakes of the Taylor Valley, Antarctica

NASA Astrophysics Data System (ADS)

Gooseff, M. N.; Bergstrom, A.

2016-12-01

The Dry Valleys of Antarctica are a polar desert ecosystem consisting of piedmont and alpine glaciers, ice-covered lakes, and vast expanses of bare soil. The ecosystem is highly dependent on glacial melt a water source. Because average summer temperatures are close to freezing, glacier ice and lake ice are very closely linked to the energy balance. A slight increase in incoming radiation or decrease in albedo can have large effects on the timing and volume of available liquid water. However, we have yet to fully characterize the seasonal evolution of albedo in the valleys. In this study, we used a camera, gps, and short wave radiometer to characterize the albedo within and across landscape types in the Taylor Valley. These instruments were attached to a helicopter and flown on a prescribed path along the valley at approximately 300 feet above the ground surface five different times throughout the season from mid-November to mid-January, 2015-2016. We used these data to calculate the albedo of each glacier, lake, and the soil surface of the lake basins in the valley for each flight. As expected, we found that all landscape types had significantly different albedo, with the glaciers consistently the highest throughout the season and the bare soils the lowest (p-value < 0.05). We hypothesized that albedo would decrease throughout the season with snow melt and increasing sediment exposure on the glacier and lake surfaces. However, small snow events (< 3 cm) caused somewhat persistent high albedo on the lakes and glaciers. Furthermore, there was a range in albedo across glaciers and each responded to seasonal snow and melt differently. These findings highlight the importance of understanding the spatial and temporal variability in albedo and the close coupling of climate and landscape response. We can use this new understanding of landscape albedo to better predict how the Dry Valley ecosystems will respond to changing climate at the basin scale.

Valley formation by groundwater seepage, pressurized groundwater outbursts and crater-lake overflow in flume experiments with implications for Mars

NASA Astrophysics Data System (ADS)

Marra, Wouter A.; Braat, Lisanne; Baar, Anne W.; Kleinhans, Maarten G.

2014-04-01

Remains of fluvial valleys on Mars reveal the former presence of water on the surface. However, the source of water and the hydrological setting is not always clear, especially in types of valleys that are rare on Earth and where we have limited knowledge of the processes involved. We investigated three hydrological scenarios for valley formation on Mars: hydrostatic groundwater seepage, release of pressurized groundwater and crater-lake overflow. Using physical modeling in laboratory experiments and numerical hydrological modeling we quantitatively studied the morphological development and processes involved in channel formation that result from these different sources of water in unconsolidated sediment. Our results show that valleys emerging from seeping groundwater by headward erosion form relatively slowly as fluvial transport takes place in a channel much smaller than the valley. Pressurized groundwater release forms a characteristic source area at the channel head by fluidization processes. This head consist of a pit in case of superlithostatic pressure and may feature small radial channels and collapse features. Valleys emerging from a crater-lake overflow event develop quickly in a run-away process of rim erosion and discharge increase. The valley head at the crater outflow point has a converging fan shape, and the rapid incision of the rim leaves terraces and collapse features. Morphological elements observed in the experiments can help in identifying the formative processes on Mars, when considerations of experimental scaling and lithological characteristics of the martian surface are taken into account. These morphological features might reveal the associated hydrological settings and formative timescales of a valley. An estimate of formative timescale from sediment transport is best based on the final channel dimensions for groundwater seepage valleys and on the valley dimensions for pressurized groundwater release and crater-lake overflow valleys. Our

Geology and ground water in Russian River Valley areas and in Round, Laytonville, and Little Lake Valleys, Sonoma and Mendocino Counties, California

USGS Publications Warehouse

Cardwell, G.T.

1965-01-01

This report describes the occurrence, availability, and quality of ground water in seven valley areas along the course of the Russian River in Sonoma and Mendocino Counties, Calif., and in three valleys in the upper drainage reach of the Eel River in Mendocino County. Except for the westward-trending lower Russian River valley, the remaining valley areas along the Russian River (Healdsburg, Alexander, Cloverdale, Sanel, Ukiah, and Potter Valleys) lie in northwest-trending structurally controlled depressions formed in marine rocks of Jurassic and Cretaceous age. The principal aquifer in all the valleys is the alluvium of Recent age, which includes highly permeable channel deposits of gravel and sand. Water for domestic, irrigation, industrial, and other uses is developed by (1) direct diversion from the Russian River and its tributaries, (2) withdrawal of ground water and river water from shallow wells near the river, and (3) withdrawals of ground water from wells in alluvial deposits at varying distances from the river. Surface water in the Russian River and most tributaries is of good chemical quality. The water is a calcium magnesium bicarbonate type and contains 75,200 parts per million of dissolved solids. Ground water is also of good chemical quality throughout most of the drainage basin, but the concentration of dissolved solids (100-300 parts per million) is somewhat higher than that in the surface water. Round, Laytonville, and Little Lake Valleys are in central and northern Mendocino County in the drainage basin of the northwestward flowing Eel River. In Round Valley the alluvium of Recent age yields water of good chemical quality in large quantities. Yields are lower and the chemical quality poorer in Laytonville Valley. Ground water in Little Lake Valley is relatively undeveloped. Selected descriptions of wells, drillers' logs, chemical analyses, and hydrographs showing water-level fluctuations are included in the report. Accompanying maps show the

Strontium isotopic signatures of the streams and lakes of Taylor Valley, Southern Victoria Land, Antarctica: Chemical weathering in a polar climate

USGS Publications Warehouse

Lyons, W.B.; Nezat, C.A.; Benson, L.V.; Bullen, T.D.; Graham, E.Y.; Kidd, J.; Welch, K.A.

2002-01-01

We have collected and analyzed a series of water samples from three closed-basin lakes (Lakes Bonney, Fryxell, and Hoare) in Taylor Valley, Antarctica, and the streams that flow into them. In all three lakes, the hypolimnetic waters have different 87Sr/86Sr ratios than the surface waters, with the deep water of Lakes Fryxell and Hoare being less radiogenic than the surface waters. The opposite occurs in Lake Bonney. The Lake Fryxell isotopic ratios are lower than modern-day ocean water and most of the whole-rock ratios of the surrounding geologic materials. A conceivable source of Sr to the system could be either the Cenozoic volcanic rocks that make up a small portion of the till deposited in the valley during the Last Glacial Maximum or from marble derived from the local basement rocks. The more radiogenic ratios from Lake Bonney originate from ancient salt deposits that flow into the lake from Taylor Glacier and the weathering of minerals with more radiogenic Sr isotopic ratios within the tills. The Sr isotopic data from the streams and lakes of Taylor Valley strongly support the notion documented by previous investigators that chemical weathering has been, and is currently, a major process in determining the overall aquatic chemistry of these lakes in this polar desert environment.

Techniques, analysis, and noise in a Salt Lake Valley 4D gravity experiment

USGS Publications Warehouse

Gettings, P.; Chapman, D.S.; Allis, R.

2008-01-01

Repeated high-precision gravity measurements using an automated gravimeter and analysis of time series of 1-Hz samples allowed gravity measurements to be made with an accuracy of 5 ??Gal or better. Nonlinear instrument drift was removed using a new empirical staircase function built from multiple station loops. The new technique was developed between March 1999 and September 2000 in a pilot study conducted in the southern Salt Lake Valley along an east-west profile of eight stations from the Wasatch Mountains to the Jordan River. Gravity changes at eight profile stations were referenced to a set of five stations in the northern Salt Lake Valley, which showed residual signals of <10 ??Gal in amplitude, assuming a reference station near the Great Salt Lake to be stable. Referenced changes showed maximum amplitudes of -40 through +40 ??Gal at profile stations, with minima in summer 1999, maxima in winter 1999-2000, and some decrease through summer 2000. Gravity signals were likely a composite of production-induced changes monitored by well-water levels, elevation changes, precipitation-induced vadose-zone changes, and local irrigation effects for which magnitudes were estimated quantitatively. ?? 2008 Society of Exploration Geophysicists. All rights reserved.

Inter-group violence among early Holocene hunter-gatherers of West Turkana, Kenya.

PubMed

Mirazón Lahr, M; Rivera, F; Power, R K; Mounier, A; Copsey, B; Crivellaro, F; Edung, J E; Maillo Fernandez, J M; Kiarie, C; Lawrence, J; Leakey, A; Mbua, E; Miller, H; Muigai, A; Mukhongo, D M; Van Baelen, A; Wood, R; Schwenninger, J-L; Grün, R; Achyuthan, H; Wilshaw, A; Foley, R A

2016-01-21

The nature of inter-group relations among prehistoric hunter-gatherers remains disputed, with arguments in favour and against the existence of warfare before the development of sedentary societies. Here we report on a case of inter-group violence towards a group of hunter-gatherers from Nataruk, west of Lake Turkana, which during the late Pleistocene/early Holocene period extended about 30 km beyond its present-day shore. Ten of the twelve articulated skeletons found at Nataruk show evidence of having died violently at the edge of a lagoon, into which some of the bodies fell. The remains from Nataruk are unique, preserved by the particular conditions of the lagoon with no evidence of deliberate burial. They offer a rare glimpse into the life and death of past foraging people, and evidence that warfare was part of the repertoire of inter-group relations among prehistoric hunter-gatherers.

Possible future lakes resulting from continued glacier shrinkage in the Aosta Valley Region (Western Alps, Italy)

NASA Astrophysics Data System (ADS)

Viani, Cristina; Machguth, Horst; Huggel, Christian; Godio, Alberto; Perotti, Luigi; Giardino, Marco

2017-04-01

Aosta Valley (NW-Alps, Italy) is the region with the largest glaciarized area of Italy (133.73 km2). Like the other alpine regions it has shown a significant glacier retreat starting from the end of the Little Ice Age (LIA, ca. 1850 AD), by losing about 60% of its glaciarized area. As a direct consequence of glacier shrinkage, within glacially-sculpted landscapes, glacier-bed overdeepenings become exposed, offering suitable conditions for glacier lakes formation. In the Aosta Valley region, about 200 glacier lakes have been recognized in different time periods within LIA maximum extent boundaries, mainly dammed by bedrock landforms. With respect to human activities, glacier lakes represent both opportunities (e.g. Miage lake for tourism) and risks (e.g. outburst flood of the Gran Croux lake above Cogne in August 2016) in such a densely populated and developed region. The objective of this contribution is to assess locations of possible future glacier lakes in the Aosta Valley by using the GlabTop2 model (Glacier Bed Topography model version 2). Understanding where future lakes will appear is of fundamental importance for the identification of potential hazards and the interpretation of conditioning factors and dynamics. We first assessed ice thickness and consequently glacier bed topography over large glaciated areas of the region, by using both glaciers outlines related to 1999 (provided by the GlaRiskAlp project) and the regional DEM of 1990 (provided by the Aosta Valley Region) as input data. We performed several runs by varying different input parameters (e,g.: pixel size and basal shear stress). Then we compared modelled results on selected test glaciers (Rutor and Grand Etrèt) with available GPR data. As a validation, we also carried out a GPR survey during summer 2016 on the central area of Indren Glacier (Monte Rosa massif) where GlabTop2 shows the presence of a possible subglacial overdeepening morphology. We found that ice thickness and consequently the

Limnology of the Green Lakes Valley: Phytoplankton ecology and dissolved organic matter biogeochemistry at a long-term ecological research site

USGS Publications Warehouse

Miller, Matthew P.; McKnight, Diane M.

2015-01-01

Background: Surface waters are the lowest points in the landscape, and therefore serve as excellent integrators and indicators of changes taking place in the surrounding terrestrial and atmospheric environment.Aims: Here we synthesise the findings of limnological studies conducted during the past 15 years in streams and lakes in the Green Lakes Valley, which is part of the Niwot Ridge Long-term Ecological Research (LTER) Site.Methods: The importance of these studies is discussed in the context of aquatic ecosystems as indicators, integrators, and regulators of environmental change. Specifically, investigations into climatic, hydrologic, and nutrient controls on present-day phytoplankton, and historical diatom, community composition in the alpine lake, Green Lake 4, are reviewed. In addition, studies of spatial and temporal patterns in dissolved organic matter (DOM) biogeochemistry and reactive transport modelling that have taken place in the Green Lakes Valley are highlighted.Results and conclusions: The findings of these studies identify specific shifts in algal community composition and DOM biogeochemistry that are indicative of changing environmental conditions and provide a framework for detecting future environmental change in the Green Lakes Valley and in other alpine watersheds. Moreover, the studies summarised here demonstrate the importance of long-term monitoring programmes such as the LTER programme.

Structural controls on geothermal circulation in Surprise Valley, California: A re-evaluation of the Lake City fault zone

USGS Publications Warehouse

Anne E. Egger,; Glen, Jonathan; McPhee, Darcy K.

2014-01-01

Faults and fractures play an important role in the circulation of geothermal fluids in the crust, and the nature of that role varies according to structural setting and state of stress. As a result, detailed geologic and geophysical mapping that relates thermal springs to known structural features is essential to modeling geothermal systems. Published maps of Surprise Valley in northeastern California suggest that the “Lake City fault” or “Lake City fault zone” is a significant structural feature, cutting obliquely across the basin and connecting thermal springs across the valley. Newly acquired geophysical data (audio-magnetotelluric, gravity, and magnetic), combined with existing geochemical and geological data, suggest otherwise. We examine potential field profiles and resistivity models that cross the mapped Lake City fault zone. While there are numerous geophysical anomalies that suggest subsurface structures, they mostly do not coincide with the mapped traces of the Lake City fault zone, nor do they show a consistent signature in gravity, magnetics, or resistivities that would suggest a through-going fault that would promote connectivity through lateral fluid flow. Instead of a single, continuous fault, we propose the presence of a deformation zone associated with the growth of the range-front Surprise Valley fault. The implication for geothermal circulation is that this is a zone of enhanced porosity but lacks length-wise connectivity that could conduct fluids across the valley. Thermal fluid circulation is most likely controlled primarily by interactions between N-S–trending normal faults.

Heating the Ice-Covered Lakes of the McMurdo Dry Valleys, Antarctica - Decadal Trends in Heat Content, Ice Thickness, and Heat Exchange

NASA Astrophysics Data System (ADS)

Gooseff, M. N.; Priscu, J. C.; Doran, P. T.; Chiuchiolo, A.; Obryk, M.

2014-12-01

Lakes integrate landscape processes and climate conditions. Most of the permanently ice-covered lakes in the McMurdo Dry Valleys, Antarctica are closed basin, receiving glacial melt water from streams for 10-12 weeks per year. Lake levels rise during the austral summer are balanced by sublimation of ice covers (year-round) and evaporation of open water moats (summer only). Vertical profiles of water temperature have been measured in three lakes in Taylor Valley since 1988. Up to 2002, lake levels were dropping, ice covers were thickening, and total heat contents were decreasing. These lakes have been gaining heat since the mid-2000s, at rates as high as 19.5x1014 cal/decade). Since 2002, lake levels have risen substantially (as much as 2.5 m), and ice covers have thinned (1.5 m on average). Analyses of lake ice thickness, meteorological conditions, and stream water heat loads indicate that the main source of heat to these lakes is from latent heat released when ice-covers form during the winter. An aditional source of heat to the lakes is water inflows from streams and direct glacieal melt. Mean lake temperatures in the past few years have stabilized or cooled, despite increases in lake level and total heat content, suggesting increased direct inflow of meltwater from glaciers. These results indicate that McMurdo Dry Valley lakes are sensitive indicators of climate processes in this polar desert landscape and demonstrate the importance of long-term data sets when addressing the effects of climate on ecosystem processes.

Factors affecting fish biodiversity in floodplain lakes of the Mississippi Alluvial Valley

USGS Publications Warehouse

Miranda, Leandro E.; Dembkowski, Daniel J.

2012-01-01

River-floodplain ecosystems offer some of the most diverse and dynamic environments in the world. Accordingly, floodplain habitats harbor diverse fish assemblages. Fish biodiversity in floodplain lakes may be influenced by multiple variables operating on disparate scales, and these variables may exhibit a hierarchical organization depending on whether one variable governs another. In this study, we examined the interaction between primary variables descriptive of floodplain lake large-scale features, suites of secondary variables descriptive of water quality and primary productivity, and a set of tertiary variables descriptive of fish biodiversity across a range of floodplain lakes in the Mississippi Alluvial Valley of Mississippi and Arkansas (USA). Lakes varied considerably in their representation of primary, secondary, and tertiary variables. Multivariate direct gradient analyses indicated that lake maximum depth and the percentage of agricultural land surrounding a lake were the most important factors controlling variation in suites of secondary and tertiary variables, followed to a lesser extent by lake surface area. Fish biodiversity was generally greatest in large, deep lakes with lower proportions of watershed agricultural land. Our results may help foster a holistic approach to floodplain lake management and suggest the framework for a feedback model wherein primary variables can be manipulated for conservation and restoration purposes and secondary and tertiary variables can be used to monitor the success of such efforts.

Turkana Children's Sociocultural Practices of Pastoralist Lifestyles and Science Curriculum and Instruction in Kenyan Early Childhood Education

ERIC Educational Resources Information Center

Ng'asike, John Teria

2010-01-01

This dissertation discusses the findings of an ethnographic exploratory study of Turkana nomadic pastoralist children's sociocultural practices of their everyday lifestyles and science curriculum and instruction in Kenyan early childhood curriculum. The study uses the findings from Turkana elders to challenge the dominant society in Kenya that…

Insights from analyzing and modelling cascading multi-lake outburst flood events in the Santa Cruz Valley (Cordillera Blanca, Perú)

NASA Astrophysics Data System (ADS)

Emmer, Adam; Mergili, Martin; Juřicová, Anna; Cochachin, Alejo; Huggel, Christian

2016-04-01

Since the end of Little Ice Age, the Cordillera Blanca of Perú has experienced tens of lake outburst floods (LOFs), resulting in the loss of thousands of lives and significant material damages. Most commonly involving glacial lakes, such events are often directly or indirectly related to glacier retreat. Here we analyze an event on 8th February 2012 involving four lakes and affecting two valleys (Santa Cruz and Artizón) in the northern part of the Cordillera Blanca. Using the combination of field data, satellite images, digital elevation model (DEM) and GIS-based modelling approaches, the main objectives are: (i) to better understand complex multi-lake outburst flood and related foregoing and induced geomorphological processes; and (ii) to evaluate and discuss the suitability, potentials and limitations of the r.avaflow model for modelling such complex process chains. Analyzing field geomorphological evidence and remotely-sensed images, we reconstruct the event as follows: a landslide from the recently deglaciated left lateral moraine of Lake Artizón Alto (4 639 m a.s.l.), characterized by steep slopes and a height of more than 200 m produced a displacement wave which overtopped the bedrock dam of the lake. The resulting flood wave breached the dam of the downstream moraine-/landslide-dammed Lake Artizón Bajo (4 477 m a.s.l.), decreasing the lake level by 10 m and releasing 3 x 105 m3 of water. Significant amounts of material were eroded from the steeper parts of the Artizón Valley (mean slope >15°) and deposited further downstream in the flatter part of the Santa Cruz Valley (mean slope <2°; confluence of the two valleys at 3 985 m a.s.l.). The flood affected two debris cone-dammed lakes (Jatuncocha and Ichiccocha) in the Santa Cruz Valley. Some minor damages to the dam of Lake Jatuncocha were documented. Geomprohological evidence of the event was observed more than 20 km downstream from Lake Artizón Alto. The described multi-LOF event was employed as a

Large-eddy simulations of a Salt Lake Valley cold-air pool

NASA Astrophysics Data System (ADS)

Crosman, Erik T.; Horel, John D.

2017-09-01

Persistent cold-air pools are often poorly forecast by mesoscale numerical weather prediction models, in part due to inadequate parameterization of planetary boundary-layer physics in stable atmospheric conditions, and also because of errors in the initialization and treatment of the model surface state. In this study, an improved numerical simulation of the 27-30 January 2011 cold-air pool in Utah's Great Salt Lake Basin is obtained using a large-eddy simulation with more realistic surface state characterization. Compared to a Weather Research and Forecasting model configuration run as a mesoscale model with a planetary boundary-layer scheme where turbulence is highly parameterized, the large-eddy simulation more accurately captured turbulent interactions between the stable boundary-layer and flow aloft. The simulations were also found to be sensitive to variations in the Great Salt Lake temperature and Salt Lake Valley snow cover, illustrating the importance of land surface state in modelling cold-air pools.

Formation of Particulate Matter during Wintertime Inversions in the Salt Lake Valley.

NASA Astrophysics Data System (ADS)

Hrdina, A. I. H.; Baasandorj, M.; Lin, J. C.; Murphy, J. G.; McKeen, S. A.

2017-12-01

In the wintertime, the air quality in Salt Lake City is frequently impacted by inversions that cause high levels of particulate matter. An inversion describes a highly stable air mass, where a cold air pool (CAP) is trapped by warmer air aloft. In the right conditions, these CAPs can persist for several days allowing the accumulation of various pollutants, such as NOx and NH3, leading to secondary particle formation. Concentrations of reactive trace gases (HCl, HNO3, HONO, NH3, SO2) and particle phase constituents (Cl-, NO2-, NO3-, SO42-, Na+, NH4+, K+, Mg2+, Ca2+) from particles less than 2.5 microns in diameter (PM2.5) were continuously measured using an online ambient ion monitor ion chromatograph (AIM-IC) within the Salt Lake Valley, Utah, from Jan 17 - Feb 21 2017, as part of the Utah Fine Particulate Study (UWFPS 2017). A consistent diurnal pattern of ammonia mixing ratios was observed, with mixing ratios ranging from 0.1 - 7 ppb. Two persistent cold air pool events occurred during the measurement period during which the suppression of vertical mixing led to the buildup of PM2.5 in the valley. The total PM2.5 level in the valley was as high as 60 μg m-3 and was dominated by ammonium nitrate. The air pollution transport within the valley during the entire campaign period was examined using Stochastic Time-Inverted Lagrangian Transport (STILT) model. Calculated flux footprints, based on back-trajectories with 15 minute time steps at a grid resolution of 0.1 degree, highlight the potential source regions for PM2.5 precursors during the observed PCAP events. Observations were also compared to output from the Weather Research and Forecasting model coupled with chemistry (WRF-Chem) simulations of the UWFPS campaign.

Dynamics of bacterial class Bacilli in the deepest valley lake of Kashmir-the Manasbal Lake.

PubMed

Shafi, Sana; Kamili, Azra N; Shah, Manzoor A; Bandh, Suhaib A; Dar, Rubiya

2017-03-01

In recognition of the importance of bacteria as ecological indicators of the aquatic systems a comprehensive and systematic analysis was carried out on Manasbal Lake, the deepest spring fed valley lake of Kashmir. The main objective envisaged was to analyze bacterial community composition (BCC) and for this purpose systematic and regular sampling of waters from ten different sampling stations, predetermined in the Lake according to differences in degree of human interference and also as zones of special ecological interests were selected. The isolated species were identified according to Bergey's Manual specification by examining their micro and macro morphological characteristics and biochemical characteristics on different culture media. Further confirmation was done by sequencing the 16s rRNA gene by using universal bacterial primers 27F and 1429R. From all the sampling stations the class Bacilli showed a maximum relative abundance with a contribution of 16 bacterial species. The whole process resulted in the identification of Bacillus aerius, Bacillus altitudinis, Bacillus anthracis, Bacillus cereus, Bacillus ginsengisoli, Bacillus pumilus, Bacillus safensis, Bacillus stratosphericus, Bacillus subtilis, Bacillus tequilensis, Bacillus thermocopriae, Bacillus thuringiensis, Brevibacillus agri strain, Lysinibacillus boronitolerans, Lysinibacillus pakistanensis and Lysinibacillus sphaericus. Copyright © 2017 Elsevier Ltd. All rights reserved.

Leaf wax biomarker reconstruction of Early Pleistocene hydrological variation during hominin evolution in West Turkana, Kenya

NASA Astrophysics Data System (ADS)

Lupien, R.; Russell, J. M.; Cohen, A. S.; Feibel, C. S.; Beck, C.; Castañeda, I. S.

2016-12-01

Climate change is thought to play a critical role in human evolution; however, this hypothesis is difficult to test due to a lack of long, high-quality paleoclimate records from key hominin fossil locales. To address this issue, we examine Plio-Pleistocene lake sediment drill cores from East Africa that were recovered by the Hominin Sites and Paleolakes Drilling Project, an international effort to study the environment in which our hominin ancestors evolved and dispersed. With new data we test various evolutionary hypotheses, such as the "variability selection" hypothesis, which posits that high-frequency environmental variations selected for generalist traits that allowed hominins to expand into variable environments. We analyzed organic geochemical signals of climate in lake cores from West Turkana, Kenya, which span 1.87-1.38 Ma and contain the first fossils from Homo erectus. In particular, we present a compound-specific hydrogen isotopic analysis of terrestrial plant waxes (δDwax) that records regional hydrology. The amount effect dominates water isotope fractionation in the tropics; therefore, these data are interpreted to reflect mean annual rainfall, which affects vegetation structure and thus, hominin habitats. The canonical view of East Africa is that climate became drier and increasingly felt high-latitude glacial-interglacial cycles during the Plio-Pleistocene. However, the drying trend seen in some records is not evident in Turkana δDwax, signifying instead a climate with a steady mean state. Spectral and moving variance analyses indicate paleohydrological variations related to both high-latitude glaciation (41 ky cycle) and local insolation-forced monsoons (21 ky cycle). An interval of particularly high-amplitude rainfall variation occurs at 1.7 Ma, which coincides with the intensification of the Walker Circulation. These results identify high- and low-latitude controls on East African paleohydrology during Homo erectus evolution. In particular, the

Elastic-wave propagation and site amplification in the Salt Lake Valley, Utah, from simulated normal faulting earthquakes

USGS Publications Warehouse

Benz, H.M.; Smith, R.B.

1988-01-01

The two-dimensional seismic response of the Salt Lake valley to near- and far-field earthquakes has been investigated from simulations of vertically incident plane waves and from normal-faulting earthquakes generated on the basin-bounding Wasatch fault. The plane-wave simulations were compared with observed site amplifications in the Salt Lake valley, based on seismic recordings from nuclear explosions in southern Nevada, that show 10 times greater amplification with the basin than measured values on hard-rock sites. Synthetic seismograms suggest that in the frequency band 0.3 to 1.5 Hz at least one-half the site amplitication can be attributed to the impedance contrast between the basin sediments and higher velocity basement rocks. -from Authors

Selected hydrologic data for Salt Lake Valley, Utah, October 1968 to October 1985

USGS Publications Warehouse

Seiler, R.L.

1986-01-01

This report contains hydrologic data collected in Salt Lake Valley from October 1968 to October 1985. The report area is bounded by the Wasatch Range on the east, the Oquirrh Mountains on the west, the Traverse Mountains on the south, and the boundary between Davis and Salt Lake Counties on the north. Hely and others (1971) defined two aquifers of major importance in the valley the principal aquifer and the shallow aquifer. The principal aquifer is a source of water for public supply and industry, whereas the shallow aquifer in many places contains water that is contaminated and is unsuitable for public supply (Seiler and Waddell, 1984). Most of the data in this report were collected by the U.S. Geological Survey in cooperation with the Utah Department of Natural Resources, Division of Water Rights, Salt Lake County Water Conservancy District, Central Utah Water Conservancy District, Granger-Hunter Improvement District, Magna Water Co. and Improvement District, City of Midvale, Salt Lake City Department of Public Utilities, City of Sandyr City of South Salt Lake, Taylorsville Bennion Improvement District, City of West Jordan, Holladay Water Company, and White City Water Co. Some of the data were published previously by Hely, Mower, and Horr (1967, 1968, and 1969), lorns, Mower, and Horr (1966a and b), Marine and Price (1963), and Seiler and Waddell (1984).The purpose of this report is to provide hydrologic data for use by the general public and by officials who manage water resources and to supplement interpretive reports for the area. Information about wells, water levels in wells, and the chemical and physical properties of ground water is given in tables 1-4, and the well locations are shown on plate 1.

Groundwater quality in the Bear Valley and Lake Arrowhead Watershed, California

USGS Publications Warehouse

Mathany, Timothy; Burton, Carmen; Fram, Miranda S.

2017-06-20

Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. The Bear Valley and Lake Arrowhead Watershed study areas in southern California compose one of the study units being evaluated.

Siphateles (Gila) sp. and Catostomus sp. from the Pleistocene OIS-6 Lake Gale, Panamint Valley, Owens River system, California

NASA Astrophysics Data System (ADS)

Jayko, A. S.; Forester, R. M.; Smith, G. R.

2014-12-01

Panamint Valley lies within the Owens River system which linked southeastern Sierra Nevada basins between Mono Lake and Death Valley during glacial-pluvial times. Previous work indicates that late Pleistocene glacial-pluvial Lake Gale, Panamint Valley was an open system during OIS-6, a closed ground water supported shallow lake during OIS-4, and the terminal lake basin for the Owens River system during OIS-2. We here report the first occurrence of fossil fish from the Plio-Pleistocene Panamint basin. Fish remains are present in late Pleistocene OIS-6 nearshore deposits associated with a highstand that was spillway limited at Wingate Wash. The deposits contain small minnow-sized remains from both Siphateles or Gila sp. (chubs) and Catostomus sp. (suckers) from at least four locations widely dispersed in the basin. Siphateles or Gila sp. and Catostomus are indigenous to the Pleistocene and modern Owens River system, in particular to the historic Owens Lake area. Cyprinodon (pupfish) and Rhinichthys (dace) are known from the modern Amargosa River and from Plio-Pleistocene deposits in Death Valley to the east. The late Pleistocene OIS-6 to OIS-2 lacustrine and paleohydrologic record in Panamint basin is interpreted from ostracod assemblages, relative abundance of Artemia sp. pellets, shallow water indicators including tufa fragments, ruppia sp. fragments and the relative abundance of charophyte gyrogonites obtained from archived core, as well as faunal assemblages from paleoshoreline and nearshore deposits. The OIS-4 groundwater supported shallow saline lake had sufficiently low ratios of alkalinity to calcium (alk/Ca) to support the occurrence of exotic Elphidium sp. (?) foraminfera which are not observed in either OIS-2 or OIS-6 lacustrine deposits. The arrival of Owens River surface water into Panamint Basin during OIS-2 is recorded by the first appearance of the ostracod Limnocythere sappaensis at ~27 m depth in an ~100 m archived core (Smith and Pratt, 1957) which

Late Quaternary MIS 6-8 shoreline features of pluvial Owens Lake, Owens Valley, eastern California

USGS Publications Warehouse

Jayko, A.S.; Bacon, S.N.

2008-01-01

The chronologic history of pluvial Owens Lake along the eastern Sierra Nevada in Owens Valley, California, has previously been reported for the interval of time from ca. 25 calibrated ka to the present. However, the age, distribution, and paleoclimatic context of higher-elevation shoreline features have not been formally documented. We describe the location and characteristics of wave-formed erosional and depositional features, as well as fluvial strath terraces that grade into an older shoreline of pluvial Owens Lake. These pluvial-lacustrine features are described between the Olancha area to the south and Poverty Hills area to the north, and they appear to be vertically deformed -20 ?? 4 m across the active oblique-dextral Owens Valley fault zone. They occur at elevations from 1176 to 1182 m along the lower flanks of the Inyo Mountains and Coso Range east of the fault zone to as high as -1204 m west of the fault zone. This relict shoreline, referred to as the 1180 m shoreline, lies -20-40 m higher than the previously documented Last Glacial Maximum shoreline at -1160 m, which occupied the valley during marine isotope stage 2 (MIS 2). Crosscutting relations of wave-formed platforms, notches, and sandy beach deposits, as well as strath terraces on lava flows of the Big Pine volcanic field, bracket the age of the 1180 m shoreline to the time interval between ca. 340 ?? 60 ka and ca. 130 ?? 50 ka. This interval includes marine oxygen isotope stages 8-6 (MIS 8-6), corresponding to 260-240 ka and 185-130 ka, respectively. An additional age estimate for this shoreline is provided by a cosmogenic 36Cl model age of ca. 160 ?? 32 ka on reefal tufa at ???1170 m elevation from the southeastern margin of the valley. This 36Cl model age corroborates the constraining ages based on dated lava flows and refines the lake age to the MIS 6 interval. Documentation of this larger pluvial Owens Lake offers insight to the hydrologic balance along the east side of the southern Sierra

Sensitivity of the East African rift lakes to climate variability

NASA Astrophysics Data System (ADS)

Olaka, L.; Trauth, M. H.

2009-04-01

Lakes in the East African Rift have provided excellent proxies to reconstruct past climate changes in the low latitudes. The lakes occupy volcano-tectonic depressions with highly variable climate and hydrological setting, that present a good opportunity to study the climatic and hydrogeological influences on the lake water budget. Previous studies have used lake floor sediments to establish the sensitivity of the East African rift lakes. This study focuses on geomorphology and climate to offer additional or alternative record of lake history that are key to quantifying sensitivity of these lakes as archives to external and internal climatic forcings. By using the published Holocene lake areas and levels, we analyze twelve lakes on the eastern arm of the East African rift; Ziway, Awassa, Turkana, Suguta, Baringo, Nakuru, Elmenteita, Naivasha, Natron, Manyara and compare with Lake Victoria, that occupies the plateau between the east and the western arms of the rift. Using the SRTM data, Hypsometric (area-altitude) analysis has been used to compare the lake basins between latitude 80 North and 30 South. The mean elevation for the lakes, is between 524 and 2262 meters above sea level, the lakes' hypsometric integrals (HI), a measure of landmass volume above the reference plane, vary from 0.31 to 0.76. The aridity index (Ai), defined as Precipitation/ Evapotranspiration, quantifies the water available to a lake, it encompasses land cover and climatic effects. It is lowest (arid) in the basin between the Ethiopian rift and the Kenyan rift and at the southern termination of the Kenyan Rift in the catchments of lake Turkana, Suguta, Baringo and Manyara with values of 0.55, 0.43, 0.43 and 0.5 respectively. And it is highest (wet) in the catchments of, Ziway, Awassa, Nakuru and Naivasha as 1.33,1.03 and 1.2 respectively, which occupy the highest points of the rift. Lake Victoria has an index of 1.42 the highest of these lakes and receives a high precipitation. We use a

Evaporation estimation of rift valley lakes: comparison of models.

PubMed

Melesse, Assefa M; Abtew, Wossenu; Dessalegne, Tibebe

2009-01-01

Evapotranspiration (ET) accounts for a substantial amount of the water flux in the arid and semi-arid regions of the World. Accurate estimation of ET has been a challenge for hydrologists, mainly because of the spatiotemporal variability of the environmental and physical parameters governing the latent heat flux. In addition, most available ET models depend on intensive meteorological information for ET estimation. Such data are not available at the desired spatial and temporal scales in less developed and remote parts of the world. This limitation has necessitated the development of simple models that are less data intensive and provide ET estimates with acceptable level of accuracy. Remote sensing approach can also be applied to large areas where meteorological data are not available and field scale data collection is costly, time consuming and difficult. In areas like the Rift Valley regions of Ethiopia, the applicability of the Simple Method (Abtew Method) of lake evaporation estimation and surface energy balance approach using remote sensing was studied. The Simple Method and a remote sensing-based lake evaporation estimates were compared to the Penman, Energy balance, Pan, Radiation and Complementary Relationship Lake Evaporation (CRLE) methods applied in the region. Results indicate a good correspondence of the models outputs to that of the above methods. Comparison of the 1986 and 2000 monthly lake ET from the Landsat images to the Simple and Penman Methods show that the remote sensing and surface energy balance approach is promising for large scale applications to understand the spatial variation of the latent heat flux.

The lowering of Glacial Lake Hitchcock in the Upper Connecticut Valley (New Hampshire and Vermont) as registered by varved sediments

NASA Astrophysics Data System (ADS)

Bigl, M.; Kelly, M. A.

2012-12-01

Subsequent to the last glacial maximum, the Laurentide Ice Sheet retreated northward through New England and New York and large glacial lakes formed in the Hudson, Connecticut and Merrimack Valleys. Varved sediments in these former lake basins preserve an incredible record of the timing and rates of ice sheet recession as well as regional climatic conditions. Here, we test the hypothesis that these varves also preserve a history of the lowering and drainage of the lakes. We present evidence of sudden increases in varve thicknesses within the former Glacial Lake Hitchcock (GLH) basin in the Connecticut River Valley of New Hampshire and Vermont and test the hypothesis that these result from lake-level lowering events. GLH existed in the Connecticut Valley due to a sediment dam at its southern end near Rocky Hill, CT. At its maximum, it may have extended from Rocky Hill to near Lyndon, VT. A breach of the Rocky Hill dam at ~13.5 ka caused the drainage of the southern basin of GLH, located south of the Holyoke Range in Massachusetts, but the northern basin of GLH (in the Upper Valley region of New Hampshire and Vermont) retained water until ~11.5 ka (Stone, 1999). However, no studies have focused on lake level fluctuation, exact timing of GLH drainage, and whether the lake drained in one episode or as a longer sequence of drainage events. We use sediment cores from modern lake basins to examine the lowering and final drainage of GLH in the Upper Valley region. As GLH lowered, these modern basins emerged (with higher elevation basins emerging first) and deposition in each basin transitioned from glacial varves to non-varved and organic-rich sediments. We hypothesize that during a lowering event a basin submerged by GLH would have received an increase in sediment flux from deposits exposed at the lakeshore and, thus, a sudden thickening of varves would occur. We test this hypothesis by comparing the age of the transition from glacial varves to non-varved and organic

Dispersion of Perfluorocarbon Tracers within the Salt Lake Valley during VTMX 2000

NASA Astrophysics Data System (ADS)

Fast, Jerome D.; Allwine, K. Jerry; Dietz, Russell N.; Clawson, Kirk L.; Torcolini, Joel C.

2006-06-01

Six perfluorocarbon tracer experiments were conducted in Salt Lake City, Utah, during October 2000 as part of the Vertical Transport and Mixing (VTMX) field campaign. Four tracers were released at different sites to obtain information on dispersion during stable conditions within down-valley flow, canyon outflow, and interacting circulations in the downtown area. Some of the extensive tracer data that were collected are presented in the context of the meteorological field campaign measurements. Tracer measurements at building-top sites in the downtown area and along the lower slopes of the Wasatch Front indicated that vertical mixing processes transported material up to at least 180 m above the valley floor, although model simulations suggest that tracers were transported upward to much higher elevations. Tracer data provided evidence of downward mixing of canyon outflow, upward mixing within down-valley flow, horizontal transport above the surface stable layer, and transport within horizontal eddies produced by the interaction of canyon and down-valley flows. Although point meteorological measurements are useful in evaluating the forecasts produced by mesoscale models, the tracer data provide valuable information on how the time-varying three-dimensional mean and turbulent motions over urban and valley spatial scales affect dispersion. Although the mean tracer transport predicted by the modeling system employed in this study was qualitatively similar to the measurements, improvements are needed in the treatment of turbulent vertical mixing.

Quaternary Sedimentary and Geomorphic History of River Valleys in the Lake Titicaca Basin, Peru and Bolivia

NASA Astrophysics Data System (ADS)

Rigsby, C. A.; Farabaugh, R. L.; Baker, P. A.

2002-12-01

Lacustrine sediments have become important archives of paleoclimatic history in the tropical Andes of South America. The history of lake level of Lake Titicaca (LT) has played a central role in these reconstructions. Here we report on our ongoing studies of the late Quaternary sedimentary and geomorphic histories of two of the major tributaries to LT (the Rios Ramis and Ilave) and on our earlier studies of LT's only outlet (the Rio Desaguadero). The strata and fluvial terraces in these valleys record large-scale aggradation and downcutting events that are apparently correlative with both climate changes in the LT basin and local complex response mechanisms (changes in sediment source, topographic variability, etc.). Both the Ramis and Ilave valleys have 5 terrace tracts, ranging from less than 1 m to approximately 53 m above the river level and occurring as both paired and unpaired tracts and as cut-fill, fill-, and strath terraces. The Rio Desaguadero valley has 4, locally paired, cut-fill and fill terrace tracts that range in height from approximately 2 m to 40 m above river level. In all three valleys, the terraces are underlain by meandering- and braided-river sands and gravels and by lacustrine muds. Radiocarbon dates from the Ilave and Desaguadero valleys suggest that strata in these valleys aggraded during periods of high or rising levels of LT, high or increasing sedimentation rates in the Rio Ilave delta, high (but variable) regional precipitation, and lacustrine sedimentation in the upstream-most reaches of the Rio Desaguadero valley. These same strata were downcut during periods of low or falling levels of LT, low or rapidly decreasing sedimentation rates in the Rio Ilave delta, and lower regional precipitation and runoff. In all three valleys, aggradational periods are punctuated by equilibrium periods of soil formation, downcutting events are episodic, and the most recent events are aggradation and subsequent downcutting of a low, young fill

Mono Lake excursion recorded in sediment of the Santa Clara Valley, California

USGS Publications Warehouse

Mankinen, Edward A.; Wentworth, Carl M.

2004-01-01

Two intervals recording anomalous paleomagnetic inclinations were encountered in the top 40 meters of research drill hole CCOC in the Santa Clara Valley, California. The younger of these two intervals has an age of 28,090 ± 330 radiocarbon years B.P. (calibrated age ∼32.8 ka). This age is in excellent agreement with the latest estimate for the Mono Lake excursion at the type locality and confirms that the excursion has been recorded by sediment in the San Francisco Bay region. The age of an anomalous inclination change below the Mono Lake excursion was not directly determined, but estimates of sedimentation rates indicate that the geomagnetic behavior it represents most likely occurred during the Mono Lake/Laschamp time interval (∼45–28 ka). If true, it may represent one of several recurring fluctuations of magnetic inclination during an interval of a weak geomagnetic dipole, behavior noted in other studies in the region.

MX Siting Investigation. Geotechnical Evaluation. Aggregate Resources Study, Lake Valley, Nevada.

DTIC Science & Technology

1981-02-27

KILOMETERS Mx SITING INVESTIGATION IGURE IPARTMENT OF TNt Ag1 FORCE - GMO 2 -_ONiO NATIONAL INC. FlU It FN-TR-37-f 5 2. Aerial and ground reconnaissance...fine, or crushed rock) and potential construction use ( con - crete and/or road base). TOM. FN-TR -37-f 6 2.0 STUDY APPROACH 2.1 EXISTING DATA Collection...2 the southwestern part of Lake Valley. This formation also pro - vides Class I crushed rock aggregate material in the southern White Rock Mountains

Holocene intramontane lake development: A new model in the Jáchal River Valley, Andean Precordillera, San Juan, Argentina

NASA Astrophysics Data System (ADS)

Colombo, Ferran; Busquets, Pere; Sole de Porta, Nuria; Limarino, Carlos Oscar; Heredia, Nemesio; Rodriguez-Fernandez, Luis Roberto; Alvarez-Marron, Joaquina

2009-10-01

The Jáchal River Valley displays a number of significant Holocene sedimentary accumulations made up of fine-grained materials. These deposits are interpreted as the sedimentary infill of shallow temporary lakes that were generated by slow growing episodes of alluvial fans that obstructed the Jáchal River Valley. The association of fossil remains through the Holocene sedimentary sequence suggests that the accumulation of lacustrine sediments was affected by climate variations. The predominant aridity was punctuated by very few humid episodes characterised by fresh-water gastropoda and the intercalations of muddy sediments. The high proportion of charcoal particles in some samples indicates periodic forest fires. Abundant non-pollen forest remains suggest that an open zone dominated by several types of grasses underwent a dry season during part of the year. The palynomorph associations found in the Jáchal River Valley Holocene lacustrine sediments suggest that the humid conditions were less intense than those in the San Juan River Valley located more than one hundred kilometres southwards. Our study suggests that lake formation could have been controlled by climate oscillation probably related to the ENSO variation at 30° south latitude.

Hierarchy in factors affecting fish biodiversity in floodplain lakes of the Mississippi Alluvial Valley

USGS Publications Warehouse

Dembkowski, D.J.; Miranda, L.E.

2012-01-01

River-floodplain ecosystems offer some of the most diverse and dynamic environments in the world. Accordingly, floodplain habitats harbor diverse fish assemblages. Fish biodiversity in floodplain lakes may be influenced by multiple variables operating on disparate scales, and these variables may exhibit a hierarchical organization depending on whether one variable governs another. In this study, we examined the interaction between primary variables descriptive of floodplain lake large-scale features, suites of secondary variables descriptive of water quality and primary productivity, and a set of tertiary variables descriptive of fish biodiversity across a range of floodplain lakes in the Mississippi Alluvial Valley of Mississippi and Arkansas (USA). Lakes varied considerably in their representation of primary, secondary, and tertiary variables. Multivariate direct gradient analyses indicated that lake maximum depth and the percentage of agricultural land surrounding a lake were the most important factors controlling variation in suites of secondary and tertiary variables, followed to a lesser extent by lake surface area. Fish biodiversity was generally greatest in large, deep lakes with lower proportions of watershed agricultural land. Our results may help foster a holistic approach to floodplain lake management and suggest the framework for a feedback model wherein primary variables can be manipulated for conservation and restoration purposes and secondary and tertiary variables can be used to monitor the success of such efforts. ?? 2011 Springer Science+Business Media B.V.

Integrated hazard assessment of Cirenmaco glacial lake in Zhangzangbo valley, Central Himalayas

NASA Astrophysics Data System (ADS)

Wang, Weicai; Gao, Yang; Iribarren Anacona, Pablo; Lei, Yanbin; Xiang, Yang; Zhang, Guoqing; Li, Shenghai; Lu, Anxin

2018-04-01

Glacial lake outburst floods (GLOFs) have recently become one of the primary natural hazards in the Himalayas. There is therefore an urgent need to assess GLOF hazards in the region. Cirenmaco, a moraine-dammed lake located in the upstream portion of Zhangzangbo valley, Central Himalayas, has received public attention after its damaging 1981 outburst flood. Here, by combining remote sensing methods, bathymetric survey and 2D hydraulic modeling, we assessed the hazard posed by Cirenmaco in its current status. Inter-annual variation of Cirenmaco lake area indicates a rapid lake expansion from 0.10 ± 0.08 km2 in 1988 to 0.39 ± 0.04 km2 in 2013. Bathymetric survey shows the maximum water depth of the lake in 2012 was 115 ± 2 m and the lake volume was calculated to be 1.8 × 107 m3. Field geomorphic analysis shows that Cirenmaco glacial lake is prone to GLOFs as mass movements and ice and snow avalanches can impact the lake and the melting of the dead ice in the moraine can lower the dam level. HEC-RAS 2D model was then used to simulate moraine dam failure of the Cirenmaco and assess GLOF impacts downstream. Reconstruction of Cirenmaco 1981 GLOF shows that HEC-RAS can produce reasonable flood extent and water depth, thus demonstrate its ability to effectively model complex GLOFs. GLOF modeling results presented can be used as a basis for the implementation of disaster prevention and mitigation measures. As a case study, this work shows how we can integrate different methods to GLOF hazard assessment.

Basin-floor Lake Bonneville stratigraphic section as revealed in paleoseismic trenches at the Baileys Lake site, West Valley fault zone, Utah

USGS Publications Warehouse

Hylland, Michael D.; DuRoss, Christopher B.; McDonald, Greg N.; Olig, Susan S.; Oviatt, Charles G.; Mahan, Shannon; Crone, Anthony J.; Personius, Stephen

2012-01-01

 Recent paleoseismic trenching on the Granger fault of the West Valley fault zone in Salt Lake County, Utah, exposed a nearly complete section of late Pleistocene Lake Bonneville deposits, and highlights challenges related to accurate interpretation of basin-floor stratigraphy in the absence of numerical age constraints. We used radiocarbon and luminescence dating as well as ostracode biostratigraphy to provide chronostratigraphic control on the Lake Bonneville section exposed at the Baileys Lake trench site. The fault trenches exposed folded and faulted pre- to post- Bonneville sediments, including about 0.7 m of pre-Bonneville wetland/fluvial-marsh deposits, a nearly complete Bonneville section 2.5–4.0 m thick, and 0.4–1.0 m of post-Bonneville deposits consisting primarily of loess with minor scarp-derived colluvium. The relatively thin Bonneville section compares favorably with basin-floor Bonneville sections documented in boreholes and seismic reflection profiles beneath Great Salt Lake. Distinctive features of the Bonneville section at the Baileys Lake site include a sequence of turbidites in the upper part of the Bonneville transgressive deposits, evidence for an earthquake during Provo-shoreline time that disturbed lake-bottom sediments and destroyed any stratigraphic signature of the Bonneville Flood, tufa deposition associated with Gilbert-phase shoreline transgression, and stratigraphic evidence for two Gilbert transgressions across the site.

The water balance of the urban Salt Lake Valley: a multiple-box model validated by observations

NASA Astrophysics Data System (ADS)

Stwertka, C.; Strong, C.

2012-12-01

A main focus of the recently awarded National Science Foundation (NSF) EPSCoR Track-1 research project "innovative Urban Transitions and Arid-region Hydro-sustainability (iUTAH)" is to quantify the primary components of the water balance for the Wasatch region, and to evaluate their sensitivity to climate change and projected urban development. Building on the multiple-box model that we developed and validated for carbon dioxide (Strong et al 2011), mass balance equations for water in the atmosphere and surface are incorporated into the modeling framework. The model is used to determine how surface fluxes, ground-water transport, biological fluxes, and meteorological processes regulate water cycling within and around the urban Salt Lake Valley. The model is used to evaluate the hypotheses that increased water demand associated with urban growth in Salt Lake Valley will (1) elevate sensitivity to projected climate variability and (2) motivate more attentive management of urban water use and evaporative fluxes.

Quality and sources of shallow ground water in areas of recent residential development in Salt Lake Valley, Salt Lake County, Utah

USGS Publications Warehouse

Thiros, Susan A.

2003-01-01

Residential and commercial development of about 80 square miles that primarily replaced undeveloped and agricultural areas occurred in Salt Lake Valley, Utah, from 1963 to 1994. This study evaluates the occurrence and distribution of natural and anthropogenic compounds in shallow ground water underlying recently developed (post 1963) residential and commercial areas. Monitoring wells from 23 to 153 feet deep were installed at 30 sites. Water-quality data for the monitoring wells consist of analyses of field parameters, major ions, trace elements, nutrients, dissolved organic carbon, pesticides, and volatile organic compounds.Dissolved-solids concentration ranged from 134 to 2,910 milligrams per liter (mg/L) in water from the 30 monitoring wells. Dissolved arsenic concentration in water from 12 wells exceeded the drinking-water maximum contaminant level of 10 micrograms per liter. Water from monitoring wells in the northwestern part of the valley generally contained higher arsenic concentrations than did water from other areas. Nitrate concentration in water sampled from 26 of the 30 monitoring wells (86.7 percent) was higher than a background level of 2 mg/L, indicating a possible human influence. Nitrate concentrations ranged from less than 0.05 to 13.3 mg/L.Fifteen of the 104 pesticides and pesticide degradation products analyzed for were detected in 1 or more water samples from the monitoring wells. No pesticides were detected at concentrations that exceeded U.S. Environmental Protection Agency drinking-water standards or guidelines for 2002. The high detection frequency of atrazine, a restricted-use pesticide, in residential areas on the west side of Salt Lake Valley may be the result of application in agricultural or industrial areas that have been converted to residential uses or application in areas upgradient from the residential areas that was then transported by ground water.Fifteen of the 86 volatile organic compounds analyzed for were detected in 1 or

Glacier lake outburst floods caused by glacier shrinkage: case study of Ala-Archa valley, Kyrgyz Ala Too, northern Tian Shan, Kyrgyzstan

NASA Astrophysics Data System (ADS)

Petrakov, D.; Erochin, S. A.; Harbor, J.; Ivanov, M.; Rogozhina, I.; Stroeven, A. P.; Usubaliev, R.

2012-12-01

Changes in glacier extent and runoff in Central Asia increase socio-economic stress and may result in political conflict between donors of freshwater (Kyrgyzstan, Tajikistan) and recipients of freshwater (Uzbekistan, China). Glaciers in the Pamir and Tian Shan regions have experienced an unprecedented downwasting due to regional climate changes over the past decades. This is because air temperature increases are in some areas accompanied by a decrease in precipitation. Such conditions have already resulted in a reduction of glacier runoff, especially in the northern and western Tian Shan, and an increase of the number and area of glacial lakes in Kyrgyzstan. Even though glacial lakes in the mountains are in general relatively small and located far from densely populated areas, their outbursts often produce destructive debris flows. Such debris flows are especially common in Kyrgyzstan because of its steep river channels and abundance of Holocene and Quaternary glacier deposits that can be remobilized. The glacial lake outburst flood (GLOF) in the Shakhimardan river catchment in 1999, for example, resulted in 100 fatalities in Uzbekistan, and the GLOF from the Zyndan glacial lake led to substantial economic losses in 2009. According to the latest inventory, there are more than 350 glacial lakes in Kyrgyzstan of which about 70 occur in the Kyrgyz Ala Too. The Ala-Archa valley is among the most important glacierized catchments in Kyrgyzstan. Despite the presence of a relatively small glacier-covered area of 36 km2, the Ala-Archa river is of critical importance to the Bishkek area, its agriculture, and its population which currently exceeds one million. GLOFs are therefore a threat to both numerous settlements of touristic value in the Ala-Archa headwaters and to Bishkek. The Teztor lake in the Adygene catchment of the Ala-Archa river system experienced an outburst during 1988 and 2005. On the early morning of July 31, 2012, this lake began draining through a dam

Understanding the behavior of carbon dioxide and surface energy fluxes in semiarid Salt Lake Valley, Utah, USA

NASA Astrophysics Data System (ADS)

Ramamurthy, Prathap

This dissertation reports the findings from the Salt Lake Valley flux study. The Salt Lake Valley flux study was designed to improve our understanding of the complex land-atmosphere interactions in urban areas. The flux study used the eddy covariance technique to quantify carbon dioxide and surface energy budget in the semiarid Salt Lake Valley. Apart from quantifying fluxes, the study has also added new insight into the nature of turbulent scalar transport in urban areas and has addressed some of the complications in using Eddy Covariance technique in urban areas. As part of this experiment, eddy fluxes of CO2 and surface energy fluxes were measured at two sites, with distinct urban landforms; One site was located in a suburban neighborhood with substantial vegetative cover, prototypical of many residential neighborhoods in the valley. The other CO2 site was in a preurban surrounding that resembled the Salt Lake Valley before it was urbanized. The two sites were intentionally chosen to illustrate the impact of urbanization on CO 2 and surface energy flux cycles. Results indicate that the suburban site acted as a sink of CO2 during the midday period due to photosynthesis and acted as a source of CO2 during the evening and nighttime periods. The vegetative cover around the suburban site also had a significant impact on the surface energy fluxes. Contribution from latent heat flux was substantially high at the suburban site during the summer months compared to sensible heat. The turbulence investigation found that the general behavior of turbulence was very much influenced by local factors and the statistics did not always obey Monin-Obukhov Similarity parameters. This investigation also found that the scalar (co)spectra observed at the suburban site were characterized by multiple peaks and were different compared to (co)spectra reported over forest and crop canopies. The study also observed multiscale CO2 transport at the suburban site during the convective period

Quality and sources of ground water used for public supply in Salt Lake Valley, Salt Lake County, Utah, 2001

USGS Publications Warehouse

Thiros, Susan A.; Manning, Andrew H.

2004-01-01

Ground water supplies about one-third of the water used by the public in Salt Lake Valley, Utah. The occurrence and distribution of natural and anthropogenic compounds in ground water used for public supply in the valley were evaluated. Water samples were collected from 31 public-supply wells in 2001 and analyzed for major ions, trace elements, radon, nutrients, dissolved organic carbon, methylene blue active substances, pesticides, and volatile organic compounds. The samples also were analyzed for the stable isotopes of water (oxygen-18 and deuterium), tritium, chlorofluorocarbons, and dissolved gases to determine recharge sources and ground-water age.Dissolved-solids concentration ranged from 157 to 1,280 milligrams per liter (mg/L) in water from the 31 public-supply wells. Comparison of dissolved-solids concentration of water sampled from the principal aquifer during 1988-92 and 1998-2002 shows a reduction in the area where water with less than 500 mg/L occurs. Nitrate concentration in water sampled from 12 of the 31 public-supply wells was higher than an estimated background level of 2 mg/L, indicating a possible human influence. At least one pesticide or pesticide degradation product was detected at a concentration much lower than drinking-water standards in water from 13 of the 31 wells sampled. Chloroform was the most frequently detected volatile organic compound (17 of 31 samples). Its widespread occurrence in deeper ground water is likely a result of the recharge of chlorinated public-supply water used to irrigate lawns and gardens in residential areas of Salt Lake Valley.Environmental tracers were used to determine the sources of recharge to the principal aquifer used for public supply in the valley. Oxygen-18 values and recharge temperatures computed from dissolved noble gases in the ground water were used to differentiate between mountain and valley recharge. Maximum recharge temperatures in the eastern part of the valley generally are below the range

Miscellaneous High-Resolution Seismic Imaging Investigations in Salt Lake and Utah Valleys for Earthquake Hazards

USGS Publications Warehouse

Stephenson, W.J.; Williams, R.A.; Odum, J.K.; Worley, D.M.

2007-01-01

Introduction In support of earthquake hazards and ground motion studies by researchers at the Utah Geological Survey, University of Utah, Utah State University, Brigham Young University, and San Diego State University, the U.S. Geological Survey Geologic Hazards Team Intermountain West Project conducted three high-resolution seismic imaging investigations along the Wasatch Front between September 2003 and September 2005. These three investigations include: (1) a proof-of-concept P-wave minivib reflection imaging profile in south-central Salt Lake Valley, (2) a series of seven deep (as deep as 400 m) S-wave reflection/refraction soundings using an S-wave minivib in both Salt Lake and Utah Valleys, and (3) an S-wave (and P-wave) investigation to 30 m at four sites in Utah Valley and at two previously investigated S-wave (Vs) minivib sites. In addition, we present results from a previously unpublished downhole S-wave investigation conducted at four sites in Utah Valley. The locations for each of these investigations are shown in figure 1. Coordinates for the investigation sites are listed in Table 1. With the exception of the P-wave common mid-point (CMP) reflection profile, whose end points are listed, these coordinates are for the midpoint of each velocity sounding. Vs30 and Vs100, also shown in Table 1, are defined as the average shear-wave velocities to depths of 30 and 100 m, respectively, and details of their calculation can be found in Stephenson and others (2005). The information from these studies will be incorporated into components of the urban hazards maps along the Wasatch Front being developed by the U.S. Geological Survey, Utah Geological Survey, and numerous collaborating research institutions.

Modeling the Thickness of Perennial Ice Covers on Stratified Lakes of the Taylor Valley, Antarctica

NASA Technical Reports Server (NTRS)

Obryk, M. K.; Doran, P. T.; Hicks, J. A.; McKay, C. P.; Priscu, J. C.

2016-01-01

A one-dimensional ice cover model was developed to predict and constrain drivers of long term ice thickness trends in chemically stratified lakes of Taylor Valley, Antarctica. The model is driven by surface radiative heat fluxes and heat fluxes from the underlying water column. The model successfully reproduced 16 years (between 1996 and 2012) of ice thickness changes for west lobe of Lake Bonney (average ice thickness = 3.53 m; RMSE = 0.09 m, n = 118) and Lake Fryxell (average ice thickness = 4.22 m; RMSE = 0.21 m, n = 128). Long-term ice thickness trends require coupling with the thermal structure of the water column. The heat stored within the temperature maximum of lakes exceeding a liquid water column depth of 20 m can either impede or facilitate ice thickness change depending on the predominant climatic trend (temperature cooling or warming). As such, shallow (< 20 m deep water columns) perennially ice-covered lakes without deep temperature maxima are more sensitive indicators of climate change. The long-term ice thickness trends are a result of surface energy flux and heat flux from the deep temperature maximum in the water column, the latter of which results from absorbed solar radiation.

Who were the Nataruk people? Mandibular morphology among late Pleistocene and early Holocene fisher-forager populations of West Turkana (Kenya).

PubMed

Mounier, Aurélien; Correia, Maria; Rivera, Frances; Crivellaro, Federica; Power, Ronika; Jeffery, Joe; Wilshaw, Alex; Foley, Robert A; Mirazón Lahr, Marta

2018-05-29

Africa is the birthplace of the species Homo sapiens, and Africans today are genetically more diverse than other populations of the world. However, the processes that underpinned the evolution of African populations remain largely obscure. Only a handful of late Pleistocene African fossils (∼50-12 Ka) are known, while the more numerous sites with human fossils of early Holocene age are patchily distributed. In particular, late Pleistocene and early Holocene human diversity in Eastern Africa remains little studied, precluding any analysis of the potential factors that shaped human diversity in the region, and more broadly throughout the continent. These periods include the Last Glacial Maximum (LGM), a moment of extreme aridity in Africa that caused the fragmentation of population ranges and localised extinctions, as well as the 'African Humid Period', a moment of abrupt climate change and enhanced connectivity throughout Africa. East Africa, with its range of environments, may have acted as a refugium during the LGM, and may have played a critical biogeographic role during the heterogene`ous environmental recovery that followed. This environmental context raises a number of questions about the relationships among early Holocene African populations, and about the role played by East Africa in shaping late hunter-gatherer biological diversity. Here, we describe eight mandibles from Nataruk, an early Holocene site (∼10 Ka) in West Turkana, offering the opportunity of exploring population diversity in Africa at the height of the 'African Humid Period'. We use 3D geometric morphometric techniques to analyze the phenotypic variation of a large mandibular sample. Our results show that (i) the Nataruk mandibles are most similar to other African hunter-fisher-gatherer populations, especially to the fossils from Lothagam, another West Turkana locality, and to other early Holocene fossils from the Central Rift Valley (Kenya); and (ii) a phylogenetic connection may have

CRUSTAL REFRACTION PROFILE OF THE LONG VALLEY CALDERA, CALIFORNIA, FROM THE JANUARY 1983 MAMMOTH LAKES EARTHQUAKE SWARM.

USGS Publications Warehouse

Luetgert, James H.; Mooney, Walter D.

