This report was prepared as an account of work sponsored by an agency of the United States Govern... more This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
Coring and mapping of proximal and distal fan deposits and adjacent marsh and peat deposits on th... more Coring and mapping of proximal and distal fan deposits and adjacent marsh and peat deposits on the Leidy Creek fan in Fish Lake Valley, Nevada-California, provide unequivocal evidence that fan deposition in this valley has been extensive in the Holocene and suggest that soils were forming on stable fan surfaces with no debris-flow deposition during the late Wisconsin. Seven cores up to 12 meters long, taken along the axis of Leidy Creek fan, have been correlated by radiocarbon dates, tephra layers, and stratigraphy. Radiocarbon ages and tephra layers indicate a record of peat deposition spanning the last 12,000 years and fluvial sedimentation extending to at least 24,240 yr B.P. Recent mapping in Fish Lake Valley (Reheis, 1991, 1992; Reheis and others, 1993) documents a Pliocene to middle Pleistocene pluvial lake in Fish Lake Valley whose 770-ka shoreline has been vertically offset across the Furnace Creek fault zone as much as 240 m (Reheis and McKee, 1991). CORING AND LOGGING METHODS Core samples were collected from seven drill sites (fig. 2), including four sites from the distal part of the Leidy Creek fan, two sites from a peat bog at the toe of the fan, and a site within marsh deposits adjacent to the peat bog. The sites were cored using a 10-ton truck mounted drill rig, hollow-stem augers, and 3-foot long, 3-inch diameter sampling barrels to obtain a continuous record. Sediment records as long as 12 meters were recovered at the site. Overall core recovery was 96 percent. A 5 meter-wide, 5 meter-long trench was excavated by backhoe on the distal part of the Leidy Creek fan, about 0.5 km southeast of site 5 (fig. 2). The trench was mapped using a 1-meter grid system, placed over the trench wall. Each core consists of segments representing each separate drive into the borehole. The depth of the top of each segment is determined by the driller's depth for that segment. Selected core segments were extruded on site with a piston extruder into a hard plastic casing that had been split lengthwise. Each extruded core segment was wrapped in plastic film to * Depths are approximate due to channeling and depositional irregularities in unit contacts. %or core samples, analysis was determined by Loss on ignition;-, not determined. Determined by Chittick method. 4Clay size is < 0.5 microns for core samples. For trench samples refers to fine silt and cky (clay fractions not analyzed due to lab error). *Sieve analysis by phi (0) scale.
Lineaments and faults in Quaternary and late Tertiary deposits in the southern part of the Walker... more Lineaments and faults in Quaternary and late Tertiary deposits in the southern part of the Walker Lane are potentially active and form patterns that are anomalous with respect to the typical fault patterns in most of the Great Basin. Little work has been done to identify and characterize these faults, with the exception of those in the Death Valley-Furnace Creek fault zone (DVFCFZ) and those in and near the Nevada Test Site. This report includes two quadrangle maps and portions of four others at a scale of 1:100,000; these maps complete a project (previous maps include U.S.G.S. Open-File Reports 90-41 and 90-500) to summarize the existing knowledge about these lineaments and faults within 100 km of the potential high-level nuclear waste repository at Yucca Mountain, based on extensive aerial-photo interpretation, limited field investigations, and published geologic maps. The map area can be divided into two areas. The principal area, covering all of the map area except the southeast corner in the Las Vegas quadrangle, contains mainly northtrending lineaments and faults with a lesser number of east-to northeast-trending faults and a few inactive northwest-trending faults. The north-trending features include rangebounding faults and scarps, faults within volcanic plateaus (Pahute Mesa), and some clusters of faults and scarps on valley floors. The orientations and sense of slip within this domain indicate that the least principal stress direction is northwest-southeast. In the southeastern area, faults and lineaments associated with the Pahrump fault zone trend northwest and north; in this domain, the least principal stress direction is about east-west. Most of the area, and particularly the eastern part of the principal area, has previously been considered to be tectonically inactive, at least since the late Miocene. The abundance of steep straight range-front segments and scarps in Quaternary deposits, however, indicates that faulting and extension in this area are still active. 117°-37° 30' ,-36° 30' Figure l.-Sketch map showing physiography, geographic features, principal fault zones, and boundaries of plates.
Table 11. Arithmetic mean, observed range, geometric mean, and geometric deviation of ash content... more Table 11. Arithmetic mean, observed range, geometric mean, and geometric deviation of ash content and contents of 10 major and minor oxides in the laboratory ash of coal samples from the Williams Fork Formation, northwestern Colorado 93 12. Arithmetic mean, observed range, geometric mean, and geometric deviation of 37 elements in 100 coal samples from the Williams Fork Formation, northwestern Colorado 94 vii EXPLANATION OF FIGURES 2 AND 3
ABSTRACT Arid and semi-arid regions constitute over 35% of global lands. The utilization of these... more ABSTRACT Arid and semi-arid regions constitute over 35% of global lands. The utilization of these areas is increasing rapidly in response to rising human populations and attendant food needs. In addition, they are also foci for activities associated with energy production, mineral extraction, military training and conflict, and recreation. The resultant disturbance reduces the protective cover of plants and physical and biological soil crusts. This leads to accelerated soil loss by both wind and water, across a wide range of parent materials, textures, or soil surface ages. Further vulnerability to soil erosion is expected with predicted future drier and hotter climates, as plant cover declines and fires increase. Synergistic effects, such as surface disturbance occurring during drought periods in plant communities dominated by annual weeds, can exacerbate the situation further. At a local scale, the redistribution of soil by wind and water results in nutrients being more heterogeneously distributed, subsequently altering abundance and distribution of plants, animals, and rates of biogeochemical cycling. Particles transported by wind from disturbed settings can be deposited in washes, subsequently entering streams and rivers.Particles saltating across the soil surface are also frequently deposited in washes, subsequently entering streams and rivers. This process represents a local loss of soil fertility and a local and regional decrease in water quality, as sediment and salts enter water bodies. At the larger watershed scale, dust is deposited on nearby snow cover, darkening the snow and increasing melt rates. Increased melt rates decrease the length of the snow-cover season, increasing water losses to evapotranspiration and thus the amount of water entering streams and rivers. As water quantity decreases, salts and sediments are concentrated, thereby further decreasing water quality. As water becomes scarcer in drylands around the world, the diminishing integrity of the soil surface is likely to become a major issue for land managers. In addition, the spatial decoupling between the people engaged in the upstream activities that lower water availability/quality and the downstream users facing water shortages will likely result in new combinations of interest groups and the need for novel ways to address their differences. The science of ecohydrology has an important role to play in these conversations.