1985-01-01

Seismic-refraction profiles recorded north of Mammoth Lakes, California, using earthquake sources from the January 1983 swarm complement earlier explosion refraction profiles and provide velocity information from deeper in the crust in the area of the Long Valley caldera. Eight earthquakes from a depth range of 4. 9 to 8. 0 km confirm the observation of basement rocks with seismic velocities ranging from 5. 8 to 6. 4 km/sec extending at least to depths of 20 km. The data provide further evidence for the existence of a partial melt zone beneath Long Valley caldera and constrain its geometry. Refs.

Paleolimnology of the McMurdo Dry Valleys, Antarctica

NASA Technical Reports Server (NTRS)

Doran, P. T.; Wharton, R. A. Jr; Lyons, W. B.; Wharton RA, J. r. (Principal Investigator)

1994-01-01

The McMurdo Dry Valleys presently contain more than 20 permanent lakes and ponds, which vary markedly in character. All, with the exception of a hypersaline pond, have a perennial ice-cover. The dry valley lakes, and lakes in other ice-free regions of continental Antarctica, are unique on this planet in that they consistently maintain a thick year-round ice cover (2.8-6.0 m) over liquid water. The persistent ice covers minimize wind-generated currents and reduce light penetration, as well as restricting sediment deposition into a lake and the exchange of atmospheric gases between the water column and the atmosphere. From a paleolimnological perspective, the dry valley lakes offer an important record of catchment and environmental changes. These lakes are also modern-day equivalents of periglacial lakes that were common during glacial periods at temperate latitudes. The present lakes are mostly remnants of larger glacial lakes that occupied the valleys in the past, perhaps up to 4.6 Ma ago. Two of the valleys contain evidence of being filled with large glacial lakes within the last 10000 years. Repeated drying and filling events since then have left a characteristic impression on the salt profiles of some lakes creating a unique paleo-indicator within the water column. These events are also marked in the sediments by the concentration and dilution of certain chemical constituents, particularly salts, and are also corroborated by carbonate speciation and oxygen isotope analysis. Stratigraphic analysis of dry valley lake sediments is made difficult by the occurrence of an 'old carbon' reservoir creating spurious radiocarbon dates, and by the high degree of spatial variability in lake sedimentation. From a biological perspective, the lakes are relatively simple, containing various taxa of planktonic and benthic microorganisms, but no higher forms of life, which is an advantage to paleolimnologists because there is no bioturbation in the sediments. Useful biological

Paleolimnology of the McMurdo Dry Valleys, Antarctica.

PubMed

Doran, P T; Wharton, R A; Lyons, W B

1994-01-01

The McMurdo Dry Valleys presently contain more than 20 permanent lakes and ponds, which vary markedly in character. All, with the exception of a hypersaline pond, have a perennial ice-cover. The dry valley lakes, and lakes in other ice-free regions of continental Antarctica, are unique on this planet in that they consistently maintain a thick year-round ice cover (2.8-6.0 m) over liquid water. The persistent ice covers minimize wind-generated currents and reduce light penetration, as well as restricting sediment deposition into a lake and the exchange of atmospheric gases between the water column and the atmosphere. From a paleolimnological perspective, the dry valley lakes offer an important record of catchment and environmental changes. These lakes are also modern-day equivalents of periglacial lakes that were common during glacial periods at temperate latitudes. The present lakes are mostly remnants of larger glacial lakes that occupied the valleys in the past, perhaps up to 4.6 Ma ago. Two of the valleys contain evidence of being filled with large glacial lakes within the last 10000 years. Repeated drying and filling events since then have left a characteristic impression on the salt profiles of some lakes creating a unique paleo-indicator within the water column. These events are also marked in the sediments by the concentration and dilution of certain chemical constituents, particularly salts, and are also corroborated by carbonate speciation and oxygen isotope analysis. Stratigraphic analysis of dry valley lake sediments is made difficult by the occurrence of an 'old carbon' reservoir creating spurious radiocarbon dates, and by the high degree of spatial variability in lake sedimentation. From a biological perspective, the lakes are relatively simple, containing various taxa of planktonic and benthic microorganisms, but no higher forms of life, which is an advantage to paleolimnologists because there is no bioturbation in the sediments. Useful biological

A 28,000 year history of vegetation and climate from Lower Red Rock Lake, Centennial Valley, Southwestern Montana, USA

USGS Publications Warehouse

Mumma, Stephanie Ann; Whitlock, Cathy; Pierce, Kenneth

2012-01-01

A sediment core extending to 28,000 cal yr BP from Lower Red Rock Lake in the Centennial Valley of southwestern Montana provides new information on the nature of full-glacial vegetation as well as a history of late-glacial and Holocene vegetation and climate in a poorly studied region. Prior to 17,000 cal yr BP, the eastern Centennial Valley was occupied by a large lake (Pleistocene Lake Centennial), and valley glaciers were present in adjacent mountain ranges. The lake lowered upon erosion of a newly formed western outlet in late-glacial time. High pollen percentages of Juniperus, Poaceae, Asteraceae, and other herbs as well as low pollen accumulation rates suggest sparse vegetation cover. Inferred cold dry conditions are consistent with a strengthened glacial anticyclone at this time. Between 17,000 and 10,500 cal yr BP, high Picea and Abies pollen percentages suggest a shift to subalpine parkland and warmer conditions than before. This is attributed to the northward shift of the jet stream and increasing summer insolation. From 10,500 to 7100 cal yr BP, pollen evidence of open dry forests suggests warm conditions, which were likely a response to increased summer insolation and a strengthened Pacific subtropical high-pressure system. From 7100 to 2400 cal yr BP, cooler moister conditions promoted closed forest and wetlands. Increases in Picea and Abies pollen percentages after 2400 cal yr BP suggest increasing effective moisture. The postglacial pattern of Pseudotsuga expansion indicates that it arrived later on the Atlantic side of the Continental Divide than on the Pacific side. The Divide may have been a physical barrier for refugial populations or it delimited different climate regions that influenced the timing of Pseudotsuga expansion.

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)

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

2013-12-01

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

Hydrologic Modeling of Relatively Recent Martian Streams and Lake

NASA Image and Video Library

2016-09-15

This map of an area within the Arabia Terra region on Mars shows where hydrologic modeling predicts locations of depressions that would have been lakes (black), overlaid with a map of the preserved valleys (blue lines, with width exaggerated for recognition) that would have been streams. The area today holds numerous features called "fresh shallow valleys." Research findings in 2016 interpret the fresh shallow valleys as evidence for flows of liquid water that occurred several hundred million years -- up to about a billion years -- after the ancient lakes and streams previously documented on Mars. Most of the fresh shallow valleys in this northern portion of Arabia Terra terminate at the margins of model-predicted submerged basins, consistent with an interpretation of flows into lakes and out of lakes. Some valley segments connect to form longer systems, consistent with connections forged by flowing water between interspersed lakes. In the area mapped here, for example, valleys connect basin "A" to basin "B," and basin B to "Heart Lake," each lower in elevation in that chain. http://photojournal.jpl.nasa.gov/catalog/PIA20839

Reconstructing late Pliocene to middle Pleistocene Death Valley lakes and river systems as a test of pupfish (Cyprinodontidae) dispersal hypotheses

USGS Publications Warehouse

Knott, J.R.; Machette, M.N.; Klinger, R.E.; Sarna-Wojcicki, A. M.; Liddicoat, J.C.; Tinsley, J. C.; David, B.T.; Ebbs, V.M.

2008-01-01

During glacial (pluvial) climatic periods, Death Valley is hypothesized to have episodically been the terminus for the Amargosa, Owens, and Mojave Rivers. Geological and biological studies have tended to support this hypothesis and a hydrological link that included the Colorado River, allowing dispersal of pupfish throughout southeastern California and western Nevada. Recent mitochondrial deoxyribonucleic acid (mtDNA) studies show a common pupfish (Cyprinodontidae) ancestry in this region with divergence beginning 3-2 Ma. We present tephrochronologic and paleomagnetic data in the context of testing the paleohydrologic connections with respect to the common collection point of the Amargosa, Owens, and Mojave Rivers in Death during successive time periods: (1) the late Pliocene to early Pleistocene (3-2 Ma), (2) early to middle Pleistocene (1.2-0.5 Ma), and (3) middle to late Pleistocene (<0.70.03 Ma; paleolakes Manly and Mojave). Using the 3.35 Ma Zabriskie Wash tuff and 3.28 Ma Nomlaki Tuff Member of the Tuscan and Tehama Formations, which are prominent marker beds in the region, we conclude that at 3-2 Ma, a narrow lake occupied the ancient Furnace Creek Basin and that Death Valley was not hydrologically connected with the Amargosa or Mojave Rivers. A paucity of data for Panamint Valley does not allow us to evaluate an Owens River connection to Death Valley ca. 3-2 Ma. Studies by others have shown that Death Valley was not hydrologically linked to the Amargosa, Owens, or Mojave Rivers from 1.2 to 0.5 Ma. We found no evidence that Lake Manly flooded back up the Mojave River to pluvial Lake Mojave between 0.18 and 0.12 Ma, although surface water flowed from the Amargosa and Owens Rivers to Death Valley at this time. There is also no evidence for a connection of the Owens, Amargosa, or Mojave Rivers to the Colorado River in the last 3-2 m.y. Therefore, the hypothesis that pupfish dispersed or were isolated in basins throughout southeastern California and western

Investigating the Spatial Trends in the Level of Organic Contaminants in the Ethiopian Rift Valley Lakes Using Semipermeable Membrane Devices.

PubMed

Deribe, Ermias

2018-05-21

Organic pollutants in the Ethiopian Rift Valley Lakes are the major factors that contribute to severe environmental problem. SPMDs were deployed for the analysis of selected organic pollutants for 1 month at 2 sites in Lakes Hawassa, Ziway and Koka, Ethiopia. From SPMDs placed in the three lakes, the predominant OCPs were DDT which comprise 67% and followed by endosulfan 23% of the total organochlorine pesticides (OCPs) retrieved. The highest level of OCPs, in general, was found in the SPMDs deployed in Lake Ziway with the mean concentration of 308.5 ng/SPMD. However, the concentrations of polychlorinated biphenyls (PCBs) were the highest in the SPMDs deployed in Lake Hawassa with mean concentration of 50.2 ng/SPMD. Spatial variation on the accumulation of OCPs and PCBs among the lakes depends on the shoreline activities, distance of the lakes from point and non-point sources, and the biofouling factors.

A Revised Holocene History of Lake Kivu, East Africa

NASA Astrophysics Data System (ADS)

Votava, J. E.; Johnson, T. C.; Hecky, R. E.

2013-12-01

The great lakes of the East African Rift valley are a vast chain of lakes formed in a region of active tectonics. These large, deep lakes are relatively old and many (e.g. Tanganyika, Malawi, and Turkana) have greatly influenced our understanding of terrestrial, tropical East African paleoclimate. Lake Kivu (max depth, 485m) sits at the heart of these rift lakes, north of Lake Tanganyika between the Democratic Republic of the Congo and Rwanda (roughly 250 km west of Lake Victoria). At over 1,400 meters in elevation, this 2,060 km2 mesotrophic lake has a complex stratification regime imposed by hydrothermal springs and deep waters supersaturated at STP in CO2 and CH4 gasses. The active Virunga Volcanoes to the north of the lake supply heated, high-salinity waters below 280 meters water depth maintaining the modern crenogenic meromixis. Based on detailed studies of diatom assemblages and bulk sedimentology, previous workers have suggested this hydrothermal activity began roughly 5,000 years BP. Unfortunately, dating and stratigraphic correlations of these original cores from the 1970 Woods Hole Oceanographic Institution's expedition have been problematic. Here we offer an improved chronology and new carbonate analyses from cores recovered in 2012 and 2013. Our AMS radiocarbon ages come from six terrigeneous macrofossils spanning the last 9,100 years (cal BP). These ages suggest a rather high sedimentation rate on the order of 70cm/kyr, and hence, our 8 m-long core provides us with a high-resolution lake history for the past 10,000 years. Most notable over the past 5,000 years in the lake history is the repeated onset and cessation of carbonate deposition, punctuated by organic-rich intervals. Earlier studies of the Woods Hole cores placed the onset of carbonate deposition at ca. 11,000 years BP suggesting changes in lake hydrology (i.e. closed to open), while the abrupt cessation of carbonate was dated at ca. 5,000 years BP and attributed to the beginning of

Chemodenitrification in the cryoecosystem of Lake Vida, Victoria Valley, Antarctica.

PubMed

Ostrom, N E; Gandhi, H; Trubl, G; Murray, A E

2016-11-01

Lake Vida, in the Victoria Valley of East Antarctica, is frozen, yet harbors liquid brine (~20% salt, >6 times seawater) intercalated in the ice below 16 m. The brine has been isolated from the surface for several thousand years. The brine conditions (permanently dark, -13.4 °C, lack of O 2 , and pH of 6.2) and geochemistry are highly unusual. For example, nitrous oxide (N 2 O) is present at a concentration among the highest reported for an aquatic environment. Only a minor 17 O anomaly was observed in N 2 O, indicating that this gas was predominantly formed in the lake. In contrast, the 17 O anomaly in nitrate (NO3-) in Lake Vida brine indicates that approximately half or more of the NO3- present is derived from atmospheric deposition. Lake Vida brine was incubated in the presence of 15 N-enriched substrates for 40 days. We did not detect microbial nitrification, dissimilatory reduction of NO3- to ammonium (NH4+), anaerobic ammonium oxidation, or denitrification of N 2 O under the conditions tested. In the presence of 15 N-enriched nitrite (NO2-), both N 2 and N 2 O exhibited substantial 15 N enrichments; however, isotopic enrichment declined with time, which is unexpected. Additions of 15 N-NO2- alone and in the presence of HgCl 2 and ZnCl 2 to aged brine at -13 °C resulted in linear increases in the δ 15 N of N 2 O with time. As HgCl 2 and ZnCl 2 are effective biocides, we interpret N 2 O production in the aged brine to be the result of chemodenitrification. With this understanding, we interpret our results from the field incubations as the result of chemodenitrification stimulated by the addition of 15 N-enriched NO2- and ZnCl 2 and determined rates of N 2 O and N 2 production of 4.11-41.18 and 0.55-1.75 nmol L -1  day -1 , respectively. If these rates are representative of natural production, the current concentration of N 2 O in Lake Vida could have been reached between 6 and 465 years. Thus, chemodenitrification alone is sufficient to explain the

Hydrogeology of shallow basin-fill deposits in areas of Salt Lake Valley, Salt Lake County, Utah

USGS Publications Warehouse

Thiros, Susan A.

2003-01-01

A study of recently developed residential/commercial areas of Salt Lake Valley, Utah, was done from 1999 to 2001 in areas in which shallow ground water has the potential to move to a deeper aquifer that is used for public supply. Thirty monitoring wells were drilled and sampled in 1999 as part of the study. The ground water was either under unconfined or confined conditions, depending on depth to water and the presence or absence of fine-grained deposits. The wells were completed in the shallowest water-bearing zone capable of supplying water. Monitoring-well depths range from 23 to 154 feet. Lithologic, geophysical, hydraulic-conductivity, transmissivity, water-level, and water-temperature data were obtained for or collected from the wells.Silt and clay layers noted on lithologic logs correlate with increases in electrical conductivity and natural gamma radiation shown on many of the electromagnetic-induction and natural gamma logs. Relatively large increases in electrical conductivity, determined from the electromagnetic-induction logs, with no major changes in natural gamma radiation are likely caused by increased dissolved-solids content in the ground water. Some intervals with high electrical conductivity correspond to areas in which water was present during drilling.Unconfined conditions were present at 7 of 20 monitoring wells on the west side and at 2 of 10 wells on the east side of Salt Lake Valley. Fine-grained deposits confine the ground water. Anthropogenic compounds were detected in water sampled from most of the wells, indicating a connection with the land surface. Data were collected from 20 of the monitoring wells to estimate the hydraulic conductivity and transmissivity of the shallow ground-water system. Hydraulic-conductivity values of the shallow aquifer ranged from 30 to 540 feet per day. Transmissivity values of the shallow aquifer ranged from 3 to 1,070 feet squared per day. There is a close linear relation between transmissivity determined

Geomorphic controls on hydrology and vegetation in an arid basin: Turkana district, northern Kenya

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coppinger, K.D.; Doehring, D.O.; Schimel, D.S.

1985-01-01

As part of a broad ecological study of Kenyan pastoralist adaptation to periodic drought, a study was done to determine how arid region geomorphology affects hydrology and subsequently vegetative patterns. In this study area, 100 kilometers south of Lake Turkana, it appears that irregular precipitation is stored in bajada sediments and is available to deeply rooted vegetation over long periods of time. This vegetation provides a relatively constant food source for people's herds of browsers, the camels and goats, whereas cattle, which graze mainly on grasses, are significant producers only during wet seasons. Field observations suggest that the mountain andmore » abutting pediment soils are too shallow to store appreciable water. However, greater quantities of water are stored in the deeper bajada sediments adjacent to the pediment where pastoralists dig temporary wells in ephemeral channels during wet seasons. Density of tree growth is greater along channels, and highest canopy cover values are found about the pediment-bajada interface. Geohydrologic processes in this area provide the basis for continuous occupation by the desert people, in contrast to recurring famines in adjacent areas, by enhancing the growth of woody vegetation.« less

Rare earth elements in the water column of Lake Vanda, McMurdo Dry Valleys, Antarctica

NASA Astrophysics Data System (ADS)

De Carlo, Eric Heinen; Green, William J.

2002-04-01

We present data on the composition of water from Lake Vanda, Antarctica. Vanda and other lakes in the McMurdo Dry Valleys of Antarctica are characterized by closed basins, permanent ice covers, and deep saline waters. The meromictic lakes provide model systems for the study of trace metal cycling owing to their pristine nature and the relative simplicity of their biogeochemical systems. Lake Vanda, in the Wright Valley, is supplied by a single input, the Onyx River, and has no output. Water input to the lake is balanced by sublimation of the nearly permanent ice cap that is broken only near the shoreline during the austral summer. The water column is characterized by an inverse thermal stratification of anoxic warm hypersaline water underlying cold oxic freshwater. Water collected under trace-element clean conditions was analyzed for its dissolved and total rare earth element (REE) concentrations by inductively coupled plasma mass spectrometry. Depth profiles are characterized by low dissolved REE concentrations (La, Ce, <15 pM) in surface waters that increase slightly (La, 70 pM; Ce, 20 pM) with increasing depth to ∼55 m, the limit of the fresh oxic waters. Below this depth, a sharp increase in the concentrations of strictly trivalent REE (e.g., La, 5 nM) is observed, and a submaximum in redox sensitive Ce (2.6 nM) is found at 60- to 62-m depth. At a slightly deeper depth, a sharper Ce maximum is observed with concentrations exceeding 11 nM at a 67-m depth, immediately above the anoxic zone. The aquatic concentrations of REE reported here are ∼50-fold higher than previously reported for marine oxic/anoxic boundaries and are, to our knowledge, the highest ever observed at natural oxic/anoxic interfaces. REE maxima occur within stable and warm saline waters. All REE concentrations decrease sharply in the sulfidic bottom waters. The redox-cline in Lake Vanda is dominated by diffusional processes and vertical transport of dissolved species driven by concentration

Plio-Pleistocene magnetostratigraphy of the Turkana basin, Kenya

NASA Astrophysics Data System (ADS)

Lepre, C. J.; Quinn, R.; Feibel, C. S.; Brown, F. H.; Kent, D. V.

2012-12-01

Archaeological and fossil sites from the Turkana basin provide a unique record of important human evolutionary junctures, which have been linked to terrestrial environmental change as a consequence of late Cenozoic climate phenomenon. However, because of low geochronological resolution, spatial discontinuities, and the episodic nature of sedimentation in the half-graben basins of the East African Rift System, it has been difficult to directly connect the terrestrial sites with marine archives of Pliocene and Pleistocene climate. For the purpose of addressing these issues, a magnetic polarity stratigraphy and a corresponding geochronology are presented for 12 sampling sites spanning about 400 m of continental sediments that crop out in eastern (Areas 118 and 130 of the Karari ridge, Areas 102 and 104 of the Koobi Fora ridge, Areas 107 and 123 of Bara Hasuma) and western (Kokiselei, Naiyena Engol, Kalochoro, Lomekwi, South Turkwel, and Kanapoi) parts of the Turkana basin. Characteristic magnetizations isolated through thermal demagnetization experiments on mudstone specimens pass reversal tests and are indistinguishable in mean direction regardless if samples were collected from ancient fluvial floodplain or lacustrine strata of correlative stratigraphic intervals. The sequence of the composite paleomagnetic reversal stratigraphy consists of 15 magnetozones that vary from less than a meter to tens of meters thick and can be unambiguously correlated within limits of the previously established tephrochronology to the Gilbert through Matuyama portion of the Geomagnetic Polarity Time Scale dated to about 4.0-1.5 Ma. Sedimentation rates through lacustrine intervals (e.g., 22-29 cm/kyr) are comparable with high-fidelity marine cores. This factor coupled with copious amounts of magnetic mineral detritus from basin-bounding rift volcanics probably contributes to a high natural remanent magnetization of the sediments and the recording of temporally brief magnetozones (e

An 11 000-year-long record of fire and vegetation history at Beaver Lake, Oregon, central Willamette Valley

Treesearch

Megan K. Walsh; Christopher A. Pearl; Cathy Whitlock; Patrick J. Bartlein; Marc A. Worona

2010-01-01

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...

The Morphometry of Lake Palmas, a Deep Natural Lake in Brazil

PubMed Central

Barroso, Gilberto F.; Gonçalves, Monica A.; Garcia, Fábio da C.

2014-01-01

Lake Palmas (A = 10.3km2) is located in the Lower Doce River Valley (LDRV), on the southeastern coast of Brazil. The Lake District of the LDRV includes 90 lakes, whose basic geomorphology is associated with the alluvial valleys of the Barreiras Formation (Cenozoic, Neogene) and with the Holocene coastal plain. This study aimed to investigate the relationship of morphometry and thermal pattern of a LDRV deep lake, Lake Palmas. A bathymetric survey carried out in 2011 and the analysis of hydrographic and wind data with a geographic information system allowed the calculation of several metrics of lake morphometry. The vertical profiling of physical and chemical variables in the water column during the wet/warm and dry/mild cold seasons of 2011 to 2013 has furnished a better understanding of the influence of the lake morphometry on its structure and function. The overdeepened basin has a subrectangular elongated shape and is aligned in a NW-SE direction in an alluvial valley with a maximum depth (Zmax) of 50.7m, a volume of 2.2×108 m3 (0.22km3) and a mean depth (Zmv) of 21.4m. These metrics suggest Lake Palmas as the deepest natural lake in Brazil. Water column profiling has indicated strong physical and chemical stratification during the wet/warm season, with a hypoxic/anoxic layer occupying one-half of the lake volume. The warm monomictic pattern of Lake Palmas, which is in an accordance to deep tropical lakes, is determined by water column mixing during the dry and mild cold season, especially under the influence of a high effective fetch associated with the incidence of cold fronts. Lake Palmas has a very long theoretical retention time, with a mean of 19.4 years. The changes observed in the hydrological flows of the tributary rivers may disturb the ecological resilience of Lake Palmas. PMID:25406062

Hydrological Controls on Ecosystem Dynamics in Lake Fryxell, Antarctica.

PubMed

Herbei, Radu; Rytel, Alexander L; Lyons, W Berry; McKnight, Diane M; Jaros, Christopher; Gooseff, Michael N; Priscu, John C

2016-01-01

The McMurdo Dry Valleys constitute the largest ice free area of Antarctica. The area is a polar desert with an annual precipitation of ∼ 3 cm water equivalent, but contains several lakes fed by glacial melt water streams that flow from four to twelve weeks of the year. Over the past ∼20 years, data have been collected on the lakes located in Taylor Valley, Antarctica as part of the McMurdo Dry Valley Long-Term Ecological Research program (MCM-LTER). This work aims to understand the impact of climate variations on the biological processes in all the ecosystem types within Taylor Valley, including the lakes. These lakes are stratified, closed-basin systems and are perennially covered with ice. Each lake contains a variety of planktonic and benthic algae that require nutrients for photosynthesis and growth. The work presented here focuses on Lake Fryxell, one of the three main lakes of Taylor Valley; it is fed by thirteen melt-water streams. We use a functional regression approach to link the physical, chemical, and biological processes within the stream-lake system to evaluate the input of water and nutrients on the biological processes in the lakes. The technique has been shown previously to provide important insights into these Antarctic lacustrine systems where data acquisition is not temporally coherent. We use data on primary production (PPR) and chlorophyll-A (CHL)from Lake Fryxell as well as discharge observations from two streams flowing into the lake. Our findings show an association between both PPR, CHL and stream input.

Controls of inherited lithospheric heterogeneity on rift linkage: Numerical and analog models of interaction between the Kenyan and Ethiopian rifts across the Turkana depression

NASA Astrophysics Data System (ADS)

Brune, Sascha; Corti, Giacomo; Ranalli, Giorgio

2017-09-01

Inherited rheological structures in the lithosphere are expected to have large impact on the architecture of continental rifts. The Turkana depression in the East African Rift connects the Main Ethiopian Rift to the north with the Kenya rift in the south. This region is characterized by a NW-SE trending band of thinned crust inherited from a Mesozoic rifting event, which is cutting the present-day N-S rift trend at high angle. In striking contrast to the narrow rifts in Ethiopia and Kenya, extension in the Turkana region is accommodated in subparallel deformation domains that are laterally distributed over several hundred kilometers. We present both analog experiments and numerical models that reproduce the along-axis transition from narrow rifting in Ethiopia and Kenya to a distributed deformation within the Turkana depression. Similarly to natural observations, our models show that the Ethiopian and Kenyan rifts bend away from each other within the Turkana region, thus forming a right-lateral step over and avoiding a direct link to form a continuous N-S depression. The models reveal five potential types of rift linkage across the preexisting basin: three types where rifts bend away from the inherited structure connecting via a (1) wide or (2) narrow rift or by (3) forming a rotating microplate, (4) a type where rifts bend towards it, and (5) straight rift linkage. The fact that linkage type 1 is realized in the Turkana region provides new insights on the rheological configuration of the Mesozoic rift system at the onset of the recent rift episode.

Geochemistry of the Onyx River (Wright Valley, Antarctica) and its role in the chemical evolution of Lake Vanda

NASA Astrophysics Data System (ADS)

Green, William J.; Canfield, Donald E.

1984-12-01

The Onyx River (Wright Valley, Antarctica) is a dilute meltwater stream originating in the vicinity of the Wright Lower Glacier. It acquires a significant fraction of its salt content when glacial meltwaters contact Wright Valley soils at Lake Brownworth and the concentrations of all ions increase with distance along the 28-km channel down to Lake Vanda. Average millimolar concentrations of major ions at the Vanda weir during the 1980-1981 flow season were: Ca = 0.119; Mg = 0.061; Na = 0.212; K = 0.033; Q = 0.212; SO4 = 0.045; HCO3 = 0.295; and SiO2 = 0.049. Based on the flow measurements of Chinn (1982), this amounts to an annual flux (in moles) to Lake Vanda of: Ca = 0.238 × 10 6; Mg = 0.122 × 10 6; Na = 0.424 × 10 6; K = 0.066 × 10 6; Cl = 0.424 × 10 6; SO4 = 0.09 × 10 6; HCO3 = 0.59 × 10 6; SiO2 = 0.098 × 10 6. In spite of the large salt input from this source, equilibrium evaporation of Onyx River water would have resulted in early calcite deposition and in the formation of a Na-Mg-Cl-HCO 3 brine rather than in the Ca-Na-Mg-Cl waters observed in Lake Vanda. The river alone could not have produced a brine having the qualitative geochemical features of the lower saline waters of Lake Vanda. It is proposed that the Vanda brine is instead the result of past ( > 1200 yrs BP) mixing events between Onyx River inflows and calcium chloride-rich deep groundwaters derived from the Don Juan Basin. The mixing model presented here shows that the Onyx River is the major contributor of K, HCO 3, SO 4, and (possibly) Mg found in the lake and a significant contributor (approximately one half) of the observed Na. Calcium and Cl, on the other hand, came largely from deep groundwater sources in the Don Juan Basin. All concentrations except Mg are well predicted by this model. The chemical composition of the geologically recent upper lake is explained in terms of ionic diffusion from the pre-formed brine, coupled with Onyx River inflow. Ionic ratios calculated from this

New explorations along the northern shores of Lake Bonneville

USGS Publications Warehouse

Oviatt, Charles G.; Miller, D.M.

1997-01-01

This field trip begins in Salt Lake City and makes a clockwise circuit of Great Salt Lake, with primary objectives to observe stratigraphie and geomorphic records of Lake Bonneville. Stops include Stansbury Island, Puddle Valley, gravel pits at Lakeside and the south end of the Hogup Mountains, several stops in Curlew Valley and Hansel Valley, and a final stop at the north end of Great Salt Lake east of the Promontory Mountains. Stratigraphie observations at gravel-pit and natural exposures will be linked to interpretations of lake-level change, which were caused by climate change. Evidence of paleoseismic and volcanic activity will be discussed at several sites, and will be tied to the lacustrine stratigraphic record. The trip provides an overview of the history of Lake Bonneville and introduces participants to some new localities with excellent examples of Lake Bonneville landforms and stratigraphy.

Incision of Licus Vallis, Mars, From Multiple Lake Overflow Floods

NASA Astrophysics Data System (ADS)

Goudge, Timothy A.; Fassett, Caleb I.

2018-02-01

Licus Vallis is a large valley (>350 km long, >2 km wide, and >150 m deep) that heads at the outlet breach of an 30 km diameter impact crater. We present observations of the geomorphology and topography of this paleolake outlet valley and associated tributary valleys to constrain the history of incision of the Licus Vallis system. Licus Vallis has an abrupt increase in gradient by a factor of approximately 4 along its longitudinal profile, and a knickpoint that drops 200 m over a reach of 2 km approximately 12 km downstream from the valley head. We also describe a set of paired terraces within Licus Vallis, which are continuous for tens of kilometers and define an interior valley >2 km in width. We interpret the geomorphology of Licus Vallis as recording at least two discrete, major episodes of valley incision, both driven by lake overflow floods. The main portion of Licus Vallis formed by overflow flooding from a large ( 103-104 km2) lake contained in an intercrater basin. Subsequently, overflow flooding from a lake within the 30 km diameter impact crater reactivated Licus Vallis, forming a major knickpoint at the valley head and establishing the upstream section of the valley at a lower slope. Farther down the valley, this flood event incised an interior valley bounded by paired terraces. Regional tributary valleys that feed Licus Vallis also have prominent knickpoints, which have retreated farthest for downstream valleys. We conclude that these knickpoints record successive waves of incision that swept up Licus Vallis during lake overflow flooding, with erosion in the main trunk of the valley (from overflow floods) significantly outpacing erosion in the tributary valleys (from regional surface runoff). These observations of Licus Vallis illustrate how lake overflow floods may have provided an important control on the pace of landscape evolution on Mars.

New considerations on the stratigraphy and environmental context of the oldest (2.34 Ma) Lokalalei archaeological site complex of the Nachukui Formation, West Turkana, northern Kenya Rift

NASA Astrophysics Data System (ADS)

Tiercelin, Jean-Jacques; Schuster, Mathieu; Roche, Hélène; Brugal, Jean-Philippe; Thuo, Peter; Prat, Sandrine; Harmand, Sonia; Davtian, Gourguen; Barrat, Jean-Alix; Bohn, Marcel

2010-09-01

At the northwest end of the Lake Turkana Basin (northern Kenya Rift), intensive fieldwork conducted on the Plio-Pleistocene fluvio-lacustrine Nachukui Formation by the National Museums of Kenya and the West Turkana Archaeological Project (WTAP), led to the discovery of more than 50 archaeological sites aged between 2.4 and 0.7 Ma. Among them is the Lokalalei archaeological site complex, which includes the two oldest archaeological sites (2.34 Ma) found in the Kenyan segment of the East African Rift System. The environmental background of the two sites was described as a succession of ephemeral streams with floodplain palaeosols in which the archaeological sites are situated, bordering the western bank of a large axial meandering river flowing southward. The Lokalalei 1 (LA1) and Lokalalei 2C (LA2C) archaeological sites are of extreme importance in terms of knowledge of hominins' knapping activities. The stratigraphic position of the LA1 and LA2C sites as well as implications on the technical differences between the two sites have been successively discussed by Roche et al. (1999), Brown and Gathogo (2002), and Delagnes and Roche (2005). In terms of stratigraphic position, Lokalalei 2C was estimated to be slightly higher in the section (i.e. younger) than Lokalalei 1. An alternative stratigraphic correlation was proposed by Brown and Gathogo (2002), who suggested that LA2C site should have been approximately 100,000 years younger than LA1. New considerations on the stratigraphy and environmental context of the Lokalalei sites have been developed following controversy on the stratigraphic position and time interval between the LA1 and LA2C sites. High-resolution lithostratigraphic work based on bed-to-bed field correlations, facies sedimentology and tephra geochemistry confirms that the LA2C site is slightly higher in the section than the LA1 site by about 11.20 m. This represents a time interval of ˜74,000 years based on an assumed sedimentation rate of 152 mm

Late Pleistocene to Holocene lake levels of Lake Warner, Oregon (USA) and their effect on archaeological site distribution patterns

NASA Astrophysics Data System (ADS)

Wriston, T.; Smith, G. M.

2017-12-01

Few chronological controls are available for the rise and fall of small pluvial lake systems in the Northwestern Great Basin. Within Warner Basin this control was necessary for interpretation of known archaeological sites and for predicting where evidence of its earliest inhabitants might be expected. We trenched along relic beach ridges of Lake Warner, surveyed a stratified sample of the area for archaeological sites, and excavated some sites and a nearby rockshelter. These efforts produced new ages that we used to construct a lake level curve for Lake Warner. We found that the lake filled the valley floor between ca. 30,000 cal yr BP and ca. 10,300 cal yr BP. In nearby basins, several oscillations are evident before ca. 21,100 cal yr BP, but a steep rise to the LGM maximum occurred between 21,000 and 20,000 cal yr BP. Lake Warner likely mirrored these changes, dropped to the valley floor ca. 18,340 cal yr BP, and then rose to its maximum highstand when its waters briefly reached 1454 m asl. After this highstand the lake receded to moderately high levels. Following ca. 14,385 cal yr BP, the lake oscillated between moderate to moderately-high levels through the Bolling-Allerod interstadials and into the Younger Dryas stadial. The basin's first occupants arrived along its shore around this time, while the lake still filled the valley floor. These earliest people carried either Western Stemmed or Clovis projectile points, both of which are found along the lake margin. The lake receded into the valley floor ca. 10,300 cal yr BP and dune development began, ringing wetlands and small lakes that persisted in the footprint of the once large lake. By the time Mazama tephra fell 7,600 cal yr BP it blanketed pre-existing dunes and marsh peats. Our Lake Warner lake level curve facilitates interdisciplinary testing and refinement of it and similar curves throughout the region while helping us understand the history of lake and the people who lived along its shores.

Surficial geologic map of the Red Rock Lakes area, southwest Montana

USGS Publications Warehouse

Pierce, Kenneth L.; Chesley-Preston, Tara L.; Sojda, Richard L.

2014-01-01

The Centennial Valley and Centennial Range continue to be formed by ongoing displacement on the Centennial fault. The dominant fault movement is downward, creating space in the valley for lakes and the deposition of sediment. The Centennial Valley originally drained to the northeast through a canyon now represented by a chain of lakes starting with Elk Lake. Subsequently, large landslides blocked and dammed the drainage, which created Lake Centennial, in the Centennial Valley. Sediments deposited in this late Pleistocene lake underlie much of the valley floor and rest on permeable sand and gravel deposited when the valley drained to the northeast. Cold Pleistocene climates enhanced colluvial supply of gravelly sediment to mountain streams and high peak flows carried gravelly sediment into the valley. There, the lower gradient of the streams resulted in deposition of alluvial fans peripheral to Lake Centennial as the lake lowered through time to the level of the two present lakes. Pleistocene glaciers formed in the high Centennial Range, built glacial moraines, and also supplied glacial outwash to the alluvial fans. Winds from the west and south blew sand to the northeast side of the valley building up high dunes. The central part of the map area is flat, sloping to the west by only 0.6 meters in 13 kilometers (2 feet in 8 miles) to form a watery lowland. This lowland contains Upper and Lower Red Rock Lakes, many ponds, and peat lands inside the “water plane,” above which are somewhat steeper slopes. The permeable sands and gravels beneath Lake Centennial sediments provide a path for groundwater recharged from the adjacent uplands. This groundwater leaks upward through Lake Centennial sediments and sustains wetland vegetation into late summer. Upper and Lower Red Rock Lakes are formed by alluvial-fan dams. Alluvial fans converge from both the south and the north to form outlet thresholds that dam the two shallow lakes upstream. The surficial geology aids in

California: Diamond Valley

Atmospheric Science Data Center

2014-05-15

... article title:  Watching the Creation of Southern California's Largest Reservoir     ... Valley Lake is designed to provide protection against drought and a six-month emergency supply in the event of earthquake damage to a ...

Steady, modest slip over multiple earthquake cycles on the Owens Valley and Little Lake fault zones

NASA Astrophysics Data System (ADS)

Amos, C. B.; Haddon, E. K.; Burgmann, R.; Zielke, O.; Jayko, A. S.

2015-12-01

A comprehensive picture of current plate-boundary deformation requires integration of short-term geodetic records with longer-term geologic strain. Comparing rates of deformation across these time intervals highlights potential time-dependencies in both geodetic and geologic records and yields critical insight into the earthquake deformation process. The southern Walker Lane Belt in eastern California represents one location where short-term strain recorded by geodesy apparently outpaces longer-term geologic fault slip measured from displaced rocks and landforms. This discrepancy persists both for individual structures and across the width of the deforming zone, where ~1 cm/yr of current dextral shear exceeds Quaternary slip rates summed across individual faults. The Owens Valley and Little Lake fault systems form the western boundary of the southern Walker Lane and host a range of published slip rate estimates from ~1 - 7 mm/yr over varying time intervals based on both geodetic and geologic measurements. New analysis of offset geomorphic piercing lines from airborne lidar and field measurements along the Owens Valley fault provides a snapshot of deformation during individual earthquakes and over many seismic cycles. Viewed in context of previously reported ages from pluvial and other landforms in Owens Valley, these offsets suggest slip rates of ~0.6 - 1.6 mm/yr over the past 103 - 105 years. Such rates agree with similar estimates immediately to the south on the Little Lake fault, where lidar measurements indicate dextral slip averaging ~0.6 - 1.3 mm/yr over comparable time intervals. Taken together, these results suggest steady, modest slip in the absence of significant variations over the Mid-to-Late Quaternary for a ~200 km span of the southwestern Walker Lane. Our findings argue against the presence of long-range fault interactions and slip-rate variations for this portion of the larger, regional fault network. This result also suggests that faster slip

Ice-dammed lateral lake and epishelf lake insights into Holocene dynamics of Marguerite Trough Ice Stream and George VI Ice Shelf, Alexander Island, Antarctic Peninsula

NASA Astrophysics Data System (ADS)

Davies, Bethan J.; Hambrey, Michael J.; Glasser, Neil F.; Holt, Tom; Rodés, Angél; Smellie, John L.; Carrivick, Jonathan L.; Blockley, Simon P. E.

2017-12-01

We present new data regarding the past dynamics of Marguerite Trough Ice Stream, George VI Ice Shelf and valley glaciers from Ablation Point Massif on Alexander Island, Antarctic Peninsula. This ice-free oasis preserves a geological record of ice stream lateral moraines, ice-dammed lakes, ice-shelf moraines and valley glacier moraines, which we dated using cosmogenic nuclide ages. We provide one of the first detailed sediment-landform assemblage descriptions of epishelf lake shorelines. Marguerite Trough Ice Stream imprinted lateral moraines against eastern Alexander Island at 120 m at Ablation Point Massif. During deglaciation, lateral lakes formed in the Ablation and Moutonnée valleys, dammed against the ice stream in George VI Sound. Exposure ages from boulders on these shorelines yielded ages of 13.9 to 9.7 ka. Following recession of the ice stream, George VI Ice Shelf formed in George VI Sound. An epishelf lake formed at 15-20 m asl in Ablation and Moutonnée valleys, dated from 9.4 to 4.6 ka, suggesting that the lake was stable and persistent for some 5000 years. Lake-level lowering occurred after this, with the lake level at 12 m at 3.1 ± 0.4 ka and at 5 m asl today. A readvance of the valley glaciers on Alexander Island at 4.4 ± 0.7 ka is recorded by valley glacier moraines overlying epishelf lake sediments. We speculate that the glacier readvance, which occurred during a period of warmth, may have been caused by a dynamic response of the glaciers to a lowering in surface elevation of George VI Ice Shelf.

An 11 000-year-long record of fire and vegetation history at Beaver Lake, Oregon, central Willamette Valley

USGS Publications Warehouse

Walsh, Megan K.; Pearl, Christopher A.; Whitlock, Cathy; Bartlein, Patrick J.; Worona, Marc A.

2010-01-01

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.

Correlation of Pliocene and Pleistocene tephra layers between the Turkana Basin of East Africa and the Gulf of Aden

USGS Publications Warehouse

Brown, F.H.; Sarna-Wojcicki, A. M.; Meyer, C.E.; Haileab, B.

1992-01-01

Electron-microprobe analyses of glass shards from volcanic ash in Pliocene and Pleistocene deep-sea sediments in the Gulf of Aden and the Somali Basin demonstrate that most of the tephra layers correlate with tephra layers known on land in the Turkana Basin of northern Kenya and southern Ethiopia. Previous correlations are reviewed, and new correlations proposed. Together these data provide correlations between the deep-sea cores, and to the land-based sections at eight levels ranging in age from about 4 to 0.7 Ma. Specifically, we correlate the Moiti Tuff (???4.1 Ma) with a tephra layer at 188.6 m depth in DSDP hole 231 and with a tephra layer at 150 m depth in DSDP hole 241, the Wargolo Tuff with a tephra layer at 179.7 m in DSDP Hole 231 and with a tephra layer at 155.3 m depth in DSDP Hole 232, the Lomogol Tuff (defined here) with a tephra layer at 165 m in DSDP Hole 232A, the Lokochot Tuff with a tephra layer at 140.1 m depth in DSDP Hole 232, the Tulu Bor Tuff with a tephra layer at 160.8 m depth in DSDP Hole 231, the Kokiselei Tuff with a tephra layer at 120 m depth in DSDP Hole 231 and with a tephra layer at 90.3 m depth in DSDP Hole 232, the Silbo Tuff (0.74 Ma) with a tephra layer at 35.5 m depth in DSDP Hole 231 and possibly with a tephra layer at 10.9 m depth in DSDP Hole 241. We also present analyses of other tephra from the deep sea cores for which correlative units on land are not yet known. The correlated tephra layers provide eight chronostratigraphic horizons that make it possible to temporally correlate paleoecological and paleoclimatic data between the terrestrial and deep-sea sites. Such correlations may make it possible to interpret faunal evolution in the Lake Turkana basin and other sites in East Africa within a broader regional or global paleoclimatic context. ?? 1992.

Paleoenvironmental change as seen from a multiproxy perspective in the West Turkana Kaitio core (WTK13), Kenya

NASA Astrophysics Data System (ADS)

Beck, C. C.; Feibel, C. S.; Lupien, R.; Yost, C. L.; Rucina, S.; Russell, J. M.; Deino, A. L.; Sier, M.; Cohen, A. S.; Campisano, C. J.

2017-12-01

The Hominin Sites and Paleolakes Drilling Project's (HSPDP) primary goal is to provide high quality environmental records to test whether and how Earth system dynamics influenced the evolution of hominins in Africa. To this end, multiproxy records from individual basins are essential to understanding how paleoenvironments changed in relation to shifts in the climatic and/or tectonic regimes both locally on a basin-scale and regionally across East Africa. Because of its rich combination of paleoanthropologic and geologic data, the West Turkana Kaitio (WTK13) core is an important component of this synthesis. Using a combination of tephra chronology and paleomagnetic data, the core has been dated to 1.87-1.37 Ma. The sedimentology records deposition on a dynamic lacustrine margin becoming more influenced by channel and floodplain processes through time. Multiproxy records provide a window into paleoevironments of the Turkana Basin that operated on shorter time scales than this dominant first-order facies shift. Processional cycles (21 kyr) are picked up by indicator records where the preservation of the archive was good enough to allow for high-resolution analysis. However, interestingly, the biomarker record suggests that the hydroclimate of the Turkana Basin, while highly variable at the Milankovitch-scale, exhibits no directional trend in the mean values towards wetter or drier conditions. The combined phytolith and pollen records suggest that grasses, albeit with fluctuating abundances of C4 mesophytic and C4 xerophytic taxa, dominated the landscape throughout most of the core. This indicates that despite climatic variability, resource availability may have maintained some general consistency for hominins in the area. Ultimately, the time period spanned by the WTK13 record is significant for our understanding of hominin evolution as it covers an interval of increasing aridity on the African continent as observed in distal marine records. This synthesis

New structural/tectonical model and its implication on hydrological thinking and groundwater management - the Lake Tiberias, Jordan Rift Valley

NASA Astrophysics Data System (ADS)

Inbar, Nimrod; Magri, Fabien; Yellin-Dror, Annat; Rosenthal, Eliahu; Möller, Peter; Siebert, Christian; Guttman, Josef

2014-05-01

Lake Tiberias is a fresh water lake located at the Kinneret basin which is approximately 30 km long and 10 km wide. It comprises a link in the chain of pull-apart basins that characterizes the structure of the conspicuous Jordan Rift Valley (JRV). The basin surface is about 200 m below mean sea level (msl) and basin-fill attains a thickness of up to 8 km. Until recently, studies focused mainly on the upper strata of basin fill. Consequently, a complete three dimensional geological model, including clear view of the tectonic framework at the Kinneret Basin was incomplete. This situation imposes great difficulty in understanding the local hydrological system and as consequence enforce constrains on groundwater management of the regional aquifers that flows towards the lake. A recently proposed structural/tectonical model (Inbar, 2012) enables revaluation of several geohydrological aspects at Sea of Galilee and its surroundings and a new hydrological model based on those findings aims to clarify those aspects with relation to groundwater management. The deep-seated stratigraphical units were seismically studied at the Kinnarot Valley (southern part of Kinneret basin) where sufficient information is available (Inbar, 2012). This study shows the subsidence and northwestward tilting of the basin floor (pre-rift formations) and the flow of thick Late Miocene salt accumulation accordingly. Furthermore, shallower seismic data, collected at the lake itself, shows a suspected salt dome close to the western boundary fault of the basin (Resnikov et al., 2004). Salt flow is now suggested to be a substantial factor in the tectonic play. At the lake surroundings there are several springs and boreholes where brine immerges from an estimated depth of about 2-3 kilometers. Significant differences in brine characteristics raised questions regarding the location of brine traps, flow mechanism and the mixture process between the fresh water and the brine. However, the effect of the

Chlorine-36 tracing of salinity sources in the Dry Valleys of Victoria Land, Antarctica

NASA Astrophysics Data System (ADS)

Carlson, Catherine A.; Phillips, Fred M.; Elmore, David; Bentley, Harold W.

1990-02-01

Chlorine-36 was used to trace the origins of salts in six saline lakes in the Dry Valleys of Southern Victoria Land, Antarctica. Characteristic 36Cl signatures were estimated for the various potential chloride sources, which include atmospheric deposition, rock weathering, seawater, and deep ground water. 36Cl /Cl ratios were measured in natural waters and salts from the Dry Valleys. Dilute lake waters (Cl - < 100 mg/l) were found to have 36Cl /Cl ratios in the range 100 × 10 -15 to 1,700 × 10 -15, whereas saline waters (Cl - > 1000 mg/l) had ratios in the range 9 × 10 -15 to 40 × 10 -15. Simple mixing models were employed to quantify the relative contributions of the various chloride sources to Lake Vanda and Don Juan Pond. These results show that Lake Vanda has received its chloride from both deep ground water and the Onyx River. Don Juan Pond has received nearly all its chloride from deep ground water, probably ultimately from rock-water interaction. Deep ground water is the principal source of chloride to the lakes of Wright Valley. However, preliminary data suggest that marine-derived salts or relict sea water may be a significant source of chloride to the lakes of Taylor Valley, implying a possible recent marine invasion that did not affect Wright Valley.

McMurdo LTER: streamflow measurements in Taylor Valley

USGS Publications Warehouse

McKnight, D.; House, H.; Von Guerard, P.

1994-01-01

Has established a stream gaging network for the three major lake basins in Taylor Valley. These data are critical for determining nutrient budgets for the lake ecosystems and for understanding physical factors controlling microbial mats in the streams.

Investigations into the Fish Lake Valley Fault Zone (FLVFZ) and its interactions with normal faulting within Eureka and Deep Springs Valleys

NASA Astrophysics Data System (ADS)

Lawson, M. J.; Rhodes, E.; Yin, A.

2016-12-01

In most textbooks, the San Andreas Fault is stated to be the plate boundary between the North American and the Pacific plates, as plate tectonics assumes that boundaries are essentially discrete. In the Western United States this is not the case, as up to 25% of relative plate motion is accommodated on other structures within the Walker Lane Shear Zone (WLSZ) in a diffuse 100 km margin (Faulds et al., 2005; Oldow et al., 2001). Fish Lake Valley Fault Zone (FLVFZ), situated at the northern border of Death Valley National Park, is the northern continuation of the Furnace Creek Fault Zone (FCFZ), and is an important transfer structure within the Walker Lane Shear Zone. Though the FLVFZ has a long term rate (since 10 Ma) of 5 mm/yr (Reheis and Sawyer, 1997), it has a highly variable slip rate. In the middle Pleistocene, the rate has a maximum of up to 11 mm/yr which would accommodate nearly the entirety of slip within the Walker Lane, and yet this rate decreases significantly ( 2.5 to 3 mm/yr) by the late Pleistocene due to unknown causes (Frankel et al. 2007). This variation in slip rate has been proposed by previous workers to be due to strain transience, an increase in the overall strain rate, or due to other unknown structures (Lee et al., 2009). Currently, we are investigating the cause of this variation, and the possibility of the transfer of slip to faults south of the FLVFZ on oblique normal faults within Eureka and Deep Springs Valleys. Preliminary data will be shown utilizing scarp transects, geomorphic scarp modeling, and Optically Stimulated Luminescence (OSL) dating techniques.

Characterize the hydrogeological properties and probe the stress field in Salt Lake Valley, Utah using SAR imagery

NASA Astrophysics Data System (ADS)

Hu, X.; Lu, Z.; Barbot, S.; Wang, T.

2017-12-01

Aquifer skeletons deform actively in response to the groundwater redistribution and hydraulic head changes with varied time scales of delay and sensitivity, that can also, in some instances, trigger earthquakes. However, determining the key hydrogeological properties and understanding the interactions between aquifer and seismicity generally requires the analysis of dense water level data combined with expensive drilling data (borehole breakouts). Here we investigate the spatiotemporal correlation among ground motions, hydrological changes, earthquakes, and faults in Salt Lake Valley, Utah, based on InSAR observations from ENVISAT ASAR (2004-2010) and Sentinel-1A (2015-2016). InSAR results show a clear seasonal and long-term correlation between surface uplift/subsidence and groundwater recharge/discharge, with evidence for an average net uplift of 15 mm/yr for a period of 7 years. The long-term uplift, remarkably bounded by faults, reflects a net increase in pore pressure associated with prolonged water recharge probably decades ago. InSAR-derived ground deformation and its correlation with head variations allow us to quantify hydrogeological properties - decay coefficient, storage coefficient, and bulk compressibility. We also model the long-term deformation using a shallow vertical shearing reservoir to constrain its thickness and strain rate. InSAR-derived deformation help reveal the coupled hydrological and tectonic processes in Salt Lake Valley: the embedded faults disrupt the groundwater flow and partition the hydrological units, and the pore pressure changes rearrange the aquifer skeleton and modulate the stress field, which may affect the basin-wide seismicity.

Geohydrology, water quality, and simulation of groundwater flow in the stratified-drift aquifer system in Virgil Creek and Dryden Lake Valleys, Town of Dryden, Tompkins County, New York

USGS Publications Warehouse

Miller, Todd S.; Bugliosi, Edward F.

2013-01-01

In 2002, the U.S. Geological Survey, in cooperation with the Tompkins County Planning Department and the Town of Dryden, New York, began a study of the stratified-drift aquifer system in the Virgil Creek and Dryden Lake Valleys in the Town of Dryden, Tompkins County. The study provided geohydrologic data needed by the town and county to develop a strategy to manage and protect their water resources. In this study area, three extensive confined sand and gravel aquifers (the upper, middle, and lower confined aquifers) compose the stratified-drift aquifer system. The Dryden Lake Valley is a glaciated valley oriented parallel to the direction of ice movement. Erosion by ice extensively widened and deepened the valley, truncated bedrock hillsides, and formed a nearly straight, U-shaped bedrock trough. The maximum thickness of the valley fill in the central part of the valley is about 400 feet (ft). The Virgil Creek Valley in the east part of the study area underwent less severe erosion by ice than the Dryden Lake Valley, and hence, it has a bedrock floor that is several hundred feet higher in altitude than that in the Dryden Lake Valley. The sources and amounts of recharge were difficult to identify in most areas because the confined aquifers are overlain by confining units. However, in the vicinity of the Virgil Creek Dam, the upper confined aquifer crops out at land surface in the floodplain of a gorge eroded by Virgil Creek, and this is where the aquifer receives large amounts of recharge from precipitation that directly falls over the aquifer and from seepage losses from Virgil Creek. The results of streamflow measurements made in Virgil Creek where it flows through the gorge indicated that the stream lost 1.2 cubic feet per second (ft3/s) or 0.78 million gallons per day (Mgal/d) of water in the reach extending from 220 ft downstream from the dam to 1,200 ft upstream from the dam. In the southern part of the study area, large amounts of recharge also replenish the

Ciliate diversity, community structure, and novel taxa in lakes of the McMurdo Dry Valleys, Antarctica.

PubMed

Xu, Yuan; Vick-Majors, Trista; Morgan-Kiss, Rachael; Priscu, John C; Amaral-Zettler, Linda

2014-10-01

We report an in-depth survey of next-generation DNA sequencing of ciliate diversity and community structure in two permanently ice-covered McMurdo Dry Valley lakes during the austral summer and autumn (November 2007 and March 2008). We tested hypotheses on the relationship between species richness and environmental conditions including environmental extremes, nutrient status, and day length. On the basis of the unique environment that exists in these high-latitude lakes, we expected that novel taxa would be present. Alpha diversity analyses showed that extreme conditions-that is, high salinity, low oxygen, and extreme changes in day length-did not impact ciliate richness; however, ciliate richness was 30% higher in samples with higher dissolved organic matter. Beta diversity analyses revealed that ciliate communities clustered by dissolved oxygen, depth, and salinity, but not by season (i.e., day length). The permutational analysis of variance test indicated that depth, dissolved oxygen, and salinity had significant influences on the ciliate community for the abundance matrices of resampled data, while lake and season were not significant. This result suggests that the vertical trends in dissolved oxygen concentration and salinity may play a critical role in structuring ciliate communities. A PCR-based strategy capitalizing on divergent eukaryotic V9 hypervariable region ribosomal RNA gene targets unveiled two new genera in these lakes. A novel taxon belonging to an unknown class most closely related to Cryptocaryon irritans was also inferred from separate gene phylogenies. © 2014 Marine Biological Laboratory.

Mohawk Lake or Mohawk meadow Sedimentary facies and stratigraphy of Quaternary deposits in Mohawk Valley, upper Middle Fork of the Feather River, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yount, J.C.; Harwood, D.S.; Bradbury, J.P.

1993-04-01

Mohawk Valley (MV) contain thick, well-exposed sections of Quaternary basin-fill sediments, with abundant interbedded tephra and a diverse assemblage of sedimentary facies. The eastern arm of MV, extending from Clio to Portola, contains as much as 100 m of trough cross-bedded cobble to pebble gravel and planar and trough cross-bedded coarse and medium sand, interpreted as braided stream deposits. Sections exposed in the western arm of MV consist in their lower parts of massive organic-rich silt and clay interbedded with blocky to fissile peat beds up to 1 m thick. Diatom assemblages are dominated by benthic species indicating fresh marshmore » environments with very shallow water depths of one meter or less. Proglacial lacustrine deposits of limited lateral extent are present within the outwash complexes as evidenced by varved fine sand and silt couplets, poorly sorted quartz-rich silt beds containing dropstones, and contorted beds of diamict grading laterally into slump blocks surrounded by wood-bearing silt and silty sand. The Rockland Ash (400 ka) is a prominent marker in the middle or lower part of many sections throughout MV, indicating that at least half of the basin-fill sequence is Late Quaternary in age. A log buried in diamict slumped into a proglacial lake lying approximately 3 km downstream from the Tioga Stage ice termini in Jamison and Gray Eagle Creeks yields an age of 18,715 [+-]235 C[sup 14] years BP. Previous interpretations of MV deposits originating in a large, deep lake with water depths in excess of 150 m are untenable given the sedimentary facies and diatom floras that dominate the valley. Unexhumed valleys such as Sierra Valley to the east and Long Valley to the northwest which contain large meadows traversed by braided streams are probably good analogs for the conditions that existed during the accumulation of the Mohawk Valley deposits.« less

Paleolimnology of Lake Tubutulik, an iron-meromictic Eocene Lake, eastern Seward Peninsula, Alaska

USGS Publications Warehouse

Dickinson, K.A.

1988-01-01

Sideritic lacustrine mudstone was found in drill core from a uranium deposit in the Death Valley area in the eastern part of the Seward Peninsula, Alaska. The precursor sediments for this rock were deposited in an unusual "iron-meromictic" Eocene lake, herein named Lake Tubutulik, which occupied part of the Boulder Creek basin, a structural graben that is probably a southern extension of the larger Death Valley basin. The Boulder Creek basin is bounded on the west by granite of the Late Cretaceous Darby Pluton, on the east by Precambrian to Paleozoic metasedimentary rocks. The lake basin was formed by basaltic flows that dammed the river valley of the ancestral Tubutulik River in early Eocene time. Lake Tubutulik contained a nearshore facies of fine-grained organic mud and an offshore facies of laminated sideritic mud. The offshore (profundal) laminated mudstone consists of alternating layers of authigenic siderite and detrital layers containing mostly quartz and clay minerals. Both lacustrine facies contain turbidities. The lacustrine sediments graded laterally into an onshore facies of colluvial and fluvial sandstone, paludal mudstone, and coal. The ancient lake apparently occupied a small deep basin in a tectonically active area of high relief. Meromixus was probably stabilized by reduced iron and bicarbonate dissolved in the monimolimnion. The intensity of meromixus decreased as the lake became shallower from sediment filling. The source of the iron, abundant in the monimolimnion of Lake Tubutulik, was probably the Eocene basalt. Based on carbon isotope analysis of the siderite, the dissolved bicarbonate in the profundal facies was largely inorganic. Sideritic carbon in one sample from the onshore paludal facies has an isotopic signature (??13C = +16.9) consistent with residual carbon formed during methanogenic fermentation. ?? 1988.

[Pediatric case series in an ophthalmic camp in Turkana (Kenya)].

PubMed

Noval, S; Cabrejas, L; Jarrín, E; Ruiz-Guerrero, M; Ciancas, E

2013-12-01

Turkana is the largest district in Kenya, situated in the Northwest of the country. It features a semi-nomadic population of 850,000. Around 60% of population lives below the poverty threshold. The ratio of doctors is 1:75,000 inhabitants. Five ophthalmologists took part in the last deployment in November. Local staff had previously selected the patients from the rural areas, as well as in Lodwar, the capital of the district. Of the 371 patients who attended the clinic, 128 required surgery. To describe the pediatric population attended to in the last «Turkana Eye Project» Camp. Description of the ophthalmic pathologies of the children seen in the clinic in this surgical camp, and the diagnostic and therapeutic options according to the limitations of the environment. Of the 371 patients, 54 were younger than 15 years old (14.5%). Four children had surgery (3.25% of the 128 patients). In 2 more cases surgery was the indicated but not performed. Therefore, of the total of 54 cases, 6 could be considered as surgical (11.1%), and 17 suffered ophthalmic problems other than refraction defects, or mild ocular surface pathologies: traumatic cataracts, neuropathies, impetigo, exophthalmos, retinal dystrophies, dermoid cysts, or nyctalopia. The etiology was traumatic in four of the 17 children (23.5%). Surgical camps are increasing in the developing countries. They are usually focused on particular pathologies, such as cataracts or trachoma. Our case series shows the importance of pediatric teams and the need to be prepared to face complex pediatric pathologies. Copyright © 2012 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.

Chlorine-36 tracing of salinity sources in the dry valleys of Victoria land, Antarctica

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlson, C.A.; Phillips, F.M.; Elmore, D.

1990-02-01

Chlorine-36 was used to trace the origins of salts in six saline lakes in the Dry Valleys of Southern Victoria Land, Antarctica. Characteristic {sup 36}Cl signatures were estimated for the various potential chloride sources, which include atmospheric deposition, rock weathering, seawater, and deep ground water. {sup 36}Cl/Cl ratios were measured in natural waters and salts from the Dry Valleys. Dilute lake waters (Cl{sup {minus}} < 100 mg/l) were found to have {sup 36}Cl/Cl ratios in the range 100 {times} 10{sup {minus}15} to 1,700 {times} 10{sup {minus}15}, whereas saline waters (Cl{sup {minus}} > 1000 mg/l) had ratios in the range 9more » {times} 10{sup {minus}15} to 40 {times} 10{sup {minus}15}. Simple mixing models were employed to quantify the relative contributions of the various chloride sources to Lake Vanda and Don Juan Pond. These results show that Lake Vanda has received its chloride from both deep ground water and the Onyx River. Don Juan Pond has received nearly all its chloride from deep ground water, probably ultimately from rock-water interaction. Deep ground water is the principal sources of chloride to the lakes of Wright Valley. However, preliminary data suggest that marine-derived salts or relict sea water may be a significant sources of chloride to the lakes of Taylor Valley, implying a possible recent marine invasion that did not affect Wright Valley.« less

79. COVERED CONDUIT ACROSS ANTELOPE VALLEY WITH WIND FARM IN ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

79. COVERED CONDUIT ACROSS ANTELOPE VALLEY WITH WIND FARM IN DISTANCE - Los Angeles Aqueduct, From Lee Vining Intake (Mammoth Lakes) to Van Norman Reservoir Complex (San Fernando Valley), Los Angeles, Los Angeles County, CA

Halomonas sp. strain A55, a novel dye decolorizing bacterium from dye-uncontaminated Rift Valley Soda lake.

PubMed

Guadie, Awoke; Gessesse, Amare; Xia, Siqing

2018-04-23

Considering the saline-alkaline nature of textile wastewater and treatment requirements, microbial samples were collected from Ethiopian Rift Valley Soda Lakes. A large number of bacteria (121) were isolated from dye-uncontaminated Lakes Chitu (81.0%), Abijata (15.7%) and Arenguadie (3.3%), of which 95 isolates (78.5%) were found dye decolorizer. Many dye decolorizer from Lake Chitu positively correlated with higher pH (10.3 ± 0.1), salinity (64.6 ± 2.0%), conductivity (6.1 ± 0.3 mS cm -1 ) and Na+ (18.4 ± 0.6 g L -1 ) values observed than Abijata and Arenguadie Lakes. Through subsequent screening mechanism, strain A55 was selected to investigate the effect of nutrient (carbon and nitrogen), dissolved oxygen and dye concentration using Reactive Red 184 (RR 184). Based on morphological, biochemical and 16S rRNA gene sequence analysis, the strain was identified as Halomonas sp. Decolorization efficiencies were significantly enhanced with carbon (≥98%) and organic nitrogen (∼100%) than non-carbon/nitrogen (both<55%) supplements. Complete decolorization efficiencies were also observed under anoxic and anaerobic growth conditions. However, growing the isolate with nitrate (<30%) and aerobic (<10%) condition significantly decreased (p < 0.05) color removal efficiency. Kinetic analysis showed that pseudo-first-order best describes RR 184 decolorization process. Overall, the ability of Halomonas sp. strain A55 decolorized different dyes indicate that alkaline soda lake isolates are the potential candidate for treating color containing effluent. Copyright © 2018 Elsevier Ltd. All rights reserved.

Uranium in Holocene valley-fill sediments, and uranium, radon, and helium in waters, Lake Tahoe-Carson Range area, Nevada and California, U.S.A.

USGS Publications Warehouse

Otton, J.K.; Zielinski, R.A.; Been, J.M.

1989-01-01

Uraniferous Holocene sediments occur in the Carson Range of Nevada and California, U.S.A., between Lake Tahoe and Carson Valley. The hosts for the uranium include peat and interbedded organic-rich sand, silt, and mud that underly valley floors, fens, and marshes along stream valleys between the crest of the range and the edge of Lake Tahoe. The known uranium accumulations extend along the Carson Range from the area just southeast of South Lake Tahoe northward to the area just east of Carson City; however, they almost certainly continue beyond the study area to the north, west, and south. Due to the young age of the accumulations, uranium in them is in gross disequilibrium with its highly radioactive daughter products. These accumulations have thus escaped discovery with radiation detection equipment in the past. The uranium content of these sediments approaches 0.6 percent; however, the average is in the range of 300-500 ppm. Waters associated with these sediments locally contain as much as 177 ppb uranium. Modest levels of helium and radon also occur in these waters. Uraniferous waters are clearly entering the private and public water supply systems in some parts of the study area; however, it is not known how much uranium is reaching users of these water supplies. Many of the waters sampled in the study area exceed the published health effects guidance level of the Environmental Protection Agency. Regulatory standards for uranium in waters have not been published, however. Much uranium is stored in the sediments along these stream valleys. Estimates for a marsh and a fen along one drainage are 24,000 and 15,000 kg, respectively. The potential effects of man-induced environmental changes on the uranium are uncertain. Laboratory studies of uraniferous sediment rich in organic matter may allow us to evaluate the potential of liberating uranium from such sediments and creating transient increases in the level of uranium moving in water in the natural environment

The Importance of Lake Overflow Floods for Early Martian Landscape Evolution: Insights From Licus Vallis

NASA Technical Reports Server (NTRS)

Goudge, T. A.; Fassett, C. I.

2017-01-01

Open-basin lake outlet valleys are incised when water breaches the basin-confining topography and overflows. Outlet valleys record this flooding event and provide insight into how the lake and surrounding terrain evolved over time. Here we present a study of the paleolake outlet Licus Vallis, a >350 km long, >2 km wide, >100 m deep valley that heads at the outlet breach of an approx.30 km diameter impact crater. Multiple geomorphic features of this valley system suggest it records a more complex evolution than formation from a single lake overflow flood. This provides unique insight into the paleohydrology of lakes on early Mars, as we can make inferences beyond the most recent phase of activity..

Response of the St. Joseph River to lake level changes during the last 12,000 years in the Lake Michigan basin

USGS Publications Warehouse

Kincare, K.A.

2007-01-01

The water level of the Lake Michigan basin is currently 177 m above sea level. Around 9,800 14C years B.P., the lake level in the Lake Michigan basin had dropped to its lowest level in prehistory, about 70 m above sea level. This low level (Lake Chippewa) had profound effects on the rivers flowing directly into the basin. Recent studies of the St. Joseph River indicate that the extreme low lake level rejuvenated the river, causing massive incision of up to 43 m in a valley no more than 1.6 km wide. The incision is seen 25 km upstream of the present shoreline. As lake level rose from the Chippewa low, the St. Joseph River lost competence and its estuary migrated back upstream. Floodplain and channel sediments partially refilled the recently excavated valley leaving a distinctly non-classical morphology of steep sides with a broad, flat bottom. The valley walls of the lower St. Joseph River are 12-18 m tall and borings reveal up to 30 m of infill sediment below the modern floodplain. About 3 ?? 108 m3 of sediment was removed from the St. Joseph River valley during the Chippewa phase lowstand, a massive volume, some of which likely resides in a lowstand delta approximately 30 km off-shore in Lake Michigan. The active floodplain below Niles, Michigan, is inset into an upper terrace and delta graded to the Calumet level (189 m) of Lake Chicago. In the lower portion of the terrace stratigraphy a 1.5-2.0 m thick section of clast-supported gravel marks the entry of the main St. Joseph River drainage above South Bend, Indiana, into the Lake Michigan basin. This gravel layer represents the consolidation of drainage that probably occurred during final melting out of ice-marginal kettle chains allowing stream piracy to proceed between Niles and South Bend. It is unlikely that the St. Joseph River is palimpsest upon a bedrock valley. The landform it cuts across is a glaciofluvial-deltaic feature rather than a classic unsorted moraine that would drape over pre-glacial topography

Long Valley Caldera Lake and reincision of Owens River Gorge

USGS Publications Warehouse

Hildreth, Wes; Fierstein, Judy

2016-12-16

Owens River Gorge, today rimmed exclusively in 767-ka Bishop Tuff, was first cut during the Neogene through a ridge of Triassic granodiorite to a depth as great as its present-day floor and was then filled to its rim by a small basaltic shield at 3.3 Ma. The gorge-filling basalt, 200 m thick, blocked a 5-km-long reach of the upper gorge, diverting the Owens River southward around the shield into Rock Creek where another 200-m-deep gorge was cut through the same basement ridge. Much later, during Marine Isotope Stage (MIS) 22 (~900–866 ka), a piedmont glacier buried the diversion and deposited a thick sheet of Sherwin Till atop the basalt on both sides of the original gorge, showing that the basalt-filled reach had not, by then, been reexcavated. At 767 ka, eruption of the Bishop Tuff blanketed the landscape with welded ignimbrite, deeply covering the till, basalt, and granodiorite and completely filling all additional reaches of both Rock Creek canyon and Owens River Gorge. The ignimbrite rests directly on the basalt and till along the walls of Owens Gorge, but nowhere was it inset against either, showing that the basalt-blocked reach had still not been reexcavated. Subsidence of Long Valley Caldera at 767 ka produced a steep-walled depression at least 700 m deeper than the precaldera floor of Owens Gorge, which was beheaded at the caldera’s southeast rim. Caldera collapse reoriented proximal drainages that had formerly joined east-flowing Owens River, abruptly reversing flow westward into the caldera. It took 600,000 years of sedimentation in the 26-km-long, usually shallow, caldera lake to fill the deep basin and raise lake level to its threshold for overflow. Not until then did reestablishment of Owens River Gorge begin, by incision of the gorge-filling ignimbrite.

Groundwater quality in the Owens Valley, California

USGS Publications Warehouse

Dawson, Barbara J. Milby; Belitz, Kenneth

2012-01-01

Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. Owens Valley is one of the study areas being evaluated. The Owens study area is approximately 1,030 square miles (2,668 square kilometers) and includes the Owens Valley groundwater basin (California Department of Water Resources, 2003). Owens Valley has a semiarid to arid climate, with average annual rainfall of about 6 inches (15 centimeters). The study area has internal drainage, with runoff primarily from the Sierra Nevada draining east to the Owens River, which flows south to Owens Lake dry lakebed at the southern end of the valley. Beginning in the early 1900s, the City of Los Angeles began diverting the flow of the Owens River to the Los Angeles Aqueduct, resulting in the evaporation of Owens Lake and the formation of the current Owens Lake dry lakebed. Land use in the study area is approximately 94 percent (%) natural, 5% agricultural, and 1% urban. The primary natural land cover is shrubland. The largest urban area is the city of Bishop (2010 population of 4,000). Groundwater in this basin is used for public and domestic water supply and for irrigation. The main water-bearing units are gravel, sand, silt, and clay derived from surrounding mountains. Recharge to the groundwater system is primarily runoff from the Sierra Nevada, and by direct infiltration of irrigation. The primary sources of discharge are pumping wells, evapotranspiration, and underflow to the Owens Lake dry lakebed. The primary aquifers in Owens Valley are defined as those parts of the aquifers corresponding to the perforated intervals of wells listed in the California Department of Public Health database

Perennially ice-covered Lake Hoare, Antarctica: physical environment, biology and sedimentation

NASA Technical Reports Server (NTRS)

Wharton, R. A. Jr; Simmons, G. M. Jr; McKay, C. P.; Wharton RA, J. r. (Principal Investigator)

1989-01-01

Lake Hoare (77 degrees 38' S, 162 degrees 53' E) is a perennially ice-covered lake at the eastern end of Taylor Valley in southern Victoria Land, Antarctica. The environment of this lake is controlled by the relatively thick ice cover (3-5 m) which eliminates wind generated currents, restricts gas exchange and sediment deposition, and reduces light penetration. The ice cover is in turn largely controlled by the extreme seasonality of Antarctica and local climate. Lake Hoare and other dry valley lakes may be sensitive indicators of short term (< 100 yr) climatic and/or anthropogenic changes in the dry valleys since the onset of intensive exploration over 30 years ago. The time constants for turnover of the water column and lake ice are 50 and 10 years, respectively. The turnover time for atmospheric gases in the lake is 30-60 years. Therefore, the lake environment responds to changes on a 10-100 year timescale. Because the ice cover has a controlling influence on the lake (e.g. light penetration, gas content of water, and sediment deposition), it is probable that small changes in ice ablation, sediment loading on the ice cover, or glacial meltwater (or groundwater) inflow will affect ice cover dynamics and will have a major impact on the lake environment and biota.

The helium isotopic chemistry of Lake Bonney, Taylor Valley, Antarctica: Timing of late holocene climate change in Antarctica

USGS Publications Warehouse

Poreda, R.J.; Hunt, A.G.; Berry, Lyons W.; Welch, K.A.

2004-01-01

To better understand the long-term climate history of Antarctica, we studied Lake Bonney in Taylor Valley, Southern Victoria Land (78?? S). Helium isotope ratios and He, Ne, Ar and N2 concentration data, obtained from hydrocasts in the East (ELB) and West (WLB) Lobesof Lake Bonney, provided important constraints on the lake's Holocene evolution. Based on very low concentrations of Ar and N2 in the ELB bottom waters, ELB was free of ice until 200 ?? 50 years ago. After which, low salinity water flowing over the sill from WLB to ELB, covered ELB and formed a perennial ice cover, inhibiting the exchange of gases with the atmosphere. In contrast to the ELB, the WLB retained an ice cover through the Holocene. The brine in the WLB bottom waters has meteoric N2 and Ar gas concentrations indicating that it has not been significantly modified by atmospheric exchange or ice formation. The helium concentrations in the deep water of WLB are the highest measured in non-thermal surface water. By fitting a diffusional loss to the 3He/4He, helium, and Cl profiles, we calculate a time of ???3000 years for the initiation of flow over the sill separating the East and West Lobes. To supply this flux of helium to the lake, a helium-rich sediment beneath the lake must be providing the helium by diffusion. If at any time during the last million years the ice cover left WLB, there would be insufficient helium available to provide the current flux to WLB. The variations in water levels in Lake Bonney can be related to climatic events that have been documented within the Southern Victoria Land region and indicate that the lakes respond significantly to regional and, perhaps, global climate forcing. ?? 2004 Kluwer Academic Publishers.

Release and survival of Echinococcus eggs in different environments in Turkana, and their possible impact on the incidence of hydatidosis in man and livestock.

PubMed

Wachira, T M; Macpherson, C N; Gathuma, J M

1991-03-01

In Turkana, Kenya, a prevalence of hydatidosis of nearly 10% has been recorded among the pastoralists yet their livestock have a much lower prevalence of the disease. The present study investigated the release from dogs and subsequent survival of Echinococcus eggs in Turkana huts, water-holes and in the semi-arid environment. The results were compared with the survival of eggs of Taenia hydatigena and T. saginata. The study was repeated under the cooler and moister conditions found in Maasailand where livestock have a greater incidence of hydatid disease than in Turkana but where the incidence in man is ten times lower. The average number of Echinococcus eggs per proglottid is 823. Nine percent of these remain in proglottids 15 minutes after release from a dog and the released eggs lose their viability in less than two, 48 and 300 hours in the sun, huts and water in Turkana respectively: the major influencing factor being temperature. The greater survival of eggs in the houses, coupled with the fact that dogs congregate for most of the day in the small houses facilitating a close man:dog contact, provide ideal conditions for the transmission of the parasite to man. The hostile environmental conditions and lack of contact between dogs and livestock contributes to the lower infection rate in livestock. Conversely in Maasailand, Echinococcus eggs survive in the environment for longer than three weeks and in addition, dogs are used for herding. This partly explains the higher infection rate among Maasai livestock but the low human infection rate remains arcane and requires further study.(ABSTRACT TRUNCATED AT 250 WORDS)

An analysis of the effects of temperatures and circulations on the strength of the low-level jet in the Turkana Channel in East Africa

NASA Astrophysics Data System (ADS)

Hartman, Adam T.

2018-05-01

The Turkana Low-Level Jet (LLJ) was discovered in the early 1980s, yet there are still questions about the primary forcing mechanisms that drive and sustain the jet throughout the year. A few studies have addressed these questions, but most focus on numerical simulations of mechanical forcing mechanisms, such as orography, channeling flow, and monsoon background flow. No studies have shown the effects of thermal forcing from differential heating in the regions in and around the Turkana Channel. This paper uses National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR) data and the National Aeronautics and Space Administration (NASA) Modern-Era Retrospective Analysis for Research and Applications (MERRA) data in order to analyze and find relationships between temperature gradients and the strength of the Turkana LLJ. In addition to temperature, potential temperature, divergence, wind magnitude, wind fields, and vertical motion are also examined. This analysis attempts to show that thermal forcing is one of the most important factors, if not the primary factor, in the initiation and maintenance of the jet and propose that more research and model simulations should be implemented to determine the contributions from thermal forcing.

Tilted lake shorelines record the onset of motion along the Hilton Creek fault adjacent to Long Valley caldera, CA, USA

NASA Astrophysics Data System (ADS)

Perkins, J. P.; Finnegan, N. J.; Cervelli, P. F.; Langbein, J. O.

2010-12-01

Prominent normal faults occur within and around Long Valley caldera, in the eastern Sierra Nevada of California. However, their relationship to both the magmatic and tectonic evolution of the caldera since the 760 ka eruption of the Bishop Tuff remains poorly understood. In particular, in the Mono-Inyo Craters north of Long Valley, extensional faulting appears to be replaced by dike intrusion where magma is available in the crust. However, it is unclear whether extensional faults in Long Valley caldera have been active since the eruption of the Bishop Tuff (when the current topography was established) or are a relatively young phenomenon owing to the cooling and crystallization of the Long Valley magma reservoir. Here we use GPS geodesy and geomorphology to investigate the evolution of the Hilton Creek fault, the primary range-front fault bounding Long Valley caldera to the southwest. Our primary goals are to determine how long the Hilton Creek fault has been active and whether slip rates have been constant over that time interval. To characterize the modern deformation field, we capitalize on recently (July, 2010) reoccupied GPS benchmarks first established in 1999-2000. These fixed-array GPS data show no discernible evidence for recent slip on the Hilton Creek fault, which further highlights the need for longer-term constraints on fault motion. To establish a fault slip history, we rely on a suite of five prominent shorelines from Pleistocene Long Valley Lake whose ages are well constrained based on field relationships to dated lavas, and that are tilted southward toward the Hilton Creek fault. A preliminary analysis of shoreline orientations using GPS surveys and a 5-m-resolution Topographic Synthetic Aperture Radar (TOPSAR) digital elevation model shows that lake shorelines tilt towards the Hilton Creek fault at roughly parallel gradients (~ 0.6%). The measured shorelines range in inferred age from 100 ka to 500 ka, which constrain recent slip on the Hilton

Organisms of the Hubbard Brook Valley, New Hampshire

Treesearch

Richard T. Holmes; Gene E. Likens

1999-01-01

Lists the organisms, both plant and animal, that have been identified by scientists engaged in multidisciplinary ecological research in the Hubbard Brook Valley, New Hampshire, during the past three decades. The Valley encompasses the Hubbard Brook Experimental Forest, Mirror Lake, and nearby areas within the White Mountain region of Grafton County. The species lists...

Terrestrial Cosmogenic-Nuclide Dating of Alluvial Fans in Death Valley, California

USGS Publications Warehouse

Machette, Michael N.; Slate, Janet L.; Phillips, Fred M.

2008-01-01

We have used terrestrial cosmogenic nuclides (TCN) to establish the age of some of the most extensive Quaternary alluvial fans in Death Valley, California. These intermediate-age alluvial fans are most extensive on the western side of the valley, where tectonic deformation is considerably less pronounced than on the eastern side of the valley. These fans are characterized by a relatively smooth, densely packed desert pavement formed by well-varnished (blackened) clasts. These surfaces have been mapped as the Q2 gravel by previous workers and as unit Qai (intermediate age) by us. However, the intermediate-age gravels probably contain multiple subunits, as evidenced by slight differences in morphologic expression, soil formation, and inset geomorphic relations. The TCN technique used herein sums the cosmogenic 36Cl in approximately 2.5-meter-deep profiles through soil and host alluvium, thus avoiding some of the problems associated with the more typical surface-exposure dating of boulders or smaller clasts. Our TCN 36Cl dating of 12 depth profiles indicates that these intermediate-age (Qai) alluvial fans range from about 100 to 40 kilo-annum (ka), with a mean age of about 70 ka. An alternative interpretation is that alluvial unit Qai was deposited in two discrete episodes from 90 to 80 ka and from 60 to 50 ka, before and after MIS (marine oxygen-isotope stage) 4 (respectively). Without an intermediate-age unit, such as MIS 4 lake deposits, we can neither disprove nor prove that Qai was deposited in two discrete intervals or over a longer range of time. Thus, in Death Valley, alluvial unit Qai largely brackets MIS 4, which is not associated with a deep phase of Lake Manly. These Qai fans extend to elevations of about -46 meters (150 feet below sea level) and have not been transgressed by Lake Manly, suggesting that MIS 4 or MIS 2 lakes were rather shallow in Death Valley, perhaps because they lacked inflow from surface runoff of the Sierra Nevada drainages through

The Archaeology of Coralville Lake, Iowa. Volume 2. Evolution of Holocene Landscapes.

DTIC Science & Technology

1986-01-01

Distribution Unlimited *I THE ARCHAEOLOGY OF CORALVILLE LAKE, IOWA VOLUME II: -bhN9f EVOLUTION OA 1,4o04CE AM7-SCOPKS ,?96 DTIC Prepared By: Jeffrey D...report detailing the archaeological resources of Coralville Lake, Iowa and the planning process for managing those resources. The narrative and data...adjacent to Coralville Lake) of the Iowa River valley and its adjoining tributary valleys. Results of the investigation were to incorporate: (1) a

Spring sapping origin of the enigmatic relict valleys of Cape Cod and Martha's Vineyard and Nantucket Islands, Massachusetts

USGS Publications Warehouse

Uchupi, E.; Oldale, R.N.

1994-01-01

Steep-sided, flat-floored linear valleys that lack well developed tributaries and end in amphitheater-like heads are eroded on the outwash plains of Cape Cod, Martha's Vineyard and Nantucket Island. The valleys are restricted from the mid to the distal ends of the outwash plains and show no connection to possible water sources at the updip end of the plains. Their distribution and morphology lead us to propose that they were eroded by groundwater seeps fed by proglacial lakes (the high hydrostatic heads of the lakes led to the elevation of the water table) dammed by the outwash plains and associated moraines. The valleys on Cape Cod were initiated by seeps along the foreset surfaces of sandy deltas emplaced in lakes in Nantucket Sound and Cape Cod Bay after these lakes drained. Those on Martha's Vineyard and Nantucket islands were either eroded by seeps at the distal ends of outwash plain wedges emplaced atop the subareal continental shelf south of the islands or along the foreset surfaces of sandy deltas emplaced on a lake behind a peripheral crustal bulge south of the glacial front. Valley erosion terminated after the lakes were drained and the water table dropped. ?? 1994.

Hydrology, water quality, and nutrient loads to the Bauman Park Lake, Cherry Valley, Winnebago County, Illinois, May 1996-April 1997

USGS Publications Warehouse

Kay, Robert T.; Trugestaad, Aaron

1998-01-01

The Bauman Park Lake occupies a former sand and gravel quarry in the Village of Cherry Valley, Illinois. The lake is eutrophic, and nuisance growths of algae and aquatic macrophytes are supported by nutrients (nitrogen and phosphorus) that are derived primarily from ground-water inflow, the main source of water for the lake. The lake has an average depth of about 18 feet, a maximum depth of about 28 feet, and a volume of 466 acre-feet at a stage of about 717 feet above sea level. The lake also is subject to thermal stratification, and although most of the lake is well oxidized, nearly anoxic conditions were present at the lake bottom during part of the summer of 1996. 4,648 pounds of nitrogen compounds were added to the Bauman Park Lake from May 1996 through April 1997. Phosphorus compounds were derived primarily from inflow from ground water (68.7 percent), sediments derived from shoreline erosion (15.6 percent), internal regeneration (11.7 percent), waterfowl excrement (1.6 percent), direct precipitation and overland runoff (1.2 percent), and particulate matter deposited from the atmosphere (1.2 percent). Nitrogen compounds were derived from inflow from ground water (62.1 percent), internal regeneration (19.6 percent), direct precipitation and overland runoff (10.1 percent), particulate matter deposited from the atmosphere (3.5 percent), sediments derived from shoreline erosion (4.4 percent), and waterfowl excrement (0.3 percent). About 13 pounds of phosphorus and 318 pounds of nitrogen compounds flow out of the lake to ground water. About 28 pounds of nitrogen is removed by denitrification. Algae and aquatic macrophytes utilize nitrate, nitrite, ammonia, and dissolved phosphorus. The availability of dissolved phosphorus in the lake water controls algal growth. Uptake of the nutrients, by aquatic macrophytes and algae, temporarily removes nutrients from the water column but not from the lake basin. Because the amount of nutrients entering the lake greatly exceeds

Evaluation of reproductive function in Turkana women with enzyme immunoassays of urinary hormones in the field.

PubMed

Leslie, P W; Campbell, K L; Little, M A; Kigondu, C S

1996-02-01

The frequently reported observation that nomadic populations have lower fertility than their settled counterparts is often attributed to what are perceived as harsh, stressful conditions under which the nomads live. But the consequences of the hypothesized stresses for the reproductive biology or demography of these populations have been documented only a little. Traditionally, the Turkana of northwest Kenya are nomadic herders, but increasing numbers have settled on agricultural development schemes. We used an array of hormonal assays along with anthropometric indexes of nutritional status and interviews covering reproductive history, recent menstruation, diet, and health to compare reproductive function in nomadic and settled Turkana women. First morning urine samples were collected for three consecutive days during a series of surveys. Human choriogonadotropin (hCG; a marker for pregnancy), luteinizing hormone (LH; an indicator of ovulation), and pregnanediol glucuronide (PdG; an indicator of postovulatory luteal function) were assessed in the field with commercially available dipstick enzyme immunoassays. These assays along with the interview data allowed us to determine the reproductive status (e.g., pregnant or cycling, and if cycling, which phase of the ovarian cycle) of 166 nomadic and 194 settled Turkana women. The cross-sectional classifications allowed inferences of conception rates and normality of ovarian function. Follow-up surveys provided rates of pregnancy loss. Compared with the settled women, the nomadic women exhibited lower pregnancy rates and cycling nomadic women were less likely to show evidence of ovulation or luteal function. These results suggest that reproductive function of the nomadic women is diminished relative to the settled women. However, the settled women experienced a much higher rate of pregnancy loss, which may mean that their effective fecundability is in fact lower than that of the nomadic women. This study is the first to

Late Cenozoic geology and lacustrine history of Searles Valley, Inyo and San Bernardino Counties, California

NASA Astrophysics Data System (ADS)

Nathenson, M.; Smith, G. I.; Robinson, J. E.; Stauffer, P. H.; Zigler, J. L.

2010-12-01

George Smith’s career-long study of the surface geology of the Searles Valley was recently published by the USGS (Smith, 2009, online and printed). The co-authors of this abstract are the team responsible for completing the publication from the original materials. Searles Valley is an arid, closed basin lying 70 km east of the south end of the Sierra Nevada, California. During those parts of late Pliocene and Pleistocene time when precipitation and runoff from the east side of the Sierra Nevada into the Owens River were much greater than at present, a chain of as many as five large lakes was created, of which Searles Lake was third. The stratigraphic record left in Searles Valley when that lake expanded, contracted, or desiccated is fully revealed by cores taken from beneath the surface of Searles (dry) Lake and partly recorded by sediments cropping out around the edge of the valley. Although this outcrop record is discontinuous, it provides direct evidence of the lake’s water depths during each expansion, which the subsurface record does not. Maximum-depth lakes rose to the 2,280-ft (695 m) contour, the level of the spillway that led overflowing waters to Panamint Valley; that spillway is about 660 ft (200 m) above the present dry-lake surface. Most of this study concerns sediments of the newly described Searles Lake Formation, whose deposition spanned the period between about 150 ka and 2 ka. The outcrop record is documented in six geologic maps (scales: 1:50,000 and 1:10,000). The Searles Lake Formation is divided into seven main units. The depositional intervals of the units that make up the Searles Lake Formation are determined primarily by correlation with subsurface deposits that are dated by radiocarbon ages on organic carbon and U-series dates on salts. Shorelines, the most obvious geologic expressions of former lakes, are abundant around Searles Valley. Erosional shorelines have cut as much as 100 m into brecciated bedrock; depositional shorelines

Influence of Culture and Gender on Secondary School Students' Scientific Creativity in Biology Education in Turkana County, Kenya

ERIC Educational Resources Information Center

Aruan, Susan A.; Okere, Mark I. O.; Wachanga, Samuel

2016-01-01

The purpose of this study was to establish the extent to which biology scientific creativity skills are influenced by the students' culture and gender in Turkana County. A mixed method research design was used. This involved cross sectional survey and ethnographic study. The target population comprised all form three students in sub county schools…

Diversity of micro-fungi in an Antarctic dry valley

NASA Technical Reports Server (NTRS)

Baublis, J. A.; Wharton, R. A. Jr; Volz, P. A.; Wharton RA, J. r. (Principal Investigator)

1991-01-01

The fungal microflora of a dry valley in Southern Victoria Land near McMurdo Sound, Antarctica, was investigated. Samples were collected from introduced objects such as a mummified penguin and spent chewing tobacco in addition to the sparse soil found in rock fissures, isolated moss colonies, shoreline deposit materials, CaCO3 precipitates, and microbial mat debris obtained from the frozen surface of the lake in the basin of Taylor Valley. Using conventional media and techniques, all collection sites yielded populations of yeasts and filamentous fungi. Water samples and live microbial mats from beneath the lake ice yielded species of fungi along with an abundance of bacteria.

Preliminary Gravity and Magnetic Data of the Lake Pillsbury Region, Northern Coast Ranges, California

USGS Publications Warehouse

Langenheim, V.E.; Jachens, Robert C.; Morin, Robert L.; McCabe, Craig A.

2007-01-01

The Lake Pillsbury region is transected by the Bartlett Springs Fault zone, one of the main strike-slip faults of the San Andreas system north of San Francisco Bay, California. Gravity and magnetic data were collected to help characterize the geometry and offset of the fault zone as well as determine the geometry of the Gravelly Valley pull-apart basin and Potter Valley, an alluvial intermontane basin southwest of Lake Pillsbury. The Bartlett Springs fault zone lies at the base of a significant gravity gradient. Superposed on the gradient is a small gravity low centered over Lake Pillsbury and Gravelly Valley. Another small gravity low coincides with Potter Valley. Inversion of gravity data for basin thickness indicates a maximum thickness of 400 and 440 m for the Gravelly and Potter Valley depressions, respectively. Ground magnetic data indicate that the regional aeromagnetic data likely suffer from positional errors, but that large, long-wavelength anomalies, sourced from serpentinite, may be offset 8 km along the Bartlett Springs Fault zone. Additional gravity data collected either on the lake surface or bottom and in Potter Valley would better determine the shape of the basins. A modern, high-resolution aeromagnetic survey would greatly augment the ability to map and model the fault geometry quantitatively.

Geophysical reconnaissance of Lemmon Valley, Washoe County, Nevada

USGS Publications Warehouse

Schaefer, Donald H.; Maurer, Douglas K.

1981-01-01

Rapid growth in the Lemmon Valley area, Nevada, during recent years has put increasing importance on knowledge of stored ground water for the valley. Data that would fill voids left by previous studies are depth to bedrock and depth to good-quality water beneath the two playas in the valley. Depths to bedrock calculated from a gravity survey in Lemmon Valley indicate that the western part of Lemmon Valley is considerably deeper than the eastern part. Maximum depth in the western part is about 2 ,600 feet below land surface. This depression approximately underlies the Silver Lake playa. A smaller, shallower depression with a maximum depth of about 1,500 feet below land surface exists about 2.5 miles north of the playa. The eastern area is considerably shallower. The maximum calculated depth to bedrock is about 1,000 feet below land surface, but the depth throughout most the eastern area is only about 400 feet below land surface. An electrical resistivity survey in Lemmon Valley consisting of 10 Schlumberger soundings was conducted around the playas. The maximum depth of poor-quality water (characterized by a resistivity less than 20 ohm-meters) differed considerably from place to place. Maximum depths of poor-quality water beneath the playa east of Stead varied from about 120 feet to almost 570 feet below land surface. At the Silver Lake playa, the maximum depths varied from about 40 feet in the west to 490 feet in the east. (USGS)

Local knowledge of the link between tuberculosis and HIV-1/AIDS among the Turkana of Lodwar township: implications for tuberculosis and HIV-1/AIDS prevention.

PubMed

Owiti, John Arianda

2008-01-01

This article is extracted from a doctoral thesis that was supported by a research grant from the International Development Research Centre of Canada (IDRC)'s Ecosystem Approaches to Human Health Training Award, the Royal Anthropological Institute of Great Britain and Northern Ireland's Emslie Horniman Scholarship Fund and McGill University, Faculty of Graduate Studies and Research's Humanities and Social Sciences Research Award. This study used a broad theoretical framework encompassing an ecosystem approach to HIV-1/AIDS that partly investigated the nexus between local knowledge of tuberculosis (TB) and HIV-1/AIDS. According to the Turkana of Lodwar township, Kenya, HIV-1/AIDS and TB are largely contagious and are attributed to impersonal and natural causes. In addition, in line with biomedical knowledge, the Turkana's local knowledge emphasises a conceptual link between TB and HIV-1/AIDS. The study also demonstrates that factors of the ecosystem such as kaada, poverty, widow inheritance, migration and other socio-cultural practices play an influential role in the vulnerability of the Turkana to the contraction and transmission of both TB and HIV-1/AIDS. The article posits an integrated approach to the prevention of TB and HIV-1 and to the management of AIDS and TB.

Ground-water conditions in southern Utah Valley and Goshen Valley, Utah

USGS Publications Warehouse

Cordova, R.M.

1970-01-01

The investigation of ground-water conditions in southern Utah Valley and Goshen Valley, Utah, was made by the U. S. Geological Survey as part of a cooperative program with the Utah Department of Natural Resources, Division of Water Rights, to investigate the water resources of the State. The purposes of the investigation were to (1) determine the occurrence, recharge, discharge, movement, storage, chemical quality, and availability of ground water; (2) appraise the effects of increased withdrawal of water from wells; and (3) evaluate the effect of the Central Utah Project on the ground-water reservoir and the water supply of Utah Lake.This report presents a description of the aquifer system in the two valleys, a detailed description of the ground-water resources, and conclusions about potential development and its effect on the hydrologic conditions in the valleys. Two supplementary reports are products of the investigation. A basic-data release (Cordova, 1969) contains most of the basic data collected for the investigation, including well characteristics, drillers' logs, water levels, pumpage from wells, chemical analyses of ground and surface waters, and discharge of selected springs, drains, and streams. An interpretive report (Cordova and Mower, 1967) contains the results of a large-scale aquifer test in southern Utah Valley.

Robinson Rancheria Strategic Energy Plan; Middletown Rancheria Strategic Energy Plan, Scotts Valley Rancheria Strategic Energy Plan, Elem Indian Colony Strategic Energy Plan, Upperlake Rancheria Strategic Energy Plan, Big Valley Rancheria Strategic Energy Plan

DOE Office of Scientific and Technical Information (OSTI.GOV)

McGinnis and Associates LLC

2008-08-01

The Scotts Valley Band of Pomo Indians is located in Lake County in Northern California. Similar to the other five federally recognized Indian Tribes in Lake County participating in this project, Scotts Valley Band of Pomo Indians members are challenged by generally increasing energy costs and undeveloped local energy resources. Currently, Tribal decision makers lack sufficient information to make informed decisions about potential renewable energy resources. To meet this challenge efficiently, the Tribes have committed to the Lake County Tribal Energy Program, a multi Tribal program to be based at the Robinson Rancheria and including The Elem Indian Colony, Bigmore » Valley Rancheria, Middletown Rancheria, Habematolel Pomo of Upper Lake and the Scotts Valley Pomo Tribe. The mission of this program is to promote Tribal energy efficiency and create employment opportunities and economic opportunities on Tribal Lands through energy resource and energy efficiency development. This program will establish a comprehensive energy strategic plan for the Tribes based on Tribal specific plans that capture economic and environmental benefits while continuing to respect Tribal cultural practices and traditions. The goal is to understand current and future energy consumption and develop both regional and Tribe specific strategic energy plans, including action plans, to clearly identify the energy options for each Tribe.« less

Landslide Buries Valley of the Geysers

NASA Technical Reports Server (NTRS)

2007-01-01

Geysers are a rare natural phenomena found only in a few places, such as New Zealand, Iceland, the United States (Yellowstone National Park), and on Russia's far eastern Kamchatka Peninsula. On June 3, 2007, one of these rare geyser fields was severely damaged when a landslide rolled through Russia's Valley of the Geysers. The landslide--a mix of mud, melting snow, trees, and boulders--tore a scar on the land and buried a number of geysers, thermal pools, and waterfalls in the valley. It also blocked the Geyser River, causing a new thermal lake to pool upstream. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this infrared-enhanced image on June 11, 2007, a week after the slide. The image shows the valley, the landslide, and the new thermal lake. Even in mid-June, just days from the start of summer, the landscape is generally covered in snow, though the geologically heated valley is relatively snow free. The tree-covered hills are red (the color of vegetation in this false-color treatment), providing a strong contrast to the aquamarine water and the gray-brown slide. According to the Russian News and Information Agency (RIA) [English language], the slide left a path roughly a kilometer and a half (one mile) long and 200 meters (600 feet) wide. Within hours of the landslide, the water in the new lake inundated a number of additional geysers. The geysers directly buried under the landslide now lie under as much as 60 meters (180 feet) of material, according to RIA reports. It is unlikely that the geysers will be able to force a new opening through this thick layer, adds RIA. Among those directly buried is Pervenets (Firstborn), the first geyser found in the valley, in 1941. Other geysers, such as the Bolshoi (Greater) and Maly (Lesser) Geysers, were silenced when buried by water building up behind the new natural dam. According to Vladimir and Andrei Leonov of the Russian Federation Institute of

Sediment oxygen profiles in a super-oxygenated antarctic lake

NASA Technical Reports Server (NTRS)

Wharton, R. A. Jr; Meyer, M. A.; McKay, C. P.; Mancinelli, R. L.; Simmons, G. M. Jr; Wharton RA, J. r. (Principal Investigator)

1994-01-01

Perennially ice-covered lakes are found in the McMurdo Dry Valleys of southern Victoria Land, Antarctica. In contrast to temperate lakes that have diurnal photic periods, antarctic (and arctic) lakes have a yearly photic period. An unusual feature of the antarctic lakes is the occurrence of O2 at supersaturated levels in certain portions of the water column. Here we report the first sediment O2 profiles obtained using a microelectrode from a perennially ice-covered antarctic lake. Sediment cores collected in January and October 1987 from Lake Hoare in Taylor Valley show oxygenation down to 15, and in some cases, 25 cm. The oxygenation of sediments several centimeters below the sediment-water interface is atypical for lake sediments and may be characteristic of perennially ice-covered lakes. There is a significant difference between the observed January and October sediment O2 profiles. Several explanations may account for the difference, including seasonality. A time-dependent model is presented which tests the feasibility of a seasonal cycle resulting from the long photoperiod and benthic primary production in sediments overlain by a highly oxygenated water column.

Streamflow, water-temperature, and specific-conductance data for selected streams draining into Lake Fryxell, lower Taylor Valley, Victoria Land, Antarctica, 1990-92

USGS Publications Warehouse

Von Guerard, Paul; McKnight, Diane M.; Harnish, R.A.; Gartner, J.W.; Andrews, E.D.

1995-01-01

During the 1990-91 and 1991-92 field seasons in Antarctica, streamflow, water-temperature, and specific-conductance data were collected on the major streams draining into Lake Fryxell. Lake Fryxell is a permanently ice-covered, closed-basin lake with 13 tributary streams. Continuous streamflow data were collected at eight sites, and periodic streamflow measurements were made at three sites. Continuous water-temperature and specific- conductance data were collected at seven sites, and periodic water-temperature and specific-conductance data were collected at all sites. Streamflow for all streams measured ranged from 0 to 0.651 cubic meter per second. Water temperatures for all streams measured ranged from 0 to 14.3 degrees Celsius. Specific conductance for all streams measured ranged from 11 to 491 microsiemens per centimeter at 25 degrees Celsius. It is probable that stream- flow in the Lake Fryxell Basin during 1990-92 was greater than average. Examination of the 22-year streamflow record in the Onyx River in the Wright Valley revealed that in 1990 streamflow began earlier than for any previous year recorded and that the peak streamflow of record was exceeded. Similar high-flow conditions occurred during the 1991-92 field season. Thus, the data collected on streams draining into Lake Fryxell during 1990-92 are representative of greater than average stream- flow conditions.

American Bald Eagle Restoration Plan for Dale Hollow Lake.

DTIC Science & Technology

1987-06-01

Wildlife Resources Agency’s (TWRA) Reelfoot Lake site, Tennessee Valley Authority’s (TVA), Land Between the Lakes operation in Kentucky, and the Alabama...three active hacking sites were visited: (1) Reelfoot Lake (Tennessee), (2) Land Between the Lakes (Kentucky), and (3) Mud Creek (Alabama). These...somewhat differently. Some of the differences are hereby noted: (1) Reelfoot Lake -- The towers here are constructed in lIve cypress trees at a height

Speculations on the spatial setting and temporal evolution of a fjord-style lake

NASA Astrophysics Data System (ADS)

Sarnthein, M.; Spötl, C.

2012-04-01

The Inn Valley, a classical region of Quaternary research in the Alps, is bordered by terraces that extend over almost 70 km and record an ancient lake with a lake level near 750-830 m above sea level (a.s.l.), about 250-300 m above the modern valley floor. Over large distances, the terrace sediments consist mainly of laminated "Banded Clays", above ~750 m a.s.l. overlain by glaciofluvial gravel and finally, by tills that record the Upper Würmian ice advance of Marine Isotope Stage (MIS) 2. In the (former) clay pit of Baumkirchen this boundary forms the Alpine type locality for the onset of the Upper Würmian, well supported by 14C-based age control first established by Fliri (1971). On the basis of a recently cored sediment section at Baumkirchen, the >200 m thick "Banded Clays" store a continuous, largely undisturbed, highly resolved, and widely varved climatic archive of MIS 3. Major unknowns concern the location and origin of dams that may have barred the vast and deep Inn Valley lake. We discuss potential linkages to the pattern of moraines and ice advance of MIS 4 glaciers, which was less prominent than during MIS 2, thus leading to a distinct east-west segment¬ation of the run-off systems in Tyrol. East of Imst, for example, the lake was possibly barred by both a rock sill reaching up to 830 m a.s.l. and a lateral moraine deposited by an Ötz Valley glacier. 80 km further east, a lateral moraine of a glacier advancing from the Ziller Valley may have barred the ancient Inn Valley lake to the east. The final rapid coarsening of clastic lake sediments at the end of MIS 3 is widely ascribed to major climatic deter¬ioration. However, the MIS 3-2 boundary was linked to an only modest change of global climates and accordingly, different forcings may be considered. In turn, the rapid coarsening may document a date, when the Central Alpine glaciers had already filled the basin of Imst to the west of the Inn Valley lake. This ice mass may have forced the melt

The Health Valley: Global Entrepreneurial Dynamics.

PubMed

Dubuis, Benoit

2014-12-01

In the space of a decade, the Lake Geneva region has become the Health Valley, a world-class laboratory for discovering and developing healthcare of the future. Through visionary individuals and thanks to exceptional infrastructure this region has become one of the most dynamic in the field of innovation, including leading scientific research and exceptional actors for the commercialization of academic innovation to industrial applications that will improve the lives of patients and their families. Here follows the chronicle of a spectacular expansion into the Health Valley.

Lake Geneva, France/Italy/Switzerland

NASA Image and Video Library

1994-09-30

STS068-243-076 (30 September-11 October 1994) --- Parts of the Swiss Cantons of Vaud and Valois, the French province of Chablis and parts of northwestern Italy are seen in this widely stretching image photographed from the Space Shuttle Endeavour. Pennine Alps, said to have been created 50 million years ago, have been reshaped by glaciers during Pleistocene. The glaciers created the wide valley of the Rhone River by scourting a pre-existing seam. The fertile Swiss Plateau runs northwest from the shore of Lake Geneva and is visible in lower left. The Franco-Swiss border is located in the center of the lake and follows a mountain divide east of Rhone Valley. Italy lies south of the Rhone.

Shallow Sub-Permafrost Groundwater Systems In A Buried Fjord: Taylor Valley, Antarctica

NASA Astrophysics Data System (ADS)

Foley, N.; Tulaczyk, S. M.; Auken, E.; Mikucki, J.

2014-12-01

The McMurdo Dry Valleys (MDV), Antarctica, represent a unique geologic setting where permanent lakes, ephemeral streams, and subglacial waters influence surface hydrology in a cold polar desert. Past research suggested that the MDV are underlain by several hundreds of meters of permafrost. Here, we present data collected from an Airborne EM (AEM) resistivity sensor flown over the MDV during the 2011-12 austral summer. A focus of our survey was over the Taylor Glacier where saline, iron-rich subglacial fluid releases at the glacier snout at a feature known as Blood Falls, and over Taylor Valley, where a series of isolated lakes lie between Taylor Glacier and the Ross Sea. Our data show that in Taylor Valley there are extensive areas of low resistivity, interpreted as hypersaline brines, beneath a relatively thin layer of high resistivity material, interpreted as dry- or ice-cemented permafrost. These hypersaline brines remain liquid at temperatures well below 0°C due to their salinity. They appear to be contained within the sedimentary fill deposited in Taylor Valley when it was still a fjord. This brine system continues up valley and has a subglacial extension beneath Taylor Glacier, where it may provide the source that feeds Blood Falls. By categorizing the resistivity measurements according to surficial land cover, we are able to distinguish between ice, permafrost, lake water, and seawater based on characteristic resistivity distributions. Furthermore, this technique shows that areas of surface permafrost become increasingly conductive (brine-filled) with depth, whereas the large lakes exhibit taliks that extend through the entire thickness of the permafrost. The subsurface brines represent a large, unstudied and potentially connected hydrogeologic system, in which subsurface flows may help transfer water and nutrients between lakes in the MDV and into the Ross Sea. Such a system is a potential habitat for extremophile life, similar to that already detected in

Metal dynamics in Lake Vanda (Wright Valley, Antarctica)

NASA Technical Reports Server (NTRS)

Green, W. J.; Ferdelman, T. G.; Canfield, D. E.; DeVincenzi, D. L. (Principal Investigator)

1989-01-01

Data are reported for Mn, Fe, Co, Ni, Cu and Cd in the Onyx River, and for Mn, Co, Ni, Cu and Cd in Lake Vanda, a closed-basin Antarctic lake. Oxic water concentrations for Co, Ni, Cu and Cd were quite low and approximate pelagic ocean values. Scavenging of these metals by sinking particles is strongly indicated. Deep-lake profiles reveal a sharp peak in the concentrations of Mn, Fe and Co at the oxic-anoxic boundary at 60 m. Maxima for Ni, Cu and Cd occur higher in the water column, in the vicinity of a Mn submaximum, suggesting early release of these metals from sinking manganese oxide-coated particles. A rough steady-state model leads to the conclusion that there is a large downward flux of Mn into the deep lake and that this flux is sufficient to explain the annual loss of Co, Ni, Cu and Cd. A pronounced geochemical separation between Fe and Mn apparently occurs in this system--Fe being best lost in near-shore environments and Mn being lost in deeper waters. Comparison of metal residence times in Lake Vanda with those in the oceans shows that in both systems Mn, Fe and Co are much more reactive than Ni, Cu and Cd. Energetically favorable inclusion of the more highly charged metals, Mn(IV), Fe(III) and Co(III), into oxide-based lattices is a plausible explanation.

Limnology of Sawtooth Valley Lakes in 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luecke, C.; Slater, M.; Budy, P.

1996-05-01

Included in this section of the report on limnology of Lakes in the Snake River Plain are descriptions of the limnological characteristics of the four lakes in reference to their potential effect of growth and survival of juvenile sockeye salmon. Physical parameters included light penetration, Secchi transparency, and water temperature; chemical parameters included oxygen, and both dissolved and particulate forms of nitrogen and phosphorus. Phytoplankton parameters included chlorophyll concentration, biovolume of dominant taxa, and rates of primary production; zooplankton parameters included density and biomass estimate, length frequencies, and the number of eggs carried by female cladocerans. 11 figs., 5 tabs.

The occurrence of lysogenic bacteria and microbial aggregates in the lakes of the McMurdo Dry Valleys, Antarctica

USGS Publications Warehouse

Lisle, J.T.; Priscu, J.C.

2004-01-01

The McMurdo Dry Valleys of Antarctica form the coldest and driest ecosystem on Earth. Within this region there are a number of perennially ice-covered (3-6 m thick) lakes that support active microbial assemblages and have a paucity of metazoans. These lakes receive limited allochthonous input of carbon and nutrients, and primary productivity is limited to only 6 months per year owing to an absence of sunlight during the austral winters. In an effort to establish the role that bacteria and their associated viruses play in carbon and nutrient cycling in these lakes, indigenous bacteria, free bacteriophage, and lysogen abundances were determined. Total bacterial abundances (TDC) ranged from 3.80 ?? 104 to 2.58 ?? 107 cells mL-1 and virus-like particle (VLP) abundances ranged from 2.26 ?? 105 to 5.56 ?? 107 VLP mL-1. VLP abundances were significantly correlated (P < 0.05) with TDC, bacterial productivity (TdR), chlorophyll a (Chl a), and soluble reactive phosphorus (SRP). Lysogenic bacteria, determined by induction with mitomycin C, made up between 2.0% and 62.5% of the total population of bacteria when using significant decreases and increases in TDC and VLP abundances, respectively, and 89.5% when using increases in VLP abundances as the sole criterion for a successful induction event. The contribution of viruses released from induced lysogens contributed <0.015% to the total viral production rate. Carbohydrate and protein based organic aggregates were abundant within the water column of the lakes and were heavily colonized by bacteria and VLPs. Alkaline phosphatase activity was detected within the matrix of the aggregates, implying phosphorus deficiency and consortial nutrient exchanges among microorganisms.

Sutter Buttes-the lone volcano in California's Great Valley

USGS Publications Warehouse

Hausback, Brain P.; Muffler, L.J. Patrick; Clynne, Michael A.

2011-01-01

The volcanic spires of the Sutter Buttes tower 2,000 feet above the farms and fields of California's Great Valley, just 50 miles north-northwest of Sacramento and 11 miles northwest of Yuba City. The only volcano within the valley, the Buttes consist of a central core of volcanic domes surrounded by a large apron of fragmental volcanic debris. Eruptions at the Sutter Buttes occurred in early Pleistocene time, 1.6 to 1.4 million years ago. The Sutter Buttes are not part of the Cascade Range of volcanoes to the north, but instead are related to the volcanoes in the Coast Ranges to the west in the vicinity of Clear Lake, Napa Valley, and Sonoma Valley.

Late Quaternary faulting along the Death Valley-Furnace Creek fault system, California and Nevada

USGS Publications Warehouse

Brogan, George E.; Kellogg, Karl; Slemmons, D. Burton; Terhune, Christina L.

1991-01-01

The Death Valley-Furnace Creek fault system, in California and Nevada, has a variety of impressive late Quaternary neotectonic features that record a long history of recurrent earthquake-induced faulting. Although no neotectonic features of unequivocal historical age are known, paleoseismic features from multiple late Quaternary events of surface faulting are well developed throughout the length of the system. Comparison of scarp heights to amount of horizontal offset of stream channels and the relationships of both scarps and channels to the ages of different geomorphic surfaces demonstrate that Quaternary faulting along the northwest-trending Furnace Creek fault zone is predominantly right lateral, whereas that along the north-trending Death Valley fault zone is predominantly normal. These observations are compatible with tectonic models of Death Valley as a northwest-trending pull-apart basin. The largest late Quaternary scarps along the Furnace Creek fault zone, with vertical separation of late Pleistocene surfaces of as much as 64 m (meters), are in Fish Lake Valley. Despite the predominance of normal faulting along the Death Valley fault zone, vertical offset of late Pleistocene surfaces along the Death Valley fault zone apparently does not exceed about 15 m. Evidence for four to six separate late Holocene faulting events along the Furnace Creek fault zone and three or more late Holocene events along the Death Valley fault zone are indicated by rupturing of Q1B (about 200-2,000 years old) geomorphic surfaces. Probably the youngest neotectonic feature observed along the Death Valley-Furnace Creek fault system, possibly historic in age, is vegetation lineaments in southernmost Fish Lake Valley. Near-historic faulting in Death Valley, within several kilometers south of Furnace Creek Ranch, is represented by (1) a 2,000-year-old lake shoreline that is cut by sinuous scarps, and (2) a system of young scarps with free-faceted faces (representing several faulting

Characterizing Microbial Mat Morphology with Structure from Motion Techniques in Ice-Covered Lake Joyce, McMurdo Dry Valleys, Antarctica

NASA Astrophysics Data System (ADS)

Mackey, T. J.; Leidman, S. Z.; Allen, B.; Hawes, I.; Lawrence, J.; Jungblut, A. D.; Krusor, M.; Coleman, L.; Sumner, D. Y.

2015-12-01

Structure from Motion (SFM) techniques can provide quantitative morphological documentation of otherwise inaccessible benthic ecosystems such as microbial mats in Lake Joyce, a perennially ice-covered lake of the Antarctic McMurdo Dry Valleys (MDV). Microbial mats are a key ecosystem of MDV lakes, and diverse mat morphologies like pinnacles emerge from interactions among microbial behavior, mineralization, and environmental conditions. Environmental gradients can be isolated to test mat growth models, but assessment of mat morphology along these gradients is complicated by their inaccessibility: the Lake Joyce ice cover is 4-5 m thick, water depths containing diverse pinnacle morphologies are 9-14 m, and relevant mat features are cm-scale. In order to map mat pinnacle morphology in different sedimentary settings, we deployed drop cameras (SeaViewer and GoPro) through 29 GPS referenced drill holes clustered into six stations along a transect spanning 880 m. Once under the ice cover, a boom containing a second GoPro camera was unfurled and rotated to collect oblique images of the benthic mats within dm of the mat-water interface. This setup allowed imaging from all sides over a ~1.5 m diameter area of the lake bottom. Underwater lens parameters were determined for each camera in Agisoft Lens; images were reconstructed and oriented in space with the SFM software Agisoft Photoscan, using the drop camera axis of rotation as up. The reconstructions were compared to downward facing images to assess accuracy, and similar images of an object with known geometry provided a test for expected error in reconstructions. Downward facing images identify decreasing pinnacle abundance in higher sedimentation settings, and quantitative measurements of 3D reconstructions in KeckCAVES LidarViewer supplement these mat morphological facies with measurements of pinnacle height and orientation. Reconstructions also help isolate confounding variables for mat facies trends with measurements

Upper Neogene stratigraphy and tectonics of Death Valley - A review

USGS Publications Warehouse

Knott, J.R.; Sarna-Wojcicki, A. M.; Machette, M.N.; Klinger, R.E.

2005-01-01

New tephrochronologic, soil-stratigraphic and radiometric-dating studies over the last 10 years have generated a robust numerical stratigraphy for Upper Neogene sedimentary deposits throughout Death Valley. Critical to this improved stratigraphy are correlated or radiometrically-dated tephra beds and tuffs that range in age from > 3.58 Ma to < 1.1 ka. These tephra beds and tuffs establish relations among the Upper Pliocene to Middle Pleistocene sedimentary deposits at Furnace Creek basin, Nova basin, Ubehebe-Lake Rogers basin, Copper Canyon, Artists Drive, Kit Fox Hills, and Confidence Hills. New geologic formations have been described in the Confidence Hills and at Mormon Point. This new geochronology also establishes maximum and minimum ages for Quaternary alluvial fans and Lake Manly deposits. Facies associated with the tephra beds show that ???3.3 Ma the Furnace Creek basin was a northwest-southeast-trending lake flanked by alluvial fans. This paleolake extended from the Furnace Creek to Ubehebe. Based on the new stratigraphy, the Death Valley fault system can be divided into four main fault zones: the dextral, Quaternary-age Northern Death Valley fault zone; the dextral, pre-Quaternary Furnace Creek fault zone; the oblique-normal Black Mountains fault zone; and the dextral Southern Death Valley fault zone. Post -3.3 Ma geometric, structural, and kinematic changes in the Black Mountains and Towne Pass fault zones led to the break up of Furnace Creek basin and uplift of the Copper Canyon and Nova basins. Internal kinematics of northern Death Valley are interpreted as either rotation of blocks or normal slip along the northeast-southwest-trending Towne Pass and Tin Mountain fault zones within the Eastern California shear zone. ?? 2005 Elsevier B.V. All rights reserved.

Water resources of Beaver Valley, Utah

USGS Publications Warehouse

Lee, Willis Thomas

1908-01-01

Location and extent of area examined. Beaver Valley is located in Beaver County, in southwestern Utah, about 175 miles south of Salt Lake. It lies between the Tushar Mountains on the east and the Beaver Mountains on the west. The principal town of the valley is Beaver, which is most conveniently reached from Milford, a station on the San Pedro, Los Angeles and Salt Lake Railroad. The valley, together with its neighboring highlands, occupies the eastern third of Beaver County, an area of about 1,200 square miles. A large part of this area, however, is rocky upland and unproductive desert, the tillable land comprising a comparatively small area in the immediate vicinity of the streams.Purpose and scope of work. The purpose of this paper is to present information concerning the waters of Beaver Valley and to point out ways and means of increasing their usefulness. The presence of a large amount of water in Beaver Valley results from local topograhic conditions, the water being supplied by precipitation in the highland to the east. Its conservation and distribution result from geologic conditions, the water being held in loose gravel and sand, which are more or less confined between ridges of consolidated rocks. The rock basins were formed partly by erosion and partly by faulting and surface deformation. In order to accomplish the purpose in view it is therefore necessary to describe the geographic and geologic conditions in Beaver Valley and neighboring regions.The investigation included the determination of the flow of streams and springs, of the manner of occurrence and quantity of the underground waters as shown by the geologic and geographic conditions of the region and by the distribution of springs and wells, and of the chemical character of the waters with reference to their adaptability to domestic use and to irrigation. The chemical data were obtained (a) by field assays, which are approximately correct and probably of sufficient accuracy to be of value in

Stable isotopic biogeochemistry of carbon and nitrogen in a perennially ice-covered Antarctic lake.

PubMed

Wharton, R A; Lyons, W B; Des Marais, D J

1993-01-01

Lake Hoare (77 degrees 38' S, 162 degrees 53' E) is an amictic, oligotrophic, 34-m-deep, closed-basin lake in Taylor Valley, Antarctica. Its perennial ice cover minimizes wind-generated currents and reduces light penetration, as well as restricts sediment deposition into the lake and the exchange of atmospheric gases between the water column and the atmosphere. The biological community of Lake Hoare consists solely of microorganisms -- both planktonic populations and benthic microbial mats. Lake Hoare is one of several perennially ice-covered lakes in the McMurdo Dry Valleys that represent the end-member conditions of cold desert and saline lakes. The dry valley lakes provide a unique opportunity to examine lacustrine processes that operate at all latitudes, but under an extreme set of environmental conditions. The dry valley lakes may also offer a valuable record of catchment and global changes in the past and present. Furthermore, these lakes are modern-day equivalents of periglacial lakes that are likely to have been common during periods of glacial maxima at temperate latitudes. We have analyzed the dissolved inorganic carbon (DIC) of Lake Hoare for delta 13C and the organic matter of the sediments and sediment-trap material for delta 13C and delta 15N. The delta 13C of the DIC indicates that 12C is differentially removed in the shallow, oxic portions of the lake via photosynthesis. In the anoxic portions of the lake (27-34 m) a net addition of 12C to the DIC pool occurs via organic matter decomposition. The dissolution of CaCO3 at depth also contributes to the DIC pool. Except near the Canada Glacier where a substantial amount of allochthonous organic matter enters the lake, the organic carbon being deposited on the lake bottom at different sites is isotopically similar, suggesting an autochthonous source for the organic carbon. Preliminary inorganic carbon flux calculations suggest that a high percentage of the organic carbon fixed in the water column is

Stable isotopic biogeochemistry of carbon and nitrogen in a perennially ice-covered Antarctic lake

NASA Technical Reports Server (NTRS)

Wharton, R. A. Jr; Lyons, W. B.; Des Marais, D. J.; Wharton RA, J. r. (Principal Investigator)

1993-01-01

Lake Hoare (77 degrees 38' S, 162 degrees 53' E) is an amictic, oligotrophic, 34-m-deep, closed-basin lake in Taylor Valley, Antarctica. Its perennial ice cover minimizes wind-generated currents and reduces light penetration, as well as restricts sediment deposition into the lake and the exchange of atmospheric gases between the water column and the atmosphere. The biological community of Lake Hoare consists solely of microorganisms -- both planktonic populations and benthic microbial mats. Lake Hoare is one of several perennially ice-covered lakes in the McMurdo Dry Valleys that represent the end-member conditions of cold desert and saline lakes. The dry valley lakes provide a unique opportunity to examine lacustrine processes that operate at all latitudes, but under an extreme set of environmental conditions. The dry valley lakes may also offer a valuable record of catchment and global changes in the past and present. Furthermore, these lakes are modern-day equivalents of periglacial lakes that are likely to have been common during periods of glacial maxima at temperate latitudes. We have analyzed the dissolved inorganic carbon (DIC) of Lake Hoare for delta 13C and the organic matter of the sediments and sediment-trap material for delta 13C and delta 15N. The delta 13C of the DIC indicates that 12C is differentially removed in the shallow, oxic portions of the lake via photosynthesis. In the anoxic portions of the lake (27-34 m) a net addition of 12C to the DIC pool occurs via organic matter decomposition. The dissolution of CaCO3 at depth also contributes to the DIC pool. Except near the Canada Glacier where a substantial amount of allochthonous organic matter enters the lake, the organic carbon being deposited on the lake bottom at different sites is isotopically similar, suggesting an autochthonous source for the organic carbon. Preliminary inorganic carbon flux calculations suggest that a high percentage of the organic carbon fixed in the water column is

Dissolved Oxygen Levels in Lake Chabot

NASA Astrophysics Data System (ADS)

Sharma, D.; Pica, R.

2014-12-01

Dissolved oxygen levels are crucial in every aquatic ecosystem; it allows for the fish to breathe and it is the best indicator of water quality. Lake Chabot is the main backup water source for Castro Valley, making it crucial that the lake stays in good health. Last year, research determined that the water in Lake Chabot was of good quality and not eutrophic. This year, an experiment was conducted using Lake Chabot's dissolved oxygen levels to ensure the quality of the water and to support the findings of the previous team. After testing three specifically chosen sites at the lake using a dissolved oxygen meter, results showed that the oxygen levels in the lake were within the healthy range. It was then determined that Lake Chabot is a suitable backup water source and it continues to remain a healthy habitat.

Multiscalar approach to archaeological site formation at GaJj17, East Turkana, Kenya

NASA Astrophysics Data System (ADS)

Murray, B. M.; Ranhorn, K. L.; Colarossi, D.; Mavuso, S. S.; Dogandžić, T.; Ziegler, M. J.; Warren, S. L.; Braun, D. R.; Harris, J. W. K.

2017-12-01

Kenya's East Turkana region hosts a rich Plio­Pleistocene record of fossils, archaeological artifacts, and sedimentary features whose chronostratigraphic histories are often obscured by landscape changes from erosional events and tectonic activity. The Middle Stone Age (MSA) record of the Koobi Fora Formation (KF Fm.) has particularly been subjected to this complex depositional history, making it a sparse unit and, consequently, widely understudied. Stratigraphically located in between the maximum capping unconformity of the KF Fm.'s Chari tuff ( 1.39 Ma) and that of the Galana Boi Fm. ( 10 ka), the unit provides a unique window into understanding the Late Pleistocene of the region. The MSA surface scatters at archaeological site GaJj17 prompted further study into the site's age and depositional chronology. The GaJj17 ridge is locally distinguished by its cap of Late Pleistocene sands overlying strata containing tuffs likely of the Upper Burgi (2.0­-1.87 Ma) or KBS (1.87­-1.56 Ma) members. To investigate whether GaJj17's preservation is due to tectonic deformation, a broader scale examination of the structural geology was conducted through surveys and aerial imagery. Regions of deformation were identified and mapped to establish the geological history of the locality. Resultant observations and elevation data offer insight into regional faults at the root of prolonged structural alterations which have facilitated the unique preservation of MSA materials. Through a multiscalar approach it is possible to understand both the formation of GaJj17 and the underlying processes behind preservation and destruction in the changing landscape of the Turkana basin, enabling future identification of archaeological sites through proxies of elevation, regional stratigraphy, and fault mapping. This research was supported by IRES grants 1358178 and 1358200 from the U.S. National Science Foundation.

Astrobiology of Antarctic ice Covered Lakes

NASA Astrophysics Data System (ADS)

Doran, P. T.; Fritsen, C. H.

2005-12-01

Antarctica contains a number of permanently ice-covered lakes which have often been used as analogs of purported lakes on Mars in the past. Antarctic subglacial lakes, such as Lake Vostok, have also been viewed as excellent analogs for an ice covered ocean on the Jovian moon Europa, and to a lesser extend on Mars. Lakes in the McMurdo Dry Valleys of East Antarctica have ice covers that range from 3 to 20 meters thick. Water salinities range from fresh to hypersaline. The thinner ice-covered lakes have a well-documented ecology that relies on the limited available nutrients and the small amount of light energy that penetrates the ice covers. The thickest ice-covered lake (Lake Vida in Victoria Valley) has a brine beneath 20 m of ice that is 7 times sea water and maintains a temperature below -10 degrees Celsius. This lake is vastly different from the thinner ice-covered lakes in that there is no communication with the atmosphere. The permanent ice cover is so thick, that summer melt waters can not access the sub-ice brine and so the ice grows from the top up, as well as from the bottom down. Brine trapped beneath the ice is believed to be ancient, stranded thousands of years ago when the ice grew thick enough to isolate it from the surface. We view Lake Vida as an excellent analog for the last aquatic ecosystem to have existed on Mars under a planetary cooling. If, as evidence is now increasingly supporting, standing bodies of water existed on Mars in the past, their fate under a cooling would be to go through a stage of permanent ice cover establishment, followed by a thickening of that ice cover until the final stage just prior to a cold extinction would be a Lake Vida-like lake. If dust storms or mass movements covered these ancient lakes, remnants may well be in existence in the subsurface today. A NASA Astrobiology Science and Technology for Exploring Planets (ASTEP) project will drill the Lake Vida ice cover and access the brine and sediments beneath in

A Pleistocene palaeovegetation record from plant wax biomarkers from the Nachukui Formation, West Turkana, Kenya

PubMed Central

Uno, Kevin T.; Polissar, Pratigya J.; Kahle, Emma; Feibel, Craig; Harmand, Sonia; Roche, Hélène; deMenocal, Peter B.

2016-01-01

Reconstructing vegetation at hominin fossil sites provides us critical information about hominin palaeoenvironments and the potential role of climate in their evolution. Here we reconstruct vegetation from carbon isotopes of plant wax biomarkers in sediments of the Nachukui Formation in the Turkana Basin. Plant wax biomarkers were extracted from samples from a wide range of lithologies that include fluvial–lacustrine sediments and palaeosols, and therefore provide a record of vegetation from diverse depositional environments. Carbon isotope ratios from biomarkers indicate a highly dynamic vegetation structure (ca 5–100% C4 vegetation) from 2.3 to 1.7 Ma, with an overall shift towards more C4 vegetation on the landscape after about 2.1 Ma. The biomarker isotope data indicate ca 25–30% more C4 vegetation on the landscape than carbon isotope data of pedogenic carbonates from the same sequence. Our data show that the environments of early Paranthropus and Homo in this part of the Turkana Basin were primarily mixed C3–C4 to C4-dominated ecosystems. The proportion of C4-based foods in the diet of Paranthropus increases through time, broadly paralleling the increase in C4 vegetation on the landscape, whereas the diet of Homo remains unchanged. Biomarker isotope data associated with the Kokiselei archaeological site complex, which includes the site where the oldest Acheulean stone tools to date were recovered, indicate 61–97% C4 vegetation on the landscape. This article is part of the themed issue ‘Major transitions in human evolution’. PMID:27298466

The McMurdo Dry Valleys, Antarctica: Terrestrial and aquatic ecosystems responding to climatic events that enhance hydrologic transport acress the landscape

NASA Astrophysics Data System (ADS)

McKnight, D. M.; Lyons, W. B.; Fountain, A. G.; Gooseff, M. N.; Doran, P. T.; Wall, D. H.; Virginia, R. A.; Priscu, J. C.; Adams, B.; Vesbach-Takacs, C.; Barrett, J. E.; Howkins, A.

2014-12-01

The McMurdo Dry Valleys of Antarctica is comprised of alpine and terminal glaciers, large expanses of patterned ground, and permanently ice-covered lakes in the valley floors, which are linked by glacial meltwater streams that flow during the austral summer. These valleys were first explored by Robert Scott and his party in 1903. In 1968 the New Zealand Antarctic Program began a gauging network on the Onyx River, a 32 km river in Wright Valley which is the longest river in Antarctica. As part of the McMurdo Dry Valleys Long-Term Ecological research project our research group has monitored meteorological conditions, glacial mass balance, lake level and streamflow in the adjacent Taylor Valley. The extent of liquid water throughout the landscape is strongly controlled by summer climate, and the availability of liquid water in turn is a limitation to the microscopic life that is present in the diverse habitats in the valleys. We have studied the responses of soil, lake, stream and cryoconite ecosystems through a sustained cooling period that has been driven by atmospheric changes associated with the ozone hole. In the past decade, this cooling period appears to have ceased and summer conditions have become more variable. Three warm sunny summers have occurred since 2001/02. These conditions have created weeks long "flood events" in the valleys, causing wet areas to emerge in the soils, thermokarsting in some stream channels and increases in lake level. These flood events can be considered as pulse events that drive an increase in ecosystem connectivity, changing rates of biogeochemical processes and the distribution of biota. Collectively the ecosystems of the McMurdo Dry Valleys are highly responsive to dynamic climatic influences associated with the ozone hole and global warming.

Surficial Geology of the Floor of Lake Mead (Arizona and Nevada) as Defined by Sidescan-Sonar Imagery, Lake-Floor Topography, and Post-Impoundment Sediment Thickness

USGS Publications Warehouse

Twichell, D.C.; Cross, V.A.

2009-01-01

Sidescan-sonar imagery collected in Lake Mead during 1999-2001, a period of high lake level, has been used to map the surficial geology of the floor of this large reservoir that formed upon completion of the Hoover Dam in 1935. Four surficial geologic units were identified and mapped: rock exposures and alluvial deposits that existed prior to the formation of the lake and thin post-impoundment sediments ( 1 m) deposited since the lake formed. Exposures of rock are most extensive in the narrow, steep-sided sections of the lake, while alluvial deposits are most extensive on the gentle flanks of the broader basin sections of the lake. Post-impoundment sediment is restricted to the floors of the original river valleys that now lie below lake level. These sediments are thickest in the deltas that form at the mouths of the Colorado River and its tributaries, but cover the entire length of the valley floors of the lake. This sediment distribution is consistent with deposition from turbidity currents. Lake level has dropped more than 30 m between collection of the sidescan imagery and publication of this report. During this time, thick delta deposits have been eroded and redistributed to deeper parts of the lake by turbidity currents. While present-day post-impoundment sediment distribution should be similar to what it was in 2001, the thickness may be greater in some of the deeper parts of the lake now.

Chemical characterization of microbial-dominated soil organic matter in the Garwood Valley, Antarctica

NASA Astrophysics Data System (ADS)

Feng, Xiaojuan; Simpson, André J.; Gregorich, Edward G.; Elberling, Bo; Hopkins, David W.; Sparrow, Ashley D.; Novis, Philip M.; Greenfield, Lawrence G.; Simpson, Myrna J.

2010-11-01

Despite its harsh environmental conditions, terrestrial Antarctica contains a relatively large microbial biomass. Natural abundance carbon and nitrogen stable isotope signatures of organic materials in the dry valleys indicate mixed provenance of the soil organic matter (SOM) with varying proportions of contributions from lichens, mosses, lake-derived algae and cyanobacteria. Here we employed two complementary analytical techniques, biomarker measurements by gas chromatography/mass spectrometry and solution-state 1H nuclear magnetic resonance spectroscopy, to provide further information at a molecular-level about the composition and possible source of SOM in the Garwood Valley, Antarctica. The predominance of branched alkanes and short-chain lipids in the solvent extracts indicates that the primary contribution to the SOM was microbial-derived. Chemical structures in the NaOH extracts from soils were also dominated by amide, peptides, and a CH 3-dominating aliphatic region that were characteristic of microbial signatures. Furthermore, the SOM in the Garwood Valley contained compounds that were different from those in the cyanobacteria-dominated mat from a nearby lake (including monoethyl alkanes and enriched side-chain protons). This observation suggests that easily degradable carbon sources from the nearby lake did not dominate the SOM, which is consistent with a fast turnover of the mat-derived organic matter found in the valley. This study highlights the important role of native soil microbes in the carbon transformation and biogeochemistry in terrestrial Antarctica.

Hydrogeologic implications of increased septic-tank-soil-absorption system density, Ogden Valley, Weber County, Utah

USGS Publications Warehouse

Lowe, Mike; Miner, Michael L.; ,

1990-01-01

Ground water in Ogden Valley occurs in perched, confined, and unconfined aquifers in the valley fill to depths of 600 feet and more. The confined aquifer, which underlies only the western portion of the valley, is overlain by cleyey silt lacustrine sediments probably deposited during the Bonneville Basin's Little Valley lake cycle sometime between 90,000 and 150,000 years ago. The top of this cleyey silt confining layer is generally 25 to 60 feet below the ground surface. Unconfined conditions occur above and beyond the outer margin of the confining layer. The sediments overlying the confining layer are primarily Lake Bonneville deposits. Water samples from springs, streams, and wells around Pineview Reservoir, and from the reservoir itself, were collected and analyzed. These samples indicate that water quality in Ogden Valley is presently good. Average nitrate concentrations in the shallow unconfined aquifer increase toward the center of Ogden Valley. This trend was not observed in the confined aquifer. There is no evidence, however, of significant water-quality deterioration, even in the vicinity of Huntsville, a town that has been densely developed using septic-tank-soil-absorption systems for much of the time since it was founded in 1860.

Mladotice Lake, Czechia: The unique genesis and evolution of the lake basin

NASA Astrophysics Data System (ADS)

Janský, Bohumír; Šobr, Miroslav; Kliment, Zdeněk; Chalupová, Dagmar

2016-04-01

The Mladotice Lake is a lake of unique genetic type in Czechia. In May 1872 a landslide as a result an extreme rainfall event occurred in western Czechia, blocking the Mladoticky stream valley and creating the Mladotice Lake. The 1952 and 1975 air images document that collective farming had a great impact on the lake basin evolution when balks and field terraces were removed and fields were made much larger. Because of this change in land use we expected higher soil erosion and a related increase in the sedimentation rate. First bathymetric measurements of the newly created lake were carried out in 1972 and were repeated in 1999, in 2003 and in 2014. Our analysis of the sedimentary record aims to identify the sediment stratigraphy, its basic physical and chemical properties, isotope content and thin sections yield a detailed temporal resolution of the sedimentation chronology. In some areas a sediment thickness of 4 m was detected. Hence, the average sedimentation rate is from 2.2 to 2.7 cm per year. KEY WORDS: Mladotice Lake - extreme rainfall event - landslide - land use changes - flood events - bathymetric measurements - sedimentation dynamics - stratigraphy and geochemistry of lake sediments - analyses of isotopes - sedimentation rates.

Post-glacial rock avalanches in the Obersee Valley, Glarner Alps, Switzerland

NASA Astrophysics Data System (ADS)

Nagelisen, Jan; Moore, Jeffrey R.; Vockenhuber, Christoph; Ivy-Ochs, Susan

2015-06-01

The geological record of prehistoric rock avalanches provides invaluable data for assessing the hazard posed by these rare but destructive mass movements. Here we investigate two large rock avalanches in the Obersee valley of the Glarner Alps, Switzerland, providing detailed mapping of landslide and related Quaternary phenomena, revised volume estimates for each event, and surface exposure dating of rock avalanche deposits. The Rautispitz rock avalanche originated from the southern flank of the Obersee valley, releasing approximately 91 million m3 of limestone on steeply-dipping bedding planes. Debris had maximum horizontal travel distance of ~ 5000 m, a fahrboeschung angle (relating fall height to length) of 18°, and was responsible for the creation of Lake Obersee; deposits are more than 130 m thick in places. The Platten rock avalanche encompassed a source volume of 11 million m3 sliding from the northern flank of the Obersee valley on similar steeply-dipping limestone beds (bedrock forms a syncline under the valley). Debris had a maximum horizontal travel distance of 1600 m with a fahrboeschung angle of 21°, and is more than 80 m thick in places. Deposits of the Platten rock avalanche are superposed atop those from the Rautispitz event at the end of the Obersee valley where they dam Lake Haslensee. Runout for both events was simulated using the dynamic analysis code DAN3D; results showed excellent match to mapped deposit extents and thickness and helped confirm the hypothesized single-event failure scenarios. 36Cl cosmogenic nuclide surface exposure dating of 13 deposited boulders revealed a Younger Dryas age of 12.6 ± 1.0 ka for the Rautispitz rock avalanche and a mid-Holocene age of 6.1 ± 0.8 ka for the Platten rock avalanche. A seismological trigger is proposed for the former event due to potentially correlated turbidite deposits in nearby Lake Zurich.

Ground water in Tooele Valley, Utah

USGS Publications Warehouse

Gates, J.S.; Keller, O.A.

1970-01-01

This short report was written by condensing parts of a technical report on the ground water in Tooele Valley, which was prepared as part of a cooperative program between the Utah Department of Natural Resources, Division of Water Rights, and the U. S. Geological Survey to study water in Utah. If you would like to read the more detailed technical report, write for a copy of the Utah State Engineer Technical Publication 12, “Reevaluation of the ground-water resources of Tooele Valley, Utah” by J. S. Gates. Copies can be obtained free of charge from the Division of Water Rights, State Capitol, Salt Lake City, Utah 84114.

Inland diatoms from the McMurdo Dry Valleys and James Ross Island, Antarctica

USGS Publications Warehouse

Esposito, R.M.M.; Spaulding, S.A.; McKnight, Diane M.; Van De Vijver, B.; Kopalova, K.; Lubinski, D.; Hall, B.; Whittaker, T.

2008-01-01

Diatom taxa present in the inland streams and lakes of the McMurdo Dry Valleys and James Ross Island, Antarctica, are presented in this paper. A total of nine taxa are illustrated, with descriptions of four new species (Luticola austroatlantica sp. nov., Luticola dolia sp. nov., Luticola laeta sp. nov., Muelleria supra sp. nov.). In the perennially ice-covered lakes of the McMurdo Dry Valleys, diatoms are confined to benthic mats within the photic zone. In streams, diatoms are attached to benthic surfaces and within the microbial mat matrix. One species, L. austroatlantica, is found on James Ross Island, of the southern Atlantic archipelago, and the McMurdo Dry Valleys. The McMurdo Dry Valley populations are at the lower range of the size spectrum for the species. Streams flow for 6-10 weeks during the austral summer, when temperatures and solar radiation allow glacial ice to melt. The diatom flora of the region is characterized by species assemblages favored under harsh conditions, with naviculoid taxa as the dominant group and several major diatom groups conspicuously absent. ?? 2008 NRC.

Trace element mobility and transfer to vegetation within the Ethiopian Rift Valley lake areas.

PubMed

Kassaye, Yetneberk A; Skipperud, Lindis; Meland, Sondre; Dadebo, Elias; Einset, John; Salbu, Brit

2012-10-26

To evaluate critical trace element loads in native vegetation and calculate soil-to-plant transfer factors (TFs), 11 trace elements (Cr, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Pb and Mn) have been determined in leaves of 9 taxonomically verified naturally growing terrestrial plant species as well as in soil samples collected around 3 Ethiopian Rift Valley lakes (Koka, Ziway and Awassa). The Cr concentration in leaves of all the plant species was higher than the "normal" range, with the highest level (8.4 mg per kg dw) being observed in Acacia tortilis from the Lake Koka area. Caper species (Capparis fascicularis) and Ethiopian dogstooth grass (Cynodon aethiopicus) from Koka also contained exceptionally high levels of Cd (1 mg per kg dw) and Mo (32.8 mg per kg dw), respectively. Pb, As and Cu concentrations were low in the plant leaves from all sites. The low Cu level in important fodder plant species (Cynodon aethiopicus, Acacia tortilis and Opuntia ficus-indicus) implies potential deficiency in grazing and browsing animals. Compared to the Canadian environmental quality guideline and maximum allowable concentration in agricultural soils, the total soil trace element concentrations at the studied sites are safe for agricultural crop production. Enrichment factor was high for Zn in soils around Lakes Ziway and Awassa, resulting in moderate to high transfer of Zn to the studied plants. A six step sequential extraction procedure on the soils revealed a relatively high mobility of Cd, Se and Mn. Strong association of most trace elements with the redox sensitive fraction and mineral lattice was also confirmed by partial redundancy analysis. TF (mg per kg dw plants/mg per kg dw soil) values based on the total (TF(total)) and mobile fractions (TF(mobile)) of soil trace element concentrations varied widely among elements and plant species, with the averaged TF(total) and TF(mobile) values ranging from 0.01-2 and 1-60, respectively. Considering the mobile fraction in soils should

Evidence of deep circulation in two perennially ice-covered Antarctic lakes

USGS Publications Warehouse

Tyler, S.W.; Cook, P.G.; Butt, A.Z.; Thomas, J.M.; Doran, P.T.; Lyons, W.B.

1998-01-01

The perennial ice covers found on many of the lakes in the McMurdo Dry Valley region of the Antarctic have been postulated to severely limit mixing and convective turnover of these unique lakes. In this work, we utilize chlorofluorocarbon (CFC) concentration profiles from Lakes Hoare and Fryxell in the McMurdo Dry Valley to determine the extent of deep vertical mixing occurring over the last 50 years. Near the ice-water interface, CFC concentrations in both lakes were well above saturation, in accordance with atmospheric gas supersaturations resulting from freezing under the perennial ice covers. Evidence of mixing throughout the water column at Lake Hoare was confirmed by the presence of CFCs throughout the water column and suggests vertical mixing times of 20-30 years. In Lake Fryxell, CFC-11, CFC-12, and CFC-113 were found in the upper water column; however, degradation of CFC-11 and CFC-12 in the anoxic bottom waters appears to be occurring with CFC-113 only present in these bottom waters. The presence of CFC-113 in the bottom waters, in conjunction with previous work detecting tritium in these waters, strongly argues for the presence of convective mixing in Lake Fryxell. The evidence for deep mixing in these lakes may be an important, yet overlooked, phenomenon in the limnology of perennially ice-covered lakes.

Results of a conservation agreement and strategy for Rabbit Valley gilia (Gilia caespitosa)

Treesearch

L. A. Armstrong; T. O. Clark; R. B. Campbell

2001-01-01

Gilia caespitosa Gray (Rabbit Valley gilia) is a rare species restricted to scattered occurrences from the northern Waterpocket Fold to Thousand Lakes Mountain and Rabbit Valley in Wayne County, Utah. This species is a very narrow endemic, known only from unstable and faulting soils of detrital Navajo Sandstone. Species occurrences are often found with limited numbers...

Sedimentation architecture of the volcanically-dammed Alf valley in the West Eifel Volcanic Field, Germany

NASA Astrophysics Data System (ADS)

Eichhorn, Luise; Lange, Thomas; Engelhardt, Jörn; Polom, Ulrich; Pirrung, Michael; Büchel, Georg

2015-04-01

In the southeastern part of the Quaternary West Eifel Volcanic Field, the Alf valley with its morphologically wide (~ 500 m) and flat valley bottom is visibly outstanding. This flat valley bottom was formed during the Marine Isotope Stage 2 due to fluviolacustrine sediments which deposited upstream of a natural volcanic dam. The dam consisted of lava and scoria breccia from the Wartgesberg Volcano complex (Cipa 1958, Hemfler et al. 1991) that erupted ~ 31 BP (40Ar/ 39Ar dating on glass shards, Mertz, pers. communication 2014). Due to this impoundment, the Alf creek turned into a dendritic lake, trapping the catchment sediments. The overall aim is to create the sedimentation architecture of the Alf valley. In comparison to maar archives like Holzmaar or Meerfelder Maar in the vicinity, the fluviolacustrine sediments of the Alf valley show clay-silt lamination despite the water percolation. This archive covers the transition from the Last Glacial Maximum to Early Holocene (Pirrung et al. 2007). Focus of this study is the creation of a 3D model by applying the program ESRI ArcGIS 10.2 to reconstruct the pre-volcanic Alf valley. Moreover, the sedimentation architecture is reconstructed and the sediment fill quantified. Therefore, the digital elevation model with 5 m resolution from the State Survey and Geobasis Information of Rhineland-Palatinate, polreduced magnetic data measured on top of the Strohn lava stream, shear seismic data and core stratigraphies were utilized. Summarizing previous results, Lake Alf had a catchment area of ~ 55 km² (Meerfelder Maar: 1.27 km²) and a surface area of 8.2 km² (Meerfelder Maar: 0.24 km²) considering a maximum lake water level of 410 m a.s.l.. In the deepest parts (~ 50 m) of Lake Alf, lake sediments are laminated, up to 21 m thick and show a very high sedimentation rate ~ 3 mm a-1 (Dehner Maar ~ 1.5 mm a-1, (Sirocko et al. 2013)). The sediments become coarser upstream und stratigraphically above the fine-grained lake sediments

Geothermal activity and hydrothermal mineral deposits at southern Lake Bogoria, Kenya Rift Valley: Impact of lake level changes

NASA Astrophysics Data System (ADS)

Renaut, Robin W.; Owen, R. Bernhart; Ego, John K.

2017-05-01

Lake Bogoria, a saline alkaline closed-lake in a drainage basin of Neogene volcanic rocks in the central Kenya Rift, is fed partly by ∼200 hot alkaline springs located in three groups along its margins. Hot springs along the midwest shoreline (Loburu, Chemurkeu) and their travertine deposits have been studied, but little is known about the geothermal activity at southern Lake Bogoria. Observations, field measurements and analyses (geochemical and mineralogical) of the spring waters and deposits, spanning three decades, show that the southern spring waters are more saline, the hydrothermal alteration there is more intense, and that most hot spring deposits are siliceous. Geothermal activity at southern Lake Bogoria (Ng'wasis, Koibobei, Losaramat) includes littoral boiling springs and geysers, with fumaroles at slightly higher elevations. Modern spring deposits are ephemeral sodium carbonates, opal-A crusts and silica gels. Local fossil spring deposits include diatomaceous silica-cemented conglomerates that formed subaqueously when the lake was then dilute and higher than today, and outlying calcite tufa deposits. In contrast, mineral deposits around neighbouring fumarole vents and sites of hydrothermal alteration include clays (kaolinite), sulfate minerals (jarosite, alunite), and Fe-oxyhydroxides linked to rising acidic fluids. When lake level falls, the zone of acidity moves downwards and may overprint older alkaline spring deposits. In contrast, rising lake level leads to lake water dilution and vents in the lower parts of the acidic zone may become dilute alkaline springs. The new evidence at Lake Bogoria shows the potential for using the mineralogy of geothermal sediments to indicate former changes in lake level.

Numerical simulation of local atmospheric circulations in the pre-Alpine area between Lake Garda and Verona

NASA Astrophysics Data System (ADS)

Laiti, L.; Serafin, S.; Zardi, D.

2010-09-01

The pre-Alpine area between Lake Garda and Verona displays a very complex and heterogeneous territory, allowing the development of several interacting systems of thermally driven local winds, the major being the lake/land breeze system on the coasts of Lake Garda and the up/down-valley wind system between the plain and the river Adige Valley. In order to investigate the local wind patterns, a series of nested numerical simulations with a horizontal resolution of 500 m were carried out using the ARPS 5.2.9 model (Xue et al. 2000, 2001), considering a fair weather day suitable for a clear development of the expected circulations (15th July 2003). The simulated wind speed and direction, pressure, temperature and water vapour mixing ratio were compared to synoptic scale meteorological charts, to vertical profiles from radiosoundings taken at the major sounding stations of the alpine region and to local scale measurements performed at the surface station of Dolcè (at the inlet of the Adige Valley). Numerical results at all scales were found to be in very good agreement with the available sets of meteorological observations. The analysis of the diurnal evolution of the 3D fields of temperature, moisture content, wind and turbulent kinetic energy allowed the identification of a very shallow and clearly defined breeze front of cold and humid air moving from off-shore towards the Lake Garda coast, from the late morning (10:00 LST) until the evening (20:00 LST). The diurnal up-valley breeze was also well reproduced: the valley atmosphere displays a thick mixed layer dominated by shallow turbulent convection between 11:00 LST and 21:00 LST. Lateral slope winds were also recognized, as they created cross-valley convective cells. While no clear evidence of a nocturnal land breeze was found in the simulations, the nocturnal down-valley wind in the Adige Valley was clearly reproduced. Finally, a scalar transport equation was added to the ARPS model in order to simulate transport

Arsenic and selenium in soils and shallow ground water in the Turtle Lake, New Rockford, Harvey Pumping, Lincoln Valley, and LaMoure irrigation areas of the Garrison Diversion Unit, North Dakota

USGS Publications Warehouse

Berkas, W.R.; Komor, S.C.

1996-01-01

The Garrison Diversion Unit project was authorized as part of the Pick-Sloan Missouri River Basin program to divert water from Lake Sakakawea to irrigation areas in North Dakota. A special Garrison Commission was created to evaluate an environmental concern that return flow from the irrigation areas might contain metals in toxic concentrations. This report summarizes the results of detailed investigations of the Turtle Lake, New Rockford, Harvey Pumping, Lincoln Valley, and LaMoure irrigation areas. A total of 223 soil samples were collected from the irrigation areas and analyzed for elemental composition. Water extractions were done on 40 of the 223 soil samples using a 1:5 soil-to-water extraction method, and the solution from the extraction was analyzed for elemental composition. A total of 52 ground-water samples were collected and analyzed for inorganic constituents and organic carbon.Average arsenic concentrations in the entire soil column ranged from 1.0 milligram per kilogram in the Harvey Pumping irrigation area to 70 milligrams per kilogram in the New Rockford irrigation area. Average selenium concentrations ranged from less than 0.1 milligram per kilogram in the Turtle Lake, New Rockford, Harvey Pumping, and Lincoln Valley irrigation areas to 6.0 milligrams per kilogram in the Turtle Lake irrigation area. In the Turtle Lake irrigation area, average arsenic and selenium concentrations generally increased with depth through the topsoil, oxidized soil, and transition soil but decreased in the reduced soil at the bottom of the sampled horizons. Average arsenic concentrations in the New Rockford irrigation area follow the same pattern as in the Turtle Lake irrigation area, but selenium concentrations do not show a clear pattern of variation with depth. In the Harvey Pumping and Lincoln Valley irrigation areas, arsenic and selenium concentrations do not appear to vary systematically with depth. No correlation is shown between the concentrations in soils and

Paleogeomorphology of the early Colorado River inferred from relationships in Mohave and Cottonwood Valleys, Arizona, California and Nevada

USGS Publications Warehouse

Pearthree, Philip; House, P. Kyle

2014-01-01

Geologic investigations of late Miocene–early Pliocene deposits in Mohave and Cottonwood valleys provide important insights into the early evolution of the lower Colorado River system. In the latest Miocene these valleys were separate depocenters; the floor of Cottonwood Valley was ∼200 m higher than the floor of Mohave Valley. When Colorado River water arrived from the north after 5.6 Ma, a shallow lake in Cottonwood Valley spilled into Mohave Valley, and the river then filled both valleys to ∼560 m above sea level (asl) and overtopped the bedrock divide at the southern end of Mohave Valley. Sediment-starved water spilling to the south gradually eroded the outlet as siliciclastic Bouse deposits filled the lake upstream. When sediment accumulation reached the elevation of the lowering outlet, continued erosion of the outlet resulted in recycling of stored lacustrine sediment into downstream basins; depth of erosion of the outlet and upstream basins was limited by the water levels in downstream basins. The water level in the southern Bouse basin was ∼300 m asl (modern elevation) at 4.8 Ma. It must have drained and been eroded to a level <150 m asl soon after that to allow for deep erosion of bedrock divides and basins upstream, leading to removal of large volumes of Bouse sediment prior to massive early Pliocene Colorado River aggradation. Abrupt lowering of regional base level due to spilling of a southern Bouse lake to the Gulf of California could have driven observed upstream river incision without uplift. Rapid uplift of the entire region immediately after 4.8 Ma would have been required to drive upstream incision if the southern Bouse was an estuary.

Dietary changes of large herbivores in the Turkana Basin, Kenya from 4 to 1 Ma

NASA Astrophysics Data System (ADS)

Cerling, Thure E.; Andanje, Samuel A.; Blumenthal, Scott A.; Brown, Francis H.; Chritz, Kendra L.; Harris, John M.; Hart, John A.; Kirera, Francis M.; Kaleme, Prince; Leakey, Louise N.; Leakey, Meave G.; Levin, Naomi E.; Kyalo Manthi, Fredrick; Passey, Benjamin H.; Uno, Kevin T.

2015-09-01

A large stable isotope dataset from East and Central Africa from ca. 30 regional collection sites that range from forest to grassland shows that most extant East and Central African large herbivore taxa have diets dominated by C4 grazing or C3 browsing. Comparison with the fossil record shows that faunal assemblages from ca. 4.1-2.35 Ma in the Turkana Basin had a greater diversity of C3-C4 mixed feeding taxa than is presently found in modern East and Central African environments. In contrast, the period from 2.35 to 1.0 Ma had more C4-grazing taxa, especially nonruminant C4-grazing taxa, than are found in modern environments in East and Central Africa. Many nonbovid C4 grazers became extinct in Africa, notably the suid Notochoerus, the hipparion equid Eurygnathohippus, the giraffid Sivatherium, and the elephantid Elephas. Other important nonruminant C4-grazing taxa switched to browsing, including suids in the lineage Kolpochoerus-Hylochoerus and the elephant Loxodonta. Many modern herbivore taxa in Africa have diets that differ significantly from their fossil relatives. Elephants and tragelaphin bovids are two groups often used for paleoecological insight, yet their fossil diets were very different from their modern closest relatives; therefore, their taxonomic presence in a fossil assemblage does not indicate they had a similar ecological function in the past as they do at present. Overall, we find ecological assemblages of C3-browsing, C3-C4-mixed feeding, and C4-grazing taxa in the Turkana Basin fossil record that are different from any modern ecosystem in East or Central Africa.

Dietary changes of large herbivores in the Turkana Basin, Kenya from 4 to 1 Ma

PubMed Central

Cerling, Thure E.; Andanje, Samuel A.; Blumenthal, Scott A.; Brown, Francis H.; Chritz, Kendra L.; Harris, John M.; Hart, John A.; Kirera, Francis M.; Kaleme, Prince; Leakey, Louise N.; Leakey, Meave G.; Levin, Naomi E.; Manthi, Fredrick Kyalo; Passey, Benjamin H.; Uno, Kevin T.

2015-01-01

A large stable isotope dataset from East and Central Africa from ca. 30 regional collection sites that range from forest to grassland shows that most extant East and Central African large herbivore taxa have diets dominated by C4 grazing or C3 browsing. Comparison with the fossil record shows that faunal assemblages from ca. 4.1–2.35 Ma in the Turkana Basin had a greater diversity of C3–C4 mixed feeding taxa than is presently found in modern East and Central African environments. In contrast, the period from 2.35 to 1.0 Ma had more C4-grazing taxa, especially nonruminant C4-grazing taxa, than are found in modern environments in East and Central Africa. Many nonbovid C4 grazers became extinct in Africa, notably the suid Notochoerus, the hipparion equid Eurygnathohippus, the giraffid Sivatherium, and the elephantid Elephas. Other important nonruminant C4-grazing taxa switched to browsing, including suids in the lineage Kolpochoerus-Hylochoerus and the elephant Loxodonta. Many modern herbivore taxa in Africa have diets that differ significantly from their fossil relatives. Elephants and tragelaphin bovids are two groups often used for paleoecological insight, yet their fossil diets were very different from their modern closest relatives; therefore, their taxonomic presence in a fossil assemblage does not indicate they had a similar ecological function in the past as they do at present. Overall, we find ecological assemblages of C3-browsing, C3–C4-mixed feeding, and C4-grazing taxa in the Turkana Basin fossil record that are different from any modern ecosystem in East or Central Africa. PMID:26240344

Carbon-14 analyses reveal fine structure of the urban carbon dioxide dome in the Salt Lake Valley, Utah, USA

NASA Astrophysics Data System (ADS)

Ehleringer, J. R.; Hopkins, F. M.; Xu, X.; Barnette, J.; Randerson, J. T.; Bush, S.; Lai, C.

2013-12-01

Carbon-14 analyses of mature deciduous tree leaves (aspen and cottonwood) were used to measure the increases in atmospheric carbon dioxide within the expansive urbanizing Salt Lake Valley, Utah, USA associated with fossil fuel combustion. Our objectives were twofold: to understand the fine scale spatial structure of elevated carbon dioxide levels in this urban environment and to relate these observations to actual carbon dioxide observations collected using both long-term monitoring sites and a mobile measurement vehicle. Paired observations of aspen and cottonwood at sites across the valley showed that there was no significant difference in carbon-14 values, allowing spatial pattern evaluations at sites where one but not the other species was present. Statistically significant patterns were observed over a two-year measurement period, with elevated carbon dioxide levels associated with carbon-14 depleted leaves, particularly in regions with higher vehicle travel. Carbon-14 content of leaves was significantly lower on 4-lane roads than on nearby 2-lane roads in both residential and commercial zones, consistent with atmospheric carbon dioxide observations. The analysis of spatial patterns in the carbon-14 in leaves was then used to evaluate how well these observations compared to instantaneous and long-term observations of carbon dioxide using traditional infrared gas analyzer approaches.

Hydrogeology of a drift-filled bedrock valley near Lino Lakes, Anoka County, Minnesota

USGS Publications Warehouse

Winter, T.C.; Pfannkuch, H.O.

1976-01-01

The bedrock surface of east-central Minnesota is dissected by an intricate network of valleys. Outside the bedrock valley at site B, 3 mi (4. 8 km) from site A, 100 ft (30 m) of drift overlies the bedrock surface. Observation wells were installed at the two sites to determine the vertical ground-water movement between the various aquifer units and the lateral movement between the two sites. An aquifer test of the lowest valley-fill aquifer at site A showed that the observation well completed in the same aquifer as the pumping well responded immediately; whereas a lag of about 100 min occurred between the lower valley fill and uppermost body of sand and gravel. This indicates that the hydraulic connection between these two layers is poor at the immediate site. Test results show that the lower sand-and-gravel aquifer has a transmissivity between 14,000 and 27,000 ft2/d (1,300 and 2,500 m2/d). Although the hydraulic gradient is vertically downward in the valley, much of the drift fill is poorly permeable. This suggests that the quantity of downward-percolating water reaching the lowest valley-fill aquifer is relatively small at the test site. Because valley cut through a number of bedrock aquifers in the region, they could potentially be an important avenue of contamination from land-surface waste. In addition, the vast network of bedrock valleys in the Twin Cities area might cause contaminants to disseminate rather rapidly throughout a large area.

Sedimentary record of the 1872 earthquake and "Tsunami" at Owens Lake, southeast California

USGS Publications Warehouse

Smoot, J.P.; Litwin, R.J.; Bischoff, J.L.; Lund, S.J.

2000-01-01

In 1872, a magnitude 7.5-7.7 earthquake vertically offset the Owens Valley fault by more than a meter. An eyewitness reported a large wave on the surface of Owens Lake, presumably initiated by the earthquake. Physical evidence of this event is found in cores and trenches from Owens Lake, including soft-sediment deformation and fault offsets. A graded pebbly sand truncates these features, possibly over most of the lake floor, reflecting the "tsunami" wave. Confirmation of the timing of the event is provided by abnormally high lead concentrations in the sediment immediately above and below these proposed earthquake deposits derived from lead-smelting plants that operated near the eastern lake margin from 1869-1876. The bottom velocity in the deepest part of the lake needed to transport the coarsest grain sizes in the graded pebbly sand provides an estimate of the minimum initial 'tsunami' wave height at 37 cm. This is less than the wave height calculated from long-wave numerical models (about 55 cm) using average fault displacement during the earthquake. Two other graded sand deposits associated with soft-sediment deformation in the Owens Lake record are less than 3000 years old, and are interpreted as evidence of older earthquake and tsunami events. Offsets of the Owens Valley fault elsewhere in the valley indicate that at least two additional large earthquakes occurred during the Holocene, which is consistent with our observations in this lacustrine record.

Excitation of high-frequency surface waves with long duration in the Valley of Mexico

NASA Astrophysics Data System (ADS)

Iida, Masahiro

1999-04-01

During the 1985 Michoacan earthquake (Ms = 8.1), large-amplitude seismograms with extremely long duration were recorded in the lake bed zone of Mexico City. We interpret high-frequency seismic wave fields in the three geotechnical zones (the hill, the transition, and the lake bed zones) in the Valley of Mexico on the basis of a systematic analysis for borehole strong motion recordings. We make identification of wave types for real seismograms. First, amplitude ratios between surface and underground seismograms indicate that predominant periods of the surface seismograms are largely controlled by the wave field incident into surficial layers in the Valley of Mexico. We interpret recorded surface waves as fundamental-mode Love waves excited in the Mexican Volcanic Belt by calculating theoretical amplification for different-scale structures. Second, according to a cross-correlation analysis, the hill and transition seismograms are mostly surface waves. In the lake bed zone, while early portions are noisy body waves, late portions are mostly surface waves. Third, using two kinds of surface arrays with different station intervals, we investigate high-frequency surface-wave propagation in the lake bed zone. The wave propagation is very complicated, depending upon the time section and the frequency band. Finally, on the basis of a statistical time series model with an information criterion, we separate S- and surface-wave portions from lake bed seismograms. Surface waves are dominant and are recognized even in the early time section. Thus high-frequency surface waves with long duration in the Valley of Mexico are excited by the Mexican Volcanic Belt.

Partitioning of sublimation and evaporation from Lake Bonney using water vapor isotope and latent heat fluxes

NASA Astrophysics Data System (ADS)

Bellagamba, A. W.; Berkelhammer, M. B.; Winslow, L.; Peter, D.; Myers, K. F.

2017-12-01

The landscapes of the McMurdo Dry Valleys in Antarctica are characterized by a series of frozen lakes. Although the conditions in this region are severe, the lakes share common characteristics with lakes at glacial termini elsewhere. Geochemical and geomorphological evidence suggest these lakes have experienced large historical changes indicative of changes water balances. While part of these shifts in lake volume arise from changes in glacial inflow, they likely also reflect changes in the latent heat flux from the lake surfaces. Here we present a joint analysis of the stable isotopic ratio of surface ice/water and the water vapor flux over Dry Valley frozen lakes to ascertain the processes controlling water losses from the lake surfaces. We compare the isotopic ratio of the latent heat flux with the surface water isotopes to derive a fractionation factor associated with latent flux. This data is then used to provide insight into how much of the water vapor flux is sublimated versus evaporated, as well as how the sublimation and evaporative components of the flux change with synoptic weather. We used a Picarro L2130-I isotopic water analyzer to measure humidity and the isotopic ratio of water vapor at three heights over Lake Bonney in Taylor Valley, Antarctica and used the flux-gradient approach to convert the isotopic ratio of the vapor to an "isoflux". An on-site meteorological station recorded temperature, relative humidity and wind direction/intensity at two different heights above the lake and an infrared radiometer recorded lake skin temperature. These data were used to calculate the sensible and latent heat fluxes. The fractionation factor was close to 0, which indicates that sublimation was the primary component of the flux although evaporation became increasingly prominent following a katabatic wind event. The results suggest this technique could be an effective tool to study the sensitivity of latent heat fluxes to weather here and in other similar

Dry Valley streams in Antarctica: Ecosystems waiting for water

USGS Publications Warehouse

McKnight, Diane M.; Niyogi, D.K.; Alger, A.S.; Bomblies, A.; Conovitz, P.A.; Tate, C.M.

1999-01-01

An axiom of ecology is: 'Where there is water, there is life.' In dry valley ecosystems of Antarctica, this axiom can be extended to: 'Where there has been and will be water, there is life.' Stream communities in the dry valleys can withstand desiccation on an annual basis and also for longer periods - as much as decades or even centuries. These intact ecosystems, consisting primarily of cyanobacteria and eukaryotic algae, spring back to life with the return of water. Soil organisms in the dry valleys also have remarkable survival capabilities (Virginia and Wall 1999), emerging from dormancy with the arrival of water. Streams in the dry valleys carry meltwater from a glacier or ice-field source to the lakes on the valley floors and generally flow for 4-10 weeks during the summer, depending on climatic conditions. Many of these streams contain abundant algal mats that are perennial in the sense that they are in a freeze-dried state during the winter and begin growing again within minutes of becoming wetted by the first flow of the season. The algal species present in the streams are mainly filamentous cyanobacteria (approximately 20 species of the genera Phormidium, Oscillatoria, and Nostoc), two green algal species of the genus Prasiola, and numerous diatom taxa that are characteristic of soil habitats and polar regions. Algal abundances are greatest in those streams in which periglacial processes, acting over periods of perhaps a century, have produced a stable stone pavement in the streambed. This habitat results in a less turbulent flow regime and limits sediment scour from the streambed. Because dry valley glaciers advance and retreat over periods of centuries and millennia and stream networks in the dry valleys evolve through sediment deposition and transport, some of the currently inactive stream channels may receive flow again in the future. Insights- into the process of algal persistence and reactivation will come from long-term experiments that study the

Scenario earthquake hazards for the Long Valley Caldera-Mono Lake area, east-central California (ver. 2.0, January 2018)

USGS Publications Warehouse

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

2014-06-30

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 also for 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 on California Earthquake Probabilities (WGCEP) and the USGS National Seismic Hazard Mapping 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 Zone to the east of the study area.In this report, an earthquake scenario is intended to depict the potential consequences of significant earthquakes. A scenario earthquake is not necessarily the largest or most damaging earthquake possible on a recognized fault. Rather it is both large enough and likely enough that emergency planners should consider it in regional emergency response plans. In particular, the ground motion predicted for a given scenario earthquake does not represent a full probabilistic hazard assessment, and thus it does not provide the basis for hazard zoning and earthquake-resistant building design.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). Alternatives

75 FR 61174 - Warner Valley Comprehensive Site Plan, Final Environmental Impact Statement, Lassen Volcanic...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-04

... Warner Valley fen and wetland areas; (3) Removal or repair of Dream Lake Dam and restoration of... project planning area. This area includes Dream Lake Dam, built in 1932 by Alex Sifford, which impounds an... built the 10 structures which now form the core of Drakesbad Guest Ranch Historic District (both Dream...

Morphometry and mixing regime of a tropical lake: Lake Nova (Southeastern Brazil).

PubMed

Gonçalves, Monica A; Garcia, Fábio C; Barroso, Gilberto F

2016-09-01

Lake Nova (15.5 km2) is the second largest lake in the Lower Doce River Valley (Southeastern Brazil). A better understanding of ecosystem structure and functioning requires knowledge about lake morphometry, given that lake basin form influences water column stratification. The present study aims to contribute to the understanding of relationship between morphometry and mixing patterns of deep tropical lakes in Brazil. Water column profiles of temperature and dissolved oxygen were taken on four sampling sites along the lake major axis during 2011, 2012 and 2013. The bathymetric survey was carried out in July 2011, along 131.7 km of hydrographic tracks yield 51,692 depth points. Morphometric features of lake size and form factors describe the relative deep subrectangular elongated basin with maximum length of 15.7 km, shoreline development index 5.0, volume of 0.23 km3, volume development of 1.3, and maximum, mean and relative depths of 33.9 m, 14.7 m and 0.7 %, respectively. The deep basin induces a monomictic pattern, with thermal stratification during the wet/warm season associated with anoxic bottom waters (1/3 of lake volume), and mixing during dry and cool season. Based on in situ measurements of tributary river discharges, theoretical retention time (RT) has been estimated in 13.4 years. The morphometry of Lake Nova promote long water RT and the warm monomictic mixing pattern, which is in accordance to the deep tropical lakes in Brazil.

Impacts of Flooding Regime Modification on Wildlife Habitats of Bottomland Hardwood Forests in the Lower Mississippi Valley.

DTIC Science & Technology

1981-10-01

Illinois River Valley, Illinois; the Jonesboro and Stuttgart regions of Arkansas; Union and Alexander Counties in southern Illinois; Reelfoot Lake and Lake ...food habits of mammals in the vicinity of Reelfoot Lake Biological Station, III. Discussion of the mammals recorded from the area. J. Tennessee Acad...Yeager and Anderson (1944) found that fox squir- rels were present in all timbered areas of a leveed bottomland lake in Illinois. Lowery (1974) stated

Rare earth element content of thermal fluids from Surprise Valley, California

DOE Data Explorer

Andrew Fowler

2015-09-23

Rare earth element measurements for thermal fluids from Surprise Valley, California. Samples were collected in acid washed HDPE bottles and acidified with concentrated trace element clean (Fisher Scientific) nitric acid. Samples were pre-concentratated by a factor of approximately 10 using chelating resin with and IDA functional group and measured on magnetic sector ICP-MS. Samples include Seyferth Hot Springs, Surprise Valley Resort Mineral Well, Leonard's Hot Spring, and Lake City Mud Volcano Boiling Spring.

Pleistocene glaciers, lakes, and floods in north-central Washington State

USGS Publications Warehouse

Waitt, Richard B.; Haugerud, Ralph A.; Kelsey, Harvey M.

2017-01-01

The Methow, Chelan, Wenatchee, and other terrane blocks accreted in late Mesozoic to Eocene times. Methow valley is excavated in an exotic terrane of folded Mesozoic sedimentary and volcanic rocks faulted between crystalline blocks. Repeated floods of Columbia River Basalt about 16 Ma drowned a backarc basin to the southeast. Cirques, aretes, and U-shaped hanging troughs brand the Methow, Skagit, and Chelan headwaters. The Late Wisconsin Cordilleran icesheet beveled the alpine topography and deposited drift. Cordilleran ice flowed into the heads of Methow tributaries and overflowed from Skagit tributaries to greatly augment Chelan trough's glacier. Joined Okanogan and Methow ice flowed down Columbia valley and up lower Chelan trough. This tongue met the icesheet tongue flowing southeast down Chelan valley. Successively lower ice-marginal channels and kame terraces show that the icesheet withered away largely by downwasting. Immense late Wisconsin floods from glacial Lake Missoula occasionally swept the Chelan-Vantage reach of Columbia valley by different routes. The earliest debacles, nearly 19,000 cal yr BP (by radiocarbon methods), raged 335 m deep down the Columbia and built high Pangborn bar at Wenatchee. As Cordilleran ice blocked the northwest of Columbia valley, several giant floods descended Moses Coulee and backflooded up the Columbia. As advancing ice then blocked Moses Coulee, Grand Coulee to Quincy basin became the westmost floodway. From Quincy basin many Missoula floods backflowed 50 km upvalley past Wenatchee 18,000 to 15,500 years ago. Receding ice dammed glacial Lake Columbia centuries more--till it burst about 15,000 years ago. After Glacier Peak ashfall about 13,600 years ago, smaller great flood(s) swept down the Columbia from glacial Lake Kootenay in British Columbia. A cache of huge fluted Clovis points had been laid atop Pangborn bar (East Wenatchee) after the Glacier Peak ashfall. Clovis people came two and a half millennia after the last

Luminescence dating of paleolake deltas and glacial deposits in Garwood Valley, Antarctica: Implications for climate, Ross ice sheet dynamics, and paleolake duration

USGS Publications Warehouse

Levy, Joseph S.; Rittenour, Tammy M.; Fountain, Andrew G.; O'Connor, Jim E.

2017-01-01

The formation of perched deltas and other lacustrine deposits in the McMurdo Dry Valleys of Antarctica is widely considered to be evidence of valley-filling lakes dammed by the grounded Ross Sea ice sheet during the local Last Glacial Maximum, with lake drainage interpreted as a record of grounding line retreat. We used luminescence dating to determine the age of paleolake deltas and glacial tills in Garwood Valley, a coastal dry valley that opens to the Ross Sea. Luminescence ages are stratigraphically consistent with radiocarbon results from algal mats within the same delta deposits but suggest radiocarbon dates from lacustrine carbonates may overestimate deposit ages by thousands of years. Results suggest that late Holocene delta deposition into paleolake Howard in Garwood Valley persisted until ca. 3.5 ka. This is significantly younger than the date when grounded ice is thought to have retreated from the Ross Sea. Our evidence suggests that the local, stranded ice-cored till topography in Garwood Valley, rather than regional ice-sheet dynamics, may have controlled lake levels for some McMurdo Dry Valleys paleolakes. Age control from the supraglacial Ross Sea drift suggests grounding and up-valley advance of the Ross Sea ice sheet into Garwood valley during marine oxygen isotope stage (MIS) 4 (71–78 ka) and the local Last Glacial Maximum (9–10 ka). This work demonstrates the power of combining luminescence dating with existing radiocarbon data sets to improve understanding of the relationships among paleolake formation, glacial position, and stream discharge in response to climate change.

Lake Chad, Chad, Africa

NASA Technical Reports Server (NTRS)

1992-01-01

Hydrologic and ecologic changes in the Lake Chad Basin are shown in this Oct 1992 photograph. In space photo documentation, Lake Chad was at its greatest area extent (25,000 sq. km.) during Gemini 9 in June 1966 (see S66-38444). Its reduction during the severe droughts from 1968 to 1974 was first noted during Skylab (1973-1974). After the drought began again in 1982, the lake reached its minimum extent (1,450 sq. km.) in Space Shuttle photographs taken in 1984 and 1985. In this STS-52 photograph, Lake Chad has begun to recover. The area of the open water and interdunal impoundments in the southern basin (the Chari River Basin) is estimated to be 1,900 to 2100 sq. km. Note the green vegetation in the valley of the K'Yobe flow has wetted the northern lake basin for the first time in several years. There is evidence of biomass burning south of the K'Yobe Delta and in the vegetated interdunal areas near the dike in the center of the lake. Also note the dark 'Green Line' of the Sahel (the g

Landscape of Former Lakes and Streams on Northern Mars

NASA Image and Video Library

2016-09-15

Valleys younger than better-known ancient valley networks on Mars are evident on the landscape in the northern Arabia Terra region of Mars, particularly in the area mapped here with color-coded topographical information overlaid onto a photo mosaic. The area includes a basin informally named "Heart Lake" at upper left (northwest). Data from the Mars Orbiter Laser Altimeter (MOLA) on NASA's Mars Global Surveyor orbiter are coded here as white and purple for lower elevations, yellow for higher elevation. The elevation information is combined with a mosaic of images from the Thermal Emission Imaging System (THEMIS) camera on NASA's Mars Odyssey orbiter, covering an area about 120 miles (about 190 kilometers) wide. The mapped area is centered near 35.91 degrees north latitude, 1 degree east longitude on Mars. These lakes and streams held water several hundred million years after better-known ancient lake environments on Mars, according to 2016 findings. http://photojournal.jpl.nasa.gov/catalog/PIA20838

Groundwater-Mining-Induced Subsidence and Earth Fissures in Cedar Valley, Southwestern Utah

NASA Astrophysics Data System (ADS)

Knudsen, T. R.; Inkenbrandt, P.; Lund, W. R.; Lowe, M.; Bowman, S. D.

2014-12-01

Groundwater pumping in excess of recharge (groundwater mining) has lowered the potentiometric surface in Cedar Valley, southwestern Utah, by as much as 114 feet since 1939. Lowering the potentiometric surface (head decline) has caused permanent compaction of fine-grained sediments of the Cedar Valley aquifer. Recently acquired interferometric synthetic aperture radar (InSAR) imagery shows that land subsidence is occurring over an ~100 square-mile area, including two pronounced subsidence bowls in the northeastern (Enoch graben) and southwestern (Quichapa Lake area) parts of the valley. A lack of accurate historical benchmark elevation data over much of the valley prevents detailed long-term quantification of subsidence. In response to the land subsidence, earth fissures have formed along the margins of the Enoch graben and north and west of Quichapa Lake. Our initial inventory of Cedar Valley fissures, which relied on aerial-photography analysis, identified 3.9 miles of fissures in 2009. With newly acquired light detection and ranging (LiDAR) coverage in 2011, we more than doubled the total length of mapped fissures to 8.3 miles. Fissures on the west side of the Enoch graben exhibit ongoing vertical surface displacement with rates as high as 1.7 inches/year. The largest Enoch-graben-west fissure has displaced street surfaces, curb and gutter, and sidewalks, and has reversed the flow direction of a sewer line in a partially developed subdivision. Several Cedar Valley fissures are closely associated with, and in some places coincident with, mapped Quaternary faults. While the majority of Cedar Valley fissures are mapped in agricultural areas, continued groundwater mining and resultant subsidence will likely cause existing fissures to lengthen and new fissures to form that may eventually impact other developed areas of the valley.

Measuring historic water levels of Lake Balaton and tributary wetlands using georeferenced maps

NASA Astrophysics Data System (ADS)

Zlinszky, A.

2009-04-01

Lake Balaton is a large and relatively shallow lake located in western Hungary. The lake is joined by small wetlands on the north shore and larger water-filled valleys on the south separated by and elevated sand bar. These wetlands are assumed to have been connected with Lake Balaton before the water level was artificially lowered in 1893. No regular measurements of the water level of the lake or these wetlands were carried out before the draining of the lake. Most of the wetlands were completely isolated from the water system of the lake after the water level change as roads, railway and holiday homes were built. The low valleys of the southern shore still hold many fishponds, swamps and wet meadows, which are important sanctuaries for rare wetland species, and are often less disturbed than the lake, which is a popular holiday resort. Hydrologic restoration of these wetlands is only possible if accurate information exists on the original, natural state. The 1776 Krieger-map and the first military survey (1782-1785) are the most accurate known maps of the original state of the Lake Balaton area. These maps were surveyed using triangulation and leveling, and are accurate enough to be compared with the present-day situation. Some of the depicted buildings and landmarks still survive and can be used as control points for georeferencing and correcting these maps. Since the bathymetry of the lake and the topography of the surrounding countryside have hardly changed, existing digital elevation models of the present-day relief could be compared to these georeferenced maps. The elevation profile of the lake shore and wetland borders can be calculated by tracing these lines on a Digital Elevation Model. The shore area of Lake Balaton has been filled in and changed, so present-day land topography can not be used to estimate the water level from the elevation profile of the shore line. However, the Krieger-map also shows bathymetric contours, and previous studies have shown

Late Quaternary megafloods from Glacial Lake Atna, Southcentral Alaska, U.S.A.

NASA Astrophysics Data System (ADS)

Wiedmer, Michael; Montgomery, David R.; Gillespie, Alan R.; Greenberg, Harvey

2010-05-01

Geomorphic, stratigraphic, geotechnical, and biogeographic evidence indicate that failure of a Pleistocene ice dam between 15.5 and 26 ka generated a megaflood from Glacial Lake Atna down the Matanuska Valley. While it has long been recognized that Lake Atna occupied ≥ 9000 km 2 of south-central Alaska's Copper River Basin, little attention has focused on the lake's discharge locations and behaviors. Digital elevation model and geomorphic analyses suggest that progressive lowering of the lake level by decanting over spillways exposed during glacial retreat led to sequential discharges down the Matanuska, Susitna, Tok, and Copper river valleys. Lake Atna's size, ˜ 50 ka duration, and sequential connection to four major drainages likely made it a regionally important late Pleistocene freshwater refugium. We estimate a catastrophic Matanuska megaflood would have released 500-1400 km 3 at a maximum rate of ≥ 3 × 10 6 m 3 s - 1 . Volumes for the other outlets ranged from 200 to 2600 km 3 and estimated maximum discharges ranged from 0.8 to 11.3 × 10 6 m 3 s - 1 , making Lake Atna a serial generator of some of the largest known freshwater megafloods.

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

NASA Astrophysics Data System (ADS)

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

2009-06-01

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 μm diameter cocci, <2.5 μm 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.

Ciliated protozoa of two antarctic lakes: analysis by quantitative protargol staining and examination of artificial substrates

NASA Technical Reports Server (NTRS)

Kepner, R. L. Jr; Wharton, R. A. Jr; Coats, D. W.; Wharton RA, J. r. (Principal Investigator)

1999-01-01

Planktonic and artificial substrate-associated ciliates have been identified in two perennially ice-covered antarctic lakes of the McMurdo Dry Valleys. Abundances estimated by quantitative protargol staining ranged from < 5 to 31690 cells l-1, levels that are comparable to those previously obtained using other methods. Nineteen ciliate taxa were identified from these lakes, with the most frequently encountered genera being Plagiocampa, Askenasia, Monodinium, Sphaerophrya and Vorticella. The taxonomic findings compare favorably with those of previous investigators; however four previously unreported genera were observed in both Lakes Fryxell and Hoare. The variability in the depth distributions of ciliates in Lake Fryxell is explained in terms of lake physicochemical properties and ciliate prey distributions, while factors related to temporal succession in the Lake Hoare assemblage remain unexplained. Local marine or temperate zone freshwater habitats are a more likely source than the surrounding dry valleys soils for present ciliate colonists in these lakes. Although the taxonomic uncertainties require further examination, our results suggest that ciliate populations in these antarctic lakes undergo significant fluctuations and are more diverse than was previously recognized.

Floodplain lakes and alluviation cycles of the lower Colorado River

NASA Astrophysics Data System (ADS)

Malmon, D.; Felger, T. J.; Howard, K. A.

2007-05-01

The broad valleys along the lower Colorado River contain numerous bodies of still water that provide critical habitat for bird, fish, and other species. This chain of floodplain lakes is an important part of the Pacific Flyway - the major north-south route of travel for migratory birds in the western Hemisphere - and is also used by many resident bird species. In addition, isolated floodplain lakes may provide the only viable habitat for endangered native fish such as the razorback sucker, vulnerable to predation by introduced species in the main stem of the Colorado River. Floodplain lakes typically occupy former channel courses of the river and formed as a result of river meandering or avulsion. Persistent fluvial sediment deposition (aggradation) creates conditions that favor rapid formation and destruction of floodplain lakes, while long term river downcutting (degradation) inhibits their formation and evolution. New radiocarbon dates from wood recovered from drill cores near Topock, AZ indicate that the river aggraded an average of 3 mm/yr in the middle and late Holocene. Aggradational conditions before Hoover Dam was built were associated with rapid channel shifting and frequent lake formation. Lakes had short life spans due to rapid infilling with fine-grained sediment during turbid floods on the unregulated Colorado River. The building of dams and of armored banks had a major impact on floodplain lakes, not only by drowning large portions of the valley beneath reservoirs, but by preventing new lake formation in some areas and accelerating it in others. GIS analyses of three sets of historical maps show that both the number and total area of isolated (i.e., not linked to the main channel by a surface water connection) lakes in the lower Colorado River valley increased between 1902 and the 1950s, and then decreased though the 1970s. River bed degradation below dams inhibits channel shifting and floodplain lake formation, and the capture of fines behind the

Origin of the Valley Networks On Mars: A Hydrological Perspective

NASA Technical Reports Server (NTRS)

Gulick, Virginia C.

2000-01-01

The geomorphology of the Martian valley networks is examined from a hydrological perspective for their compatibility with an origin by rainfall, globally higher heat flow, and localized hydrothermal systems. Comparison of morphology and spatial distribution of valleys on geologic surfaces with terrestrial fluvial valleys suggests that most Martian valleys are probably not indicative of a rainfall origin, nor are they indicative of formation by an early global uniformly higher heat flow. In general, valleys are not uniformly distributed within geologic surface units as are terrestrial fluvial valleys. Valleys tend to form either as isolated systems or in clusters on a geologic surface unit leaving large expanses of the unit virtually untouched by erosion. With the exception of fluvial valleys on some volcanoes, most Martian valleys exhibit a sapping morphology and do not appear to have formed along with those that exhibit a runoff morphology. In contrast, terrestrial sapping valleys form from and along with runoff valleys. The isolated or clustered distribution of valleys suggests localized water sources were important in drainage development. Persistent ground-water outflow driven by localized, but vigorous hydrothermal circulation associated with magmatism, volcanism, impacts, or tectonism is, however, consistent with valley morphology and distribution. Snowfall from sublimating ice-covered lakes or seas may have provided an atmospheric water source for the formation of some valleys in regions where the surface is easily eroded and where localized geothermal/hydrothermal activity is sufficient to melt accumulated snowpacks.

Is Lake Chabot Eutrophic?

NASA Astrophysics Data System (ADS)

Pellegrini, K.; Logan, J.; Esterlis, P.; Lew, A.; Nguyen, M.

2013-12-01

Introduction/Abstract: Lake Chabot is an integral part of the East Bay watershed that provides habitats for animals and recreation for humans year-round. Lake Chabot has been in danger of eutrophication due to excessive dumping of phosphorous and nitrogen into the water from the fertilizers of nearby golf courses and neighboring houses. If the lake turned out to be eutrophified, it could seriously impact what is currently the standby emergency water supply for many Castro Valley residents. Eutrophication is the excessive richness of nutrients such as nitrogen and phosphorus in a lake, usually as a result of runoff. This buildup of nutrients causes algal blooms. The algae uses up most of the oxygen in the water, and when it dies, it causes the lake to hypoxify. The fish in the lake can't breathe, and consequently suffocate. Other oxygen-dependant aquatic creatures die off as well. Needless to say, the eutrophication of a lake is bad news for the wildlife that lives in or around it. The level of eutrophication in our area in Northern California tends to increase during the late spring/early summer months, so our crew went out and took samples of Lake Chabot on June 2. We focused on the area of the lake where the water enters, known on the map as Honker Bay. We also took readings a ways down in deeper water for comparison's sake. Visually, the lake looked in bad shape. The water was a murky green that glimmered with particulate matter that swirled around the boat as we went by. In the Honker Bay region where we focused our testing, there were reeds bathed in algae that coated the surface of the lake in thick, swirling patterns. Surprisingly enough, however, our test results didn't reveal any extreme levels of phosphorous or nitrogen. They were slightly higher than usual, but not by any significant amount. The levels we found were high enough to stimulate plant and algae growth and promote eutrophication, but not enough to do any severe damage. After a briefing with a

High pollution events in the Great Salt Lake Basin and its adjacent valleys. Insights on mechanisms and spatial distribution of the formation of secondary aerosol.

NASA Astrophysics Data System (ADS)

Franchin, A.; Middlebrook, A. M.; Baasandorj, M.; Brown, S. S.; Fibiger, D. L.; Goldberger, L.; McDuffie, E. E.; Moravek, A.; Murphy, J. G.; Thornton, J. A.; Womack, C.

2017-12-01

High pollution events are common in many locations in the U.S.A. and around the world. They can last several days or up to weeks and they negatively affect human health, deteriorate visibility, and increase premature mortality. The main causes for high pollution events are related to meteorology and sources. They often happen in the winter, when high emissions, stagnation and reduced mixing, due to a shallow boundary layer, cause high concentrations of pollutants to accumulate. In the last decades, the air quality in the U.S. has seen an overall improvement, due to the reductions in particulate and gaseous pollutants. However, some areas remain critical. The Great Salt Lake Basin and its adjacent valleys are currently areas where high pollution events are a serious environmental problem involving more than 2.4 million people. We will present the results of the Utah Wintertime Fine Particulate Study (UWFPS) that took place in winter 2017. During UWFPS, we carried out airborne measurements of aerosol chemical composition and precursor vapor concentrations over the Great Salt Lake Basin and its adjacent valleys. We will give insights into how and under which conditions conversion of precursor vapors into aerosol particles takes place in the area. We will also present a comparison of our measurements with models that will provide an insight of the mechanisms that lead to the formation of secondary aerosol particles. With the results of our work, we aim to inform strategies for pollution control in the future.

Climatological observations and predicted sublimation rates at Lake Hoare, Antarctica.

USGS Publications Warehouse

Clow, G.D.; McKay, C.P.; Simmons, G.M.; Wharton, R.A.

1988-01-01

In December 1985, an automated meteorological station was established at Lake Hoare in the dry valley region of Antarctica. Here, we report on the first year-round observations available for any site in Taylor Valley. This dataset augments the year-round data obtained at Lake Vanda (Wright Valley) by winter-over crews during the late 1960s and early 1970s. The mean annual solar flux at Lake Hoare was 92 W m-2 during 1986, the mean air temperature -17.3 degrees C, and the mean 3-m wind speed 3.3 m s-1. The local climate is controlled by the wind regime during the 4-month sunless winter and by seasonal and diurnal variations in the incident solar flux during the remainder of the year. Temperature increases of 20 degrees-30 degrees C are frequently observed during the winter due to strong fo??hn winds descending from the Polar Plateau. A model incorporating nonsteady molecular diffusion into Kolmogorov-scale eddies in the interfacial layer and similarity-theory flux-profiles in the surface sublayer, is used to determine the rate of ice sublimation from the acquired meteorological data. Despite the frequent occurrence of strong winter fo??hns, the bulk of the annual ablation occurs during the summer due to elevated temperatures and persistent moderate winds. The annual ablation from Lake Hoare is estimated to have been 35.0 +/- 6.3 cm for 1986.

A catastrophic meltwater flood event and the formation of the Hudson Shelf Valley

USGS Publications Warehouse

Thieler, E. Robert; Butman, Bradford; Schwab, William C.; Allison, Mead A.; Driscoll, Neal W.; Donnelly, John P.; Uchupi, Elazar

2007-01-01

The Hudson Shelf Valley (HSV) is the largest physiographic feature on the U.S. mid-Atlantic continental shelf. The 150-km long valley is the submerged extension of the ancestral Hudson River Valley that connects to the Hudson Canyon. Unlike other incised valleys on the mid-Atlantic shelf, it has not been infilled with sediment during the Holocene. Analyses of multibeam bathymetry, acoustic backscatter intensity, and high-resolution seismic reflection profiles reveal morphologic and stratigraphic evidence for a catastrophic meltwater flood event that formed the modern HSV. The valley and its distal deposits record a discrete flood event that carved 15-m high banks, formed a 120-km2 field of 3- to 6-m high bedforms, and deposited a subaqueous delta on the outer shelf. The HSV is inferred to have been carved initially by precipitation and meltwater runoff during the advance of the Laurentide Ice Sheet, and later by the drainage of early proglacial lakes through stable spillways. A flood resulting from the failure of the terminal moraine dam at the Narrows between Staten Island and Long Island, New York, allowed glacial lakes in the Hudson and Ontario basins to drain across the continental shelf. Water level changes in the Hudson River basin associated with the catastrophic drainage of glacial lakes Iroquois, Vermont, and Albany around 11,450 14C year BP (∼ 13,350 cal BP) may have precipitated dam failure at the Narrows. This 3200 km3 discharge of freshwater entered the North Atlantic proximal to the Gulf Stream and may have affected thermohaline circulation at the onset of the Intra-Allerød Cold Period. Based on bedform characteristics and fluvial morphology in the HSV, the maximum freshwater flux during the flood event is estimated to be ∼ 0.46 Sv for a duration of ∼ 80 days.

Chemical quality of ground water in Salt Lake Valley, Utah, 1969-85

USGS Publications Warehouse

Waddell, K.M.; Seiler, R.L.; Solomon, D.K.

1986-01-01

During 1979-84, 35 wells completed in the principal aquifer in the Salt Lake Valley, Utah, that had been sampled during 1962-67 were resampled to determine if water quality changes had occurred. The dissolved solids concentration of the water from 13 of the wells has increased by more than 10% since 1962-67. Much of the ground water between the mouth of Bingham Canyon and the Jordan River about 10 mi to the east has been contaminated by seepage from reservoirs and evaporation ponds associated with mining activities. Many domestic and irrigation wells yield water with concentrations of dissolved solids that exceed 2,000 mg/L. A reservoir in the mouth of Bingham Canyon contains acidic waters with a pH of 3 to 4 and concentrations of dissolved solids ranging from 43,000 to 68,000 mg/L. Seepage from evaporation ponds, which are about 4.5 mi east of the reservoir, also is acidic and contains similar concentrations of dissolved solids. East of the reservoir, where a steep hydraulic gradient exists along the mountain front, the velocities of contaminant movement were estimated to range from about 680-1,000 ft/yr. Groundwater underlying part of the community of South Salt Lake near the Jordan River has been contaminated by leachate from uranium-mill tailings. The major effect of the leachate from the tailings of the Vitro Chemical Co. on the shallow unconfined aquifer downgradient from the tailings was the contribution of measurable quantities of dissolved solids, chloride, sulfate, iron, and uranium. The concentration of dissolved solids in uncontaminated water was 1,650 mg/L, whereas downgradient from the tailings area, the concentrations ranged from 2,320-21,000 mg/L. The maximum volume of contaminated water was estimated to be 7,800 acre-ft. The major effect of the leachate from the Vitro tailings on the confined aquifer was the contribution of measurable quantities of dissolved solids, chloride, sulfate, and iron. The concentration of dissolved solids upgradient from

Review of surgical management of cystic hydatid disease in a resource limited setting: Turkana, Kenya.

PubMed

Cooney, Rachel M; Flanagan, Kevin P; Zehyle, Ebehard

2004-11-01

Cystic hydatid disease is a zoonotic infection of humans caused by infection with the larval stage of Echinococcus granulosus. The prevalence rate (5-10%) in Turkana, Northern Kenya is among the highest worldwide. With an increase in foreign travel and migration of peoples, practitioners need to be aware of diseases common in these countries and their rarer manifestations. The objective of this study was to review the management of this disease in a poorly resourced high-prevalence area. The surgical records of Kakuma Mission Hospital, Turkana from July 1981 to May 2002 were reviewed. A total of 710 (female : male, 3 : 2) surgical procedures for hydatid disease were recorded, the average age being 27 years (range, 3-65 years). There were 663 patients, and therefore 47 patients had repeat procedures. A total of 52.8% (n = 375) had hepatic cysts (248 right sided, 30 left sided, 97 site undefined), and 10.1% (n = 72) had multiple abdominal cysts. Other intra-abdominal sites included 8.16% mesenteric (n = 58), 2.9% retroperitoneal (n = 21), 3.5% spleen (n = 25), the abdominal wall (n = 4). There was no information on the site of disease in 5.9% of cases (n = 42). More unusual sites were retro-orbital, gluteal, zygomatic, brachial, parotid, uterine, tibial and foot. The largest volume of cyst fluid was 7 l. There was one intraoperative death and one postoperative death recorded. Endocystectomy +/- a scolicidal was the commonest procedure performed. However, 165 percutaneous aspiration injection of a scolicidal agent and reaspiration procedures were performed, six being on pregnant women. This is one of the largest series of surgical hydatid patients from Africa and demonstrates the wide diversity in cyst location.

Upper Cenozoic sediments of the lower Delaware Valley and the northern Delmarva Peninsula, New Jersey, Pennsylvania, Delaware, and Maryland

USGS Publications Warehouse

Owens, James Patrick; Minard, James Pierson

1979-01-01

The 'yellow gravels' referred to by R. D. Salisbury in 1898 and the 'Trenton gravel,' as defined by H. C. Lewis in 1880, were investigated along the inner edge of the New Jersey Coastal Plain in southern New Jersey and in the northern Delmarva Peninsula. The highest level deposits, the Beacon Hill gravel, are found on only the highest hills in the New Jersey Coastal Plain. Their distribution suggests deposition from north to south across the plain. After deposition of the Beacon Hill, probably in middle or late Miocene time, a narrow valley was formed paralleling the inner edge of the New Jersey Coastal Plain between Raritan Bay and Camden. South of Camden, the valley broadened, covering much of southern New Jersey. The deposits in this valley are largely the Bridgeton Formation as we have redefined it. A second narrow valley was entrenched through the Bridgeton between Trenton and Salem, N.J. This valley broadens and covers much of the northern Delmarva Peninsula west of the Delaware River. The fill in the valley is largely the Pensauken Formation, as we have redefined it in our report. Collectively, the Beacon Hill, the Bridgeton, and the Pensauken were originally the 'yellow gravels' of Salisbury. These deposits are all fluviatile in origin and were largely formed as a series of step like downcutting channels. The Delaware Valley between Trenton and the lower Delaware Bay region is occupied by the 'Trenton gravel,' which is below the average level of the 'yellow gravels.' Two units recognized throughout the area and informally named the Spring Lake beds and the Van Sciver Lake beds are lithologically distinct from the 'yellow gravel' formations. The lithologies of the Spring Lake beds and the Van Sciver Lake beds are much more heterogeneous than those of the older formations. These two units, particularly, contain much greater amounts of silt and clay, often in thick beds. The depositional environments associated with the two units include fluviatile, estuarine

Ground water in Tooele Valley, Tooele County, Utah

USGS Publications Warehouse

Thomas, H.E.

1946-01-01

Tooele Valley is a typical basin of the Basin and Range Province located about 30 miles southwest of Salt Lake City. It is roughly 15 miles long and 10 miles wide and has a population of about 7,000. Bordered on the west by the Stansbury Range, on the east by the Oquirrh Range, and on the south by South Mountain, it opens northward to Great Salt Lake. The bordering mountain ranges are formed by Paleozoic rocks ranging in age from Lower Cambrian to Pennsylvanian but with the Ordovician and Silurian periods unrepresented. There is no sedimentary record of the interval between Pennsylvanian and Tertiary times, and the Tertiary, Quaternary, and Recent sediments are of continental origin. These continental deposits play the dominant role in the ground-water hydrology of the basin, and were mapped and studied in detail. Pleistocene sediments are of major importance because they form the surface rock over most of the area, and give rise to conditions which yield water by artesian flow in the lower part of the valley.The development of the present land forms in this area began with the folding of Paleozoic and probably Mesozoic sediments during the Laramide revolution. The cycle of highland erosion and lowland deposition thus initiated has continued through recurrent uplift along Basin-Range faults to the present day. The principal physiographic subdivisions of the valley were developed as a result of the Basin-Range faulting, which began early in the Tertiary and has continued to Recent times.There are about 1,100 wells in Tooele Valley, about 90 per cent of which yield or have yielded water by artesian flow. Most of them are located in the lower part of the valley below an altitude of 4,400 feet. These wells and many of the springs derive their water from the unconsolidated Quaternary sediments, which include discontinuous, lenticular and commonly elongated bodies of sand, clay, gravel, and boulders of alluvial origin alternating and inter-fingered with lacustrine beds

Periodic jökulhlaups from Pleistocene glacial Lake Missoula-New evidence from varved sediment in northern Idaho and Washington

USGS Publications Warehouse

Waitt, Richard B.

1984-01-01

Newly examined exposures in northern Idaho and Washington show that catastrophic floods from glacial Lake Missoula during late Wisconsin time were repeated, brief jökulhlaups separated by decades of quiet glaciolacustrine and subaerial conditions. Glacial Priest Lake, dammed in the Priest River valley by a tongue of the Purcell trench lobe of the Cordilleran ice sheet, generally accumulated varved mud; the varved mud is sharply interrupted by 14 sand beds deposited by upvalley-running currents. The sand beds are texturally and structurally similar to slackwater sediment in valleys in southern Washington that were backflooded by outbursts from glacial Lake Missoula. Beds of varved mud also accumulated in glacial Lake Spokane (or Columbia?) in Latah Creek valley and elsewhere in northeastern Washington; the mud beds were disrupted, in places violently, during emplacement of each of 16 or more thick flood-gravel beds. This history corroborates evidence from southern Washington that only one graded bed is deposited per flood, refuting a conventional idea that many beds accumulated per flood. The total number of such floodlaid beds in stratigraphic succession near Spokane is at least 28. The mud beds between most of the floodlaid beds in these valleys each consist of between 20 and 55 silt-to-clay varves. Lacustrine environments in northern Idaho and Washington therefore persisted for two to six decades between regularly recurring, colossal floods from glacial Lake Missoula.

Utilizing Lidar Data for Detection of Channel Migration: Taylor Valley, Antarctica

NASA Astrophysics Data System (ADS)

Barlow, M. C.; Telling, J. W.; Glennie, C.; Fountain, A.

2017-12-01

The McMurdo Dry Valleys is the largest ice-free expanse in Antarctica and one of the most studied regions on the continent. The valleys are a hyper-arid, cold-polar desert that receives little precipitation (<50 mm weq yr-1). The valley bottoms are covered in a sandy-gravel, dotted with ice-covered lakes and ponds, and alpine glaciers that descend from the surrounding mountains. Glacial melt feeds the lakes via ephemeral streams that flow 6 - 10 weeks each summer. Field observations indicate that the valley floors, particularly in Taylor Valley, contain numerous abandoned stream channels but, given the modest stream flows, channel migration is rarely observed. Only a few channels have been surveyed in the field due to the slow pace of manual methods. Here we present a method to assess channel migration over a broad region in order to study the pattern of channel migration as a function of climatic and/or geologic gradients in Taylor Valley. Raster images of high-resolution topography were created from two lidar (Light Detection and Ranging) datasets and were used to analyze channel migration in Taylor Valley. The first lidar dataset was collected in 2001 by NASA's Airborne Topographic Mapper (ATM) and the second was collected by the National Center for Airborne Laser Mapping (NCALM) in 2014 with an Optech Titan Sensor. The channels were extracted for each dataset using GeoNet, which is an open source tool used for the automatic extraction of channel networks. Channel migration was found to range from 0 to 50 cm per year depending upon the location. Channel complexity was determined based on the change in the number of channel branches and their length. We present the results for various regions in Taylor Valley with differing degrees of stream complexity. Further research is being done to determine factors that drive channel migration rates in this unique environment.

The Antarctic dry valley lakes: Relevance to Mars

NASA Technical Reports Server (NTRS)

Wharton, R. A., Jr.; Mckay, Christopher P.; Mancinelli, Rocco L.; Clow, G. D.; Simmons, G. M., Jr.

1989-01-01

The similarity of the early environments of Mars and Earth, and the biological evolution which occurred on early Earth, motivates exobiologists to seriously consider the possiblity of an early Martian biota. Environments are being identified which could contain Martian life and areas which may presently contain evidence of this former life. Sediments which were thought to be deposited in large ice-covered lakes are present on Mars. Such localities were identified within some of the canyons of the Valles Marineris and more recently in the ancient terrain in the Southern Hemisphere. Perennially ice-covered Antarctic lakes are being studied in order to develop quantitative models that relate environmental factors to the nature of the biological community and sediment forming processes. These models will be applied to the Martian paleolakes to establish the scientific rationale for the exobiological study of ancient Martian sediments.

Extent of Pleistocene lakes in the western Great Basin

USGS Publications Warehouse

Reheis, Marith C.

1999-01-01

During the Pliocene to middle Pleistocene, pluvial lakes in the western Great Basin repeatedly rose to levels much higher than those of the well-documented late Pleistocene pluvial lakes, and some presently isolated basins were connected. Sedimentologic, geomorphic, and chronologic evidence at sites shown on the map indicates that Lakes Lahontan and Columbus-Rennie were as much as 70 m higher in the early-middle Pleistocene than during their late Pleistocene high stands. Lake Lahontan at its 1400-m shoreline level would submerge present-day Reno, Carson City, and Battle Mountain, and would flood other now-dry basins. To the east, Lakes Jonathan (new name), Diamond, Newark, and Hubbs also reached high stands during the early-middle(?) Pleistocene that were 25-40 m above their late Pleistocene shorelines; at these very high levels, the lakes became temporarily or permanently tributary to the Humboldt River and hence to Lake Lahontan. Such a temporary connection could have permitted fish to migrate from the Humboldt River southward into the presently isolated Newark Valley and from Lake Lahontan into Fairview Valley. The timing of drainage integration also provides suggested maximum ages for fish to populate the basins of Lake Diamond and Lake Jonathan. Reconstructing and dating these lake levels also has important implications for paleoclimate, tectonics, and drainage evolution in the western Great Basin. For example, shorelines in several basins form a stair-step sequence downward with time from the highest levels, thought to have formed at about 650 ka, to the lowest, formed during the late Pleistocene. This descending sequence indicates progressive drying of pluvial periods, possibly caused by uplift of the Sierra Nevada and other western ranges relative to the western Great Basin. However, these effects cannot account for the extremely high lake levels during the early middle Pleistocene; rather, these high levels were probably due to a combination of increased

Gravity anomaly at a Pleistocene lake bed in NW Alaska interpreted by analogy with Greenland's Lake Taserssauq and its floating ice tongue

USGS Publications Warehouse

Barnes, D.F.

1987-01-01

A possible example of a very deep glacial excavation is provided by a distinctive gravity low located at the front of a valley glacier that once flowed into glacial Lake Aniuk (formerly Lake Noatak) in the western Brooks Range. Geologic and geophysical data suggest that sediments or ice filling a glacially excavated valley are the most probable cause of the 30-50 mGal anomaly. Reasonable choices of geometric models and density contrasts indicate that the former excavation is now filled with a buried-ice thickness of 700 m or sediment thicknesses greater than 1 km. No direct evidence of efficient excavation was observed in Greenland, but efficient glacial erosion behind a floating polar ice tongue could explain the excavation that caused the Alaskan gravity anomaly. -from Author

Underground water in Sanpete and central Sevier valleys, Utah

USGS Publications Warehouse

Richardson, George Burr

1907-01-01

Sanpete and central Sevier valleys are situated at the border of the Basin Range and Plateau provinces in south-central Utah. They are bounded on the east by the Wasatch and Sevier plateaus and on the west by the Gunnison Plateau and the Valley and Pavant ranges, and are drained by Sevier River, which empties into Sevier Lake in the Great Basin. (See fig. 1, p. 6.)These valleys rank with the richest parts of the State. They were occupied a few years after the Mormon pioneers founded Salt Lake City, in 1847, when settlements, which soon became thriving farming communities, were established where water for irrigation was most available. A variety of crops, especially wheat, are successfully grown, and the valleys are popularly known as the "granary of Utah." Sheep raising is also an important industry, the adjacent highlands being used for summer pastures. The climate is arid, and there is a striking contrast between those areas which in their natural state are covered with sagebrush and grease wood and the fruitful cultivated tracts. (See PI. I, A and B.) Trees are normally absent in the valleys, but they flourish to a limited extent on the adjacent highlands, where there are thin growths of quaking aspen, scrub oak, and stunted conifers. Irrigation is necessary for the production of crops. Canal systems are maintained by San Pitch Creek and Sevier River, and the mountain streams are tapped by ditches near the mouths of the canyons, but this supply is insufficient and attention is being turned to the subterranean store.This report is a preliminary statement of the general conditions of occurrence of underground water in Sanpete and central Sevier valleys. The field work was carried on in cooperation with Sanpete and Sevier counties through the State engineer, Mr. Caleb Tanner, who detailed Mr. C. S. Jarvis to collect the data embodied in the list of springs and wells on pages 51-60.

Audiomagnetotelluric Data and Two-Dimensional Models from Spring, Snake, and Three Lakes Valleys, Nevada

USGS Publications Warehouse

McPhee, Darcy K.; Chuchel, Bruce A.; Pellerin, Louise

2007-01-01

Audiomagnetotelluric (AMT) data along thirteen profiles in Spring, Snake, and Three Lakes Valleys, and the corresponding two-dimensional (2-D) inverse models, are presented. The AMT method is a valuable tool for estimating the electrical resistivity of the Earth over depth ranges of a few meters to roughly one kilometer. It is important for revealing subsurface structure and stratigraphy within the Basin and Range province of eastern Nevada that can be used to define the geohydrologic framework of the region. We collected AMT data using the Geometrics StrataGem EH4 system. Profiles were 1.2 to 4.6 km in length with station spacing of 100-400 m. Data were recorded in a coordinate system parallel to and perpendicular to the assumed regional geologic strike direction. We show station locations, sounding curves of apparent resistivity, phase, and coherency, and 2-D models. The 2-D inverse models are computed from the transverse electric (TE), transverse magnetic (TM), and TE+TM mode data using the conjugate gradient, finite-difference method of Rodi and Mackie (2001). Preliminary interpretation of these models defines the structural framework of the basins and the resistivity contrasts between alluvial basin-fill, volcanic units, and carbonate/clastic rocks.

[An ethnographic approach to the concepts of health and disease in the Turkana tribe: a project to improve the health of the nomads of the Ilemi Triangle, Kenya].

PubMed

Cardós García, José Javier; Lillo Crespo, Manuel; Climent Rubio, Andrés; Hernández Urrutia, Emiliano; Mejias Moreno, Beatriz

2016-01-01

This paper aims to provide a broad view of the Turkana tribe of the Ilemi Triangle in northwestern Kenya, especially regarding the way the members of this nomadic ethnic group understand and shape their own construct of health and disease. It is based in an ethnographic study carried out in July and August 2014, including participant observation of 15 villages of the Turkana tribe, formal interviews and in-depth interviews carried out with the collaboration of two translators of the tribe and a nurse. Field notes as well videos and audio records were captured and transcribed for later analysis. Among the primary results of this study, it should be highlighted that the concepts of both health and disease differ greatly from the western approach that external projects bring with them a priori and it is likely that the lack of adherence to these projects is related to the scant cultural knowledge regarding such constructs on the part of the health professionals.

Measurements of Refractory Black Carbon (rBC) Aerosols in the McMurdo Dry Valleys, Antarctica

NASA Astrophysics Data System (ADS)

Khan, A. L.; McMeeking, G. R.; Lyons, W. B.; Schwarz, J. P.; Welch, K. A.; McKnight, D. M.

2015-12-01

Measurements of light absorbing particles in the boundary layer of the high southern latitudes are scarce. During the 2013-2014 austral summer field season refractory black carbon (rBC) aerosols were quantified by a single particle soot photometer (SP2) in the McMurdo Dry Valleys, Antarctica. The dark rBC particles absorb more radiation thereby increasing atmospheric heating, as well as reducing surface albedo and enhancing hydrologic melt when deposited on highly reflective surfaces such as snow and ice. Quantifying both local and long-range atmospheric transport of rBC to this region of a remote continent mostly covered by ice and snow would be useful in understanding meltwater generation as climate changes. Although the Dry Valleys are the largest ice-free region of Antarctica, they contain many alpine glaciers, some of which are fed from the East Antarctic Ice Sheet (EAIS). Continuous rBC measurements were collected at Lake Hoare Camp in the Taylor Valley for two months, along with shorter periods at more remote locations within the Dry Valleys. Conditions at the Lake Hoare Camp were dominated by up-valley winds from McMurdo Sound, however, winds also brought air down-valley from the EAIS polar plateau. Here we investigated periods dominated by both up and down-valley winds to explore differences in rBC concentrations, size distributions, and scattering properties. The average background rBC mass concentration was 1ng/m3, though concentrations as high as 50 ng/m3 were observed at times, likely due to local sources.

The last interglaciation at Owens Lake, California; Core OL-92

USGS Publications Warehouse

Bischoff, James L.

1998-01-01

Owens Lake, located at the eastern base of the central Sierra Nevada (Fig. 1), was the terminus of the Owens River prior to the lake's complete desiccation shortly after 1913 due to river diversion by the City of Los Angeles. During earlier wetter cycles, the lake overflowed to fill a series of downstream basins including China Lake Basin, Searles Valley, Panamint Valley, and ultimately, Death Valley (Smith and Street-Perrott, 1983). In 1992 the U.S. Geological Survey drilled a 323-m-deep core (OL-92) into Owens Lake sediments near the depocenter of the basin to obtain a continuous record of silty-clay sediment spanning the last 800,000 yrs. A multi-parameter reconnaissance study of the entire core (ca 7000-yr resolution), was reported in a 13-chapter summary volume (Smith and Bischoff, 1997). A document containing the numerical and other detailed forms of raw data collected by that volume's authors was prepared earlier (Smith and Bischoff, 1993). The reconnaissance study provided an approximate time-depth model for the entire core, based on radiocarbon dates from the top 31m, the Bishop Ash (759,000 yrs) at 304 m, ten within-Brunhes paleomagnetic excursions, and a compaction-corrected mass-accumulation rate of 51.4 g/cm/l000yr (Bischoff et al., 1997a). Application of this model to observed sediment parameters indicates that Owens Lake was saline, alkaline, and biologically productive at times of decreased water-flow, and was generally hydrologically flushed and relatively unproductive during times of increased water-flow. Grain size, abundance of CaCO3, organic carbon, clay mineralogy, cation-exchange capacity of the clay fraction, fossil pollen, fish, ostracodes, and diatoms (see summary by Smith et al., 1997) all show cyclic variation down the core. CaCO3 abundance, in particular, strongly reflects an approximately 100 ka dominant cycle, characteristic of global ice-volume indicated by the MIS δ18O record. Four of the last five marine isotope terminations are

Lake Vanda: A sentinel for climate change in the McMurdo Sound Region of Antarctica

NASA Astrophysics Data System (ADS)

Castendyk, Devin N.; Obryk, Maciej K.; Leidman, Sasha Z.; Gooseff, Michael; Hawes, Ian

2016-09-01

Lake Vanda is a perennially ice-covered, meromictic, endorheic lake located in the McMurdo Dry Valleys of Antarctica, and an exceptional sentinel of climate change within the region. Lake levels rose 15 m over the past 68 years in response to climate-driven variability in ice-cover sublimation, meltwater production, and annual discharge of the Onyx River, the main source of water to the lake. Evidence from a new bathymetric map and water balance model combined with annual growth laminations in benthic mats suggest that the most recent filling trend began abruptly 80 years ago, in the early 1930s. This change increased lake volume by > 50%, triggered the formation of a new, upper, thermohaline convection cell, and cooled the lower convection cell by at least 2 °C and the bottom-most waters by at > 4 °C. Additionally, the depth of the deep chlorophyll a maximum rose by > 2 m, and deep-growing benthic algal mats declined while shallow benthic mats colonized freshly inundated areas. We attribute changes in hydrology to regional variations in air flow related to the strength and position of the Amundsen Sea Low (ASL) pressure system which have increased the frequency of down-valley, föhn winds associated with surface air temperature warming in the McMurdo Dry Valleys. The ASL has also been implicated in the recent warming of the Antarctic Peninsula, and provides a common link for climate-related change on opposite sides of the continent. If this trend persists, Lake Vanda should continue to rise and cool over the next 200 years until a new equilibrium lake level is achieved. Most likely, future lake rise will lead to isothermal conditions not conducive to thermohaline convection, resulting in a drastically different physical, biogeochemical, and biological structure than observed today.

Impact of Flooding on Land Use/ Land Cover Transformation in Wular Lake and its Environs, Kashmir Valley, India Using Geoinformatics

NASA Astrophysics Data System (ADS)

Ahmad, T.; Pandey, A. C.; Kumar, A.

2017-11-01

Wular lake, located at an elevation of 1520 m above sea level in Kashmir valley, India. In the present study, the immediate and long term impact of flood (2014) over the Wular lake environs was analyzed by using satellite images and employing supervised classification technique in GIS environment. The LULC classification was performed on the images of 25th August 2014 (pre flood) and 13th September 2015 (post flood) and was compared, which indicated marked decrease in terrestrial vegetation (23.7 %), agriculture (43.7 %) and water bodies (39.9 %). Overlaying analysis was performed with pre and post flood classified images with reference to the satellite image of 10th September 2014(during flood) which indicated total area inundated during flood was 88.77 km2. With the pre-flood situation, the aquatic vegetation of 34.06 km2, 13.89 km2 of agriculture land and terrestrial vegetation of 3.13 km2 was inundated. In the post flood situation, it was also came into focus that more than the half of the area under water bodies was converted into sand deposits (22.76 km2) due to anomalous increase in siltation. The overlay analysis on post flood classified image indicated that aquatic vegetation followed by agriculture and sand deposits lie within the flood inundated area. Further spatial analysis was performed within the flood inundated area (88.77 km2) with pre and post classified image to understand the situation before and after the flood and to calculate the changes. These land use-land cover transformations signifies the ill effect of flooding on the biodiversity of Wular Lake.

Monitoring of Bashkara glacial lakes (the Central Caucasus) and modelling of their potential outburst.

NASA Astrophysics Data System (ADS)

Krylenko, I.; Norin, S.; Petrakov, D.; Tutubalina, O.; Chernomorets, S.

2009-04-01

In recent decades due to glacier retreat the glacial lakes in the Central Caucasus, as well as in other high-mountainous areas of the world, have expanded intensively. As result the risk of lake outbursts and destructive floods is raising. In this paper we present one of the most potentially hazardous lakes of this region - a group of glacial lakes near the Bashkara glacier in the upper Adylsu river valley, to the southeast of Mt. Elbrus. Total area of these lakes is about 100,000m2, and a total volume exceeds 1,000,000 m3. The biggest of them - the Bashkara lake has formed in late 1930s - early 1940s and the small Lapa lake has appeared in the end of 1980s. The Bashkara lake outburst occurred twice in the end of 1950s and produced devastating debris flows of ca. 2 million m3. We have monitored these lakes since 1999. Our work includes detailed field research: constant measurements of water level during warm period, annually repeated bathymetric surveys, geodetic surveys, observations on dam condition and some special measurements (i.e. water temperature distribution, current velocity). Also we use aerial and satellite images to obtain data about dynamic of areas for the lakes. From 2001 to 2006 years volume of the Lapa lake has increased 5 times (from 30,000 m3 to 140,000 m3), the Bashkara lake in this period was quasi-stable. In 2006-2008 volume of the Lapa lake has decreased due to sedimentation, however, rapid growth of water level in Bashkara lake (more than 20 sm. per day) has suddenly begun. As a result, volume of the Bashkara lake exceeded 1,000000 m3 in July 2008 whereas in 2001 -2007 year it was about 800,000 m3. Previous maximum of water level was exceeded on 3,5 m, moraine dam with ice core was overtopped and overflow has started. Thus, Bashkara glacier lakes are unstable and risk of outburst is increasing. To assess parameters and zones of potential outburst flood in the Adylsu River valley we have carried out hydrodynamic simulation. Two computer

Late Cenozoic geology and lacustrine history of Searles Valley, Inyo and San Bernardino Counties, California

USGS Publications Warehouse

Smith, George I.

2009-01-01

Searles Valley is an arid, closed basin lying 70 km east of the south end of the Sierra Nevada, California. It is bounded on the east and northeast by the Slate Range, on the west by the Argus Range and Spangler Hills, and on the south by the Lava Mountains; Searles (dry) Lake occupies the north-central part of the valley. During those parts of late Pliocene and Pleistocene time when precipitation and runoff from the east side of the Sierra Nevada into the Owens River were much greater than at present, a chain of as many as five large lakes was created, of which Searles Lake was third. The stratigraphic record left in Searles Valley when that lake expanded, contracted, or desiccated, is fully revealed by cores from beneath the surface of Searles (dry) Lake and partly recorded by sediments cropping out around the edge of the valley. The subsurface record is described elsewhere. This volume includes six geologic maps (scales: 1:50,000 and 1:10,000) and a text that describes the outcrop record, most of which represents sedimentation since 150 ka. Although this outcrop record is discontinuous, it provides evidence indicating the lake's water depths during each expansion, which the subsurface record does not. Maximum-depth lakes rose to the 2,280-ft (695 m) contour, the level of the spillway that led overflowing waters to Panamint Valley; that spillway is about 660 ft (200 m) above the present dry-lake surface. Several rock units of Tertiary and early Quaternary ages crop out in Searles Valley. Siltstone and sandstone of Tertiary age, mostly lacustrine in nature and locally deformed to near-vertical dips, are exposed in the southern part of the valley, as is the younger(?) upper Miocene Bedrock Spring Formation. Unnamed, mostly mafic volcanic rocks of probable Miocene or Pliocene age are exposed along the north and south edges of the basin. Slightly deformed lacustrine sandstones are mapped in the central-southwestern and southern parts of the study area. The Christmas

Estimating the volume of Alpine glacial lakes

NASA Astrophysics Data System (ADS)

Cook, S. J.; Quincey, D. J.

2015-09-01

Supraglacial, moraine-dammed and ice-dammed lakes represent a potential glacial lake outburst flood (GLOF) threat to downstream communities in many mountain regions. This has motivated the development of empirical relationships to predict lake volume given a measurement of lake surface area obtained from satellite imagery. Such relationships are based on the notion that lake depth, area and volume scale predictably. We critically evaluate the performance of these existing empirical relationships by examining a global database of measured glacial lake depths, areas and volumes. Results show that lake area and depth are not always well correlated (r2 = 0.38), and that although lake volume and area are well correlated (r2 = 0.91), there are distinct outliers in the dataset. These outliers represent situations where it may not be appropriate to apply existing empirical relationships to predict lake volume, and include growing supraglacial lakes, glaciers that recede into basins with complex overdeepened morphologies or that have been deepened by intense erosion, and lakes formed where glaciers advance across and block a main trunk valley. We use the compiled dataset to develop a conceptual model of how the volumes of supraglacial ponds and lakes, moraine-dammed lakes and ice-dammed lakes should be expected to evolve with increasing area. Although a large amount of bathymetric data exist for moraine-dammed and ice-dammed lakes, we suggest that further measurements of growing supraglacial ponds and lakes are needed to better understand their development.

Three-dimensional numerical model of ground-water flow in northern Utah Valley, Utah County, Utah

USGS Publications Warehouse

Gardner, Philip M.

2009-01-01

) flowing and pumping wells, (2) drains and springs, (3) evapotranspiration, (4) Utah Lake, (5) the Jordan River and mountain streams, and (6) Salt Lake Valley by subsurface outflow through the Jordan Narrows.During steady-state calibration, variables were adjusted within probable ranges to minimize differences between model-computed and measured water levels as well as between model-computed and independently estimated flows that include: recharge by seepage from individual streams and canals, discharge by seepage to individual streams and the Jordan River, discharge to Utah Lake, discharge to drains and springs, discharge by evapotranspiration, and subsurface flows into and out of northern Utah Valley from Cedar Valley and to Salt Lake Valley, respectively. The transient-state simulation was calibrated to measured water levels and water-level changes with consideration given to annual changes in the flows listed above.

The Role of Source Material in Basin Sedimentation, as Illustrated within Eureka Valley, Death Valley National Park, CA.

NASA Astrophysics Data System (ADS)

Lawson, M. J.; Yin, A.; Rhodes, E. J.

2015-12-01

Steep landscapes are known to provide sediment to sink regions, but often petrological factors can dominate basin sedimentation. Within Eureka Valley, in northwestern Death Valley National Park, normal faulting has exposed a steep cliff face on the western margin of the Last Chance range with four kilometers of vertical relief from the valley floor and an angle of repose of nearly 38 degrees. The cliff face is composed of Cambrian limestone and dolomite, including the Bonanza King, Carrara and Wood Canyon formations. Interacting with local normal faulting, these units preferentially break off the cliff face in coherent blocks, which result in landslide deposits rather than as finer grained material found within the basin. The valley is well known for a large sand dune, which derives its sediment from distal sources to the north, instead of from the adjacent Last Chance Range cliff face. During the Holocene, sediment is sourced primary from the northerly Willow Wash and Cucomungo canyon, a relatively small drainage (less than 80 km2) within the Sylvan Mountains. Within this drainage, the Jurassic quartz monzonite of Beer Creek is heavily fractured due to motion of the Fish Valley Lake - Death Valley fault zone. Thus, the quartz monzonite is more easily eroded than the well-consolidated limestone and dolomite that forms the Last Change Range cliff face. As well, the resultant eroded material is smaller grained, and thus more easily transported than the limestone. Consequently, this work highlights an excellent example of the strong influence that source material can have on basin sedimentation.

Deep groundwater and potential subsurface habitats beneath an Antarctic dry valley

PubMed Central

Mikucki, J. A.; Auken, E.; Tulaczyk, S.; Virginia, R. A.; Schamper, C.; Sørensen, K. I.; Doran, P. T.; Dugan, H.; Foley, N.

2015-01-01

The occurrence of groundwater in Antarctica, particularly in the ice-free regions and along the coastal margins is poorly understood. Here we use an airborne transient electromagnetic (AEM) sensor to produce extensive imagery of resistivity beneath Taylor Valley. Regional-scale zones of low subsurface resistivity were detected that are inconsistent with the high resistivity of glacier ice or dry permafrost in this region. We interpret these results as an indication that liquid, with sufficiently high solute content, exists at temperatures well below freezing and considered within the range suitable for microbial life. These inferred brines are widespread within permafrost and extend below glaciers and lakes. One system emanates from below Taylor Glacier into Lake Bonney and a second system connects the ocean with the eastern 18 km of the valley. A connection between these two basins was not detected to the depth limitation of the AEM survey (∼350 m). PMID:25919365

The analysis of changes in oxbow lakes characteristics using remote sensing data. A case study from Biebrza River in Poland.

NASA Astrophysics Data System (ADS)

Slapinska, Malgorzata; Chormanski, Jaroslaw

2014-05-01

Biebrza River Valley is located in North-Eastern part of Poland. Biebrza is a river of intermediate size with almost natural character. River has numerous of oxbow lakes. Biebrza River Valley consists of three Basins: Upper, Middle and Lower, which are characterized by different geomorphological structure. Biebrza River Valley is an area of significant ecological importance, especially because it is one of the biggest wetlands in Europe. It consists of almost undisturbed floodplain marshes and fens. Biebrza river is also characterised by low contamination level and small human influence. Because of those characteristics Biebrza River can be treated as a reference area for other floodplains and fen ecosystems in Europe. Since oxbow lakes are the least known part of the river valleys there is a need for more research on them. The objective of this study is the characterisation of the oxbow lake water quality and indirectly oxbow lake state using remote sensing method. For achieving the objective two remote sensing datasets has been analysed: IKONOS and hyperspectral camera AISA. The utility of both data sources was compared and time variability of oxbow lakes was defined. The first part of the remote sensing analysis of oxbow lakes was held with the usage of the satellite images from IKONOS satellite from 20.07.2008 (images were taken from Biebrza National Park resources). All analysis were made in ArcGIS 10.0 and ENVI 5.0. The second part of the image analysis was conducted with the data gained from airborne hyperspectral camera AISA Eagle in August 2013. The oxbow lakes have been described on: state of the habitat, transparency, state of overgrowing, connectivity with the river, maximum area and maximum length. The general method of describing oxbow lakes is visual habitat state, related with natural succession. Three main habitat states of oxbow lakes were designated: privileged (described as 'good'), eutrophic and disappearing. The results confirm the fact that

La Farge Lake, Kickapoo River, Vernon County, Wisconsin, Final Environmental Statement.

DTIC Science & Technology

1972-02-18

topography of the river basin is rugged, of steep-walled valleys separated by narrow, rounded divides. U • ommunities of Steuben, Gays Mills, Soldiers...upon the economy and sociology of the Kickapoo Valley. Lasis in the lake area would shift from agriculture to tourism ,r by possible industrial...expected as new businesses develop and existing businesses expand to accommodate tourism . Any business that caters to the recreationist can expect to F

Moat Development and Evolution on a Perennialy Ice-Covered Lake in East Antarctica

NASA Astrophysics Data System (ADS)

Wayt, M. E.; Myers, K. F.; Doran, P.

2017-12-01

Lake Fryxell is a closed basin lake located in the lower end of Taylor Valley in McMurdo Dry Valleys of east Antarctica. The lake has an 4 m thick perennial ice-cover, however during the austral summers an ice-free moat forms around the lake margin due to increased temperatures and stream run off. Satellite imagery paired with ground-based camera data from Lake Fryxell were used to determine onset of moat formation, moat duration, and total area of open water at peak formation from 2009 through 2015. Temperature data from a meteorological station on the shore of Lake Fryxell were used to correlate degree days above freezing (DDAF) with moat formation and extent. The results showed that overall, the moat was smallest in 2009-10, accounting for roughly .61% percent of the surface area of Lake Fryxell. In 2010-11 and 2011-12 moat extent increase by roughly 1% and then decreased by 4% in 2012-13. In 2013-14 the moat was at its largest, accounting for about 11% with a decrease in area of 6% the following summer. Preliminary analysis of temperature data suggest a correlation between DDAF and moat extent. Moats make up on average 9% of lake area and are likely sites of elevated primary productivity in the summer. Moats are ice free which allows for unobstructed photosynthetically active radiation to penetrate the shallow water column. We hypothesize projected increases in air temperatures will lead to continued rise in lake level and larger moat areas, making it critical to understand these delicate and rapidly changing ecosystems.

Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

USGS Publications Warehouse

Lopes, Thomas J.; Allander, Kip K.

2009-01-01

The Walker River is the main source of inflow to Walker Lake, a closed-basin lake in west-central Nevada. The only outflow from Walker Lake is evaporation from the lake surface. Between 1882 and 2008, upstream agricultural diversions resulted in a lake-level decline of more than 150 feet and storage loss of 7,400,000 acre-feet. Evaporative concentration increased dissolved solids from 2,500 to 17,000 milligrams per liter. The increase in salinity threatens the survival of the Lahontan cutthroat trout, a native species listed as threatened under the Endangered Species Act. This report describes streamflow in the Walker River basin and an updated water budget of Walker Lake with emphasis on the lower Walker River basin downstream from Wabuska, Nevada. Water budgets are based on average annual flows for a 30-year period (1971-2000). Total surface-water inflow to the upper Walker River basin upstream from Wabuska was estimated to be 387,000 acre-feet per year (acre-ft/yr). About 223,000 acre-ft/yr (58 percent) is from the West Fork of the Walker River; 145,000 acre-ft/yr (37 percent) is from the East Fork of the Walker River; 17,000 acre-ft/yr (4 percent) is from the Sweetwater Range; and 2,000 acre-ft/yr (less than 1 percent) is from the Bodie Mountains, Pine Grove Hills, and western Wassuk Range. Outflow from the upper Walker River basin is 138,000 acre-ft/yr at Wabuska. About 249,000 acre-ft/yr (64 percent) of inflow is diverted for irrigation, transpired by riparian vegetation, evaporates from lakes and reservoirs, and recharges alluvial aquifers. Stream losses in Antelope, Smith, and Bridgeport Valleys are due to evaporation from reservoirs and agricultural diversions with negligible stream infiltration or riparian evapotranspiration. Diversion rates in Antelope and Smith Valleys were estimated to be 3.0 feet per year (ft/yr) in each valley. Irrigated fields receive an additional 0.8 ft of precipitation, groundwater pumpage, or both for a total applied-water rate

Geohydrology of Big Bear Valley, California: phase 1--geologic framework, recharge, and preliminary assessment of the source and age of groundwater

USGS Publications Warehouse

Flint, Lorraine E.; Brandt, Justin; Christensen, Allen H.; Flint, Alan L.; Hevesi, Joseph A.; Jachens, Robert; Kulongoski, Justin T.; Martin, Peter; Sneed, Michelle

2012-01-01

The Big Bear Valley, located in the San Bernardino Mountains of southern California, has increased in population in recent years. Most of the water supply for the area is pumped from the alluvial deposits that form the Big Bear Valley groundwater basin. This study was conducted to better understand the thickness and structure of the groundwater basin in order to estimate the quantity and distribution of natural recharge to Big Bear Valley. A gravity survey was used to estimate the thickness of the alluvial deposits that form the Big Bear Valley groundwater basin. This determined that the alluvial deposits reach a maximum thickness of 1,500 to 2,000 feet beneath the center of Big Bear Lake and the area between Big Bear and Baldwin Lakes, and decrease to less than 500 feet thick beneath the eastern end of Big Bear Lake. Interferometric Synthetic Aperture Radar (InSAR) was used to measure pumping-induced land subsidence and to locate structures, such as faults, that could affect groundwater movement. The measurements indicated small amounts of land deformation (uplift and subsidence) in the area between Big Bear Lake and Baldwin Lake, the area near the city of Big Bear Lake, and the area near Sugarloaf, California. Both the gravity and InSAR measurements indicated the possible presence of subsurface faults in subbasins between Big Bear and Baldwin Lakes, but additional data are required for confirmation. The distribution and quantity of groundwater recharge in the area were evaluated by using a regional water-balance model (Basin Characterization Model, or BCM) and a daily rainfall-runoff model (INFILv3). The BCM calculated spatially distributed potential recharge in the study area of approximately 12,700 acre-feet per year (acre-ft/yr) of potential in-place recharge and 30,800 acre-ft/yr of potential runoff. Using the assumption that only 10 percent of the runoff becomes recharge, this approach indicated there is approximately 15,800 acre-ft/yr of total recharge in

The 1988 glacial lake outburst flood in Guangxieco Lake, Tibet, China

NASA Astrophysics Data System (ADS)

Liu, J.-J.; Cheng, Z.-L.; Li, Y.

2014-11-01

The 1988 glacial lake outburst flood (GLOF) in Guangxieco Lake is studied based on geomorphological evidence, interviews with local residents, field surveys in 1990 and 2007, and satellite images from different years. The findings are as follows. (1) The outburst event was caused by two major factors, namely, intense pre-precipitation and persistent high temperatures before the outburst and the low self-stability of the terminal moraine dam as a result of perennial piping. (2) The GLOF, with the peak discharge rate of 1270 m3 s-1, evolved along Midui Valley in the following order: sediment-laden flow, viscous debris flow, non-viscous debris flow, and sediment-laden flood, which was eventually blocked by Palongzangbu River. (3) A comparison between the conditions during the outburst in 1988 and the present conditions suggests a small possibility of a future outburst unless drastic changes occur in landscape and climate. Reconstructing the outburst conditions and the GLOF processes is helpful in assessing a potential outburst in glacier lakes in Tibet.

Audiomagnetotelluric Data and Preliminary Two-Dimensional Models from Spring, Dry Lake, and Delamar Valleys, Nevada

USGS Publications Warehouse

McPhee, Darcy K.; Chuchel, Bruce A.; Pellerin, Louise

2008-01-01

This report presents audiomagnetotelluric (AMT) data along fourteen profiles in Spring, Delamar, and Dry Lake Valleys, and the corresponding preliminary two-dimensional (2-D) inverse models. The AMT method is a valuable tool for estimating the electrical resistivity of the Earth over depth ranges from a few meters to less than one kilometer, and it is important for revealing subsurface structure and stratigraphy within the Basin and Range province of eastern Nevada, which can be used to define the geohydrologic framework of the region. We collected AMT data by using the Geometrics StrataGem EH4 system. Profiles were 0.7 - 3.2 km in length with station spacing of 50-400 m. Data were recorded in a coordinate system parallel to and perpendicular to the regional geologic-strike direction with Z positive down. We show AMT station locations, sounding curves of apparent resistivity, phase, and coherency, and 2-D models of subsurface resistivity along the profiles. The 2-D inverse models are computed from the transverse electric (TE), transverse magnetic (TM), and TE+TM mode data by using a conjugate gradient, finite-difference method. Preliminary interpretation of the 2-D models defines the structural framework of the basins and the resistivity contrasts between alluvial basin-fill, volcanic units, and carbonate basement rocks.

Estimating the volume of Alpine glacial lakes

NASA Astrophysics Data System (ADS)

Cook, S. J.; Quincey, D. J.

2015-12-01

Supraglacial, moraine-dammed and ice-dammed lakes represent a potential glacial lake outburst flood (GLOF) threat to downstream communities in many mountain regions. This has motivated the development of empirical relationships to predict lake volume given a measurement of lake surface area obtained from satellite imagery. Such relationships are based on the notion that lake depth, area and volume scale predictably. We critically evaluate the performance of these existing empirical relationships by examining a global database of glacial lake depths, areas and volumes. Results show that lake area and depth are not always well correlated (r2 = 0.38) and that although lake volume and area are well correlated (r2 = 0.91), and indeed are auto-correlated, there are distinct outliers in the data set. These outliers represent situations where it may not be appropriate to apply existing empirical relationships to predict lake volume and include growing supraglacial lakes, glaciers that recede into basins with complex overdeepened morphologies or that have been deepened by intense erosion and lakes formed where glaciers advance across and block a main trunk valley. We use the compiled data set to develop a conceptual model of how the volumes of supraglacial ponds and lakes, moraine-dammed lakes and ice-dammed lakes should be expected to evolve with increasing area. Although a large amount of bathymetric data exist for moraine-dammed and ice-dammed lakes, we suggest that further measurements of growing supraglacial ponds and lakes are needed to better understand their development.

Mid-latitude Ozone Depletion Events Caused by Halogens from the Great Salt Lake in Utah

NASA Astrophysics Data System (ADS)

Fibiger, D. L.; Goldberger, L.; Womack, C.; McDuffie, E. E.; Dube, W. P.; Franchin, A.; Middlebrook, A. M.; Thornton, J. A.; Brown, S. S.

2017-12-01

Halogens are highly reactive chemicals and play an important role in atmospheric chemistry. They can be involved in many cycles which influence the oxidizing capacity of the atmosphere, including through destruction of ozone (O3). While the influence of halogens on O3 is well documented in the arctic, there are very few observations of O3 depletion driven by halogens in the mid-latitudes. To date, the most comprehensive study observed co-occurring plumes of BrO and depleted O3 near the Dead Sea in 1997. During the Utah Wintertime Fine Particulate Study (UWFPS) in winter 2017, simultaneous measurements of a comprehensive suite of halogen measurements by I- chemical ionization mass spectrometry and O3 from cavity ring-down spectroscopy, both at 1-second time resolution, were taken on a NOAA Twin Otter Aircraft over the Great Salt Lake and in the surrounding valleys. Many O3 depletion events were observed over the lake with O3 values sometimes below the instrument detection limit of 0.5 ppbv. Corresponding increases in BrO and/or ClO were observed. Many of these events were caused by extremely high levels of halogens (up to 1 ppmv Cl2) emitted from the U.S. Magnesium plant on the edge of the lake. The O3 depletion caused by U.S. Magnesium was usually isolated to a distinct vertical layer, but in other cases O3 depletion was vertically mixed and the origin of halogen activation was not immediately clear. The most complete O3 depletion was observed over the lake, but there were smaller events of a few ppbv observed in the adjacent valleys, including the highly populated Salt Lake Valley, with corresponding plumes of BrO and ClO, due to transport from the lake. Additionally, meteorology played a role in the observed O3 depletion. The strongest O3 depletion was observed during inversion events, when there is a low boundary layer and little mixing out of the air above the lake. During non-inversion conditions, only small depletions were observed, covering a much smaller

Groundwater and Thaw Legacy of a Large Paleolake in Taylor Valley, East Antarctica as Evidenced by Airborne Electromagnetic and Sedimentological Techniques

NASA Astrophysics Data System (ADS)

Doran, P. T.; Myers, K. F.; Foley, N.; Tulaczyk, S. M.; Dugan, H. A.; Auken, E.; Mikucki, J.; Virginia, R. A.

2017-12-01

The McMurdo Dry Valleys (MDVs) in east Antarctica contain a number of perennial ice-covered lakes fed by ephemeral meltwater streams. Lake Fryxell in Taylor Valley, is roughly 5.5 km long and approximately 22 m deep. Paleodeltas and paleoshorelines throughout Fryxell Basin provide evidence of significant lake level change occurring since the Last Glacial Maximum (LGM). During the LGM, grounded ice in the Ross Sea extended into the eastern portion of Taylor Valley, creating a large ice dammed paleolake. Glacial Lake Washburn (GLW) was roughly 300 m higher than modern day Lake Fryxell and its formation and existence has been debated. In this study, we use Geographical Information System and remote sensing techniques paired with regional resistivity data to provide new insight into the paleohydrology of the region. The existence of GLW is supported by new findings of a deep groundwater system beneath Lake Fryxell, which is interpreted as the degrading thaw bulb of GLW. Airborne resistivity data collected by SkyTEM, a time-domain airborne electromagnetic sensor system was used to map groundwater systems in the lake basin. Subsurface characteristics can be inferred from the relationship of resistivity to temperature, salinity, porosity, and degree of saturation. A large low resistivity region indicative of liquid water extends hundreds of meters away from the modern lake extent which is consistent with the presence of a degrading thaw bulb from GLW. As lake level in Fryxell Basin fell to modern levels, the saturated sediment beneath the lake began to freeze as it became exposed to low atmospheric temperatures. We hypothesize that this process is ongoing and will continue until equilibrium is reached between the geothermal gradient and atmospheric temperatures. Though liquid groundwater systems were previously thought to be minimal or nonexistent in the MDVs, regional resistivity data now show that extensive groundwater reservoirs exist beneath these lakes. In addition

The Bear River's history and diversion: Constraints, unsolved problems, and implications for the Lake Bonneville record: Chapter 2

USGS Publications Warehouse

Pederson, Joel L.; Janecke, Susanne U.; Reheis, Marith; Kaufmann, Darrell S.; Oaks, R. Q.

2016-01-01

The shifting course of the Bear River has influenced the hydrologic balance of the Bonneville basin through time, including the magnitude of Lake Bonneville. This was first recognized by G.K. Gilbert and addressed in the early work of Robert Bright, who focused on the southeastern Idaho region of Gem Valley and Oneida Narrows. In this chapter, we summarize and evaluate existing knowledge from this region, present updated and new chronostratigraphic evidence for the Bear River's drainage history, and discuss implications for the Bonneville record as well as future research needs.The Bear River in Plio-Pleistocene time joined the Snake River to the north by following the present-day Portneuf or Blackfoot drainages, with it likely joining the Portneuf River by middle Pleistocene time. An episode of volcanism in the Blackfoot-Gem Valley volcanic field, sparsely dated to ~ 100–50 ka, diverted the Bear River southward from where the Alexander shield volcano obstructed the river's path into Gem Valley. Previous chronostratigraphic and isotopic work on the Main Canyon Formation in southern Gem Valley indicates internal-basin sedimentation during the Quaternary, with a possible brief incursion of the Bear River ~ 140 ka. New evidence confirms that the Bear River's final diversion at 60–50 ka led to its integration into the Bonneville basin by spillover at a paleo-divide above present-day Oneida Narrows. This drove rapid incision before the rise of Lake Bonneville into the canyon and southern Gem Valley.Bear River diversion at 60–50 ka coincides with the end of the Cutler Dam lake cycle, at the onset of marine isotope stage 3. The Bear River subsequently contributed to the rise of Lake Bonneville, the highest pluvial lake known in the basin, culminating in the Bonneville flood. Key research questions include the prior path of the upper Bear River, dating and understanding the complex geologic relations within the Gem Valley-Blackfoot volcanic field, resolving

Controls on the distribution of productivity and organic resources in Antarctic Dry Valley soils.

PubMed

Hopkins, D W; Sparrow, A D; Novis, P M; Gregorich, E G; Elberling, B; Greenfield, L G

2006-11-07

The Antarctic Dry Valleys are regarded as one of the harshest terrestrial habitats on Earth because of the extremely cold and dry conditions. Despite the extreme environment and scarcity of conspicuous primary producers, the soils contain organic carbon and heterotrophic micro-organisms and invertebrates. Potential sources of organic compounds to sustain soil organisms include in situ primary production by micro-organisms and mosses, spatial subsidies from lacustrine and marine-derived detritus, and temporal subsidies ('legacies') from ancient lake deposits. The contributions from these sources at different sites are likely to be influenced by local environmental conditions, especially soil moisture content, position in the landscape in relation to lake level oscillations and legacies from previous geomorphic processes. Here we review the abiotic factors that influence biological activity in Dry Valley soils and present a conceptual model that summarizes mechanisms leading to organic resources therein.

Towards a Detailed Seismic Structure of the Valley of Mexico's Xochimilco Lake Zone.

NASA Astrophysics Data System (ADS)

Rabade, S.; Sanchez-Sanchez, J.; Ayala Hernandez, M.; Macias, M. A.; Aguilar Calderon, L. A.; Alcántara, L.; Almora Mata, D.; Castro Parra, G.; Delgado, R.; Leonardo Suárez, M.; Molina Avila, I.; Mora, A.; Perez-Yanez, C.; Ruiz, A. L.; Sandoval, H.; Torres Noguez, M.; Vazquez Larquet, R.; Velasco Miranda, J. M.; Aguirre, J.; Ramirez-Guzmán, L.

2017-12-01

Six centuries of gradual, intentional sediment filling in the Xochimilco Lake Zone have drastically reduced the size of the lake. The basin structure and the lake's clay limits and thickness are poorly constrained, and yet, essential to explain the city's anomalous ground motion. Therefore, we conducted an experiment to define the 3D velocity model of Mexico's capital; the CDMX-E3D. The initial phase involved the deployment of a moving set of 18-broadband stations with an interstation distance of 500m over a period of 19 weeks. We collected the data and analyzed the results for the Xochimilco Lake Zone using H/V Spectral Ratios (Nakamura, 1989), which provided an improved fundamental period map of the region. Results show that periods in the former lake zone have larger variability than values previously estimated. In order to obtain group velocity maps at different periods, we estimated Green's functions from ambient noise cross-correlations following standard methodologies to invert Rayleigh wave travel times (Bensen et al., 2007). Preliminary result show very low-velocity zones (100 m/s) and thick sediment layers in most of the former Xochimilco Lake area. This Project was funded by the Secretaria de Ciencia, Tecnología e Innovación (SECITI) of Mexico City. Project SECITI/073/2016.

Field Surveys, IOC Valleys. Volume III, Part I. Cultural Resources Survey, Dry Lake Valley, Nevada.

DTIC Science & Technology

1981-08-01

and from* Catherine Fowler, Great Basin ethnographer and bibliographer. Personnel from Facilitators, Inc. and HDR provided information on contemporary...Caliente (see Figure 1-6 above). Together with Muleshoe Valley to the north, it occupies a surficially closel trough in the Basin and Range physiographic...province of the Great Basin (Eakin, ; Fenneman, 1931). It is bounded on the east by the Burnt Springs, Ely, Highland, and aristol ranges. The Chief

Ancient lakes on Mars?

NASA Technical Reports Server (NTRS)

Goldspiel, J. M.; Squyres, S. W.

1989-01-01

The valley systems in Mars' ancient cratered terrain provide strong evidence for a warmer and wetter climate very early in planetary history. The valley systems in some instances debouch into closed depressions that could have acted as local ponding basins for the flow. A survey of the Martian equatorial region shows that numerous local depressions at the confluence of valley systems exist. These depressions (approximately 100 km) typically are characterized by many valleys flowing into them and few or none flowing out. If ponding did take place, these basin would have contained lakes for some period during Mars' early warmer epoch. Although the collection basins are numerous, location of ones that have not suffered significant subsequent geologic modification is difficult. Some morphologic features suggest that volcanic lavas may have filled them subsequent to any early fluvial activity. Two detailed maps of valley systems and local ponding basins in USGC 1:2,000,000 subquadrangles were completed and a third is in progress. The completed regions are in Mare Tyrrhenum (MC-22 SW) and Margarifter Sinus (MC-19 SE), and the region in progress is in Iapygia (MC-21 NW). On the maps, the valley systems and interpreted margins of ponding basins are indicated. The depressions are of interest for two reasons. First, the depressions were surely the sites in which the materials eroded from the valleys were deposited. Such sediments could preserve important information about the physical conditions at the time of deposition. Second, the sediments could preserve evidence of water-atmosphere interactions during the early period of the Martian climate. Atmospheric carbon dioxide would dissolve in water, and solid carbonate minerals would tend to precipitate out to form carbonate sedimentary deposits. Formation of carbonates in this manner might account for some of the CO2 lost from the early more dense atmosphere.

Antarctic lakes (above and beneath the ice sheet): Analogues for Mars

NASA Technical Reports Server (NTRS)

Rice, J. W., Jr.

1992-01-01

The perennial ice covered lakes of the Antarctic are considered to be excellent analogues to lakes that once existed on Mars. Field studies of ice covered lakes, paleolakes, and polar beaches were conducted in the Bunger Hills Oasis, Eastern Antarctica. These studies are extended to the Dry Valleys, Western Antarctica, and the Arctic. Important distinctions were made between ice covered and non-ice covered bodies of water in terms of the geomorphic signatures produced. The most notable landforms produced by ice covered lakes are ice shoved ridges. These features form discrete segmented ramparts of boulders and sediments pushed up along the shores of lakes and/or seas. Sub-ice lakes have been discovered under the Antarctic ice sheet using radio echo sounding. These lakes occur in regions of low surface slope, low surface accumulations, and low ice velocity, and occupy bedrock hollows. The presence of sub-ice lakes below the Martian polar caps is possible. The discovery of the Antarctic sub-ice lakes raises possibilities concerning Martian lakes and exobiology.

Spatial Heterogeneity of Ice Cover Sediment and Thickness and Its Effects on Photosynthetically Active Radiation and Chlorophyll-a Distribution: Lake Bonney, Antarctica

NASA Astrophysics Data System (ADS)

Obryk, M.; Doran, P. T.; Priscu, J. C.; Morgan-Kiss, R. M.; Siebenaler, A. G.

2012-12-01

The perennially ice-covered lakes in the McMurdo Dry Valleys, Antarctica have been extensively studied under the Long Term Ecological Research project. But sampling has been spatially restricted due to the logistical difficulty of penetrating the 3-6 m of ice cover. The ice covers restrict wind-driven turbulence and its associated mixing of water, resulting in a unique thermal stratification and a strong vertical gradient of salinity. The permanent ice covers also shade the underlying water column, which, in turn, controls photosynthesis. Here, we present results of a three-dimensional record of lake processes obtained with an autonomous underwater vehicle (AUV). The AUV was deployed at West Lake Bonney, located in Taylor Valley, Dry Valleys, to further understand biogeochemical and physical properties of the Dry Valley lakes. The AUV was equipped with depth, conductivity, temperature, under water photosynthetically active radiation (PAR), turbidity, chlorophyll-and-DOM fluorescence, pH, and REDOX sensors. Measurements were taken over the course of two years in a 100 x 100 meter spaced horizontal sampling grid (and 0.2 m vertical resolution). In addition, the AUV measured ice thickness and collected 200 images looking up through the ice, which were used to quantify sediment distribution. Comparison with high-resolution satellite QuickBird imagery demonstrates a strong correlation between aerial sediment distribution and ice cover thickness. Our results are the first to show the spatial heterogeneity of lacustrine ecosystems in the McMurdo Dry Valleys, significantly improving our understanding of lake processes. Surface sediment is responsible for localized thinning of ice cover due to absorption of solar radiation, which in turn increases total available PAR in the water column. Higher PAR values are negatively correlated with chlorophyll-a, presenting a paradox; historically, long-term studies of PAR and chlorophyll-a have shown positive trends. We hypothesized

Space Radar Image of Salt Lake City, Utah

NASA Technical Reports Server (NTRS)

1994-01-01

This radar image of Salt Lake City, Utah, illustrates the different land use patterns that are present in the Utah Valley. Salt Lake City lies between the shores of the Great Salt Lake (the dark area on the left side of the image) and the Wasatch Front Range (the mountains in the upper half of the image). The Salt Lake City area is of great interest to urban planners because of the combination of lake, valley and alpine environments that coexist in the region. Much of the southern shore of the Great Salt Lake is a waterfowl management area. The green grid pattern in the right center of the image is Salt Lake City and its surrounding communities. The Salt Lake City airport is visible as the brown rectangle near the center of the image. Interstate Highway 15 runs from the middle right edge to the upper left of the image. The bright white patch east of Interstate 15 is the downtown area, including Temple Square and the state capitol. The University of Utah campus is the yellowish area that lies at the base of the mountains, east of Temple Square. The large reservoir in the lower left center is a mine tailings pond. The semi-circular feature in the mountains at the bottom edge of the image is the Kennecott Copper Mine. The area shown is 60 kilometers by 40 kilometers (37 miles by 25 miles) and is centered at 40.6 degrees north latitude, 112.0 degrees west longitude. North is toward the upper left. This image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on April 10, 1994. The colors in this image represent the following radar channels and polarizations: red is L-band, horizontally transmitted and received; green is L-band, horizontally transmitted and vertically received; and blue is C-band, horizontally transmitted and vertically received. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth program.

Space Radar Image of Salt Lake City, Utah

NASA Image and Video Library

1999-04-15

This radar image of Salt Lake City, Utah, illustrates the different land use patterns that are present in the Utah Valley. Salt Lake City lies between the shores of the Great Salt Lake (the dark area on the left side of the image) and the Wasatch Front Range (the mountains in the upper half of the image). The Salt Lake City area is of great interest to urban planners because of the combination of lake, valley and alpine environments that coexist in the region. Much of the southern shore of the Great Salt Lake is a waterfowl management area. The green grid pattern in the right center of the image is Salt Lake City and its surrounding communities. The Salt Lake City airport is visible as the brown rectangle near the center of the image. Interstate Highway 15 runs from the middle right edge to the upper left of the image. The bright white patch east of Interstate 15 is the downtown area, including Temple Square and the state capitol. The University of Utah campus is the yellowish area that lies at the base of the mountains, east of Temple Square. The large reservoir in the lower left center is a mine tailings pond. The semi-circular feature in the mountains at the bottom edge of the image is the Kennecott Copper Mine. The area shown is 60 kilometers by 40 kilometers (37 miles by 25 miles) and is centered at 40.6 degrees north latitude, 112.0 degrees west longitude. North is toward the upper left. This image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on April 10, 1994. The colors in this image represent the following radar channels and polarizations: red is L-band, horizontally transmitted and received; green is L-band, horizontally transmitted and vertically received; and blue is C-band, horizontally transmitted and vertically received. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth program. http

The hydrogeology of the Tully Valley, Onondaga County, New York: an overview of research, 1992-2012

USGS Publications Warehouse

Kappel, William M.

2014-01-01

Onondaga Creek begins approximately 15 miles south of Syracuse, New York, and flows north through the Onondaga Indian Nation, then through Syracuse, and finally into Onondaga Lake in central New York. Tully Valley is in the upper part of the Onondaga Creek watershed between U.S. Route 20 and the Valley Heads end moraine near Tully, N.Y. Tully Valley has a history of several unusual hydrogeologic phenomena that affected past land use and the water quality of Onondaga Creek; the phenomena are still present and continue to affect the area today (2014). These phenomena include mud volcanoes or mudboils, landslides, and land-surface subsidence; all are considered to be naturally occurring but may also have been influenced by human activity. The U.S. Geological Survey (USGS), in cooperation with the U.S. Environmental Protection Agency and the Onondaga Lake Partnership, began a study of the Tully Valley mudboils beginning in October 1991 in hopes of understanding (1) what drives mudboil activity in order to remediate mudboil influence on the water quality of Onondaga Creek, and (2) land-surface subsidence issues that have caused a road bridge to collapse, a major pipeline to be rerouted, and threatened nearby homes. Two years into this study, the 1993 Tully Valley landslide occurred just over 1 mile northwest of the mudboils. This earth slump-mud flow was the largest landslide in New York in more than 70 years (Fickies, 1993); this event provided additional insight into the geology and hydrology of the valley. As the study of the Tully Valley mudboils progressed, other unusual hydrogeologic phenomena were found within the Tully Valley and provided the opportunity to perform short-term, small-scale studies, some of which became graduate student theses—Burgmeier (1998), Curran (1999), Morales-Muniz (2000), Baldauf (2003), Epp (2005), Hackett, (2007), Tamulonis (2010), and Sinclair (2013). The unusual geology and hydrology of the Tully Valley, having been investigated for

One hour of catastrophic landscape change in the upper Rhine River valley 9400 years ago

NASA Astrophysics Data System (ADS)

Clague, John; von Poschinger, Andreas; Calhoun, Nancy

2017-04-01

The Flims rockslide, which happened about 9400 years ago in the eastern Swiss Alps, is the largest postglacial terrestrial landslide in Europe. The landslide and the huge secondary mass flow it induced completely changed the floor and lower slopes of the Vorderrhein valley over a distance of several tens of kilometres, probably in one hour or less. The landslide began with the sudden detachment of 10-12 km3 of Jurassic and Cretaceous limestone from the north wall of the Vorderrhein valley. The detached rock mass rapidly fragmented as it accelerated and then struck the Rhein valley floor and the opposing valley wall. Tongues of debris traveled up and down the Vorderrhein. The impact liquefied approximately 1 km3 of valley-fill sediments, mainly fluvial and deltaic gravel and sand. The liquefied sediment moved as a slurry - the Bonaduz gravel - tens of kilometres downvalley from the impact site, carrying huge fragments of rockslide debris that became stranded on the valley floor, forming hills termed 'tumas'. Part of the flow was deflected by a cross-valley barrier and flowed 16 km up the Hinterrhein valley (the main tributary of the Vorderrhein), carrying tumas with it. Bonaduz gravel is >65 m thick and fines upward from massive sandy cobble gravel at its base to silty sand at its top. Sedimentologic and geomorphic evidence indicates that the liquefied sediment was transported as a hyperconcentated flow, possibly above a basal carpet of coarse diamictic sediment that behaved as a debris flow. The large amount of water involved in the Bonaduz flow indicates that at least part of the Flims rockslide entered a former lake in Vorderrhein valley. The rockslide debris impounded the Vorderrhein and formed Lake Ilanz, which persisted for decades or longer before the dam was breached in series of outburst floods. These floods further changed the valley floor below the downstream limit of the landslide. Today, Vorderrhein flows in a spectacular 8-km-long gorge incised up to

Neodymium Isotope Variations in Late Quaternary Carbonate Lake Sediments, Owens Valley, Eastern California.

NASA Astrophysics Data System (ADS)

Minervini, J. M.; Stewart, B. W.

2001-12-01

Owens Lake is situated in a mostly-closed basin fed by water and sediments derived primarily from the eastern Sierra Nevada range. Chemical and sedimentological variations in USGS Owens Lake Core OL-92, which extends back 800 ka, have been shown to be sensitive tracers of Great Basin paleoclimate. Here we report preliminary neodymium (Nd) isotope data from core OL-92 to investigate sediment provenance, the chemical behavior of rare earth elements (REE) in non-marine systems, and possible climate-related shifts in weathering patterns of the eastern Sierra Nevada during the last glacial-interglacial transition. Neodymium isotopic analyses were carried out on the carbonate fraction of sediment samples ranging in age from 16.8 to 6.9 ka from Owens Lake core OL-92. Samples were treated with ammonium acetate to remove exchangeable cations from coexisting silicate material, and subsequently leached with 8% acetic acid to dissolve carbonate minerals. Based on the mass of sediment leached with acetic acid, the fraction of carbonate (relative to clastic silicate material) increases from 6.6 to 66.5% over the 10 ka period represented by these samples. This increase in carbonate reflects desiccation of the Owens Lake basin; as streamwater flow is reduced, the lake spends a greater proportion of its time saturated in carbonate minerals, and clastic input might also be reduced. Concentrations of Nd in Owens Lake carbonate range from 7 to 170 ppm, values that are 2-1000 times higher than marine planktonic foraminifera (e.g., Vance and Burton, 1999, EPSL 173, 365). In general, high concentrations of Nd in Owens Lake carbonate are associated with older sediment samples with lower carbonate fractions. The decrease in Nd concentration over this time period could be a result of extraction of Nd from lake waters by precipitation of carbonate as desiccation proceeded. Epsilon-Nd values of Owens Lake carbonate range from -5.3 to -6.5, and are consistent with eastern Sierra Nevada

Brief description as of April, 1968, of the geology and hydrology of the Lake Minnequa area, Pueblo, Colorado, and suggested solutions for trouble caused by a high water table

USGS Publications Warehouse

Scott, Glenn R.

1972-01-01

Lake Minnequa lies in a poorly drained broad upland buried valley west of the valley of Salt Creek. Immediately north of Lake Minnequa the buried valley is sharply constricted in sees. 11 and 12, T. 21 S., R. 65 W., where it is entrenched in a buried ridge of bedrock (see geologic map).  The bedrock throughout the buried valley is composed of calcareous shale, limestone, and chalk of the Smoky Hill Shale Member of the Niobrara Formation.  These beds are relatively impermeable to the flow of ground water, but contribute large quantities of sodium sulfate to both the surface and ground water.

Holocene depositional environments and surface-level changes at Lake Fryxell, Antarctica

USGS Publications Warehouse

Whittaker, T.E.; Hall, B.L.; Hendy, C.H.; Spaulding, S.A.

2008-01-01

We report on Holocene surface-level variations of Lake Fryxell, Antarctica, as determined from multi-proxy analyses of 18 sediment cores. During this time accumulating sediments were predominantly aeolian sand with algal and carbonate laminae. Based on stratigraphy, mineralogy and diatom assemblages we suggest some carbonate laminae were deposited when lake level dropped, leading to concentration and subsequent precipitation of salts. Although lake level appears to have remained relatively stable throughout the Holocene, minor (<4.5 m below present) lowstands occurred at approximately 6400, 4700, 3800 and ??? 1600 cal. yr BP. The stability of Lake Fryxell during the Holocene contrasts with large-scale variability at other Dry Valleys lakes (eg, Lake Vanda) and with suggestions from chemical diffusion models of a near-desiccation at ???1200 cal. yr BP. The reason for the comparative stability of Lake Fryxell is uncertain, but may be the result of basin morphology and the number, aspect and proximity of meltwater sources. ?? 2008 SAGE Publications.

Comparison of Skylab and LANDSAT images for geologic mapping in Northern Arizona. [Shivwits Plateau, Verde Valley, Coconino Plateau, and Red Lake in Arizona

NASA Technical Reports Server (NTRS)

Goetz, A. F. H. (Principal Investigator); Abrams, M. J.; Gillespie, A. R.; Siegal, B. S.; Elston, D. P.; Lucchitta, I.; Wu, S. S. C.; Sanchez, A.; Dipaola, W. D.; Schafer, F. J.

1976-01-01

The author has identified the following significant results. It was found that based on resolution, the Skylab S190A products were superior to LANDSAT images. Based on measurements of shoreline features in Lake Mead S190A images had 1.5 - 3 times greater resolution than LANDSAT. In general, the higher resolution of the Skylab data yielded better discrimination among rock units, but in the case of structural features, lower sun angle LANDSAT images (50 deg) were superior to higher sun angle Skylab images (77 deg). The most valuable advantage of the Skylab over the LANDSAT image products is the capability of producing stereo images. Field spectral reflectance measurements on the Coconino Plateau were made in an effort to determine the best spectral band for discrimination of the six geologic units in question, and these bands were 1.3, 1.2, 1.0, and 0.5 microns. The EREP multispectral scanner yielded data with a low signal to noise ratio which limited its usefulness for image enhancement work. Sites that were studied in Arizona were Shivwits Plateau, Verde Valley, Coconino Plateau, and Red Lake. Thematic maps produced by the three classification algorithms analyzed were not as accurate as the maps produced by photointerpretation of composites of enhanced images.

High-resolution aeromagnetic survey of the Mono Basin-Long Valley Caldera region, California

NASA Astrophysics Data System (ADS)

Ponce, D. A.; Mangan, M.; McPhee, D.

2013-12-01

A new high-resolution aeromagnetic survey of the Mono Basin-Long Valley Caldera region greatly enhances previous magnetic interpretations that were based on older, low-resolution, and regional aeromagnetic data sets and provides new insights into volcano-tectonic processes. The surveyed area covers a 8,750 km2 NNW-trending swath situated between the Sierra Nevada to the west and the Basin and Range Province to the east. The surveyed area includes the volcanic centers of Mono Lake, Mono-Inyo Craters, Mammoth Mountain, Devils Postpile, and Long Valley Caldera. The NW-trending eastern Sierra frontal fault zone crosses through the study area, including the active Mono Lake, Silver Lake, Hartley Springs, Laurel Creek, and Hilton Creek faults. Over 6,000 line-kilometers of aeromagnetic data were collected at a constant terrain clearance of 150 m, a flight-line spacing of 400 m, and a tie-line spacing of 4 km. Data were collected via helicopter with an attached stinger housing a magnetic sensor using a Scintrex CS-3 cesium magnetometer. In the northern part of the survey area, data improve the magnetic resolution of the individual domes and coulees along Mono Craters and a circular shaped magnetic anomaly that coincides with a poorly defined ring fracture mapped by Kistler (1966). Here, aeromagnetic data combined with other geophysical data suggests that Mono Craters may have preferentially followed a pre-existing plutonic basement feature that may have controlled the sickle shape of the volcanic chain. In the northeastern part of the survey, aeromagnetic data reveal a linear magnetic anomaly that correlates with and extends a mapped fault. In the southern part of the survey, in the Sierra Nevada block just south of Long Valley Caldera, aeromagnetic anomalies correlate with NNW-trending Sierran frontal faults rather than to linear NNE-trends observed in recent seismicity over the last 30 years. These data provide an important framework for the further analysis of the

Ground water in Dale Valley, New York

USGS Publications Warehouse

Randall, Allan D.

1979-01-01

Dale Valley is a broad valley segment, enlarged by glacial erosion, at the headwaters of Little Tonawanda Creek near Warsaw , New York. A thin, shallow alluvial aquifer immediately underlies the valley floor but is little used. A deeper gravel aquifer, buried beneath many feet of lake deposits, is tapped by several industrial wells. A finite-difference digital model treated the deep aquifer as two-dimensional with recharge and discharge through a confining layer. It was calibrated by simulating (1) natural conditions, (2) an 18-day aquifer test, and (3) 91 days of well-field operation. Streamflow records and model simulations suggest that in moderately wet years such as 1974, a demand of 750 gallons per minute could be met by withdrawal from the creek and from the aquifer without excessive drawdown at production wells or existing domestic wells. With reasonable but unverified model adjustments to simulate an unusually dry year, the model predicts that a demand of 600 gallons per minute could be met from the same sources. Water high in chloride has migrated from bedrock into parts of the deep aquifer. Industrial pumpage, faults in the bedrock, and the natural flow system may be responsible. (Woodard-USGS)

The Role of Trans Tensional Structures and Lake Mead Reservoir in Groundwater Flow in Black Canyon, Lake Mead National Recreation Area, NV-AZ

NASA Astrophysics Data System (ADS)

Justet, L.; Beard, S.

2010-12-01

Hot springs and seeps discharging into Black Canyon (BC) along the Colorado River in north Colorado River Valley (CRV) support endemic riparian ecosystems in the Lake Mead National Recreation Area. Increases in groundwater development in southern NV and northwestern AZ may impact spring discharge. Sources of spring discharge in BC were evaluated using geochemical methods. Kinematic analysis and geologic mapping of structures associated with BC springs were used to evaluate structural controls on groundwater flow in BC. Geochemical analysis indicates groundwater discharge near Hoover Dam (HD) and along the faulted edge of the Boulder City Pluton is derived from Lake Mead, high δ87Sr Proterozoic or Tertiary crystalline rock and, possibly, Tertiary sedimentary rock. Reducing conditions indicated by 234U/238U and δ34S concentrations suggest the groundwater is confined and/or derived from greater depths while carbon isotopes indicate the groundwater is old. Lighter δD and δO-18, modern tritium concentrations, post-Dam U disequilibrium ages, and occurrence of anthropogenic perchlorate support the presence of a young Lake Mead component. South of the pluton, the Lake Mead component is absent. More oxidizing conditions in this part of BC, indicated by the U and S isotope concentrations, suggest the groundwater is less confined and/or derived from shallower depths compared to groundwater discharging near HD. Older apparent groundwater ages and heavier δD and δO-18 values south of the pluton indicate slower flow paths from a lower elevation or latitude source. Clarifying the nature of groundwater flow in eastern NV, the analyses indicate that hydraulic connection between the regional carbonate aquifer and BC is unlikely. Instead, the data indicate sources of BC springs are derived relatively locally in CRV and, possibly, south Lake Mead Valley. Results of the geologic and kinematic analyses indicate faults that formed from the interaction of E-W extension related to

Dynamic deformations of shallow sediments in the Valley of Mexico, Part II: Single-station estimates

USGS Publications Warehouse

Singh, S.K.; Santoyo, M.; Bodin, P.; Gomberg, J.

1997-01-01

We develop simple relations to estimate dynamic displacement gradients (and hence the strains and rotations) during earthquakes in the lake-bed zone of the Valley of Mexico, where the presence of low-velocity, high-water content clays in the uppermost layers cause dramatic amplification of seismic waves and large strains. The study uses results from a companion article (Bodin et al., 1997) in which the data from an array at Roma, a lake-bed site, were analyzed to obtain displacement gradients. In this article, we find that the deformations at other lake-bed sites may differ from those at Roma by a factor of 2 to 3. More accurate estimates of the dominant components of the deformation at an individual instrumented lake-bed site may be obtained from the maximum horizontal velocity and displacement, ??max and umax, at the surface. The maximum surface strain ??max is related to ??max by ??max = ??max/C, with C ??? 0.6 km/sec. From the analysis of data from sites equipped with surface and borehole sensors, we find that the vertical gradient of peak horizontal displacement (??umax/??z) computed from sensors at 0 and 30 m equals (umax)z = 0/??z, ??z = 30 m, within a factor of 1.5. This is the largest gradient component, and the latter simple relation permits its estimation from surface records alone. The observed profiles of umax versus depth suggest a larger gradient in some depth range of 10 to 20 m, in agreement with synthetic calculations presented in Bodin et al. (1997). From the free-field recordings of the 19 September 1985 Michoacan earthquake, we estimate a maximum surface strain, ??max, between 0.05% and 0.11%, and a lower bound for the peak vertical gradient (??umax/??z) between 0.3% and 1.3%. This implies that (1) the extensive failure of water pipe joints during the Michoacan earthquake in the valley occurred at axial strains of about 0.1%, not 0.38% as previously reported, and (2) the clays of the valley behave almost linearly even at shear strain of about 1

Characteristics of a Recent and Prehistoric Landslides in the Pine River Valley, BC: a Mapping Effort

NASA Astrophysics Data System (ADS)

Heijenk, R.; Geertsema, M.; Miller, B.; de Jong, S. M.

2015-12-01

Spreads and other low gradient landslides are common in glacial lake sediments in north eastern British Columbia. Both pre and post glacial lake sediments, largely derived from shale bedrock are susceptible to low-gradient landslides. Bank erosion by rivers and streams and high pore pressures, have contributed to the landslides. We used LiDAR for mapping the extent of the glaciolacustrine sediments and map and characterise landslides in the Pine River valley, near Chetwynd, British Columbia. We included metrics such as travel angle, length, area, and elevation to distinguish rotational and translational landslides. We mapped 45 landslides in the Pine River valley distinguishing between rotational and translational landslides. The rotational landslides commonly have a smaller area and smaller travel length than translational landslides. Most rotational slides involved overlying alluvial fans, while most translational slides involved terraces.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dunkelman, T.J.; Karson, J.A.; Rosendahl, B.R.

Multifold seismic reflection and geologic mapping in part of the eastern branch of the East African Rift system of northern Kenya reveal a major rift structure containing at least 3 km of Neogene sediment fill beneath Lake Turkana. This includes a series of half-graben basins, with centrally located quaternary volcanic centers, which are linked end-to-end by structural accommodation zones. Whereas the geometry of rifting is similar to that of the nonvolcanic western branch of the East African Rift system, the Turkana half-grabens are much smaller and may reflect extension of a thinner lithosphere or development of more closely spaced fracturemore » patterns during rift evolution, or both.« less

FOP 2012 stop, Honey Lake fault, Doyle, CA

USGS Publications Warehouse

Gold, Ryan; Briggs, Richard W.; Crone, Anthony; Angster, Steve; Seitz, Gordon G.

2012-01-01

The Honey Lake fault system (HLFS) strikes north-northwestward across Long Valley near Doyle, CA and is part of a network of active, dextral strike-slip faults in the northern Walker Lane (Figure 1). Geologic investigations of a right-laterally offset terrace riser along the north bank of Long Valley Creek, which we refer to as site 1 (Figure 2), indicate a latest Quaternary slip rate of 1.1-2. 6 mm/yr [Wills and Borchardt, 1993] and 1.7 ± 0.6 mm/yr [Turner and others, 2008] (Table 1). These studies also document evidence of at least four post-6.8 ka surface-rupturing earthquakes at this site.

Starting Where the People Are: The African Medical and Research Foundation (AMREF). Carnegie Quarterly, Volume XXXII, Number 2.

ERIC Educational Resources Information Center

Carnegie Quarterly, 1987

1987-01-01

This issue of the "Carnegie Quarterly" describes three projects that are being conducted by the African Medical and Research Foundation (AMREF). The projects are the following: (1) building community participation in health care at Lake Kenyatta; (2) the role of community education in disease control among the Turkana people at…

Structural and lithologic study of northern coast ranges and Sacramento Valley, California

NASA Technical Reports Server (NTRS)

Rich, E. I. (Principal Investigator)

1973-01-01

The author has identified the following significant results. Analysis of ERTS-1 imagery of the Northern California Coast Ranges has disclosed a potential relation between a heretofore unrecognized fracture system and known deposits of mercury and geothermally active areas in the Coast Range and between oil and gas fields in the Sacramento Valley. Three potentially important systems of linear elements within the Coast Ranges, detected on ERTS-1 imagery, may represent fault systems or zones of shearing because topographic offset and stratigraph disruption can be seen along one or two of the lineations. One of the systems in subparallel to the San Andreas fault and is confined to the Pacific Coastal Belt. Another set is confined to the central core of the Coast Ranges. The third set of linear features (Valley System) has not heretofore been recognized. Some of the known mercury deposits and geothermally active areas near Clear Lake, in the Coast Ranges, are along the Valley System or at the intersection of the Central and Valley Systems. The plotted locations of some of the oil and gas fields in the Sacramento Valley are associated with the Valley and/or Central Systems. If these relations prove reliable, the ERTS-1 imagery may prove to be an extremely useful exploration tool.

Heterogeneous Status of Glacial Terminal-Contacted Lakes in Himalayas Due to Different Geomorphology and Glacier Characters

NASA Astrophysics Data System (ADS)

Liu, Q.; Nie, Y.; Liu, S.

2014-12-01

Widespread expanding of glacial lakes around the Himalayas, which has led (or will lead) to hazard risks in their downstream valleys due to the potential glacial outburst flood (GLOF), has been widely reported during the past decades. Among all type of glacial lakes, those lakes contacted with the terminals of modern glaciers are generally found experienced most remarkable area increases. That is mostly due to the coupled processes, such as calving, between the lake growths and ice tongue retreats. Thermal absorption and convection of lake water are important for calving at the ice cliff or sub-marine melting under the supra-ponded water bodies. Currently, many larger moraine dammed lakes, e. g., Imja Tsho (Nepal) and Longbasaba Lake (China), are observed undergoing remarkable growths and synchronically with the rapid ice margin collapses due to calving. Some newly formed and rapidly growing supraglacial lakes are also identified on the debris-covered region of Himalayan glaciers, e. g., the Rongbuk Glacier (China), Ngozumpa Glacier (Nepal) and Thorthormi Glacier (Butan), which are speculated to experience accelerated expanding in the near future and finally developing as bigger terminal-calving lakes. However, not all such lake-glacier systems present the same scenes. After experienced the phases of rapid lake growth and terminal retreat, despite the contacting and calving still existing, the positions of the calving lines may be balanced by the positive advances of the ice tongue. We have observed several lakes with stagnation of growth or even shrinkage in lake area as the advance of the calving ice margin. The heterogeneous status of these ice-contacted glacial lakes are mainly due to the different local geomorphology (e. g., slope, lake-basin shape and valley aspect) and glacier characters (e. g., debris cover, velocity and mass balance). These related factors are important for both the prediction of lake and glacier changes and the evaluation of GLOF hazards

Earth observations during Space Shuttle flight STS-41 - Discovery's mission to planet earth

NASA Technical Reports Server (NTRS)

Lulla, Kamlesh P.; Helfert, Michael R.; Amsbury, David L.; Whitehead, Victor S.; Richards, Richard N.; Cabana, Robert D.; Shepherd, William M.; Akers, Thomas D.; Melnick, Bruce E.

1991-01-01

An overview of space flight STS-41 is presented, including personal observations and comments by the mission astronauts. The crew deployed the Ulysses spacecraft to study the polar regions of the sun and the interplanetary space above the poles. Environmental observations, including those of Lake Turkana, Lake Chad, biomass burning in Madagascar and Argentina, and circular features in Yucatan are described. Observations that include landforms and geology, continental sedimentation, desert landscapes, and river morphology are discussed.

Accumulation of fossil fuels and metallic minerals in active and ancient rift lakes

USGS Publications Warehouse

Robbins, E.I.

1983-01-01

A study of active and ancient rift systems around the world suggests that accumulations of fossil fuels and metallic minerals are related to the interactions of processes that form rift valleys with those that take place in and around rift lakes. The deposition of the precursors of petroleum, gas, oil shale, coal, phosphate, barite, Cu-Pb-Zn sulfides, and uranium begins with erosion of uplifted areas, and the consequent input of abundant nutrients and solute loads into swamps and tectonic lakes. Hot springs and volcanism add other nutrients and solutes. The resulting high biological productivity creates oxidized/reduced interfaces, and anoxic and H2S-rich bottom waters which preserves metal-bearing organic tissues and horizons. In the depositional phases, the fine-grained lake deposits are in contact with coarse-grained beach, delta, river, talus, and alluvial fan deposits. Earthquake-induced turbidites also are common coarse-grained deposits of rift lakes. Postdepositional processes in rifts include high heat flow and a resulting concentration of the organic and metallic components that were dispersed throughout the lakebeds. Postdepositional faulting brings organic- and metal-rich sourcebeds in contact with coarse-grained host and reservoir rocks. A suite of potentially economic deposits is therefore a characteristic of rift valleys. ?? 1983.

Accumulation of fossil fuels and metallic minerals in active and ancient rift lakes

NASA Astrophysics Data System (ADS)

Robbins, Eleanora Iberall

1983-05-01

A study of active and ancient rift systems around the world suggests that accumulations of fossil fuels and metallic minerals are related to the interactions of processes that form rift valleys with those that take place in and around rift lakes. The deposition of the precursors of petroleum, gas, oil shale, coal, phosphate, barite, Cu-Pb-Zn sulfides, and uranium begins with erosion of uplifted areas, and the consequent input of abundant nutrients and solute loads into swamps and tectonic lakes. Hot springs and volcanism add other nutrients and solutes. The resulting high biological productivity creates oxidized/reduced interfaces, and anoxic and H 2S-rich bottom waters which preserves metal-bearing organic tissues and horizons. In the depositional phases, the fine-grained lake deposits are in contact with coarse-grained beach, delta, river, talus, and alluvial fan deposits. Earthquake-induced turbidites also are common coarse-grained deposits of rift lakes. Postdepositional processes in rifts include high heat flow and a resulting concentration of the organic and metallic components that were dispersed throughout the lakebeds. Postdepositional faulting brings organic- and metal-rich sourcebeds in contact with coarse-grained host and reservoir rocks. A suite of potentially economic deposits is therefore a characteristic of rift valleys.

Ground-water flow and quality, and geochemical processes, in Indian Wells Valley, Kern, Inyo, and San Bernardino counties, California, 1987-88

USGS Publications Warehouse

Berenbrock, Charles; Schroeder, R.A.

1994-01-01

An existing water-quality data base for the 300- square-mile Indian Wells Valley was updated by means of chemical and isotopic analysis of ground water. The wide range in measured concentrations of major ions and of minor constituents such as fluoride, borate, nitrate, manganese, and iron is attributed to geochemical reactions within lacustrine deposits of the valley floor. These reactions include sulfate reduction accompanied by generation of alkalinity, precipitation of carbonates, exchange of aqueous alkaline-earth ions for sodium on clays, and dissolution of evaporite minerals. Differences in timing and location of recharge, which originates primarily in the Sierra Nevada to the west, and evapotranspiration from a shallow water table on the valley floor result in a wide range in ratios of stable hydrogen and oxygen isotopes. As ground water moves from alluvium into lustrine deposits of the ancestral China Lake, dissolved-solids concen- trations increase from about 200 to more than 1,000 milligrams per liter; further large increases to several thousand milligrams per liter occur beneath the China Lake playa. Historical data show an increase during the past 20 years in dissolved- solids concentration in several wells in the principal pumping areas at Ridgecrest and between Ridgecrest and Inyokern. The increase apparently is caused by induced flow of saline ground water from nearby China, Mirror, and Satellite Lakes. A simplified advective-transport model calculates ground-water travel times between parts of the valley of at least several thousand years, indi- cating the presence of old ground water. A local ground-water line and an evaporation line estimated using isotopic data from the China Lake area inter- sect at a delta-deuterium value of about -125 permil. This indicates that late Pleistocene recharge was 15 to 35 permil more negative than current recharge.

Glacial Lake Lind, Wisconsin and Minnesota

USGS Publications Warehouse

Johnson, M.D.; Addis, K.L.; Ferber, L.R.; Hemstad, C.B.; Meyer, G.N.; Komai, L.T.

1999-01-01

Glacial Lake Lind developed in the pre-late Wisconsinan St. Croix River valley, Minnesota and Wisconsin, and lasted more than 1000 yr during the retreat of the Superior lobe at the end of the Wisconsinan glaciation. Lake Lind sediment consists primarily of red varved silt and clay, but also includes mud-flow deposits, nearshore silt (penecontemporaneously deformed in places), nearshore rippled sand, and deltaic sand. Lake Lind varved red clay is not part of glacial Lake Grantsburg, as suggested by earlier authors, because the red varves are separated from overlying glacial Lake Grantsburg silt and clay by a unit of deltaic and fluvial sand. Furthermore, varve correlations indicate that the base of the red varves is younger to the north, showing that the basin expanded as the Superior lobe retreated and was not a lake basin dammed to the southwest by the advancing Grantsburg sublobe. Varve correlations indicate that the Superior lobe retreated at a rate of about 200 m/yr. Uniform winter-clay thickness throughout most of the varve couplets suggests thermal stratification in the lake with clay trapped in the epilimnion; some clay would exit the lake at the outlet prior to winter freeze. Zones of thicker winter-clay layers, in places associated with mud-flow layers, indicate outlet incision, lake-level fall, and shoreline erosion and resuspension of lake clay. The most likely outlet for glacial Lake Lind was in the southwest part of the lake near the present site of Minneapolis, Minnesota. Nearshore sediment indicates that the lake level of glacial Lake Lind was around 280 m. The elevation of the base of the Lake Lind sediments indicates water depth was 20 to 55 m. Evidence in the southern part of the lake basin suggests that the Superior lobe readvanced at least once during the early stages of glacial Lake Lind. Lake Lind ended not by drainage but by being filled in by prograding deltas and outwash plains composed of sand derived from the retreating Superior lobe. It

Last glacial maximum and Holocene lake levels of Owens Lake, eastern California, USA

USGS Publications Warehouse

Bacon, S.N.; Burke, R.M.; Pezzopane, S.K.; Jayko, A.S.

2006-01-01

Stratigraphic investigations of fluvio-deltaic and lacustrine sediments exposed in stream cuts, quarry walls, and deep trenches east of the Sierra Nevada in Owens Valley near Lone Pine, California have enabled the reconstruction of pluvial Owens Lake level oscillations. Age control for these sediments is from 22 radiocarbon (14C) dates and the identification and stratigraphic correlation of a tephra, which when plotted as a function of age versus altitude, define numerous oscillations in the level of pluvial Owens Lake during the latest Pleistocene and early Holocene. We have constructed a lake-level altitude curve for the time interval ???27,000 cal yr BP to present that is based on the integration of this new stratigraphic analysis with published surface stratigraphic data and subsurface core data. Pluvial Owens Lake regressed from its latest Pleistocene highstands from ???27,000 to ???15,300 cal yr BP, as recorded by ???15 m of down cutting of the sill from the altitudes of ???1160 to 1145 m. By ???11,600 cal yr BP, the lake had dropped ???45 m from the 1145 m sill. This lowstand was followed by an early Holocene transgression that attained a highstand near 1135 m before dropping to 1120 m at 7860-7650 cal yr BP that had not been recognized in earlier studies. The lake then lowered another ???30 m to shallow and near desiccation levels between ???6850 and 4300 cal yr BP. Fluvial cut-and-fill relations north of Lone Pine and well-preserved shoreline features at ???1108 m indicate a minor lake-level rise after 4300 cal yr BP, followed by alkaline and shallow conditions during the latest Holocene. The new latest Quaternary lake-level record of pluvial Owens Lake offers insight to the hydrologic balance along the east side of the southern Sierra Nevada and will assist regional paleoclimatic models for the western Basin and Range. ?? 2005 Elsevier Ltd. All rights reserved.

Development of an Interactive Shoreline Management Tool for the Lower Wood River Valley, Oregon - Phase I: Stage-Volume and Stage-Area Relations

USGS Publications Warehouse

Haluska, Tana L.; Snyder, Daniel T.

2007-01-01

This report presents the parcel and inundation area geographic information system (GIS) layers for various surface-water stages. It also presents data tables containing the water stage, inundation area, and water volume relations developed from analysis of detailed land surface elevation derived from Light Detection and Ranging (LiDAR) data recently collected for the Wood River Valley at the northern margin of Agency Lake in Klamath County, Oregon. Former shoreline wetlands that have been cut off from Upper Klamath and Agency Lakes by dikes might in the future be reconnected to Upper Klamath and Agency Lakes by breaching the dikes. Issues of interest associated with restoring wetlands in this way include the area that will be inundated, the volume of water that may be stored, the change in wetland habitat, and the variation in these characteristics as surface-water stage is changed. Products from this analysis can assist water managers in assessing the effect of breaching dikes and changing surface-water stage. The study area is in the approximate former northern margins of Upper Klamath and Agency Lakes in the Wood River Valley.

Neogene Rift Propagation of the East African Rift System (EARS) into Central Africa and its Implications: Tectonic, Topographic and Geomorphic Impacts of the Luangwa and Luapula Rift Valleys on the Upper Congo Drainage Basin, Lake Bangweulu Wetlands and the Development of the Diffuse Southwestern Tip of the EARS.

NASA Astrophysics Data System (ADS)

Daly, M. C.; Watts, A. B.

2017-12-01

Integration of geomorphology, seismic reflection and gravity data, seismicity, DEM analysis and modelling defines a zone of NE/SW trending rifts extending into Central and SW Africa, orthogonal to the conventionally defined East African Rift System (EARS). These large-scale tectonic features have a relatively low level of seismicity and volcanism compared to the EARS, yet they generate significant topography and control the upper Congo drainage basin. They may also represent the beginning of an active but diffuse plate boundary developing to the southwest across Central Africa. The dominant feature of this broad zone is the Luangwa Rift Valley of eastern Zambia. Seismic reflection data show the Luangwa Rift developed as a thick ( 5km) Permo-Triassic basin. Inverted in the Mesozoic, it then experienced major Neogene extensional reactivation. The latter resulted in today's major border faults of varying polarity, with fault plane escarpments of up to 1000m, and associated rift flank uplifts that elevate the Central African plateau surface by 200 m. Late Miocene alluvial fans indicate a minimum age for the initiation of reactivation. Although having similar structural features to the EARS, the Luangwa Rift has a lower level of active seismicity and volcanism. 400 km northwest of the Luangwa, the north/south Luapula rift valley passes into the NE trending Mweru and Mweru Wantipa rift lakes. Pronounced border faults and fault terraces mark the NW and SE margins of these shallow lakes. Between the Luangwa and Luapula rift valleys lies the extensive upper Congo drainage basin of the Chambeshi river and the Lake Bangweulu wetlands. DEM mapping of topography from the Luangwa rift to the Luapula-Mweru Wantipa rift shows a low amplitude, large wavelength flexure of the Central African plateau surface compatible with an effective elastic thickness of 35 km. This regional warping controls the location and shape of the Chambeshi drainage basin and the Lake Bangweulu Wetlands

Hydrogeologic Framework and Ground-Water Budget of the Spokane Valley-Rathdrum Prairie Aquifer, Spokane County, Washington, and Bonner and Kootenai Counties, Idaho

USGS Publications Warehouse

Kahle, Sue C.; Bartolino, James R.

2007-01-01

The U.S. Geological Survey, in cooperation with the Idaho Department of Water Resources and Washington State Department of Ecology, investigated the hydrogeologic framework and ground-water budget of the Spokane Valley-Rathdrum Prairie (SVRP) aquifer located in northern Idaho and northeastern Washington. Descriptions of the hydrogeologic framework, water-budget components, and further data needs are provided. The SVRP aquifer, which covers about 370 square miles including the Rathdrum Prairie, Idaho, and the Spokane Valley and Hillyard Trough, Washington, is the sole source of drinking water for more than 500,000 residents. Continued growth, water-management issues, and potential effects on water availability and water quality in the aquifer and in the Spokane and Little Spokane Rivers have illustrated the need to better understand and manage the region's water resources. The SVRP aquifer consists mostly of gravels, cobbles, and boulders - deposited during a series of outburst floods resulting from repeated collapse of the ice dam that impounded ancient Glacial Lake Missoula. In most places, the SVRP aquifer is bounded by bedrock of pre-Tertiary granite or metasedimentary rocks, or Miocene basalt and associated sedimentary deposits. Discontinuous fine-grained layers are scattered throughout the SVRP aquifer at considerably different altitudes and with considerably different thicknesses. In the Hillyard Trough and the Little Spokane River Arm of the aquifer, a massive fine-grained layer with a top altitude ranging from about 1,500 to 1,700 feet and thickness ranging from about 100 to 200 feet separates the aquifer into upper and lower units. Most of the Spokane Valley part of the aquifer is devoid of fine-grained layers except near the margins of the valley and near the mouths of lakes. In the Rathdrum Prairie, multiple fine-grained layers are scattered throughout the aquifer with top altitudes ranging from about 1,700 to 2,400 feet with thicknesses ranging from 1

Catastrophic ice lake collapse in Aram Chaos, Mars

NASA Astrophysics Data System (ADS)

Roda, Manuel; Kleinhans, Maarten G.; Zegers, Tanja E.; Oosthoek, Jelmer H. P.

2014-07-01

Hesperian chaotic terrains have been recognized as the source of outflow channels formed by catastrophic outflows. Four main scenarios have been proposed for the formation of chaotic terrains that involve different amounts of water and single or multiple outflow events. Here, we test these scenarios with morphological and structural analyses of imagery and elevation data for Aram Chaos in conjunction with numerical modeling of the morphological evolution of the catastrophic carving of the outflow valley. The morphological and geological analyses of Aram Chaos suggest large-scale collapse and subsidence (1500 m) of the entire area, which is consistent with a massive expulsion of liquid water from the subsurface in one single event. The combined observations suggest a complex process starting with the outflow of water from two small channels, followed by continuous groundwater sapping and headward erosion and ending with a catastrophic lake rim collapse and carving of the Aram Valley, which is synchronous with the 2.5 Ga stage of the Ares Vallis formation. The water volume and formative time scale required to carve the Aram channels indicate that a single, rapid (maximum tens of days) and catastrophic (flood volume of 9.3 × 104 km3) event carved the outflow channel. We conclude that a sub-ice lake collapse model can best explain the features of the Aram Chaos Valley system as well as the time scale required for its formation.

A conceptual geochemical model of the geothermal system at Surprise Valley, CA

NASA Astrophysics Data System (ADS)

Fowler, Andrew P. G.; Ferguson, Colin; Cantwell, Carolyn A.; Zierenberg, Robert A.; McClain, James; Spycher, Nicolas; Dobson, Patrick

2018-03-01

Characterizing the geothermal system at Surprise Valley (SV), northeastern California, is important for determining the sustainability of the energy resource, and mitigating hazards associated with hydrothermal eruptions that last occurred in 1951. Previous geochemical studies of the area attempted to reconcile different hot spring compositions on the western and eastern sides of the valley using scenarios of dilution, equilibration at low temperatures, surface evaporation, and differences in rock type along flow paths. These models were primarily supported using classical geothermometry methods, and generally assumed that fluids in the Lake City mud volcano area on the western side of the valley best reflect the composition of a deep geothermal fluid. In this contribution, we address controls on hot spring compositions using a different suite of geochemical tools, including optimized multicomponent geochemistry (GeoT) models, hot spring fluid major and trace element measurements, mineralogical observations, and stable isotope measurements of hot spring fluids and precipitated carbonates. We synthesize the results into a conceptual geochemical model of the Surprise Valley geothermal system, and show that high-temperature (quartz, Na/K, Na/K/Ca) classical geothermometers fail to predict maximum subsurface temperatures because fluids re-equilibrated at progressively lower temperatures during outflow, including in the Lake City area. We propose a model where hot spring fluids originate as a mixture between a deep thermal brine and modern meteoric fluids, with a seasonally variable mixing ratio. The deep brine has deuterium values at least 3 to 4‰ lighter than any known groundwater or high-elevation snow previously measured in and adjacent to SV, suggesting it was recharged during the Pleistocene when meteoric fluids had lower deuterium values. The deuterium values and compositional characteristics of the deep brine have only been identified in thermal springs and

Pliocene bats (Chiroptera) from Kanapoi, Turkana Basin, Kenya.

PubMed

Gunnell, Gregg F; Manthi, Fredrick K

2018-04-05

Fossil bats from the Pliocene of Africa are extremely rare, especially in East Africa where meager records have been reported only from two localities in the Omo River Basin Shungura Formation and from a scattering of localities in the Afar Depression, both in Ethiopia. Here we report on a diverse assemblage of bats from Kanapoi in the Turkana Basin that date to approximately 4.19 million years ago. The Kanapoi bat community consists of four different species of fruit bats including a new genus and two new species as well as five species of echolocating bats, the most common of which are two new species of the molossid genus Mops. Additionally, among the echolocating bats, a new species of the emballonurid Saccolaimus is documented at Kanapoi along with an additional Saccolaimus species and a potentially new species of the nycterid Nycteris. Compared to other East African Pliocene bat assemblages, the Kanapoi bat community is unique in preserving molossids and curiously lacks any evidence of cave dwelling bats like rhinolophids or hipposiderids, which are both common at other East African sites. The bats making up the Kanapoi community all typically roost in trees, with some preferring deeper forests and larger trees (molossids), while the others (pteropodids, nycterids and emballonurids) roost in trees near open areas. Living fruit bats that are related to Kanapoi species typically forage for fruits along the margins of forests and in open savannah. The echolocating forms from Kanapoi consist of groups that aerially hawk for insects in open areas between patches of forest and along water courses. The habitats preferred by living relatives of the Kanapoi bats are in agreement with those constructed for Kanapoi based on other lines of evidence. Copyright © 2018. Published by Elsevier Ltd.

Investigation of wintertime cold-air pools and aerosol layers in the Salt Lake Valley using a lidar ceilometer

NASA Astrophysics Data System (ADS)

Young, Joseph Swyler

This thesis investigates the utility of lidar ceilometers, a type of aerosol lidar, in improving the understanding of meteorology and air quality in persistent wintertime stable boundary layers, or cold-air pools, that form in urbanized valley and basin topography. This thesis reviews the scientific literature to survey the present knowledge of persistent cold-air pools, the operating principles of lidar ceilometers, and their demonstrated utility in meteorological investigations. Lidar ceilometer data from the Persistent Cold-Air Pool Study (PCAPS) are then used with meteorological and air quality data from other in situ and remote sensing equipment to investigate cold-air pools that formed in Utah's Salt Lake Valley during the winter of 2010-2011. The lidar ceilometer is shown to accurately measure aerosol layer depth and aerosol loading, when compared to visual observations. A linear relationship is found between low-level lidar backscatter and surface particulate measurements. Convective boundary layer lidar analysis techniques applied to cold-air pool ceilometer profiles can detect useful layer characteristics. Fine-scale waves are observed and analyzed within the aerosol layer, with emphasis on Kelvin-Helmholz waves. Ceilometer aerosol backscatter profiles are analyzed to quantify and describe mixing processes in persistent cold-air pools. Overlays of other remote and in-situ observations are combined with ceilometer particle backscatter to describe specific events during PCAPS. This analysis describes the relationship between the aerosol layer and the valley inversion as well as interactions with large-scale meteorology. The ceilometer observations of hydrometers are used to quantify cloudiness and precipitation during the project, observing that 50% of hours when a PCAP was present had clouds or precipitation below 5 km above ground level (AGL). Then, combining an objective technique for determining hourly aerosol layer depths and correcting this

Estimates of evapotranspiration from the Ruby Lake National Wildlife Refuge area, Ruby Valley, northeastern Nevada, May 1999-October 2000

USGS Publications Warehouse

Berger, David L.; Johnson, Michael J.; Tumbusch, Mary L.; Mackay, Jeffrey

2001-01-01

The Ruby Lake National Wildlife Refuge in Ruby Valley, Nevada, contains the largest area of perennial wetlands in northeastern Nevada and provides habitat to a large number of migratory and nesting waterfowl. The long-term preservation of the refuge depends on the availability of sufficient water to maintain optimal habitat conditions. In the Ruby Valley water budget, evapotranspiration (ET) from the refuge is one of the largest components of natural outflow. To help determine the amount of inflow needed to maintain wetland habitat, estimates of ET for May 1999 through October 2000 were made at major habitats throughout the refuge. The Bowen-ratio method was used to estimate daily ET at four sites: over open water, in a moderate-to-dense cover of bulrush marsh, in a moderate cover of mixed phreatophytic shrubs, and in a desert-shrub upland. The eddy-correlation method was used to estimate daily ET for periods of 2 to 12 weeks at a meadow site and at four sites in a sparse-to-moderate cover of phreatophytic shrubs. Daily ET rates ranged from less than 0.010 inch per day at all of the sites to a maximum of 0.464 inch per day at the open-water site. Average daily ET rates estimated for open water and a bulrush marsh were about four to five times greater than in areas of mixed phreatophytic shrubs, where the depth to ground water is less than 5 feet. Based on the seasonal distribution of major habitats in the refuge and on winter and summer ET rates, an estimated total of about 89,000 acre-feet of water was consumed by ET during October 1999-September 2000 (2000 water year). Of this total, about 49,800 acre-feet was consumed by ET in areas of open water and bulrush marsh.

Extinction of water plants in the Hula Valley: Evidence for climate change.

PubMed

Melamed, Yoel; Kislev, Mordechai; Weiss, Ehud; Simchoni, Orit

2011-04-01

We describe two events of water plant extinction in the Hula Valley, northern Israel: the ancient, natural extinction of 3 out of 14 extinct species at Gesher Benot Ya'aqov, which occurred some 800-700 k.yr., and an anthropogenic, near contemporary extinction of seven species in the artificial drainage of the Hula Lake in the 1950s. We conclude that the considerable fraction of water plants that disappeared from the Hula Valley in the Early-Middle Pleistocene was the result of habitat desiccation and not global warming. Thus, there is evidence that the hominins who lived in the Hula Valley inhabited a comparatively dry place. The disappearance of water plant species was partially the result of reduced seed dispersal by birds (ornitochory) as a result of the shrinkage of water bodies and their number along the Rift Valley. We suggest that the disappearance of a group of rare, local water plants can be used as an indicator of climate drying and impacts on the local vegetation. Copyright © 2010 Elsevier Ltd. All rights reserved.

Hesperian-aged Valleys on Martian Volcanoes: Snowmelt, Drainage, and Erosion on Ceraunius Tholus

NASA Astrophysics Data System (ADS)

Fassett, C. I.; Head, J. W.

2006-12-01

Most valley networks on Mars appear to have been formed during the Noachian. However, there are a few locations where valleys incise younger surfaces, including the Hesperian-aged volcanoes Ceraunius Tholus and Hecates Tholus (Gulick and Baker, 1990). Both of these volcanoes are characterized by numerous small radial valleys on their flanks (widths <~500 m). Ceraunius Tholus also has a set of large canyons on its north flank that appear qualitatively different from the smaller features (width ~2 km). The largest of these canyons originates near the lowest part of the caldera, continues 40 km down the north flank, and debauches into Rahe Crater (an oblique impact crater) where it formed a depositional fan. We have been exploring the origin of these relatively young valley features to help constrain valley formation mechanism on Mars. Recent study of climate change on Mars suggests that many low-latitude regions (especially large volcanic edifices) were periodically the sites of snow accumulation, likely triggered by variations in spin-axis/orbital parameters. As with earlier work on Hecates Tholus (Fassett and Head, 2006), numerical modeling suggests that conductive cooling from intrusions of plausible geometry within Ceraunius Tholus would provide sufficient surface heat flux to melt snowpack of a few hundred meters in thickness on these volcanoes. We interpret this process to have formed the radial valleys. Due to the geometry of the summit, meltwater would also have accumulated in the summit caldera, forming a caldera lake of significant volume. It appears that catastrophic drainage of this summit caldera lake may have formed the large canyons, in a manner most akin to terrestrial jökulhaups. The hypothesis that these canyons formed fluvially is supported by comes from the similarity in the volume of material removed from the valley and found in its depositional fan (both ~20 km3), consistent with its formation by a mechanism that was predominantly erosional

Bacterial diversity of the rock-water interface in an East Antarctic freshwater ecosystem, Lake Tawani(P)†

PubMed Central

2013-01-01

Schirmacher Oasis is one of the few ice-free plateaus in East Antarctica that maintains a unique distribution of over 120 microbial-rich, dynamic freshwater lakes, most of which are unexplored. In this study, we describe the bacterial diversity of the rock-water interface in Lake Tawani(P) using culture-independent Bacterial Tag Encoded FLX Amplicon Pyrosequencing (bTEFAP), clone library construction, and culture-based analysis targeting the eubacterial 16S rRNA gene. Lake Tawani(P)was formed in a fossil valley by the accumulation of snow and glacial melt through surface channels into a low-catchment depression. Overall this lake exhibited thirteen bacterial phyla and one-hundred and twelve genera. The Qiime bioinformatics analysis on the bTEFAP alone exhibited higher coverage of the bacterial composition in Lake Tawani(P) than the clone library construction or culture-based methodology. Particularly due to the higher sensitivity of the bTEFAP approach, we detected and differentiated members of the phyla: Chloroflexi, Gemmatimonadetes, Planctomycetes, Nitrospira, and Candidate Division TM7 that other methods were unable to reveal. Nevertheless we found that the use of multiple approaches identified a more complete bacterial community than by using any single approach. Investigating the bacterial diversity of the Schirmacher Oasis lakes, especially those connected through surface channels and encompassed by valleys, will help unravel the dynamic nature of these unique seasonal, freshwater lakes, which potentially harbors highly adapted bacterial taxa with defined ecological functions. PMID:23369372

Long Valley Coring Project

USGS Publications Warehouse

Sass, John; Finger, John; McConnel, Vicki

1998-01-01

In December 1997, the California Energy Commission (CEC) agreed to provide funding for Phase III continued drilling of the Long Valley Exploratory Well (LVEW) near Mammoth Lakes, CA, from its present depth. The CEC contribution of $1 million completes a funding package of $2 million from a variety of sources, which will allow the well to be cored continuously to a depth of between 11,500 and 12,500 feet. The core recovered from Phase III will be crucial to understanding the origin and history of the hydrothermal systems responsible for the filling of fractures in the basement rock. The borehole may penetrate the metamorphic roof of the large magmatic complex that has fed the volcanism responsible for the caldera and subsequent activity.

Influence of the Sostanj coal-fired thermal power plant on mercury and methyl mercury concentrations in Lake Velenje, Slovenia

PubMed

Kotnik; Horvat; Mandic; Logar

2000-10-02

Lake Velenje is located in one of the most polluted regions in Slovenia, the Salek Valley. The major source of pollution in the valley is the coal-fired thermal power plant in Sostanj (STPP, capacity 775 MW). It has five separate units. All units have electrostatic precipitators for fly ash removal. Unit 4 also has installed a wet flue gas desulfurisation system (FGD system). Total mercury (THg) concentrations were measured in lignite, slag and ash samples from the STPP. In flue gas, different mercury species (THg, MeHg, Hg2+, Hg0) were determined separately for unit 4 and unit 5 which use different flue gas cleaning technology. Mercury and methyl mercury (MeHg) concentrations were also measured in lake water at different depths, in inflow water, outflow water, rain, snow and lake sediments in order to establish the influence of the power plant on the lake. Most mercury emitted from the power plant is in the elemental form. The ratio between oxidised and elemental Hg depends on the flue gas cleaning technology. Mass balance calculations have been performed for the STPP. The results show that the major sources of mercury in Lake Velenje are wet deposition and lake inflows. Total and MeHg concentrations in the water column are very low and can be compared to other non-contaminated freshwater lakes in the world.

Investigating Groundwater Depletion and Aquifer Degradation in Central Valley California from Space

NASA Astrophysics Data System (ADS)

Ojha, C.; Shirzaei, M.; Werth, S.; Argus, D. F.

2017-12-01

The Central Valley in California includes one of the world's largest and yet most stressed aquifer systems. The large demand for groundwater, accelerated by population growth and extreme droughts, has been depleting the region's groundwater resources for decades. However, the lack of dense monitoring networks and inaccurate information on geophysical aquifer response pose serious challenges to water management efforts in the area and put the groundwater at high risk. Here, we performed a joint analysis of large SAR interferometric data sets acquired by ALOS L-band satellite in conjunction with the groundwater level observations across the Central Valley. We used 420 L-band SAR images acquired on the ascending orbit track during period Dec 24, 2006 - Jan 1, 2010, and generated more than 1600 interferograms with a pixel size of 100 m × 100 m. We also use data from 1600 observational wells providing continuous measurements of groundwater level within the study period for our analysis. We find that in the south and near Tulare Lake, north of Tule and south of Kaweah basin in San Joaquin valley, the subsidence rate is greatest at up to 20-25 cm/yr, while in Sacramento Valley the subsidence rate is lower at 1-3 cm/yr. From the characterization of the elastic and inelastic storage coefficients, we find that Kern, Tule, Tulare, Kaweah and Merced basins in the San Joaquin Valley are more susceptible to permanent compaction and aquifer storage loss. Kern County shows 0.23%-1.8% of aquifer storage loss during the study period, and has higher percentage loss than adjacent basins such as Tule and Tulare Lake with 0.15%-1.2% and 0.2 %-1.5% loss, respectively. Overall, we estimate that the aquifers across the valley lost a total of 28 km3 of groundwater and 2% of their storage capacity during the study period. Our unique observational evidence including valley-wide estimate of mechanical properties of aquifers and model results will not only facilitate monitoring water deficits

Evidence for slow late-glacial ice retreat in the upper Rangitata Valley, South Island, New Zealand

NASA Astrophysics Data System (ADS)

Shulmeister, J.; Fink, D.; Winkler, S.; Thackray, G. D.; Borsellino, R.; Hemmingsen, M.; Rittenour, T. M.

2018-04-01

A suite of cosmogenic radionuclide ages taken from boulders on lateral and latero-terminal moraines in the Rangitata Valley, eastern South Island, New Zealand demonstrates that relatively thick ice occupied valley reaches inland of the Rangitata Gorge until c. 21 ka. Thereafter ice began to thin, and by c. 17 ka it had retreated 33 km up-valley of the Rangitata Gorge to the Butler-Brabazon Downs, a structurally created basin in the upper Rangitata Valley. Despite its magnitude, this retreat represents a minor ice volume reduction from 21 ka to 17 ka, and numerous lateral moraines preserved suggest a relatively gradual retreat over that 4 ka period. In contrast to records from adjacent valleys, there is no evidence for an ice-collapse at c. 18 ka. We argue that the Rangitata record constitutes a more direct record of glacial response to deglacial climate than other records where glacial dynamics were influenced by proglacial lake development, such as the Rakaia Valley to the North and the major valleys in the Mackenzie Basin to the south-west. Our data supports the concept of a gradual warming during the early deglaciation in the South Island New Zealand.

[Similarities and differences in absorption characteristics and composition of CDOM between Taihu Lake and Chaohu Lake].

PubMed

Shi, Kun; Li, Yun-mei; Wang, Qiao; Yang, Yu; Jin, Xin; Wang, Yan-fei; Zhang, Hong; Yin, Bin

2010-05-01

Field experiments are conducted separately in Taihu Lake and Chaohu Lake on Apr. and Jun. 2009. The changes in absorption spectra of chromophoric dissolved organic matter (CDOM) characteristics are analyzed using spectral differential analysis technology. According the spectral differential characteristic of absorption coefficient; absorption coefficient from 240 to 450 nm is divided into different stages, and the value of spectral slope S is calculated in each stage. In Stage A, S value of CDOM in Taihu Lake and Chaohu Lake are 0.0166-0.0102 nm(-1) [average (0.0132 +/- 0.0017) nm(-1)], 0.029-0.017 nm(-1) [average (0.0214 +/- 0.0024) nm(-1)]. In Stage B, S values are 0.0187-0.0148 nm(-1) [average (0.0169 +/- 0.001) nm(-1)], 0.0179-0.0055 nm(-1) [average (0.0148 +/- 0.002) nm(-1)]. In Stage C, S values are 0.0208-0.0164 nm(-1) [average (0.0186 +/- 0.0009) nm(-1)], 0.0253-0.0161 nm(-1) [average (0.0197 +/- 0.002) nm(-1)]. The results can be concluded as: (1) Absorption coefficient of water in Taihu Lake, and its contribution to absorption of each component is less than that of water in Chaohu Lake, however the standardized absorption coefficient is larger than that in Chaohu Lake. (2) Both in Taihu Lake and Chaohu Lake, derivative spectra of CDOM absorption coefficient reached valley at 260nm, then rise to top at 290 nm, CDOM absorption coefficient can be delivered into three stages. (3) Generally speaking, content of CDOM in Taihu Lake is less than in Chaohu Lake. (4) pectrum slope (S value) of CDOM is related to composition of CDOM, when content of humic acid in CDOM gets higher, S value of Stage B is the most sensitive value, then is the S value of Stage C. Oppositely, S value of Stage B gets the most sensitive value, then is the S value of Stage A; the least sensitive value is in Stage B.

77 FR 8895 - Jimbilnan, Pinto Valley, Black Canyon, Eldorado, Ireteba Peaks, Nellis Wash, Spirit Mountain, and...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-15

..., Pinto Valley, Black Canyon, Eldorado, Ireteba Peaks, Nellis Wash, Spirit Mountain, and Bridge Canyon..., Eldorado, Ireteba Peaks, Nellis Wash, Spirit Mountain, and Bridge Canyon Wilderness Areas, Lake Mead... wilderness character; providing for reasonable use of Spirit Mountain and adjacent areas in a manner meeting...

Sediment deposition and sources into a Mississippi River floodplain lake; Catahoula Lake, Louisiana

USGS Publications Warehouse

Latuso, Karen D.; Keim, Richard F.; King, Sammy L.; Weindorf, David C.; DeLaune, Ronald D.

2017-01-01

Floodplain lakes are important wetlands on many lowland floodplains of the world but depressional floodplain lakes are rare in the Mississippi River Alluvial Valley. One of the largest is Catahoula Lake, which has existed with seasonally fluctuating water levels for several thousand years but is now in an increasingly hydrologically altered floodplain. Woody vegetation has been encroaching into the lake bed and the rate of this expansion has increased since major human hydrologic modifications, such as channelization, levee construction, and dredging for improvement of navigation, but it remains unknown what role those modifications may have played in altering lake sedimentation processes. Profiles of thirteen 137Cs sediment cores indicate sedimentation has been about 0.26 cm y− 1 over the past 60 years and has been near this rate since land use changes began about 200 years ago (210Pb, and 14C in Tedford, 2009). Carbon sequestration was low (10.4 g m− 2 y− 1), likely because annual drying promotes mineralization and export. Elemental composition (high Zr and Ti and low Ca and K) and low pH of recent (<~60 y) or surface sediments suggest Gulf Coastal Plain origin, but below the recent sediment deposits, 51% of sediment profiles showed influence of Mississippi River alluvium, rich in base cations such as K+, Ca2 +, and Mg2 +. The recent shift to dominance of Coastal Plain sediments on the lake-bed surface suggests hydrologic modification has disconnected the lake from sediment-bearing flows from the Mississippi River. Compared to its condition prior to hydrologic alterations that intensified in the 1930s, Catahoula Lake is about 15 cm shallower and surficial sediments are more acidic. Although these results are not sufficient to attribute ecological changes directly to sedimentological changes, it is likely the altered sedimentary and hydrologic environment is contributing to the increased dominance of woody vegetation.

Occurrence of methylmercury in Lake Valencia, Venezuela

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaffe, R.; Cai, Y.; West-Thomas, J.

1997-12-31

The presence of mercury in the environment has received renewed attention during recent years. This is in part due to the known human health and ecological effects of the highly toxic organomercury compounds, and to the fact that novel and improved analytical techniques such as atomic fluorescence spectroscopy (AFS) and capillary chromatography with AFS detection, have enhanced significantly the detection of trace amounts of mercury and organo mercurials in environmental samples. Such techniques have allowed for a better understanding of the biogeochemical cycle of mercury in the aquatic environment. This paper reports on the presence of methylmercury in the watermore » column and sediments of a hyper-eutrophic lake. Lake Valencia is a freshwater lake located in North-Central Venezuela`s Aragua Valley. The lake`s surface area covers approximately 350 km{sup 2}, with a mean depth of 19 m and a maximum depth of 41 m. Due to the discharge of waste waters from the cities of Maracay and Valencia, as well as from other smaller villages and agricultural areas in its watershed, Lake Valencia has become hyper-eutrophic. The population of phytoplankton, particularly of blue-green algae, has increased dramatically during the last two decades resulting in anoxic conditions in the lower part of the water column during most of the year. In addition, concentrations of anthropogenic chemicals, including heavy metals, have increased in the Lake during the last four decades. 15 refs., 2 figs.« less

Master Plan for Public Use Development and Resource Management, Lake Traverse, Minnesota - South Dakota.

DTIC Science & Technology

1979-05-01

White Rock Dam Recreation Area 25 Reservation Highway Recreation Area 27 Brown’s Valley Dike Recreation Area 28 Potential Recreation Areas 28 Section...Development 35 White Rock Dam 35 Reservation Highway 39 Brown’s Valley Dike 39 Land Use Allocation 42 Project Operations ൲ Operations: Recreation--Intensive...Facilities 4 Proposed Facilities v i i u < *1 I_ • In I . .. PROJECT DAT ~PROJECT DATA LAKE TRAVERSE AND RESERVATION DAM Reservoir Flowage rights to

Geochemistry of waters in the Valley of Ten Thousand Smokes region, Alaska

USGS Publications Warehouse

Keith, T.E.C.; Thompson, J.M.; Hutchinson, R.A.; White, L.D.

1992-01-01

Meteoric waters from cold springs and streams outside of the 1912 eruptive deposits filling the Valley of Ten Thousand Smokes (VTTS) and in the upper parts of the two major rivers draining the 1912 deposits have similar chemical trends. Thermal springs issue in the mid-valley area along a 300-m lateral section of ash-flow tuff, and range in temperature from 21 to 29.8??C in early summer and from 15 to 17??C in mid-summer. Concentrations of major and minor chemical constituents in the thermal waters are nearly identical regardless of temperature. Waters in the downvalley parts of the rivers draining the 1912 deposits are mainly mixtures of cold meteoric waters and thermal waters of which the mid-valley thermal spring waters are representative. The weathering reactions of cold waters with the 1912 deposits appear to have stabilized and add only subordinate amounts of chemical constituents to the rivers relative to those contributed by the thermal waters. Isotopic data indicate that the mid-valley thermal spring waters are meteoric, but data is inconclusive regarding the heat source. The thermal waters could be either from a shallow part of a hydrothermal system beneath the 1912 vent region or from an incompletely cooled, welded tuff lens deep in the 1912 ash-flow sheet of the upper River Lethe area. Bicarbonate-sulfate waters resulting from interaction of near-surface waters and the cooling 1953-1968 southwest Trident plug issue from thermal springs south of Katmai Pass and near Mageik Creek, although the Mageik Creek spring waters are from a well-established, more deeply circulating hydrothermal system. Katmai caldera lake waters are a result of acid gases from vigorous drowned fumaroles dissolving in lake waters composed of snowmelt and precipitation. ?? 1992.

Preliminary Water-Table Map and Water-Quality Data for Part of the Matanuska-Susitna Valley, Alaska, 2005

USGS Publications Warehouse

Moran, Edward H.; Solin, Gary L.

2006-01-01

The Matanuska-Susitna Valley is in the northeastern part of the Cook Inlet Basin, Alaska, an area experiencing rapid population growth and development proximal to many lakes. Here water commonly flows between lakes and ground water, indicating interrelation between water quantity and quality. Thus concerns exist that poorer quality ground water may degrade local lake ecosystems. This concern has led to water-quality sampling in cooperation with the Alaska Department of Environmental Conservation and the Matanuska-Susitna Borough. A map showing the estimated altitude of the water table illustrates potential ground-water flow directions and areas where ground- and surface-water exchanges and interactions might occur. Water quality measured in selected wells and lakes indicates some differences between ground water and surface water. 'The temporal and spatial scarcity of ground-water-level and water-quality data limits the analysis of flow direction and water quality. Regionally, the water-table map indicates that ground water in the eastern and southern parts of the study area flows southerly. In the northcentral area, ground water flows predominately westerly then southerly. Although ground and surface water in most areas of the Matanuska-Susitna Valley are interconnected, they are chemically different. Analyses of the few water-quality samples collected in the area indicate that dissolved nitrite plus nitrate and orthophosphorus concentrations are higher in ground water than in surface water.'

Archaeological Investigations at Rathbun Lake, Iowa

DTIC Science & Technology

1988-01-01

direction through Missouri to the town of Glasgow where it empties into the Missouri River. The Chariton River valley is deeply incised with relatively broad...are also found in Iowa. The " Plano Culture" is characterized by non-fluted lanceolate projec- tile points. The Cherokee Sewer Site in northwestern...Lake project area by McKusick and Ries (1962). The site, 13AN3, yielded a projectile point similar to those identified with the Plano Culture

Paired moraine-dammed lakes: a key landform for glaciated high mountain areas in the tropical Andes of Peru

NASA Astrophysics Data System (ADS)

Iturrizaga, Lasafam

2016-04-01

The tropical mountain range of the Cordillera Blanca hosts one of the main concentrations of proglacial lakes in high-mountain settings worldwide, which have formed as a result of the dominant trend of modern glacier retreat. Based on empirical data from field research in over 20 valleys and the analysis of air and satellite images, a genetic classification of major lake types with their barriers and a generalized model for the distribution of the present lakes and paleolakes was set up. The origin of the lakes and their recurrent distribution pattern are associated with the individual stages of the Pleistocene to modern glaciation and their corresponding geomorphological landforms. Characteristic repetitive moraine sequences are found in the upper parts of numerous valleys of the Cordillera Blanca. In terms of the spatial arrangement of the lake types, combined lakes are classified as a distinct composite lake type. These lakes occur at nearly the same elevation or at successively lower elevations, and form characteristic lake sequences of two or more lakes. They may occur as multi-moraine-dammed lakes or mixed combined lakes such as moraine-rock-dammed lakes or multi-debris-dammed lakes. From special interest are in this study the paired moraine-dammed lakes (e.g. Lagunas Qoyllurcochas, Lagunas Safuna Alta and Baja). They are composed of the Great Endmoraine (GEM), primarily formed during the Little Ice Age and earlier, and the pre-GEM, formed during the Holocene. Both moraines are located in rather close vicinity to each other at a distance of 1-3 km. In contrast to the prominent sharp-crested GEM, the pre-GEM is a low-amplitude end-moraine complex, which usually does not exceed a few meters to tens of meters in height. The latter is often composed of several inserted moraine ridges or an irregular hummocky moraine landscape. It is argued here that the process of formation of these combined lakes is mainly controlled by a combination of distinct topographical

Thickness of ice on perennially frozen lakes

USGS Publications Warehouse

McKay, C.P.; Clow, G.D.; Wharton, R.A.; Squyres, S. W.

1985-01-01

The dry valleys of southern Victoria Land, constituting the largest ice-free expanse in the Antarctic, contain numerous lakes whose perennial ice cover is the cause of some unique physical and biological properties 1-3. Although the depth, temperature and salinity of the liquid water varies considerably from lake to lake, the thickness of the ice cover is remarkably consistent1, ranging from 3.5 to 6m, which is determined primarily by the balance between conduction of energy out of the ice and the release of latent heat at the ice-water interface and is also affected by the transmission and absorption of sunlight. In the steady state, the release of latent heat at the ice bottom is controlled by ablation from the ice surface. Here we present a simple energy-balance model, using the measured ablation rate of 30 cm yr-1, which can explain the observed ice thickness. ?? 1985 Nature Publishing Group.

A coupled lake-atmosphere model (CLAM) and its application to Lake Kinneret

NASA Astrophysics Data System (ADS)

Pan, Hai

1999-08-01

Kinneret is a 166-km2 lake located in Northern Israel, in the central part of the Jordan Valley, a corridor running from north to south, between the Galilee hills in the west and the Golan Heights in the east. Both the Galilee hills and the Golan Heights reach an elevation of about 400 m above mean sea level (MSL), and the lake is about -210 m (MSL). North of the lake is the mountainous area of the Hermon, culminating at about 2800 m (MSL). About 120 km south of it is the Dead Sea, which is about -410 m (MSL), and about 45 km west of it is the Mediterranean Sea. The complexity of the terrain, combined with relatively arid soil and various ground covers surrounding the lake, results in a very complicated system of atmospheric and lake processes. To understand this system, especially the processes affecting the atmosphere and lake dynamics and thermodynamics, and their effects on Lake Kinneret evaporation, a coupled lake-atmosphere model (CLAM) was developed and applied to the lake region. The CLAM is based on the Regional Atmospheric Modeling System (RAMS) and the oceanic S-coordinate Rutgers University Model (SCRUM). Energy, mass, and momentum are conserved at the interface between the atmosphere and the lake, and appropriate balance equations are applied there. In the atmospheric module, two nested grids are employed to simulate Northern Israel at a resolution of 4 x 4 km2, and the near-lake region at a resolution of 1 x 1 km 2. Synoptic conditions obtained from the National Meteorological Center (NMC) reanalysis are assimilated by the model. Soil moisture, which appears to have a significant impact on atmospheric circulation in this region, was transformed from the normalized difference vegetation index (NDVI). Observations collected during two summers above and inside the lake emphasize the good capability of CLAM to simulate surface fluxes and other microclimatic conditions, as well as lake temperature and currents. Although the lake is small (about 12-km wide

Summit Lake landslide and geomorphic history of Summit Lake basin, northwestern Nevada

USGS Publications Warehouse

Curry, B. Brandon; Melhorn, W.N.

1990-01-01

The Summit Lake landslide, northwestern Nevada, composed of Early Miocene pyroclastic debris, Ashdown Tuff, and basalt and rhyolite of the Black Rock Range, blocked the upper Soldier Creek-Snow Creek drainage and impounded Summit Lake sometimes prior to 7840 yr B.P. The slide covers 8.2 km2 and has geomorphic features characteristic of long run-out landslides, such as lobate form, longitudinal and transverse ridges, low surface gradient (7.1 ??), and preservation of original stratigraphic position of transported blocks. However, estimated debris volume is the smallest reported (2.5 ?? 105 m3) for a landslide of this type. The outflow channel of the Summit Lake basin was a northward-flowing stream valley entrenched by Mahogany Creek. Subsequent negative tectonic adjustment of the basin by about 35 m, accompanied by concommitant progradation of a prominent alluvial fan deposited by Mahogany Creek, argues for a probable diversion of drainage from the Alvord basin southward into the Lahontan basin. The landslide occurred while the creek flowed southward, transferring about 147 km2 of watershed from the Lahontan basin back to the Alvord basin. Overflow northward occurred during high stands of Pluvial Lake Parman in the basin; otherwise, under drier climates, the Summit Lake basin has been closed. Within large depressions on the slide surface, the ca. 6800 yr old Mazama Bed and other sediments have buried a weakly developed soil. Disseminated humus in the soil yields an age of 7840 ?? 310 yr B.P. Absence of older tephra (such as St. Helens M) brackets the slide age between 7840 and 19,000 yr B.P. Projectile points found on the highest strandlines of Pluvial Lake Parman suggest a ca 8700 yr B.P. age by correlation with cultural artifacts and radiocarbon ages from nearby Last Supper Cave, Nevada. Organic matter accumulation in landslide soils suggests ages ranging from 9100 to 16,250 yr B.P. Estimation of the age of the slide from morphologic data for the isolated Summit

Biological Diversity Comprising Microbial Structures of Antarctic Ice Covered Lakes

NASA Astrophysics Data System (ADS)

Matys, E. D.

2015-12-01

Analysis of microbial membrane lipids is a rapid and non-selective method for evaluating the composition of microbial communities. To fully realise the diagnostic potential of these lipids, we must first understand their structural diversity, biological sources, physiological functions, and pathways of preservation. Particular environmental conditions likely prompt the production of different membrane lipid structures. Antarctica's McMurdo Dry Valleys host numerous ice-covered lakes with sharp chemical gradients that vary in illumination, geochemical structure, and benthic mat morphologies that are structured by nutrient availability and water chemistry. The lipid contents of these benthic mats have not received extensive study nor have the communities yet been thoroughly characterized. Accordingly, a combination of lipid biomarker and nucleic acid sequence data provides the means of assessing species diversity and environmental controls on the composition and diversity of membrane lipid assemblages. We investigated the richness and diversity of benthic microbial communities and accumulated organic matter in Lake Vanda of the McMurdo Dry Valleys. We have identified diverse glycolipids, aminolipids, and phospholipids in addition to many unknown compounds that may be specific to these particular environments. Light levels fluctuate seasonally, favoring low-light-tolerant cyanobacteria and specific lipid assemblages. Adaptations to nutrient limitations are reflected in contrasting intact polar lipid assemblages. For example, under P-limiting conditions, phospholipids are subsidiary to membrane-forming lipids that do not contain P (i.e. ornithine, betaine, and sulfolipids). The bacteriohopanepolyol (BHP) composition is dominated by bacteriohopanetetrol (BHT), a ubiquitous BHP, and 2-methylhopanoids. The relative abundance of 2-methylhopanoids is unprecedented and may reflect the unusual seasonal light regime of this polar environment. By establishing correlations

Perennial Antarctic lake ice: an oasis for life in a polar desert

NASA Technical Reports Server (NTRS)

Priscu, J. C.; Fritsen, C. H.; Adams, E. E.; Giovannoni, S. J.; Paerl, H. W.; McKay, C. P.; Doran, P. T.; Gordon, D. A.; Lanoil, B. D.; Pinckney, J. L.

1998-01-01

The permanent ice covers of Antarctic lakes in the McMurdo Dry Valleys develop liquid water inclusions in response to solar heating of internal aeolian-derived sediments. The ice sediment particles serve as nutrient (inorganic and organic)-enriched microzones for the establishment of a physiologically and ecologically complex microbial consortium capable of contemporaneous photosynthesis, nitrogen fixation, and decomposition. The consortium is capable of physically and chemically establishing and modifying a relatively nutrient- and organic matter-enriched microbial "oasis" embedded in the lake ice cover.

Perennial Antarctic lake ice: an oasis for life in a polar desert.

PubMed

Priscu, J C; Fritsen, C H; Adams, E E; Giovannoni, S J; Paerl, H W; McKay, C P; Doran, P T; Gordon, D A; Lanoil, B D; Pinckney, J L

1998-06-26

The permanent ice covers of Antarctic lakes in the McMurdo Dry Valleys develop liquid water inclusions in response to solar heating of internal aeolian-derived sediments. The ice sediment particles serve as nutrient (inorganic and organic)-enriched microzones for the establishment of a physiologically and ecologically complex microbial consortium capable of contemporaneous photosynthesis, nitrogen fixation, and decomposition. The consortium is capable of physically and chemically establishing and modifying a relatively nutrient- and organic matter-enriched microbial "oasis" embedded in the lake ice cover.

Hydrology and simulation of ground-water flow, Lake Point, Tooele County, Utah

USGS Publications Warehouse

Brooks, Lynette E.

2006-01-01

Water for new residential development in Lake Point, Utah may be supplied by public-supply wells completed in consolidated rock on the east side of Lake Point. Ground-water flow models were developed to help understand the effect the proposed withdrawal will have on water levels, flowing-well discharge, spring discharge, and ground-water quality in the study area. This report documents the conceptual and numerical ground-water flow models for the Lake Point area.The ground-water system in the Lake Point area receives recharge from local precipitation and irrigation, and from ground-water inflow from southwest of the area. Ground water discharges mostly to springs. Discharge also occurs to evapotranspiration, wells, and Great Salt Lake. Even though ground water discharges to Great Salt Lake, dense salt water from the lake intrudes under the less-dense ground water and forms a salt-water wedge under the valley. This salt water is responsible for some of the high dissolved-solids concentrations measured in ground water in Lake Point.A steady-state MODFLOW-2000 ground-water model of Tooele Valley adequately simulates water levels, ground-water discharge, and ground-water flow direction observed in Lake Point in 1969 and 2002. Simulating an additional 1,650 acre-feet per year withdrawal from wells causes a maximum projected drawdown of about 550 feet in consolidated rock near the simulated wells and drawdown exceeding 80 feet in an area encompassing most of the Oquirrh Mountains east of Lake Point. Drawdown in most of Lake Point ranges from 2 to 10 ft, but increases to more than 40 feet in the areas proposed for residential development. Discharge to Factory Springs, flowing wells, evapotranspiration, and Great Salt Lake is decreased by about 1,100 acre-feet per year (23 percent).The U.S. Geological Survey SUTRA variable-density ground-water-flow model generates a reasonable approximation of 2002 dissolved-solids concentration when simulating 2002 withdrawals. At most

Fertilisation of the Southern Atlantic: Ephemeral River Valleys as a replenishing source of nutrient-enriched mineral aerosols

NASA Astrophysics Data System (ADS)

Dansie, Andrew; Wiggs, Giles; Thomas, David

2016-04-01

Oceanic dust deposition provides biologically important iron and macronutrients (Phosphorus (P) and Nitrogen-based (N) compounds) that contribute to phytoplankton growth, marine productivity and oceanic atmospheric CO2 uptake. Research on dust emission sources to date has largely focused on the northern hemisphere and on ephemeral lakes and pans. Our work considers the ephemeral river valleys of the west coast of Namibia as an important yet overlooked source of ocean-fertilizing dust. Dust plumes are frequently emitted from the river valleys by strong easterly winds during the Southern Hemisphere winter, when the upwelling of the Benguela Current is at its weakest. We present field data from dust emission source areas along the main river channels near the coastal termini of the Huab, Kuiseb and Tsauchab river valleys. Collected data include erodible surface sediment, wind-blown flux, and associated meteorological data. Extensive surface sediment sampling was also undertaken throughout the combined 34,250 km2 extent of each river valley catchment with samples collected from within the main river channels, the main branches of each river system, selected tributaries, and into the upper watersheds. Geochemical data show valley sediment and wind-blown flux material have high concentrations of bioavailable Fe, P and N, exceeding that measured at the major dry lake basin dust sources in southern Africa. The contribution of fertilising deposition material is enhanced by both the spatial proximity of the source areas to the ocean and enrichment of source material by ephemeral fluvial accumulation and desiccation. Results show that geographical factors within each watershed play a key role in the nutrient composition of the emitting fluvial deposits in the river valleys. Analysis explores potential relationships between land use, geology, climate and precipitation in the upper watersheds and their influence on bioavailability of Fe, P and N compounds in wind

The Breakup of Temperature Inversions In Steep Valleys

NASA Astrophysics Data System (ADS)

Colette, A.; Street, R.

lake breeze and a valley wind in the Garda Valley (Northern Italy). Preliminary simulations will be presented. The support of AC by TotalFinaElf and RS by the Physical Meteorology Program of NSF and the VTMX Program of DoE is appreciated.

Ground water in the San Joaquin Valley, California

USGS Publications Warehouse

Kunkel, Fred; Hofman, Walter

1966-01-01

Ladies and gentlemen, it is a pleasure to be invited to attend this Irrigation Institute conference and to describe the Geological Survey's program of ground-water studies in the San Joaquin Valley. The U.S. Geological Survey has been making water-resources studies in cooperation with the State of California and other agencies in California for more than 70 years. Three of the earliest Geological Survey Water-Supply Papers--numbers 17, 18, and 19--published in 1898 and 1899, describe "Irrigation near Bakersfield," "Irrigation near Fresno," and "Irrigation near Merced." However, the first Survey report on ground-water occurrence in the San Joaquin Valley was "Ground Water in the San Joaquin Valley," by Mendenhall and others. The fieldwork was done from 1905 to 1910, and the report was published in 1916 as U.S. Geological Survey Water-Supply Paper 398.The current series of ground-water studies in the San Joaquin Valley was begun in 1952 as part of the California Department of Water Resources-U.S. Geological Survey cooperative water-resources program. The first report of this series is Geological Survey Water-Supply Paper 1469, "Ground-Water Conditions and Storage Capacity in the San Joaquin Valley." Other reports are Water-Supply Paper 1618, "Use of Ground-Water Reservoirs for Storage of Surface Water in the San Joaquin Valley;" Water-Supply Paper 1656, "Geology and Ground-Water Features of the Edison-Maricopa Area;" Water-Supply Paper 1360-G, "Ground- Water Conditions in the Mendota-Huron Area;" Water-Supply Paper 1457, "Ground-Water Conditions in the Avenal-McKittrick Area;" and an open-file report, "Geology, Hydrology, and Quality of Water in the Terra Bella-Lost Hills Area."In addition to the preceding published reports, ground-water studies currently are being made of the Kern Fan area, the Hanford- Visalia area, the Fresno area, the Merced area, and of the clays of Tulare Lake. Also, detailed studies of both shallow and deep subsidence in the southern part of

Subaerially exposed Holocene coral reef, Enriquillo Valley, Dominican Republic

NASA Technical Reports Server (NTRS)

Mann, P.; Taylor, F. W.; Burke, K.; Kulstad, R.

1984-01-01

An extremely well-preserved Holocene fringing coral reef occurs at an average elevation of 5 m below sea level around the margins of the central Enriquillo Valley, Dominican Republic. The reef records the latest marine incursion from the east into an 85-km-long, 12-km-wide tectonic depression and appears to represent a unique preservation. Excellent cross sections of the reef exposed in erosional gullies reveal a composition and zonation typical of modern Caribbean reefs that are found in offshore low-energy environments. Radiocarbon age determinations (2) indicate that reef growth coincided with sea-level rise following the last ice age (5,930 + or - 100 to 4,760 + or - 90 yr B.P.). Deltaic deposition and possible vertical movements on active fault scarps dammed the eastern mouth of the valley and created Lago Enriquillo, the level of which was then rapidly lowered by evaporation in an arid climate to produce a saline lake approximately 40 m below sea level. Stratigraphic studies of rocks along the valley edge and data from drill holes in the basin center indicate that there were earlier post-Miocene marine incursions similar to that described here.

Spawning sockeye salmon fossils in Pleistocene lake beds of Skokomish Valley, Washington

NASA Astrophysics Data System (ADS)

Smith, Gerald R.; Montgomery, David R.; Peterson, N. Phil; Crowley, Bruce

2007-09-01

An assemblage of fossil sockeye salmon was discovered in Pleistocene lake sediments along the South Fork Skokomish River, Olympic Peninsula, Washington. The fossils were abundant near the head of a former glacial lake at 115 m elevation. Large adult salmon are concentrated in a sequence of death assemblages that include individuals with enlarged breeding teeth and worn caudal fins indicating migration, nest digging, and spawning prior to death. The specimens were 4 yr old and 45-70 cm in total length, similar in size to modern sockeye salmon, not landlocked kokanee. The fossils possess most of the characteristics of sockeye salmon, Oncorhynchus nerka, but with several minor traits suggestive of pink salmon, O. gorbuscha. This suggests the degree of divergence of these species at about 1 million yr ago, when geological evidence indicates the salmon were deposited at the head of a proglacial lake impounded by the Salmon Springs advance of the Puget lobe ice sheet. Surficial geology and topography record a complicated history of glacial damming and river diversion that implies incision of the modern gorge of the South Fork Skokomish River after deposition of the fossil-bearing sediments.

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

Drost, Charles A.; Hart, Jan

2008-01-01

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

Fishes in paleochannels of the Lower Mississippi River alluvial valley: A national treasure

USGS Publications Warehouse

Miranda, Leandro E.

2016-01-01

Fluvial geomorphology of the alluvial valley of the Lower Mississippi River reveals a fascinating history. A prominent occupant of the valley was the Ohio River, estimated to have flowed 25,000 years ago over western Tennessee and Mississippi to join the Mississippi River north of Baton Rouge, Louisiana, 750–800 km south of the present confluence. Over time, shifts in the Mississippi and Ohio rivers toward their contemporary positions have left a legacy of abandoned paleochannels supportive of unique fish assemblages. Relative to channels abandoned in the last 500 years, paleochannels exhibit harsher environmental conditions characteristic of hypereutrophic lakes and support tolerant fish assemblages. Considering their ecological, geological, and historical importance, coupled with their primordial scenery, the hundreds of paleochannels in the valley represent a national treasure. Altogether, these waterscapes are endangered by human activities and would benefit from the conservation attention afforded to our national parks and wildlife refuges.

Ground-water conditions in Avra Valley, Pima and Pinal Counties, Arizona -1985

USGS Publications Warehouse

Cuff, Melinda K.; Anderson, S.R.

1987-01-01

Avra Valley is a north-trending alluvial basin about 15 mi west of Tucson in Pima and Pinal Counties in south-central Arizona. The valley includes about 520 sq mi of which about 100 sq mi is in the San Xavier Indian Reservation. The basin is bounded on the east by the Tortolita, Tucson, and Sierrita Mountains and on the west by the Picacho, Silverbell, and Roskruge Mountains. The climate of the valley is semiarid, the average annual precipitation ranges from 8 to 12 in., and the average annual lake evaporation ranges from 58 to 62 in. Two major ephemeral streams--Santa Cruz River and Brawley Wash--drain the area. Santa Cruz River and Brawley Wash and their tributaries provide a source of recharge to an extensive alluvial aquifer that underlies the valley floor. Since 1940, the amount of groundwater pumped from the aquifer has been greater than the amount of natural recharge from infiltration and underflow. Overdraft of the aquifer resulted in substantial water level declines throughout the valley. Until 1969, use of groundwater in Avra Valley was for irrigation. Since 1969, the city of Tucson has pumped and transported groundwater for municipal use in the adjacent Tucson basin from lands that were purchased and retired from agriculture. The purpose of this report is to describe groundwater conditions in Avra Valley as of 1985. A brief discussion of the geohydrologic setting and history of groundwater development are given to define aquifer characteristics, changes in groundwater levels, and groundwater pumpage since 1940. (Lantz-PTT)

Protist diversity in a permanently ice-covered Antarctic lake during the polar night transition.

PubMed

Bielewicz, Scott; Bell, Elanor; Kong, Weidong; Friedberg, Iddo; Priscu, John C; Morgan-Kiss, Rachael M

2011-09-01

The McMurdo Dry Valleys of Antarctica harbor numerous permanently ice-covered lakes, which provide a year-round oasis for microbial life. Microbial eukaryotes in these lakes occupy a variety of trophic levels within the simple aquatic food web ranging from primary producers to tertiary predators. Here, we report the first molecular study to describe the vertical distribution of the eukaryotic community residing in the photic zone of the east lobe (ELB) and west lobe (WLB) of the chemically stratified Lake Bonney. The 18S ribosomal RNA (rRNA) libraries revealed vertically stratified populations dominated by photosynthetic protists, with a cryptophyte dominating shallow populations (ELB-6 m; WLB-10 m), a haptophyte occupying mid-depths (both lobes 13 m) and chlorophytes residing in the deepest layers (ELB-18 and 20 m; WLB-15 and 20 m) of the photic zone. A previously undetected stramenopile occurred throughout the water column of both lobes. Temporal variation in the eukaryotic populations was examined during the transition from Antarctic summer (24-h sunlight) to polar night (complete dark). Protist diversity was similar between the two lobes of Lake Bonney due to exchange between the photic zones of the two basins via a narrow bedrock sill. However, vertical and temporal variation in protist distribution occurred, indicating the influence of the unique water chemistry on the biology of the two dry valley watersheds.

A mass balance mercury budget for a mine-dominated lake: Clear Lake, California

USGS Publications Warehouse

Suchanek, T.H.; Cooke, J.; Keller, K.; Jorgensen, S.; Richerson, P.J.; Eagles-Smith, Collin A.; Harner, E.J.; Adam, D.P.

2009-01-01

The Sulphur Bank Mercury Mine (SBMM), active intermittently from 1873–1957 and now a USEPA Superfund site, was previously estimated to have contributed at least 100 metric tons (105 kg) of mercury (Hg) into the Clear Lake aquatic ecosystem. We have confirmed this minimum estimate. To better quantify the contribution of the mine in relation to other sources of Hg loading into Clear Lake and provide data that might help reduce that loading, we analyzed Inputs and Outputs of Hg to Clear Lake and Storage of Hg in lakebed sediments using a mass balance approach. We evaluated Inputs from (1) wet and dry atmospheric deposition from both global/regional and local sources, (2) watershed tributaries, (3) groundwater inflows, (4) lakebed springs and (5) the mine. Outputs were quantified from (1) efflux (volatilization) of Hg from the lake surface to the atmosphere, (2) municipal and agricultural water diversions, (3) losses from out-flowing drainage of Cache Creek that feeds into the California Central Valley and (4) biotic Hg removal by humans and wildlife. Storage estimates include (1) sediment burial from historic and prehistoric periods (over the past 150–3,000 years) from sediment cores to ca. 2.5m depth dated using dichloro diphenyl dichloroethane (DDD), 210Pb and 14C and (2) recent Hg deposition in surficial sediments. Surficial sediments collected in October 2003 (11 years after mine site remediation) indicate no reduction (but a possible increase) in sediment Hg concentrations over that time and suggest that remediation has not significantly reduced overall Hg loading to the lake. Currently, the mine is believed to contribute ca. 322–331 kg of Hg annually to Clear Lake, which represents ca. 86–99% of the total Hg loading to the lake. We estimate that natural sedimentation would cover the existing contaminated sediments within ca. 150–300 years.

Energy Balance, Evapo-transpiration and Dew deposition in the Dead Sea Valley

NASA Astrophysics Data System (ADS)

Metzger, Jutta; Corsmeier, Ulrich

2016-04-01

The Dead Sea is a unique place on earth. It is a terminal hypersaline lake, located at the lowest point on earth with a lake level of currently -429 m above mean sea level (amsl). It is located in a transition zone of semiarid to arid climate conditions, which makes it highly sensible to climate change (Alpert1997, Smiatek2011). The Virtual Institute DEad SEa Research Venue (DESERVE) is an international project funded by the German Helmholtz Association and was established to study coupled atmospheric hydrological, and lithospheric processes in the changing environment of the Dead Sea. At the moment the most prominent environmental change is the lake level decline of approximately 1 m / year due to anthropogenic interferences (Gertman, 2002). This leads to noticeable changes in the fractions of the existing terrestrial surfaces - water, bare soil and vegetated areas - in the valley. Thus, the partitioning of the net radiation in the valley changes as well. To thoroughly study the atmospheric and hydrological processes in the Dead Sea valley, which are driven by the energy balance components, sound data of the energy fluxes of the different surfaces are necessary. Before DESERVE no long-term monitoring network simultaneously measuring the energy balance components of the different surfaces in the Dead Sea valley was available. Therefore, three energy balance stations were installed at three characteristic sites at the coast-line, over bare soil, and within vegetation, measuring all energy balance components by using the eddy covariance method. The results show, that the partitioning of the energy into sensible and latent heat flux on a diurnal scale is totally different at the three sites. This results in gradients between the sites, which are e.g. responsible for the typical diurnal wind systems at the Dead Sea. Furthermore, driving forces of evapo-transpiration at the sites were identified and a detailed analysis of the daily evaporation and dew deposition rates

Diatoms in sediments of perennially ice-covered Lake Hoare, and implications for interpreting lake history in the McMurdo Dry Valleys of Antarctica

USGS Publications Warehouse

Spaulding, S.A.; McKnight, Diane M.; Stoermer, E.F.; Doran, P.T.

1997-01-01

Diatom assemblages in surficial sediments, sediment cores, sediment traps, and inflowing streams of perennially ice-covered Lake Hore, South Victorialand, Antarctica were examined to determine the distribution of diatom taxa, and to ascertain if diatom species composition has changed over time. Lake Hoare is a closed-basin lake with an area of 1.8 km2, maximum depth of 34 m, and mean depth of 14 m, although lake level has been rising at a rate of 0.09 m yr-1 in recent decades. The lake has an unusual regime of sediment deposition: coarse grained sediments accumulate on the ice surface and are deposited episodically on the lake bottom. Benthic microbial mats are covered in situ by the coarse episodic deposits, and the new surfaces are recolonized. Ice cover prevents wind-induced mixing, creating the unique depositional environment in which sediment cores record the history of a particular site, rather than a lake=wide integration. Shallow-water (<1 m) diatom assemblages (Stauroneis anceps, Navicula molesta, Diadesmis contenta var. parallela, Navicula peraustralis) were distinct from mid-depth (4-16 m) assemblages (Diadesmis contenta, Luticola muticopsis fo. reducta, Stauroneis anceps, Diadesmis contenta var. parallela, Luticola murrayi) and deep-water (2-31 m) assemblages (Luticola murrayi, Luticola muticopsis fo. reducta, Navicula molesta. Analysis of a sediment core (30 cm long, from 11 m water depth) from Lake Hoare revealed two abrupt changes in diatom assemblages. The upper section of the sediment core contained the greatest biomass of benthic microbial mat, as well as the greatest total abundance and diversity of diatoms. Relative abundances of diatoms in this section are similar to the surficial samples from mid-depths. An intermediate zone contained less organic material and lower densities of diatoms. The bottom section of core contained the least amount of microbial mat and organic material, and the lowest density of diatoms. The dominant process

Measurements and Modeling of Turbulent Fluxes during Persistent Cold Air Pool Events in Salt Lake Valley, Utah

NASA Astrophysics Data System (ADS)

Ivey, C. E.; Sun, X.; Holmes, H.

2017-12-01

Land surface processes are important in meteorology and climate research since they control the partitioning of surface energy and water exchange at the earth's surface. The surface layer is coupled to the planetary boundary layer (PBL) by surface fluxes, which serve as sinks or sources of energy, moisture, momentum, and atmospheric pollutants. Quantifying the surface heat and momentum fluxes at the land-atmosphere interface, especially for different surface land cover types, is important because they can further influence the atmospheric dynamics, vertical mixing, and transport processes that impact local, regional, and global climate. A cold air pool (CAP) forms when a topographic depression (i.e., valley) fills with cold air, where the air in the stagnant layer is colder than the air aloft. Insufficient surface heating, which is not able to sufficiently erode the temperature inversion that forms during the nighttime stable boundary layer, can lead to the formation of persistent CAPs during wintertime. These persistent CAPs can last for days, or even weeks, and are associated with increased air pollution concentrations. Thus, realistic simulations of the land-atmosphere exchange are meaningful to achieve improved predictions of the accumulation, transport, and dispersion of air pollution concentrations. The focus of this presentation is on observations and modeling results using turbulence data collected in Salt Lake Valley, Utah during the 2010-2011 wintertime Persistent Cold Air Pool Study (PCAPS). Turbulent fluxes and the surface energy balance over seven land use types are quantified. The urban site has an energy balance ratio (EBR) larger than one (1.276). Negative Bowen ratio (-0.070) is found at the cropland site. In addition to turbulence observations, half-hourly WRF simulated net radiation, latent heat, sensible heat, ground heat fluxes during one persistent CAP event are evaluated using the PCAPS observations. The results show that sensible and latent

Recent advances in understanding Antarctic subglacial lakes and hydrology

PubMed Central

Siegert, Martin J.; Ross, Neil; Le Brocq, Anne M.

2016-01-01

It is now well documented that over 400 subglacial lakes exist across the bed of the Antarctic Ice Sheet. They comprise a variety of sizes and volumes (from the approx. 250 km long Lake Vostok to bodies of water less than 1 km in length), relate to a number of discrete topographic settings (from those contained within valleys to lakes that reside in broad flat terrain) and exhibit a range of dynamic behaviours (from ‘active’ lakes that periodically outburst some or all of their water to those isolated hydrologically for millions of years). Here we critique recent advances in our understanding of subglacial lakes, in particular since the last inventory in 2012. We show that within 3 years our knowledge of the hydrological processes at the ice-sheet base has advanced considerably. We describe evidence for further ‘active’ subglacial lakes, based on satellite observation of ice-surface changes, and discuss why detection of many ‘active’ lakes is not resolved in traditional radio-echo sounding methods. We go on to review evidence for large-scale subglacial water flow in Antarctica, including the discovery of ancient channels developed by former hydrological processes. We end by predicting areas where future discoveries may be possible, including the detection, measurement and significance of groundwater (i.e. water held beneath the ice-bed interface). PMID:26667914

Recent advances in understanding Antarctic subglacial lakes and hydrology.

PubMed

Siegert, Martin J; Ross, Neil; Le Brocq, Anne M

2016-01-28

It is now well documented that over 400 subglacial lakes exist across the bed of the Antarctic Ice Sheet. They comprise a variety of sizes and volumes (from the approx. 250 km long Lake Vostok to bodies of water less than 1 km in length), relate to a number of discrete topographic settings (from those contained within valleys to lakes that reside in broad flat terrain) and exhibit a range of dynamic behaviours (from 'active' lakes that periodically outburst some or all of their water to those isolated hydrologically for millions of years). Here we critique recent advances in our understanding of subglacial lakes, in particular since the last inventory in 2012. We show that within 3 years our knowledge of the hydrological processes at the ice-sheet base has advanced considerably. We describe evidence for further 'active' subglacial lakes, based on satellite observation of ice-surface changes, and discuss why detection of many 'active' lakes is not resolved in traditional radio-echo sounding methods. We go on to review evidence for large-scale subglacial water flow in Antarctica, including the discovery of ancient channels developed by former hydrological processes. We end by predicting areas where future discoveries may be possible, including the detection, measurement and significance of groundwater (i.e. water held beneath the ice-bed interface). © 2015 The Authors.

Water resources of Parowan Valley, Iron County, Utah

USGS Publications Warehouse

Marston, Thomas M.

2017-08-29

. Groundwater flows from the high-altitude recharge areas downward toward the basin-fill aquifer in Parowan Valley. Almost all groundwater discharge occurs as withdrawals from irrigation wells in the valley with a small amount of discharge from phreatophytic evapotranspiration. Subsurface groundwater discharge to Cedar Valley is likely minimal. Withdrawals from wells during 2013 were about 32,000 acre-ft. The estimated withdrawals from wells from 1994 to 2013 have ranged from 22,000 to 39,000 acre-ft per year. Declining water levels are an indication of the estimated average annual decrease in groundwater storage of 15,000 acre-ft from 1994 to 2013.Groundwater and surface-water samples were collected from 46 sites in Parowan Valley and Cedar Valley near the town of Enoch during June 2013. Groundwater samples from 34 wells were submitted for geochemical analysis. The total dissolved-solids concentration in water from these wells ranged from 142 to 886 milligrams per liter. Results of stable isotope analysis of oxygen and deuterium from groundwater and surface-water samples indicate that most of the groundwater in Parowan Valley and in Cedar Valley near Enoch is similar in isotopic composition to water from mountain streams, which reflects meteoric water recharged in high-altitude areas east of the valley. In addition, results of stable isotope analysis of a subset of samples from wells located near Little Salt Lake may indicate recharge of precipitation that occurred during cooler climatic conditions of the Pleistocene Epoch.

The glacial/deglacial history of sedimentation in Bear Lake, Utah and Idaho

USGS Publications Warehouse

Rosenbaum, J.G.; Heil, C.W.

2009-01-01

Bear Lake, in northeastern Utah and southern Idaho, lies in a large valley formed by an active half-graben. Bear River, the largest river in the Great Basin, enters Bear Lake Valley ???15 km north of the lake. Two 4-m-long cores provide a lake sediment record extending back ???26 cal k.y. The penetrated section can be divided into a lower unit composed of quartz-rich clastic sediments and an upper unit composed largely of endogenic carbonate. Data from modern fluvial sediments provide the basis for interpreting changes in provenance of detrital material in the lake cores. Sediments from small streams draining elevated topography on the east and west sides of the lake are characterized by abundant dolomite, high magnetic susceptibility (MS) related to eolian magnetite, and low values of hard isothermal remanent magnetization (HIRM, indicative of hematite content). In contrast, sediments from the headwaters of the Bear River in the Uinta Mountains lack carbonate and have high HIRM and low MS. Sediments from lower reaches of the Bear River contain calcite but little dolomite and have low values of MS and HIRM. These contrasts in catchment properties allow interpretation of the following sequence from variations in properties of the lake sediment: (1) ca. 26 cal ka-onset of glaciation; (2) ca. 26-20 cal ka-quasicyclical, millennial-scale variations in the concentrations of hematite-rich glacial fl our derived from the Uinta Mountains, and dolomite- and magnetite-rich material derived from the local Bear Lake catchment (reflecting variations in glacial extent); (3) ca. 20-19 cal ka-maximum content of glacial fl our; (4) ca. 19-17 cal ka-constant content of Bear River sediment but declining content of glacial fl our from the Uinta Mountains; (5) ca. 17-15.5 cal ka-decline in Bear River sediment and increase in content of sediment from the local catchment; and (6) ca. 15.5-14.5 cal ka-increase in content of endogenic calcite at the expense of detrital material. The onset

Outflow Stream from Relatively Recent Martian Lake

NASA Image and Video Library

2016-09-15

Streamlined forms and channel bars in this Martian valley resulted from the outflow of a lake hundreds of millions years more recently than an era of Martian lakes previously confirmed, according to 2016 findings. This excerpt from an image taken by the Context Camera on NASA's Mars Reconnaissance Orbiter covers an area about 8 miles (13 kilometers) wide in the northern Arabia Terra region of Mars. The flow direction was generally northward (toward the top of this image). The channel breached a water-filled basin identified as "B" in a hydrologic-modeling map at PIA20839 and flowed toward a larger basin, informally called "Heart Lake," about 50 miles (80 kilometers) to the northwest. Researchers estimate this stream and the lakes it linked held water at some time in the range of 2 billion to 3 billion years ago. That is several hundred million to about 1 billion years later than better-known ancient lake environments on Mars, such as those documented by NASA's Curiosity rover mission. The later wet period came after it is generally thought that most of Mars' original atmosphere had been lost and most of the remaining water on the planet had frozen. Seasonal melting may have fed this stream. This is a portion of Context Camera image B18_016815_2151. http://photojournal.jpl.nasa.gov/catalog/PIA20837

STS-42 Earth observation of the Rhone River / Lake Geneva in Switzerland

NASA Technical Reports Server (NTRS)

1992-01-01

STS-42 Earth observation taken aboard Discovery, Orbiter Vehicle (OV) 103, shows the Rhone River flowing into Lake Geneva in western Switzerland (46.0N, 7.0E). The sharp change in the valley's orientation is a feature of this view. Several times during cold periods of the Earth's history (the geologically recent Ice Ages of the last 1.5 million years or so), this valley has been filled with ice flowing off the mountain ranges. Ice erosion has widened and lowered the valley. The surrounding mountain chains include the highest peak in Europe, Mont Blanc (15,781 feet) on the French-Italian border, and the well-known Matterhorn (14,130) feet on the Swiss-Italian border. Ice-sculpting has generated the characteristically sharp ridges and pointed peaks of the Alps.

Landform Evolution of the Zanskar Valley, Ladakh Himalaya.

NASA Astrophysics Data System (ADS)

Chahal, P.; Kumar, A.; Sharma, P.; Sundriyal, Y.; Srivastava, P.

2017-12-01

Zanskar River flow from south-west to north-east, perpendicularly through Higher Himalayan crystalline sequences, Tethyan sedimentary sequences, and Indus Molasses; and finally merge with the Indus River at Nimu. Geologically, the Indus valley is bounded by Ladakh Batholith in the north and highly folded and thrusted Zanskar mountain ranges in the south. Sedimentary sequences of Zanskar ranges are largely of continental origin, which were uplifted and deformed via several north verging thrusts, where Zanskar counter thrust, Choksti and Indus-Bazgo thrusts are important thrust zone, and there is atleast 36 km of crustal shortening in the Zanskar section which continued from middle Miocene to the late Pleistocene. This shortening is accommodated mainly by north or north-east directed Zanskar backthrusts. Two major tributaries of Zanskar: Tsrapchu and Doda, flow in the headwaters, along the strike of South Tibetan Detachment System (STDs), an east-west trending regional fault. The present study incorporate field sedimentology, geomorphology and chronology of landform associated with Zanskar valley. In the upper Zanskar, alluvial fan, valley fill and strath terraces configured the major landforms with paleo-lake deposits­­­ in the area between the fans. The lower catchment, at the confluence of Zanskar and Indus rivers, exhibit mainly valley fill terraces and strath terraces. Chronology suggests diachronous aggradation in the upper and lower Zanskar catchments. In the upper Zanskar large scale valley aggradation took place with simultaneously fan progradation and flooding events from 45-15 ka. Luminescence chronology of the lower Zanskar indicates aggradation from 145-55 ka and 18-12 ka. The two aggradation basins are separated by a deep V-shaped gorge which is approximately 60 km long. The longitudinal profile of the Zanskar River shows several local convexities marking knick point zone, which suggests tectonically controlled topography.

Pinedale glacial history of the upper Arkansas River valley: New moraine chronologies, modeling results, and geologic mapping

USGS Publications Warehouse

Schweinsberg, Avriel D.; Briner, Jason P.; Shroba, Ralph R.; Licciardi, Joseph M.; Leonard, Eric M.; Brugger, Keith A.; Russell, Charles M.

2016-01-01

This field-trip guide outlines the glacial history of the upper Arkansas River valley, Colorado, and builds on a previous GSA field trip to the area in 2010. The following will be presented: (1) new cosmogenic 10Be exposure ages of moraine boulders from the Pinedale and Bull Lake glaciations (Marine Isotope Stages 2 and 6, respectively) located adjacent to the Twin Lakes Reservoir, (2) numerical modeling of glaciers during the Pinedale glaciation in major tributaries draining into the upper Arkansas River, (3) discharge estimates for glacial-lake outburst floods in the upper Arkansas River valley, and (4) 10Be ages on flood boulders deposited downvalley from the moraine sequences. This research was stimulated by a new geologic map of the Granite 7.5′ quadrangle, in which the mapping of surficial deposits was revised based in part on the interpretation of newly acquired LiDAR data and field investigations. The new 10Be ages of the Pinedale terminal moraine at Twin Lakes average 21.8 ± 0.7 ka (n = 14), which adds to nearby Pinedale terminal moraine ages of 23.6 ± 1.4 ka (n = 5), 20.5 ± 0.2 ka (n = 3), and 16.6 ± 1.0 ka (n = 7), and downvalley outburst flood terraces that date to 20.9 ± 0.9 ka (n = 4) and 19.0 ± 0.6 ka (n = 4). This growing chronology leads to improved understanding of the controls and timing of glaciation in the western United States, the modeling of glacial-lake outburst flooding, and the reconstruction of paleotemperature through glacier modeling.

Repeated sedimentation and exposure of glacial Lake Missoula sediments: A lake-level history at Garden Gulch, Montana, USA

NASA Astrophysics Data System (ADS)

Smith, Larry N.

2017-01-01

Glaciolacustrine sediments record lake transgression, regression, and subaerial modification of the silty lake-bottom of glacial Lake Missoula in the Clark Fork River valley. The sequence preserved at Garden Gulch, MT documents lake-level fluctuations at >65% of its full-pool volume. Twelve sedimentary cycles fine upwards from (1) very fine-grained sandy silt to (2) silt with climbing ripples to (3) rhythmically laminated silt and some clay. The cycles are fine-grained turbidites capped locally by thin layers of angular gravel derived from local bedrock outcrops. The gravels appear to be the toes of mass wasting lobes carried onto the exposed lakebed surface during repeated lake-level lowerings. Periglacial wedges, small rotational faults, involutions, and clastic dikes deform the tops of eleven cycles. The wedges are 10-30 cm wide, penetrate 30-70 cm deep, are spaced <1 m apart, and contain vertically oriented gravel and massive to laminated sediment. Wedges split and taper in plan view. A few thin silt-filled dikes, which branch and taper downwards from wedges, are interpreted as filled frost cracks. One 10-20 cm-wide sand-filled dike protrudes upward from a sand bed; it is interpreted as a liquefaction feature consistent with a filling and draining lake. The deformed cycle tops preserve evidence of periglacial cold, subaerial exposure, seasonal frost heave, and the incipient formation of sorted polygons. The lowest five cycles are thicker and display more periglacial modification at their tops than the upper seven cycles. The Garden Gulch section may represent as few as seven and as many as twelve substantial fillings and partial to complete drainings of glacial Lake Missoula.

Data Assimilation to Improve CMAQ Model Estimates of Particulate Matter Pollution during Wintertime Persistent Cold Air Pool Events in Salt Lake City, Utah

NASA Astrophysics Data System (ADS)

Ivey, C. E.; Balachandran, S.; Russell, A. G.; Hu, Y.; Holmes, H.

2017-12-01

More than one million people live in Salt Lake Valley, Utah, where wintertime pollution reaches unhealthy levels due to the unique meteorology and orography of the region. Persistent cold air pool (PCAP) events occur when high pressure ridges create stagnant conditions over a valley, which hampers large-scale advection and reduces surface wind speeds. During PCAP periods the fraction of incoming solar radiation that reaches the valley floor is also reduced, leading to temperature inversions that allow pollution to build. Pollution levels continue to climb until a washout event removes the pollutants from the valley. Washout events include high winds or precipitation events with advection or wet deposition related removal processes, respectively. In this work, novel data assimilation and source apportionment techniques are applied for January and February 2007 to analyze CMAQ-modeled source composition and source impacts for the Salt Lake Valley during PCAP events. First, a hybrid source-oriented apportionment model is applied over continental U.S. to determine observation and model-based impacts from 20 sources, including agricultural activities, fossil fuel combustion, dust, and metals processing. Then, a secondary bias correction method is applied to better quantify the source impacts on secondary PM2.5, which constitutes the majority of the PM2.5 mass. Revised concentrations reflect what was previously reported in studies of PCAP pollution in the Salt Lake Valley, where the dominant aerosol was found to be ammonium nitrate. Further, gasoline and natural gas combustion were found to be the greatest contributing sources to aerosol concentrations during the PCAP events. The benefit of the data assimilation methods is the availability of spatially and temporally resolved model estimates of source impacts that better reflect observed concentrations.

Land, lake, and fish: Investigation of fish remains from Gesher Benot Ya'aqov (paleo-Lake Hula).

PubMed

Zohar, Irit; Biton, Rebecca

2011-04-01

The question of whether or not pre-modern hominins were responsible for the accumulation of fish remains is discussed through analyses of remains recovered from two lacustrine facies (I-4 and I-5) from Area A of the Acheulian site of Gesher Benot Ya'aqov (GBY) in the Jordan Rift Valley, Israel. The fish remains provide the first glimpse into the naturally accumulated fish assemblage from the fluctuating shores of a lake that had been continually exploited by early hominins some 780,000 years ago. Preliminary analysis of the remains show that thirteen of the seventeen species native to Lake Hula were identified at GBY. These represent three of the five freshwater fish families native to the lake: Cyprinidae (carps), Cichlidae (tilapini, St. Peter's fish), and Clariidae (catfish). From a taphonomical perspective, a significant difference is found between the two lithofacies (Layers I-4 and I-5) in terms of species composition, richness, diversity, and skeleton completeness. It appears that the fish remains recovered from Layer I-4 (clay) are better preserved than those from Layer I-5 (coquina). In both lithofacies, Cyprinidae are highly abundant while Cichlidae and Clariidae are rare and under-represented, especially when compared to the Lake Hula fishery report from the 1950s. All of these identified species may have contributed significantly to the diet of GBY hominins. Copyright © 2010 Elsevier Ltd. All rights reserved.

A cold-wet middle-latitude environment on Mars during the Hesperian-Amazonian transition: Evidence from northern Arabia valleys and paleolakes

NASA Astrophysics Data System (ADS)

Wilson, Sharon A.; Howard, Alan D.; Moore, Jeffrey M.; Grant, John A.

2016-09-01

The growing inventory of post-Noachian fluvial valleys may represent a late, widespread episode of aqueous activity on Mars, contrary to the paradigm that fluvial activity largely ceased around the Noachian-Hesperian boundary. Fresh shallow valleys (FSVs) are widespread from ~30 to 45° in both hemispheres with a high concentration in northern Arabia Terra. Valleys in northern Arabia Terra characteristically start abruptly on steeper slopes and terminate in topographic depressions at elevations corresponding to model-predicted lake levels. Longer valley systems flowed into and out of chains of paleolakes. Minimum discharges based on the dimensions of the incised channel assuming medium to coarse sand-size grains ranges from tens to hundreds of m3 s-1, respectively, consistent with formation via snowmelt from surface or sub-ice flows. Hydrologic calculations indicate the valleys likely formed in hundreds of years or less, and crater statistics constrain the timing of fluvial activity to between the Hesperian and middle Amazonian. Several craters with channels extending radially outward supports evidence for overflow of interior crater lakes possibly fed by groundwater. Most FSVs occur away from young impact craters which make an association with impact processes improbable. The widespread occurrence of FSVs along with their similar morphology and shared modest state of degradation is consistent with most forming during a global interval of favorable climate, perhaps contemporaneous with alluvial fan formation in equatorial and midlatitudes. Evidence for a snowmelt-based hydrology and considerable depths of water on the landscape in Arabia supports a cold, wet, and possibly habitable environment late in Martian history.

Extent and timing of paleoglaciation in the Kanas Valley, Altai Mountains, China, based on remote sensing, field investigations and multiple dating methods

NASA Astrophysics Data System (ADS)

Zhang, Wei; Harbor, Jon; Cui, Zhijiu; Liu, Liang; Liu, Beibei; Fu, Yanjing; Shi, Yuanhuang; Gribenski, Natacha; Blomdin, Robin; Stroeven, Arjen; Caffee, Marc; Jansson, Krister

2014-05-01

Reconstructions of the timing and extent of past glaciation provide key constraints for paleoclimate and numerical modeling of past glacier behavior. As part of the multinational Central Asian Paleoglaciology Project we are reconstructing the timing and extent of past glaciation along and across a series of mountain ranges in central Asia using consistent methods for mapping, field investigations and numerical dating. Here we report on new findings for the Kanas Valley in northwest China, a large glaciated valley system on the south side of the Altai Mountains. Previous studies have concluded that the Kanas Valley has been shaped by a series of major glacial advances that produced overdeepened basins, a U-shaped valley cross profile, and extensive glacial and glaciofluvial deposits. Existing Optically Stimulated Luminescence (OSL) and Electron Spin Resonance (ESR) dating results suggest major glaciation in the Kanas Valley during Marine Oxygen Isotope Stages (MIS) 3, 5, and 6, but very limited MIS 2 glaciation. Limited MIS 2 glaciation has also been suggested for other parts of central Asia, and this contrasts with extensive MIS 2 glaciation in Europe and North America. Field studies in 2013 provided new evidence for the highest elevation extent of glaciation in the Kanas Valley in the vicinity of the 20-km long Lake Kanas, with the upper limit of distinct erratics on the valley sidewalls indicating past ice thicknesses here up to 1000 m. Upper limits of erratics extending from Lake Kanas to the mapped maximum down-valley extent of glaciation suggest an ice surface slope of 1.8 degrees for the lower half of the paleoglacier in the Kanas Valley, assuming that all the erratics were deposited at the same time. Systematic sampling of glacial erratics, basal till, terminal moraines, glacially eroded bedrock, and glaciofluvial deposits provided material that is being used for cosmogenic radionuclide, OSL and ESR dating of the glacial chronology, and for dating

Status and understanding of groundwater quality in the Bear Valley and Lake Arrowhead Watershed Study Unit, 2010: California GAMA Priority Basin Project

USGS Publications Warehouse

Mathany, Timothy; Burton, Carmen

2017-06-20

Groundwater quality in the 112-square-mile Bear Valley and Lake Arrowhead Watershed (BEAR) study unit was investigated as part of the Priority Basin Project (PBP) of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The study unit comprises two study areas (Bear Valley and Lake Arrowhead Watershed) in southern California in San Bernardino County. The GAMA-PBP is conducted by the California State Water Resources Control Board (SWRCB) in cooperation with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory.The GAMA BEAR study was designed to provide a spatially balanced, robust assessment of the quality of untreated (raw) groundwater from the primary aquifer systems in the two study areas of the BEAR study unit. The assessment is based on water-quality collected by the USGS from 38 sites (27 grid and 11 understanding) during 2010 and on water-quality data from the SWRCB-Division of Drinking Water (DDW) database. The primary aquifer system is defined by springs and the perforation intervals of wells listed in the SWRCB-DDW water-quality database for the BEAR study unit.This study included two types of assessments: (1) a status assessment, which characterized the status of the quality of the groundwater resource as of 2010 by using data from samples analyzed for volatile organic compounds, pesticides, and naturally present inorganic constituents, such as major ions and trace elements, and (2) an understanding assessment, which evaluated the natural and human factors potentially affecting the groundwater quality. The assessments were intended to characterize the quality of groundwater resources in the primary aquifer system of the BEAR study unit, not the treated drinking water delivered to consumers. Bear Valley study area and the Lake Arrowhead Watershed study area were also compared statistically on the basis of water-quality results and factors potentially affecting the groundwater quality.Relative concentrations (RCs

Principal facts for gravity stations in the Dry Valley area, west-central Nevada and east-central California

USGS Publications Warehouse

Sanger, Elizabeth A.; Ponce, David A.

2003-01-01

In June, 2002, the U.S. Geological Survey (USGS) established 143 new gravity stations and 12 new rock samples in the Dry Valley area, 30 miles north of Reno, Nevada, on the California - Nevada border (see fig. 1). This study reports on gravity, magnetic, and physical property data intended for use in modeling the geometry and depth of Dry Valley for groundwater analysis. It is part of a larger study that aims to characterize the hydrologic framework of several basins in Washoe County. Dry Valley is located south of the Fort Sage Mountains and south-east of Long Valley, on USGS 7.5’ quadrangles Constantia and Seven Lakes (fig. 2). The Cretaceous granitic rocks and Tertiary volcanic rocks that bound the sediment filled basin (fig. 3) may be especially important to future modeling because of their impact on groundwater flow. The granitic and volcanic rocks of Dry Valley exhibit densities and magnetic susceptibilities higher than the overlaying sediments, and create a distinguishable pattern of gravity and magnetic anomalies that reflect these properties.

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

NASA Technical Reports Server (NTRS)

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

1974-01-01

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.

Geologic map of the Granite 7.5' quadrangle, Lake and Chaffee Counties, Colorado

USGS Publications Warehouse

Shroba, Ralph R.; Kellogg, Karl S.; Brandt, Theodore R.

2014-01-01

The geologic map of the Granite 7.5' quadrangle, Lake and Chaffee Counties, Colorado, portrays the geology in the upper Arkansas valley and along the lower flanks of the Sawatch Range and Mosquito Range near the town of Granite. The oldest rocks, exposed in the southern and eastern parts of the quadrangle, include gneiss and plutonic rocks of Paleoproterozoic age. These rocks are intruded by younger plutonic rocks of Mesoproterozoic age. Felsic hypabyssal dikes, plugs, and plutons, ranging in age from Late Cretaceous or Paleocene to late Oligocene, locally intruded Proterozoic rocks. A small andesite lava flow of upper Oligocene age overlies Paleoproterozoic rock, just south of the Twin Lakes Reservoir. Gravelly fluvial and fan deposits of the Miocene and lower Pliocene(?) Dry Union Formation are preserved in the post-30 Ma upper Arkansas valley graben, a northern extension of the Rio Grande rift. Mostly north-northwest-trending faults displace deposits of the Dry Union Formation and older rock units. Light detection and ranging (lidar) imagery suggests that two short faults, near the Arkansas River, may displace surficial deposits as young as middle Pleistocene. Surficial deposits of middle Pleistocene to Holocene age are widespread in the Granite quadrangle, particularly in the major valleys and on slopes underlain by the Dry Union Formation. The main deposits are glacial outwash and post-glacial alluvium; mass-movement deposits transported by creep, debris flow, landsliding, and rockfall; till deposited during the Pinedale, Bull Lake, and pre-Bull Lake glaciations; rock-glacier deposits; and placer-tailings deposits formed by hydraulic mining and other mining methods used to concentrate native gold. Hydrologic and geologic processes locally affect use of the land and locally may be of concern regarding the stability of buildings and infrastructure, chiefly in low-lying areas along and near stream channels and locally in areas of moderate to steep slopes. Low

Assessment and recommendations for two sites with active and potential aquaculture production in Rift Valley and Coast Provinces, Kenya

USDA-ARS?s Scientific Manuscript database

Kenya has a long history of local fish consumption. The population in the Lake Victoria area (Rift Valley Province) Northwest of Nairobi and coastal communities (Coast Province) have historically included fish in their diet. Migration from villages to urban areas and increasing commerce has created ...

Hydrochemistry of the Lake Magadi basin, Kenya

USGS Publications Warehouse

Jones, B.F.; Eugster, H.P.; Rettig, S.L.

1977-01-01

New and more complete compositional data are presented for a large number of water samples from the Lake Magadi area, Kenya. These water samples range from dilute inflow (300 g/kg dissolved solids). Five distinct hydrologic stages can be recognized in the evolution of the water compositions: dilute streamflow, dilute ground water, saline ground water (or hot spring reservoir), saturated brines, and residual brines. Based on the assumption that chloride is conserved in the waters during evaporative concentration, these stages are related to each other by the concentration factors of about 1:28:870:7600:16,800. Dilute streamflow is represented by perennial streams entering the Rift Valley from the west. All but one (Ewaso Ngiro) of these streams disappear in the alluvium and do not reach the valley floor. Dilute ground water was collected from shallow pits and wells dug into lake sediments and alluvial channels. Saline ground water is roughly equivalent to the hot springs reservoir postulated by Eugster (1970) and is represented by the hottest of the major springs. Saturated brines represent surficial lake brines just at the point of saturation with respect to trona (Na2CO3.NaHCO3.2H2O), while residual brines are essentially interstitial to the evaporite deposit and have been subjected to a complex history of precipitation and re-solution. The new data confirm the basic hydrologic model presented by Eugster (1970) which has now been refined, particularly with respect to the early stages of evaporative concentration. Budget calculations show that only bromide is conserved as completely as chloride. Sodium follows chloride closely until trona precipitation, whereas silica and sulfate are largely lost during the very first concentration' step (dilute streamflow-dilute ground water). A large fraction of potassium and all calcium plus magnesium are removed during the first two concentration steps (dilute streamflow-dilute ground water-saline ground water). Carbonate and

Geophysical Investigation of the Lake City Fault Zone, Surprise Valley, California, and Implications for Geothermal Circulation

NASA Astrophysics Data System (ADS)

McPhee, D. K.; Glen, J. M.; Egger, A. E.; Chuchel, B. A.

2009-12-01

New audiomagnetotelluric (AMT), gravity, and magnetic data were collected in Surprise Valley, northwestern Basin and Range, in order to investigate the role that the Lake City Fault Zone (LCFZ) may play in controlling geothermal circulation in the area. Surprise Valley hosts an extensional geothermal system currently undergoing exploration for development on several scales. The focus of much of that exploration has been the LCFZ, a set of NW-SE-trending structures that has been suggested on the basis of (1) low-relief scarps in the NW portion of the zone, (2) dissolved mineral-rich groundwater chemistry along its length, and (3) parallelism with a strong regional fabric that includes the Brothers Fault Zone. The LCFZ extends across the valley at a topographic high, intersecting the N-S-trending basin-bounding faults where major hot springs occur. This relationship suggests that the LCFZ may be a zone of permeability for flow of hydrothermal fluids. Previous potential field data indicate that there is no vertical offset along this fault zone, and little signature at all in either the gravity or magnetic data; along with the lack of surface expression along most of its length, the subsurface geometry of the LCFZ and its influence on geothermal fluid circulation remains enigmatic. The LCFZ therefore provides an ideal opportunity to utilize AMT data, which measures subsurface resistivity and therefore - unlike potential field data - is highly sensitive to the presence of saline fluids. AMT data and additional gravity and magnetic data were collected in 2009 along 3 profiles perpendicular to the LCFZ in order to define the subsurface geometry and conductivity of the fault zone down to depths of ~ 500 m. AMT soundings were collected using the Geometrics Stratagem EH4 system, a four channel, natural and controlled-source tensor system recording in the range of 10 to 92,000 Hz. To augment the low signal in the natural field a transmitter of two horizontal-magnetic dipoles

Advanced seismic imaging of overdeepened alpine valleys

NASA Astrophysics Data System (ADS)

Burschil, Thomas; Buness, Hermann; Tanner, David; Gabriel, Gerald; Krawczyk, Charlotte M.

2017-04-01

Major European alpine valleys and basins are densely populated areas with infrastructure of international importance. To protect the environment by, e.g., geohazard assessment or groundwater estimation, understanding of the geological structure of these valleys is essential. The shape and deposits of a valley can clarify its genesis and allows a prediction of behaviour in future glaciations. The term "overdeepened" refers to valleys and basins, in which pressurized melt-water under the glacier erodes the valley below the fluvial level. Most overdeepened valleys or basins were thus refilled during the ice melt or remain in the form of lakes. The ICDP-project Drilling Overdeepened Alpine Valleys (DOVE) intends to correlate the sedimentary succession from boreholes between valleys in the entire alpine range. Hereby, seismic exploration is essential to predict the most promising well path and drilling site. In a first step, this DFG-funded project investigates the benefit of multi-component techniques for seismic imaging. At two test sites, the Tannwald Basin and the Lienz Basin, the Leibniz Institute for Applied Geophysics acquired P-wave reflection profiles to gain structural and facies information. Built on the P-wave information, several S-wave reflection profiles were acquired in the pure SH-wave domain as well as 6-C reflection profiles using a horizontal S-wave source in inline and crossline excitation and 3-C receivers. Five P-wave sections reveal the structure of the Tannwald Basin, which is a distal branch basin of the Rhine Glacier. Strong reflections mark the base of the basin, which has a maximum depth of 240 metres. Internal structures and facies vary strongly and spatially, but allow a seismic facies characterization. We distinguish lacustrine, glacio-fluvial, and deltaic deposits, which make up the fill of the Tannwald Basin. Elements of the SH-wave and 6-C seismic imaging correlate with major structures in the P-wave image, but vary in detail. Based on

Preliminary analysis of the role of lake basin morphology on the modern diatom flora in the Ruby Mountains and East Humboldt Range, Nevada, USA

USGS Publications Warehouse

Starratt, Scott W.

2014-01-01

As paleolimnologists, we often look at the world through a 5-cm-diameter hole in the bottom of a lake, and although a number of studies have shown that a single core in the deepest part of a lake does not necessarily reflect the entire diatom flora, time and money often limit our ability to collect more than one core from a given site. This preliminary study is part of a multidisciplinary research project to understand Holocene climate variability in alpine regions of the Great Basin, and ultimately, to compare these high elevation records to the better studied pluvial records from adjacent valleys, in this case, the Ruby Valley.

Simulations of cataclysmic outburst floods from Pleistocene Glacial Lake Missoula

USGS Publications Warehouse

Denlinger, Roger P.; O'Connell, D. R. H.

2009-01-01

Using a flow domain that we constructed from 30 m digital-elevation model data of western United States and Canada and a two-dimensional numerical model for shallow-water flow over rugged terrain, we simulated outburst floods from Pleistocene Glacial Lake Missoula. We modeled a large, but not the largest, flood, using initial lake elevation at 1250 m instead of 1285 m. Rupture of the ice dam, centered on modern Lake Pend Oreille, catastrophically floods eastern Washington and rapidly fills the broad Pasco, Yakima, and Umatilla Basins. Maximum flood stage is reached in Pasco and Yakima Basins 38 h after the dam break, whereas maximum flood stage in Umatilla Basin occurs 17 h later. Drainage of these basins through narrow Columbia gorge takes an additional 445 h. For this modeled flood, peak discharges in eastern Washington range from 10 to 20 × 106 m3/s. However, constrictions in Columbia gorge limit peak discharges to 6 m3/s and greatly extend the duration of flooding. We compare these model results with field observations of scabland distribution and high-water indicators. Our model predictions of the locations of maximum scour (product of bed shear stress and average flow velocity) match the distribution of existing scablands. We compare model peak stages to high-water indicators from the Rathdrum-Spokane valley, Walulla Gap, and along Columbia gorge. Though peak stages from this less-than-maximal flood model attain or exceed peak-stage indicators along Rathdrum-Spokane valley and along Columbia gorge, simulated peak stages near Walulla Gap are 10–40 m below observed peak-stage indicators. Despite this discrepancy, our match to field observations in most of the region indicates that additional sources of water other than Glacial Lake Missoula are not required to explain the Missoula floods.

Geology and water resources of Owens Valley, California

USGS Publications Warehouse

Hollett, Kenneth J.; Danskin, Wesley R.; McCaffrey, William F.; Walti, Caryl L.

1991-01-01

that is structurally separated into the Bishop Basin to the north and the Owens Lake Basin to the south. These two structural basins are separated by (1) a bedrock high that is the upper bedrock block of an east-west normal fault, (2) a horst block of bedrock (the Poverty Hills), and (3) Quaternary basalt flows and cinder cones that intercalate and intrude the sedimentary deposits of the valley fill. The resulting structural separation of the basins allowed separate development of fluvial and lacustrine depositional systems in each basin. Nearly all the ground water in Owens Valley flows through and is stored in the saturated valley fill. The bedrock, which surrounds and underlies the valley fill, is virtually impermeable. Three hydrogeologic units compose the valley-fill aquifer system, a defined subdivision of the ground-water system, and a fourth represents the valley fill below the aquifer system and above the bedrock. The aquifer system is divided into horizontal hydrogeologic units on the basis of either (1) uniform hydrologic characteristics of a specific lithologic layer or (2) distribution of the vertical hydraulic head. Hydrogeologic unit 1 is the upper unit and represents the unconfined part of the system, hydrogeologic unit 2 represents the confining unit (or units), and hydrogeologic unit 3 represents the confined part of the aquifer system. Hydrogeologic unit 4 represents the deep part of the ground-water system and lies below the aquifer system. Hydrogeologic unit 4 transmits or stores much less water than hydrogeologic unit 3 and represents either a moderately consolidated valley fill or a geologic unit in the valley fill defined on the basis of geophysical data. Nearly all the recharge to the aquifer system is from infiltration of runoff from snowmelt and rainfall on the Sierra Nevada. In contrast, little recharge occurs to the system by runoff from the White and Inyo Mountains or from direct precipitation on the valley floor. Ground wat

Glaciers in Equilibrium - Results from the McMurdo Dry Valleys, Antarctica

NASA Astrophysics Data System (ADS)

Fountain, A. G.; Nylen, T. H.; Doran, P. T.

2004-12-01

Since 1993 the mass balance of two glaciers in the McMurdo Dry Valleys, Antarctica (163° E 77.5° S) has been measured. The magnitude of annual mass gain or loss does not exceed 10 cm water equivalent averaged over each glacier, consistent with the local climate of a polar desert. The overall trend in mass balance shows that the glaciers are in approximate balance with the current climate and no obvious trends exist in either the winter or summer balances. These are similar to a set of mass balance measurements made in another part of the dry valleys during the 1970s (Chinn, 1985). Recent analysis of the climate of the dry valleys shows this region is cooling at a rate of 0.7° C per decade during this period since 1986, which is reflected in the overall lowering of lake levels, decreased primary productivity of the lakes, and declining number of invertebrates (Doran et al., 2002). Although an unusually warm period occurred in the summer of 2001-2002, annual temperatures continue to cool. This region seems to be isolated from the warming elsewhere in Antarctica and the cooling in this part of the Ross Sea region may be due to El Nino forcing (Bertler et al, 2004). The sluggish behavior of the glaciers results from a low mass exchange and an apparent climatic buffering, which supports evidence from the geologic record that these glaciers have not advanced more than a few hundred meters over the past 3 million years (Hall et al., 1993). Many of the glaciers, however, are advancing which probably results from a slow time-scale response from warming conditions in the past millennium.

Evaluating Water Supply and Water Quality Management Options for Las Vegas Valley

NASA Astrophysics Data System (ADS)

Ahmad, S.

2007-05-01

The ever increasing population in Las Vegas is generating huge demand for water supply on one hand and need for infrastructure to collect and treat the wastewater on the other hand. Current plans to address water demand include importing water from Muddy and Virgin Rivers and northern counties, desalination of seawater with trade- payoff in California, water banking in Arizona and California, and more intense water conservation efforts in the Las Vegas Valley (LVV). Water and wastewater in the LVV are intrinsically related because treated wastewater effluent is returned back to Lake Mead, the drinking water source for the Valley, to get a return credit thereby augmenting Nevada's water allocation from the Colorado River. The return of treated wastewater however, is a major contributor of nutrients and other yet unregulated pollutants to Lake Mead. Parameters that influence the quantity of water include growth of permanent and transient population (i.e., tourists), indoor and outdoor water use, wastewater generation, wastewater reuse, water conservation, and return flow credits. The water quality of Lake Mead and the Colorado River is affected by the level of treatment of wastewater, urban runoff, groundwater seepage, and a few industrial inputs. We developed an integrated simulation model, using system dynamics modeling approach, to account for both water quantity and quality in the LVV. The model captures the interrelationships among many variables that influence both, water quantity and water quality. The model provides a valuable tool for understanding past, present and future pathways of water and its constituents in the LVV. The model is calibrated and validated using the available data on water quantity (flows at water and wastewater treatment facilities and return water credit flow rates) and water quality parameters (TDS and phosphorus concentrations). We used the model to explore important questions: a)What would be the effect of the water transported from

Southern California climate, hydrology and vegetation over the past ~96 ka from Baldwin Lake, San Bernardino Mountains, California

NASA Astrophysics Data System (ADS)

Glover, K. C.; Kirby, M. E.; Rhodes, E. J.; Silveira, E.; Stevens, L. R.; Lydon, S. E.; Whitaker, A.; MacDonald, G. M.

2015-12-01

Continuous paleoclimate records are scarce from terrestrial sites in Southern California beyond the Last Glacial Period (i.e. Marine Isotope Stage 2, MIS 2). Baldwin Lake in the Big Bear Valley, San Bernardino Mountains (SBM), is a playa lake in the ecotone between desert and Mediterranean climate and vegetation. We recovered a 27 m core from the site in 2012, which spans ~96 - 10 ka, based upon radiocarbon dating, infrared stimulated luminescence dating, and orbital tuning. Total organic content, total carbonate content, density, magnetic susceptibility, x-ray fluorescence, and grain size data show a lake system that responded in tandem with Marine Isotope State transitions. After the basin closed during MIS 5b, Baldwin Lake was productive for MIS 5a, then cycled through an inorganic phase to a highly organic lowstand by the end of MIS 4. A stratified lake of rapidly-deposited organic silt prevailed throughout MIS 3, then shifted to an inorganic, slow sedimentation regime during MIS 2. Paleoecological data (charcoal and fossil pollen) suggest that the Valley was most prone to wildfire during climate transitions (e.g. the end of the Last Glacial Maximum, ~21 ka). Forest cover was dominated by pine for much of the basin's history, save for the dry period at the onset of MIS 2, and a greater presence of oak woodland at the beginning of MIS 3. The reduced pine cover and increased sagebrush steppe in early MIS 2 suggests a more arid landscape of sagebrush steppe c. 29 - 25 ka, before reverting to wet conditions by the LGM. Throughout MIS 5a - 2, lake organic content fluctuates in tandem with solar radiation values; a possible link between lake productivity and insolation is currently being explored with biogenic silica (BiSi) analysis. The lake was desiccated by ~10 ka, perhaps driven by increasing insolation rates at the onset of MIS 1.

Monitoring the water balance of Lake Victoria, East Africa, from space

NASA Astrophysics Data System (ADS)

Swenson, Sean; Wahr, John

2009-05-01

SummaryUsing satellite gravimetric and altimetric data, we examine trends in water storage and lake levels of multiple lakes in the Great Rift Valley region of East Africa for the years 2003-2008. GRACE total water storage estimates reveal that water storage declined in much of East Africa, by as much as 60 {mm}/{year}, while altimetric data show that lake levels in some large lakes dropped by as much as 1-2 m. The largest declines occurred in Lake Victoria, the Earth's second largest freshwater body. Because the discharge from the outlet of Lake Victoria is used to generate hydroelectric power, the role of human management in the lake's decline has been questioned. By comparing catchment water storage trends to lake level trends, we confirm that climatic forcing explains only about 50decline. This analysis provides an independent means of assessing the relative impacts of climate and human management on the water balance of Lake Victoria that does not depend on observations of dam discharge, which may not be publically available. In the second part of the study, the individual components of the lake water balance are estimated. Satellite estimates of changes in lake level, precipitation, and evaporation are used with observed lake discharge to develop a parameterization for estimating subsurface inflows due to changes in groundwater storage estimated from satellite gravimetry. At seasonal timescales, this approach provides closure to Lake Victoria's water balance to within 17 {mm}/{month}. The third part of this study uses the water balance of a downstream water body, Lake Kyoga, to estimate the outflow from Lake Victoria remotely. Because Lake Kyoga is roughly 20 times smaller in area than Lake Victoria, its water balance is strongly influenced by inflow from Lake Victoria. Lake Kyoga has been shown to act as a linear reservoir, where its outflow is proportional to the height of the lake. This model can be used with satellite altimetric lake levels to estimate a

Hydrologic conditions in the Bill Williams River National Wildlife Refuge and Planet Valley, Arizona, 2000

USGS Publications Warehouse

Wilson, Richard P.; Owen-Joyce, Sandra J.

2002-01-01

During a period of sustained base-flow conditions in the Bill Williams River below Alamo Dam in west central Arizona from March to July 2000, the channel of the river through Planet Valley was dry, and the water table sloped almost due west parallel to the main slope of the flood plain. Water from the river infiltrated into the channel bottom at the head of Planet Valley, moved downgradient in the subsurface, and reappeared in the channel about 0.3 mile downstream from the east boundary of the Bill Williams River National Wildlife Refuge. A river aquifer in hydraulic connection with the Bill Williams River was mapped from a point 6.3 miles upstream from Highway 95 to the upstream end of Planet Valley. Formations that make up the river aquifer in Planet Valley are younger alluvium, older alluviums, and fanglomerate. Total thickness of the river aquifer probably is less than 200 feet in the bedrock canyons to as much as 1,035 feet in Planet Valley. The purpose of this study was to investigate the current hydrologic conditions along the Bill Williams River, which included an inventory of wells within the river aquifer of the Colorado River and in Planet Valley, and to determine the configuration of the water table. A map shows the elevation and configuration of the water table from the east end of Planet Valley to the confluence of the Bill Williams River with Lake Havasu.

Stratigraphic evidence for the role of lake spillover in the inception of the lower Colorado River in southern Nevada and western Arizona

USGS Publications Warehouse

House, P.K.; Pearthree, P.A.; Perkins, M.E.

2008-01-01

Late Miocene and early Pliocene sediments exposed along the lower Colorado River near Laughlin, Nevada, contain evidence that establishment of this reach of the river after 5.6 Ma involved flooding from lake spillover through a bedrock divide between Cottonwood Valley to the north and Mohave Valley to the south. Lacustrine marls interfingered with and conformably overlying a sequence of post-5.6 Ma finegrained valley-fill deposits record an early phase of intermittent lacustrine inundation restricted to Cottonwood Valley. Limestone, mud, sand, and minor gravel of the Bouse Formation were subsequently deposited above an unconformity. At the north end of Mohave Valley, a coarse-grained, lithologically distinct fluvial conglomerate separates subaerial, locally derived fan deposits from subaqueous deposits of the Bouse Formation. We interpret this key unit as evidence for overtopping and catastrophic breaching of the paleodivide immediately before deep lacustrine inundation of both valleys. Exposures in both valleys reveal a substantial erosional unconformity that records drainage of the lake and predates the arrival of sediment of the through-going Colorado River. Subsequent river aggradation culminated in the Pliocene between 4.1 and 3.3 Ma. The stratigraphic associations and timing of this drainage transition are consistent with geochemical evidence linking lacustrine conditions to the early Colorado River, the timings of drainage integration and canyon incision on the Colorado Plateau, the arrival of Colorado River sand at its terminus in the Salton Trough, and a downstream-directed mode of river integration common in areas of crustal extension. ?? 2008 The Geological Society of America.

Clay deposits of the Connecticut River Valley, Connecticut: a special problem in land management

USGS Publications Warehouse

Langer, William H.

1972-01-01

When man first settled the United States, two natural features favored settlement; flat land that was easy to build on and to farm, and a nearby river that could act as a source of water, transportation, and power. The Connecticut River Valley from Middletown, Ct. north past the Connecticut-Massachusetts state line satisfied these two needs, and was favored by many early Americans in New England. This area remains an area of rapid urbanization, partly because of the broad flat lowlands. The subdued topography of this area is due in large part to deposition of fine-grained materials into glacial Lake Hitchcock. This lake was formed during the Wisconsinan age when southward drainage in the Triassic valley of Connecticut was dammed by glacial drift in the area of Rocky Hill, Connecticut. Lake Hitchcock grew to and beyond St. Johnsbury, Vt. with much of the lake being filled with cyclical lake-bottom deposits during the 2,290 to 2,350 years of its life. Aside from the relative flatness inherent in the deposition of fine-grained lake-bottom deposits, these deposits present very few characteristics that are favorable for urbanization. Favorable characteristics are possible sources of clay for manufacturing and possible sources for waste storage sites. Unfavorable characteristics include low water yields resulting in poor urban water-supply sources, and very low flows in streams during dry periods; low percolation rates resulting In drainage and septic problems; and low or uneven bearing strength which create problems in construction. Fine-grained lake-bottom deposits have been mapped for six quadrangles in the Connecticut Valley lowlands; the quadrangles of Windsor Locks, Broad Brook, Hartford North, Manchester, Hartford South, and Glastonbury (all located in Connecticut). All the maps were prepared from existing information including well and test hole data on file at the Water Resources Division in Hartford, surficial geologic quadrangle maps, and bedrock contour

Environmental variables measured at multiple spatial scales exert uneven influence on fish assemblages of floodplain lakes

USGS Publications Warehouse

Dembkowski, Daniel J.; Miranda, Leandro E.

2014-01-01

We examined the interaction between environmental variables measured at three different scales (i.e., landscape, lake, and in-lake) and fish assemblage descriptors across a range of over 50 floodplain lakes in the Mississippi Alluvial Valley of Mississippi and Arkansas. Our goal was to identify important local- and landscape-level determinants of fish assemblage structure. Relationships between fish assemblage structure and variables measured at broader scales (i.e., landscape-level and lake-level) were hypothesized to be stronger than relationships with variables measured at finer scales (i.e., in-lake variables). Results suggest that fish assemblage structure in floodplain lakes was influenced by variables operating on three different scales. However, and contrary to expectations, canonical correlations between in-lake environmental characteristics and fish assemblage structure were generally stronger than correlations between landscape-level and lake-level variables and fish assemblage structure, suggesting a hierarchy of influence. From a resource management perspective, our study suggests that landscape-level and lake-level variables may be manipulated for conservation or restoration purposes, and in-lake variables and fish assemblage structure may be used to monitor the success of such efforts.

Impacts of flamingos on saline lake margin and shallow lacustrine sediments in the Kenya Rift Valley

NASA Astrophysics Data System (ADS)

Scott, Jennifer J.; Renaut, Robin W.; Owen, R. Bernhart

2012-11-01

Studies of modern, Holocene, and Pleistocene sediments around saline to hypersaline, alkaline Lake Bogoria and Lake Magadi show that evidence of flamingo activity in marginal areas of these lakes is nearly ubiquitous. Flamingos produce discrete structures such as webbed footprints (~ 9 cm long, ~ 11 cm wide) and nest mounds (~ 30 cm wide, ~ 20 cm high), and they also extensively rework sediments in delta front, delta plain, and shoreline areas. Large (~ 0.5-2 cm in diameter), pinched, 'bubble pores' and ped-like mud clumps are formed by the trampling and churning of wet clay-rich sediments in these settings. Flamingo nest mounds, although superficially similar to some thrombolite mounds, are typically internally structureless, unless formed on pre-existing sediments that preserve internal structures. The flamingo mounds consist of a dense, packed oval-shaped core, a surrounding 'body' of packed sediment, and an external layer with a ped-like texture of clumped mud. The nests may contain open holes from roots or feather shafts incorporated into the nest, and (or) burrows produced once the nests are abandoned. In areas with high densities of flamingos, lake margin sediments may be preferentially compacted, particularly at breeding sites, and become resistant to subaerial erosion and the effects of transgressive ravinement on time scales ranging from seasons to tens of thousands of years. The relatively well-compacted nest mounds and associated sediments also contribute to the stability of delta distributary channels during regressive-transgressive cycles, and can lead to the minor channelization of unconfined flows where currents are diverted around nest mounds. Pleistocene exhumed surfaces of relatively well-indurated lake margin sediments at Lake Bogoria and Lake Magadi that are interpreted as combined regressive and transgressive surfaces (flooding surface/sequence boundary) preserve evidence of flamingo activities, and are overlain by younger, porous lacustrine

Catastrophic flooding origin of shelf valley systems in the English Channel.

PubMed

Gupta, Sanjeev; Collier, Jenny S; Palmer-Felgate, Andy; Potter, Graeme

2007-07-19

Megaflood events involving sudden discharges of exceptionally large volumes of water are rare, but can significantly affect landscape evolution, continental-scale drainage patterns and climate change. It has been proposed that a significant flood event eroded a network of large ancient valleys on the floor of the English Channel-the narrow seaway between England and France. This hypothesis has remained untested through lack of direct evidence, and alternative non-catastrophist ideas have been entertained for valley formation. Here we analyse a new regional bathymetric map of part of the English Channel derived from high-resolution sonar data, which shows the morphology of the valley in unprecedented detail. We observe a large bedrock-floored valley that contains a distinct assemblage of landforms, including streamlined islands and longitudinal erosional grooves, which are indicative of large-scale subaerial erosion by high-magnitude water discharges. Our observations support the megaflood model, in which breaching of a rock dam at the Dover Strait instigated catastrophic drainage of a large pro-glacial lake in the southern North Sea basin. We suggest that megaflooding provides an explanation for the permanent isolation of Britain from mainland Europe during interglacial high-sea-level stands, and consequently for patterns of early human colonisation of Britain together with the large-scale reorganization of palaeodrainage in northwest Europe.

Modeling a Glacial Lake Outburst Flood Process Chain: The Case of Lake Palcacocha and Huaraz, Peru

NASA Astrophysics Data System (ADS)

Chisolm, Rachel; Somos-Valenzuela, Marcelo; Rivas Gomez, Denny; McKinney, Daene C.; Portocarrero Rodriguez, Cesar

2016-04-01

One of the consequences of recent glacier recession in the Cordillera Blanca, Peru, is the risk of Glacial Lake Outburst Floods (GLOFs) from lakes that have formed at the base of retreating glaciers. GLOFs are often triggered by avalanches falling into glacial lakes, initiating a chain of processes that may culminate in significant inundation and destruction downstream. This paper presents simulations of all of the processes involved in a potential GLOF originating from Lake Palcacocha, the source of a previously catastrophic GLOF on December 13, 1941, 1800 people in the city of Huaraz, Peru. The chain of processes simulated here includes: (1) avalanches above the lake; (2) lake dynamics resulting from the avalanche impact, including wave generation, propagation, and run-up across lakes; (3) terminal moraine overtopping and dynamic moraine erosion simulations to determine the possibility of breaching; (4) flood propagation along downstream valleys; and (5) inundation of populated areas. The results of each process feed into simulations of subsequent processes in the chain, finally resulting in estimates of inundation in the city of Huaraz. The results of the inundation simulations were converted into flood intensity and hazard maps (based on an intensity-likelihood matrix) that may be useful for city planning and regulation. Three avalanche events with volumes ranging from 0.5-3 x 106 m3 were simulated, and two scenarios of 15 m and 30 m lake lowering were simulated to assess the potential of mitigating the hazard level in Huaraz. For all three avalanche events, three-dimensional hydrodynamic models show large waves generated in the lake from the impact resulting in overtopping of the damming-moraine. Despite very high discharge rates (up to 63.4 x 103 m3/s), the erosion from the overtopping wave did not result in failure of the damming-moraine when simulated with a hydro-morphodynamic model using excessively conservative soil characteristics that provide very

Modeling a glacial lake outburst flood process chain: the case of Lake Palcacocha and Huaraz, Peru

NASA Astrophysics Data System (ADS)

Somos-Valenzuela, Marcelo A.; Chisolm, Rachel E.; Rivas, Denny S.; Portocarrero, Cesar; McKinney, Daene C.

2016-07-01

One of the consequences of recent glacier recession in the Cordillera Blanca, Peru, is the risk of glacial lake outburst floods (GLOFs) from lakes that have formed at the base of retreating glaciers. GLOFs are often triggered by avalanches falling into glacial lakes, initiating a chain of processes that may culminate in significant inundation and destruction downstream. This paper presents simulations of all of the processes involved in a potential GLOF originating from Lake Palcacocha, the source of a previously catastrophic GLOF on 13 December 1941, killing about 1800 people in the city of Huaraz, Peru. The chain of processes simulated here includes (1) avalanches above the lake; (2) lake dynamics resulting from the avalanche impact, including wave generation, propagation, and run-up across lakes; (3) terminal moraine overtopping and dynamic moraine erosion simulations to determine the possibility of breaching; (4) flood propagation along downstream valleys; and (5) inundation of populated areas. The results of each process feed into simulations of subsequent processes in the chain, finally resulting in estimates of inundation in the city of Huaraz. The results of the inundation simulations were converted into flood intensity and preliminary hazard maps (based on an intensity-likelihood matrix) that may be useful for city planning and regulation. Three avalanche events with volumes ranging from 0.5 to 3 × 106 m3 were simulated, and two scenarios of 15 and 30 m lake lowering were simulated to assess the potential of mitigating the hazard level in Huaraz. For all three avalanche events, three-dimensional hydrodynamic models show large waves generated in the lake from the impact resulting in overtopping of the damming moraine. Despite very high discharge rates (up to 63.4 × 103 m3 s-1), the erosion from the overtopping wave did not result in failure of the damming moraine when simulated with a hydro-morphodynamic model using excessively conservative soil

Outburst floods from glacier-dammed lakes: The effect of mode of lake drainage on flood magnitude

USGS Publications Warehouse

Walder, J.S.; Costa, J.E.

1996-01-01

Published accounts of outburst floods from glacier-dammed lakes show that a significant number of such floods are associated not with drainage through a tunnel incised into the basal ice - the process generally assumed - but rather with ice-marginal drainage, mechanical failure of part of the ice dam, or both. Non-tunnel floods are strongly correlated with formation of an ice dam by a glacier advancing from a tributary drainage into either a main river valley or a pre-existing body of water (lake or fiord). For a given lake volume, non-tunnel floods tend to have significantly higher peak discharges than tunnel-drainage floods. Statistical analysis of data for floods associated with subglacial tunnels yields the following empirical relation between lake volume V and peak discharge script Q signp : script Q signp = 46V0.66 (r2 = 0.70), when script Q signp is expressed in metres per second and V in millions of cubic metres. This updates the so-called Clague-Mathews relation. For non-tunnel floods, the analogous relation is script Q signp = 1100V0.44 (r2 = 0.58). The latter relation is close to one found by Costa (1988) for failure of constructed earthen dams. This closeness is probably not coincidental but rather reflects similarities in modes of dam failure and lake drainage. We develop a simple physical model of the breach-widening process for non-tunnel floods, assuming that (1) the rate of breach widening is controlled by melting of the ice, (2) outflow from the lake is regulated by the hydraulic condition of critical flow where water enters the breach, and (3) the effect of lake temperature may be dealt with as done by Clarke (1982). Calculations based on the model simulate quite well outbursts from Lake George, Alaska. Dimensional analysis leads to two approximations of the form script Q signp ??? Vqf(hi, ??0), where q = 0.5 to 0.6, hi is initial lake depth, ??0 is lake temperature, and the form of f(hi, ??0) depends on the relative importance of viscous

Pacing the post-Last Glacial Maximum demise of the Animas Valley glacier and the San Juan Mountain ice cap, Colorado

NASA Astrophysics Data System (ADS)

Guido, Zackry S.; Ward, Dylan J.; Anderson, Robert S.

2007-08-01

During the Last Glacial Maximum (LGM), a 5000 km2 ice cap covered the San Juan Mountains of southwest Colorado. The largest valley glacier draining this ice cap occupied the Animas Valley and flowed 91 km to the south. To characterize the post-LGM demise of the Animas Valley glacier, we employ cosmogenic 10Be to date the LGM terrace outside the terminal moraines and a suite of seven glacially polished bedrock samples. The 10Be depth profile within the terrace sediments suggests abandonment at 19.4 ± 1.5 ka. As deglaciation began, the ponding of Glacial Lake Durango behind the terminal moraines shut off fluvial sediment supply and caused terrace abandonment. The age of the terrace therefore records the initiation of LGM retreat. Negligible 10Be inheritance in the terrace profile suggests that glacial erosion of the bedrock valley floor from which sediments were derived erased all cosmogenic inventory. Glacial polish exposure ages monotonically decrease up-valley from 17.1 to 12.3 ka, with the single exception of a sample collected from a quartzite rib, yielding an average retreat rate of 15.4 m/yr. This trend and the lack of inherited cosmogenic nuclides in the terrace sediments imply that polish ages accurately record the glacial retreat history. Retreat of the Animas lobe began at a time of regional drying recorded in sediments and shoreline elevations of large lakes. Deglaciation lasted for ˜7.2 k.y., and was complete by 12.3 ± 1.0 ka. The retreat history followed the pattern of increasing insolation and was perhaps fastest during a time of regional drying.

Supraglacial lakes on Himalayan debris-covered glacier (Invited)

NASA Astrophysics Data System (ADS)

Sakai, A.; Fujita, K.

2013-12-01

Debris-covered glaciers are common in many of the world's mountain ranges, including in the Himalayas. Himalayan debris-covered glacier also contain abundant glacial lakes, including both proglacial and supraglacial types. We have revealed that heat absorption through supraglacial lakes was about 7 times greater than that averaged over the whole debris-covered zone. The heat budget analysis elucidated that at least half of the heat absorbed through the water surface was released with water outflow from the lakes, indicating that the warm water enlarge englacial conduits and produce internal ablation. We observed some portions at debris-covered area has caved at the end of melting season, and ice cliff has exposed at the side of depression. Those depression has suggested that roof of expanded water channels has collapsed, leading to the formation of ice cliffs and new lakes, which would accelerate the ablation of debris-covered glaciers. Almost glacial lakes on the debris-covered glacier are partially surrounded by ice cliffs. We observed that relatively small lakes had non-calving, whereas, calving has occurred at supraglacial lakes with fetch larger than 80 m, and those lakes expand rapidly. In the Himalayas, thick sediments at the lake bottom insulates glacier ice and lake water, then the lake water tends to have higher temperature (2-4 degrees C). Therefore, thermal undercutting at ice cliff is important for calving processes in the glacial lake expansion. We estimated and subaqueous ice melt rates during the melt and freeze seasons under simple geomorphologic conditions. In particular, we focused on valley wind-driven water currents in various fetches during the melt season. Our results demonstrate that the subaqueous ice melt rate exceeds the ice-cliff melt rate above the water surface when the fetch is larger than 20 m with the water temperature of 2-4 degrees C. Calculations suggest that onset of calving due to thermal undercutting is controlled by water

Lead-rich sediments, Coeur d'Alene River Valley, Idaho: area, volume, tonnage, and lead content

USGS Publications Warehouse

Bookstrom, Arthur A.; Box, Stephen E.; Campbell, Julie K.; Foster, Kathryn I.; Jackson, Berne L.

2001-01-01

In north Idaho, downstream from the Coeur d?Alene (CdA) silver-lead-zinc mining district, lead-rich sediments, containing at least 1,000 ppm of lead, cover approximately 61 km2 (or 73 percent) of the 84-km2 floor of the CdA River valley, from the confluence of its North and South Forks to the top of its delta-front slope, in CdA Lake. Concentrations of lead (Pb) in surface sediments range from 15 to about 38,500 ppm, and average 3,370 ppm, which is 112 times the mean background concentration (30 ppm) of Pb in uncontaminated sediments of the CdA and St. Joe River valleys. Most of the highest concentrations of Pb are in sediments within or near the river channel, or near the base of the stratigraphic section of Pb-rich sediments. Ranges of Pb concentration in Pb-rich sediments gradually decrease with increasing distance from the river and its distributaries. Ranges of thickness of Pb-rich sediments generally decrease abruptly with increasing distance from the river, from about 3 + 3 m in the river channel to about 1 + 1m on upland riverbanks, levees and sand splays, to about 0.3 + 0.3 m in back-levee marshes and lateral lakes. Thickness of Pb-rich dredge spoils (removed from the river and deposited on Cataldo-Mission Flats) is mostly in the range 4 + 4 m, thinning away from an outfall zone north and west of the river, near the formerly dredged channel reach near Cataldo Landing. We attribute lateral variation in ranges of thickness and Pb content of Pb-rich sediments to the dynamic balance between decreasing floodwater flow velocity with increasing distance from the river and the quantity, size, density, and Pb content of particles mobilized, transported, and deposited. We present alternative median- and mean-based estimates of the volume of Pbrich sediments, their wet and dry tonnage, and their tonnage of contained Pb. We calculate separate pairs of estimates for 23 Estimation Units, each of which corresponds to a major depositional environment, divided into down-valley

Physical Controls on Delta Formation and Carbon Storage in Mountain Lakes

NASA Astrophysics Data System (ADS)

Scott, D.; Wohl, E.

2014-12-01

Carbon acts as a component in greenhouse gases that regulate global climate. It is imperative to understand the transport and storage of carbon in order to understand and manage climate change. We examine terrestrial carbon storage in mountain lake deltas as a way of furthering our understanding of the terrestrial carbon sink, which is a poorly understood but significant contributor to the global carbon cycle. We examined subalpine lake deltas in the Washington Cascade Range and Colorado Front Range to test the following hypotheses: 1) The size of the deltaic carbon sink is strongly correlated with incision at the outlet of the lake and the topography of the basin. 2) Areas of high exhumation rates will have smaller and fewer deltas because a high exhumation rate should lead to more confined basins and more colluvium available to dam lake outlets, preventing lake level drop and corresponding delta formation. 3) High-energy deltas will transport more carbon to lakes, avoiding the deltaic carbon sink. At 27 lakes, we surveyed mountain lake deltas and took sediment samples, surveyed lake outlets in the field, and measured lake valley confinement in GIS to test hypotheses 1 and 3. Across the Snoqualmie and Skykomish watersheds in the Washington Cascades and the Colorado Front Range, we took a census of the number of natural lakes and the proportion of those lakes with deltas to test hypothesis 2. Preliminary results indicate that the Washington Cascades (high exhumation rate) have a higher density of lakes, but fewer deltas, than the Colorado Front Range (low exhumation rate). We also suspect that deltas in the Washington Cascades will have a lower carbon content than the Colorado Front Range due to generally higher energy levels on deltas. Finally, we found a substantial difference in the geomorphology and sediment type between beaver-affected and non-beaver-affected lakes in the Colorado Front Range.

Geologic map of the Bartlett Springs Fault Zone in the vicinity of Lake Pillsbury and adjacent areas of Mendocino, Lake, and Glenn Counties, California

USGS Publications Warehouse

Ohlin, Henry N.; McLaughlin, Robert J.; Moring, Barry C.; Sawyer, Thomas L.

2010-01-01

The Lake Pillsbury area lies in the eastern part of the northern California Coast Ranges, along the east side of the transform boundary between the Pacific and North American plates (fig. 1). The Bartlett Springs Fault Zone is a northwest-trending zone of faulting associated with this eastern part of the transform boundary. It is presently active, based on surface creep (Svarc and others, 2008), geomorphic expression, offset of Holocene units (Lienkaemper and Brown, 2009), and microseismicity (Bolt and Oakeshott, 1982; Dehlinger and Bolt, 1984; DePolo and Ohlin, 1984). Faults associated with the Bartlett Springs Fault Zone at Lake Pillsbury are steeply dipping and offset older low to steeply dipping faults separating folded and imbricated Mesozoic terranes of the Franciscan Complex and interleaved rocks of the Coast Range Ophiolite and Great Valley Sequence. Parts of this area were mapped in the late 1970s and 1980s by several investigators who were focused on structural relations in the Franciscan Complex (Lehman, 1978; Jordan, 1975; Layman, 1977; Etter, 1979). In the 1980s the U.S. Geological Survey (USGS) mapped a large part of the area as part of a mineral resource appraisal of two U.S. Forest Service Roadless areas. For evaluating mineral resource potential, the USGS mapping was published at a scale of 1:62,500 as a generalized geologic summary map without a topographic base (Ohlin and others, 1983; Ohlin and Spear, 1984). The previously unpublished mapping with topographic base is presented here at a scale of 1:30,000, compiled with other mapping in the vicinity of Lake Pillsbury. The mapping provides a geologic framework for ongoing investigations to evaluate potential earthquake hazards and structure of the Bartlett Springs Fault Zone. This geologic map includes part of Mendocino National Forest (the Elk Creek Roadless Area) in Mendocino, Glenn, and Lake Counties and is traversed by several U.S. Forest Service Routes, including M1 and M6 (fig. 2). The study

Preliminary results of hydrogeologic investigations Humboldt River Valley, Winnemucca, Nevada

USGS Publications Warehouse

Cohen, Philip M.

1964-01-01

Most of the ground water of economic importance and nearly all the ground water closely associated with the flow o# the Humboldt River in the. 40-mile reach near Winnemucca, Nev., are in unconsolidated sedimentary deposits. These deposits range in age from Pliocene to Recent and range in character from coarse poorly sorted fanglomerate to lacustrine strata of clay, silt, sand, and gravel. The most permeable deposit consists of sand and gravel of Lake Lahontan age--the so-called medial gravel unit--which is underlain and overlain by fairly impermeable silt and clay also of Lake Lahontan age. The ultimate source of nearly all the water in the study area is precpitation within the drainage basin of the Humboldt River. Much of this water reaches the study, area as flow or underflow of the Humboldt River and as underflow from other valleys tributary to the study area. Little if any flow from the tributary streams in the study area usually reaches the Humboldt River. Most of the tributary streamflow within the study area evaporates or is transpired by vegetation, but a part percolates downward through unconsolidated deposits of the alluvial fans flanking the mountains and move downgradient as ground-water underflow toward the Humboldt River. Areas that contribute significant amounts of ground-water underflow to. the valley of the Humboldt River within the study area are (1) the valley of the Humboldt River upstream from the study area, (2) the Pole Creek-Rock Creek area, (3) Paradise Valley, and (4) Grass Valley and the northwestern slope of the Sonoma Range. The total average underflow from these areas in the period 1949-61 was about 14,000-19,000 acre-feet per year. Much of this underflow discharged into the Humboldt River within the study area and constituted a large part of the base flow of the river. Streamflow in the Humboldt River increases substantially in the early spring, principally because of runoff to the river in the reaches upstream from the study area

The Ogden Valley artesian reservoir

USGS Publications Warehouse

Thomas, H.E.

1945-01-01

Ogden Valley, in Weber County, Utah, contains an artesian reservoir from which the city of Ogden obtains all except a small part of its municipal water supply. A detailed investigation of the ground-water resources of Ogden Valley, and particularly of this artesian reservoir, was made by the Geological Survey, United States Department of the Interior, in cooperation with the city of Ogden between 1932 and 1934, and the results of this investigation have been reported by Leggette and Taylor.1 The present paper, which might be termed a sequel to that report, is based on data collected during those years, augmented by records that have been obtained (1935-1940) by the Geological Survey as part of a State-wide project in cooperation with the Utah State Engineer. The conclusions drawn from the study of these records and presented in detail in the following pages are as follows: (1) The artesian reservoir is filled to capacity nearly every year during the spring run-off from melting snow; (2) after the annual freshet, the recharge to the reservoir is insufficient to balance the discharge from artesian wells, which ordinarily is at a maximum during the summer; the reservoir is depleted and is not filled again until the following spring; (3) during the periods when the artesian reservoir is not full the rate of recharge is more or less proportional to the inflow to the valley by streams, except that rain on the recharge area may be of sufficient intensity to contribute some water by infiltration and deep penetration; and (4) the artesian reservoir thus serves to store water that would otherwise be lost to Great Salt Lake in the excess spring overflow, and available records indicate that water used by increased draft from wells would be replenished in normal years by increased recharge during the spring freshet.

Stochastic and cyclic deposition of multiple subannual laminae in an urban lake (Twin Lake, Golden Valley, Minnesota, USA)

NASA Astrophysics Data System (ADS)

Myrbo, A.; Ustipak, K.; Demet, B.

2013-12-01

Twin Lake, a small, deep, meromictic urban lake in Minneapolis, Minnesota, annually deposits two to 10 laminae that are distinguished from one another by composition and resulting color. Sediment sources are both autochthonous and allochthonous, including pure and mixed laminae of authigenic calcite, algal organic matter, and diatoms, as well as at least three distinct types of sediment gravity flow deposits. Diagenetic iron sulfide and iron phosphate phases are minor components, but can affect color out of proportion to their abundance. We used L*a*b* color from digital images of a freeze core slab, and petrographic smear slides of individual laminae, to categorize 1080 laminae deposited between 1963 and 2010 CE (based on lead-210 dating). Some causal relationships exist between the ten categories identified: diatom blooms often occur directly above the debris of gravity flows that probably disrupt the phosphate-rich monimolomnion and fertilize the surface waters; calcite whitings only occur after diatom blooms that increase calcite saturation. Stochastic events, as represented by laminae rich in siliciclastics and other terrigenous material, or shallow-water microfossils and carbonate morphologies, are the dominant sediment source. The patterns of cyclic deposition (e.g., summer and winter sedimentation) that produce 'normal' varve couplets in some lakes are continually interrupted by these stochastic events, to such an extent that spectral analysis finds only a weak one-year cycle. Sediments deposited before about 1900, and extending through the entire Holocene sequence (~10m) are varve couplets interrupted by thick (20-90 cm) debris layers, indicating that gravity flows were lower in frequency but greater in magnitude before the historical period, probably due to an increased frequency of disturbance under urban land-use.

Changes in surface area of the Böön Tsagaan and Orog lakes (Mongolia, Valley of the Lakes, 1974-2013) compared to climate and permafrost changes

NASA Astrophysics Data System (ADS)

Szumińska, Danuta

2016-07-01

The main aim of the study is the analysis of changes in surface area of lake Böön Tsagaan (45°35‧N, 99°8‧E) and lake Orog (45°3‧N, 100°44‧E) taking place in the last 40 years in the context of climate conditions and permafrost degradation. The lakes, located in Central Mongolia, at the borderline of permafrost range are fed predominantly by river waters and groundwater from the surrounding mountain areas, characterized by continuous and discontinuous permafrost occurrence - mostly the Khangai. The analysis of the Böön Tsagaan and Orog lake surface area in 1974-2013 was conducted based on satellite images, whereas climate conditions were analysed using the NOAA climate data and CRU dataset. Principal Component Analysis (PCA) was used to study the relationship patterns between the climatic factors and changes in the surface area of the lakes. A tendency for a decrease in surface area, intermittent with short episodes of resupply, was observed in both studied lakes. Climate changes recorded in the analysed period had both direct and indirect impacts on water supply to lakes. Taking into account the results of PCA analysis, the most significant factors include: fluctuation of annual precipitation, increase in air temperature and thickness of snow cover. The extended duration of snow cover in the last decades of the 20th century may constitute a key factor in relation to permafrost degradation.

Glacial lakes in Austria - Distribution and formation since the Little Ice Age

NASA Astrophysics Data System (ADS)

Buckel, J.; Otto, J. C.; Prasicek, G.; Keuschnig, M.

2018-05-01

Glacial lakes constitute a substantial part of the legacy of vanishing mountain glaciation and act as water storage, sediment traps and sources of both natural hazards and leisure activities. For these reasons, they receive growing attention by scientists and society. However, while the evolution of glacial lakes has been studied intensively over timescales tied to remote sensing-based approaches, the longer-term perspective has been omitted due a lack of suitable data sources. We mapped and analyzed the spatial distribution of glacial lakes in the Austrian Alps. We trace the development of number and area of glacial lakes in the Austrian Alps since the Little Ice Age (LIA) based on a unique combination of a lake inventory and an extensive record of glacier retreat. We find that bedrock-dammed lakes are the dominant lake type in the inventory. Bedrock- and moraine-dammed lakes populate the highest landscape domains located in cirques and hanging valleys. We observe lakes embedded in glacial deposits at lower locations on average below 2000 m a.s.l. In general, the distribution of glacial lakes over elevation reflects glacier erosional and depositional dynamics rather than the distribution of total area. The rate of formation of new glacial lakes (number, area) has continuously accelerated over time with present rates showing an eight-fold increase since LIA. At the same time the total glacier area decreased by two-thirds. This development coincides with a long-term trend of rising temperatures and a significant stepping up of this trend within the last 20 years in the Austrian Alps.

Geology and hydrology between Lake McMillan and Carlsbad Springs, Eddy County, New Mexico

USGS Publications Warehouse

Cox, Edward Riley

1967-01-01

The hydrology of the Pecos River valley between Lake McMillan and Carlsbad Springs, Eddy County, N. Mex., is influenced by facies changes in rocks of Permian age. Water stored for irrigation leaks from Lake McMillan into evaporite rocks, principally gypsum, of the Seven Rivers Formation and from Lake Avalon into carbonate rocks of the Tansill Formation. This leakage returns to the Pecos River at Major Johnson Springs and Carlsbad Springs. The river has perennial flow between Major Johnson Springs and Lake Avalon, but it loses water into evaporite rocks of the Yates Formation in this reach. Ground-water movement is generally toward the Pecos River in aquifers in the Pecos River valley except in the Rustler Formation east of the river where it moves southeastward toward playas east of Lake Avalon. The chloride content of ground and surface waters indicates that surface water moves from some reaches of the Pecos River and from surface-storage reservoirs to aquifers and also indicates the degree of mixing of ground and surface waters. About 45,000 acre-feet of ground water is stored in highly permeable rocks in a 3-mile wide part of the Seven Rivers Formation between Lake McMillan and Major Johnson Springs. This water in storage comes from leakage from Lake McMillan and from alluvium north of the springs. The flow of Major Johnson Springs is derived from this aquifer. That part of the flow derived from the alluvium north of the springs averaged 13 cfs (cubic feet per second) from 1953 through 1959 ; about 8 cfs of this flow had not been previously measured at gaging stations on the Pecos River and its tributaries. The most favorable plans for increasing terminal storage of the Carlsbad Irrigation District are to construct a dam at the Brantley site (at the downstream end of Major Johnson Springs), or to use underground storage in the permeable Seven Rivers Formation between Lake McMillan and Major Johnson brings in conjunction with surface storage. To avoid excessive

Selected hydrologic data for the Bonneville Salt Flats and Pilot Valley, western Utah, 1991-93

USGS Publications Warehouse

Mason, James L.; Brothers, William C.; Gerner, Linda J.; Muir, Pamela S.

1995-01-01

This report contains hydrologic data collected during 1991-93 in the Bonneville Salt Flats and Pilot Valley study area of western Utah. These data were collected in cooperation with the U.S. Department of the Interior, Bureau of Land Management, as part of a study to investigate possible salt loss from the Bonneville Salt Flats. The Bonneville Salt Flats and adjacent Pilot Valley are located in the western part of the Great Salt Lake Desert in Utah, near the Nevada border. The Bonneville Salt Flats playa has a thick, perennial salt crust and the Pilot Valley playa has a thin, ephemeral salt crust. Well-completion data, including well depth and screened intervals, are presented in this report for selected shallow and deep monitoring wells. Water-level measurements are reported with corresponding specfic-gravity and temperature measurements. Results of chemical analyses are reported for brine collected from wells and pore fluids extracted from cores.

Connectedness of land use, nutrients, primary production, and fish assemblages in oxbow lakes

USGS Publications Warehouse

Miranda, Leandro E.; Andrews, Caroline S.; Kroger, Robert

2013-01-01

We explored the strength of connectedness among hierarchical system components associated with oxbow lakes in the alluvial valley of the Lower Mississippi River. Specifically, we examined the degree of canonical correlation between land use (agriculture and forests), lake morphometry (depth and size), nutrients (total nitrogen and total phosphorus), primary production (chlorophyll-a), and various fish assemblage descriptors. Watershed (p < 0.01) and riparian (p = 0.02) land use, and lake depth (p = 0.05) but not size (p = 0.28), were associated with nutrient concentrations. In turn, nutrients were associated with primary production (p < 0.01), and primary production was associated with sunfish (Centrarchidae) assemblages (p < 0.01) and fish biodiversity (p = 0.08), but not with those of other taxa and functional guilds. Multiple chemical and biological components of oxbow lake ecosystems are connected to landscape characteristics such as land use and lake depth. Therefore, a top-down hierarchical approach can be useful in developing management and conservation plans for oxbow lakes in a region impacted by widespread landscape changes due to agriculture.

Microbiota within the perennial ice cover of Lake Vida, Antarctica.

PubMed

Mosier, Annika C; Murray, Alison E; Fritsen, Christian H

2007-02-01

Lake Vida, located in the McMurdo Dry Valleys, Antarctica, is an 'ice-sealed' lake with approximately 19 m of ice covering a highly saline water column (approximately 245 ppt). The lower portions of the ice cover and the lake beneath have been isolated from the atmosphere and land for circa 2800 years. Analysis of microbial assemblages within the perennial ice cover of the lake revealed a diverse array of bacteria and eukarya. Bacterial and eukaryal denaturing gradient gel electrophoresis phylotype profile similarities were low (<59%) between all of the depths compared (five depths spanning 11 m of the ice cover), with the greatest differences occurring between surface and deep ice. The majority of bacterial 16S rRNA gene sequences in the surface ice were related to Actinobacteria (42%) while Gammaproteobacteria (52%) dominated the deep ice community. Comparisons of assemblage composition suggest differences in ice habitability and organismal origin in the upper and lower portions of ice cover. Specifically, the upper ice cover microbiota likely reflect the modern day transport and colonization of biota from the terrestrial landscape, whereas assemblages in the deeper ice are more likely to be persistent remnant biota that originated from the ancient liquid water column of the lake that froze.

Identification of subsurface brines in the McMurdo Dry Valleys, Antarctica, via an airborne EM resistivity survey

NASA Astrophysics Data System (ADS)

Foley, N.; Tulaczyk, S. M.; Auken, E.; Schamper, C.; Dugan, H. A.; Mikucki, J.; Virginia, R. A.; Doran, P. T.

2015-12-01

We used a helicopter-borne time domain electromagnetic resistivity survey to detect and map hypersaline brines beneath glaciers and permafrost in the McMurdo Dry Valleys (MDV). In the MDV, a substantially ice-free region of coastal Antarctica, liquid water is present at the surface only in summer streams, ice-covered lakes with brackish to hypersaline bottom waters, and at Blood Falls, a hypersaline discharge from Taylor Glacier. Beneath the surface, however, water can remain liquid at temperatures below 0 °C (and therefore at unexpectedly shallow depths) as a hypersaline brine. These brines, which are measured as zones of low resistivity in an otherwise high resistivity environment, are widespread in Taylor Valley, where they may connect lakes, subglacial waters, and the ocean. By using surface landscape characteristics - such as the presence of lakes, glaciers, or bare ground - we are able to compare changes in resistivity with depth. We find that in areas of surface permafrost (most of the MDV) there is a marked shift to low resistivity material around 200 m below the surface. At lakes, the stratified nature of their waters is detectable and sufficiently large lakes create taliks (unfrozen 'holes' in permafrost) that penetrate to the low resistivity zone around 200 m depth, suggesting connectivity through a regional aquifer. Underneath Taylor Glacier, we detect similar brines, which are the probable source for Blood Falls. These subglacial brines extend from the snout of Taylor Glacier (where they appear to connect to the hypersaline waters of West Lake Bonney) to the limit of our detection ability several kilometers up glacier where the ice became too thick for measurements. Our measurements are consistent with limited drilling done in the MDV during the 1970s and radar measurements taken more recently on Taylor Glacier. The transition to low resistivity at ~200 m depth occurs over a temperature range measured in boreholes of about -10 to -5 °C, which is

Timing of lake-level changes for a deep last-glacial Lake Missoula: optical dating of the Garden Gulch area, Montana, USA

NASA Astrophysics Data System (ADS)

Smith, Larry N.; Sohbati, Reza; Buylaert, Jan-Pieter; Lian, Olav B.; Murray, Andrew; Jain, Mayank

2018-03-01

Glaciolacustrine sediments in the Clark Fork River valley at Garden Gulch, near Drummond, Montana, USA record highstand positions of the ice-dammed glacial Lake Missoula and repeated subaerial exposure. During these highstands the lake was at greater than 65% of its recognized maximum capacity. The initial lake transgression deposited a basal sand unit. Subsequent cycles of lake-level fluctuations are recorded by sequences of laminated and cross laminated silt, sand, and clay deformed by periglacial processes during intervening periods of lower lake levels. Optically stimulated luminescence (OSL) dating of quartz sand grains, using single-aliquot regenerative-dose procedures, was carried out on 17 samples. Comparison of infrared stimulated luminescence (IRSL) from K-rich feldspar to OSL from quartz for all the samples suggests that they were well bleached prior to deposition and burial. Ages for the basal sand and overlying glaciolacustrine exposure surfaces are indistinguishable within one standard deviation, and give a weighted mean age of 20.9 ± 1.3 ka (n = 11). Based on sedimentological and stratigraphic analysis we infer that the initial transgression, and at least six cycles of lake-level fluctuation, occurred over time scales of decades to ∼2 ka. Bioturbated sandy slopewash dated at 10.6 ± 0.9 ka and 11.9 ± 1.2 ka unconformably overlies the upper glaciolacustrine deposits. The uppermost sediments, above the glaciolacustrine section, are younger than the Glacier Peak tephra (13.7-13.4 cal ka B.P.), which was deposited across parts of the drained lake basin, but has not been found at Garden Gulch. Our study indicates that glacial Lake Missoula reached >65 percent of maximum capacity by about 20.9 ± 1.3 ka and either partially or completely drained twelve times from this position. Rapid lowering from the lake's highstand position due to ice-dam failure likely led to scour in the downstream portions of the glacial Lake Missoula basin and megafloods in the

Seroprevalence of Rift Valley fever, Q fever, and brucellosis in ruminants on the southeastern shore of Lake Chad.

PubMed

Abakar, Mahamat Fayiz; Naré, Ngandolo B; Schelling, Esther; Hattendorf, Jan; Alfaroukh, Idriss O; Zinsstag, Jakob

2014-10-01

The seroprevalence of Rift Valley fever (RVF), brucellosis, and Q fever among domestic ruminants on the southeastern shore of Lake Chad was studied. The study area consisted of two parts, including mainland and islands. On the mainland, the study was conducted in nine randomly selected villages and camps. On the islands, samples were collected from all four available sites. A total of 985 serum samples were collected and 924 were analyzed using enzyme-linked immunosorbent assay (ELISA) for RVF. A total of 561 samples collected from islands were analyzed using ELISA for Q fever and both ELISA and Rose Bengal tests (RBT) for brucellosis. The apparent RVF seroprevalence by species was 37.8% (95% confidence interval [CI] 34.2-41.3) in cattle, 18.8% (95% CI 12.3-25.2) in goats, and 10.8% (95% CI 3.0-18.5) in sheep. For brucellosis and Q fever, only cattle samples from islands were analyzed. For Q fever, the apparent seroprevalence was 7.8% (95% CI 5.6-10.1). For brucellosis, the RBT showed a prevalence of 5.7% (95% CI 3.8-7.6), and ELISA showed 11.9% (95% CI 9.3-14.6) with a kappa value of 0.53 showing a moderate agreement between the two tests. This study confirms the presence of the three diseases in the study area. More research is required to assess the importance for public health and conservation of the Kouri cattle breed.

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

USGS Publications Warehouse

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

2002-01-01

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.

Seismic structure of the uppermost mantle beneath the Kenya rift

USGS Publications Warehouse