Sediment cores taken near extant springs along the western margin of Soda Lake playa, as well as ... more Sediment cores taken near extant springs along the western margin of Soda Lake playa, as well as from the playa center, reveal dramatic hydrologic changes that occurred in the central Mojave Desert during the late Quaternary. Results of stratigraphic, chronologic, physical, chemical, and microfossil analyses of seven cores, ranging in length from 5 to 23 m, help refine the timing and character of the final stages of pluvial Lake Mojave during the late Pleistocene and define distinct periods of wetland development in the early and late Holocene. Evidence shows that an incipient lake occupied the central Soda Lake basin by at least 25.0 ka (ka ¼ thousands of calibrated 14 C years before present), and a fully developed Lake Mojave was present between 20.5 and 12.8 ka, before receding and ultimately yielding to playa conditions by 11.0 ka. Organic-rich "black mats" appear in several cores along the playa margin between 10.7 and 9.0 ka, suggesting that spring-fed wetlands persisted in this area long after the lake had regressed. The basin remained relatively dry throughout most of the Holocene until wetland ecosystems expanded along the margins between 0.73 and 0.18 ka, coincident with part of the Medieval Climate Anomaly and Little Ice Age. Overall, our results demonstrate that buried sediments surrounding extant and extinct springs can be used to reconstruct past hydrologic conditions in desert environments on a variety of spatial and temporal scales, and provide important baseline information for effective management of limited desert resources.
The Las Vegas Formation (LVF) is a well-characterized sequence of groundwater discharge (GWD) dep... more The Las Vegas Formation (LVF) is a well-characterized sequence of groundwater discharge (GWD) deposits exposed in and around the Las Vegas Valley in southern Nevada. Nearly monolithologic bedrock surrounds the valley, which provides an excellent opportunity to test the hypothesis that GWD deposits include an aeolian component. Mineralogical data indicate that the LVF sediments are dominated by carbonate minerals, similar to the local bedrock, but silicate minerals are also present. The median particle size is ~35 μm, consistent with modern dust in the region, and magnetic properties contrast strongly with local bedrock, implying an extralocal origin. By combining geochemical data from the LVF sediments and modern dust, we found that an average of ~25% of the LVF deposits were introduced by aeolian processes. The remainder consists primarily of authigenic groundwater carbonate as well as minor amounts of alluvial material and soil carbonate. Our data also show that the aeolian sediments accumulated in spring ecosystems in the Las Vegas Valley in a manner that was independent of both time and the specific hydrologic environment. These results have broad implications for investigations of GWD deposits located elsewhere in the southwestern U.S. and worldwide.
This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey e... more This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards and stratigraphic nomenclature. Any use of trade names is for descriptive purposes only and does not imply endorsement by the USGS.
Thin loess deposits on the uplands of the southeastern Colorado Plateau have previously not been ... more Thin loess deposits on the uplands of the southeastern Colorado Plateau have previously not been well studied. We sampled deposits and soils from trenches on Hatch Point mesa near Canyonlands National Park, Utah, and from two outcrops in Mesa Verde National Park, Colorado. At Hatch Point, the oldest buried unit yielded two OSL ages of 10,370 and 7,555 yr; the middle unit yielded 10 OSL ages from 6220 to 1385 yr; and the youngest unit has a single age of 1740 yr. At Mesa Verde, three loess units are preserved in the two outcrops we examined; six OSL ages range from 51 to 17 ka. At least one buried soil is present between two units with ages of about 50 and 40 ka. The ages of the loess units in both study areas correspond well with OSL-dated dune sands in Canyonlands National Park and with dune sands on Black Mesa, Arizona. Particle size distribution combined with chemical and magnetic data indicate that Hatch Point loess was derived mostly from nearby sandstone sources with a small component of far-traveled atmospheric dust, whereas Mesa Verde loess was sourced both from the nearby sandstone and the San Juan River and its tributaries.
This report was prepared as an account of work sponsored by an agency of the United States Govern... more This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
Coring and mapping of proximal and distal fan deposits and adjacent marsh and peat deposits on th... more Coring and mapping of proximal and distal fan deposits and adjacent marsh and peat deposits on the Leidy Creek fan in Fish Lake Valley, Nevada-California, provide unequivocal evidence that fan deposition in this valley has been extensive in the Holocene and suggest that soils were forming on stable fan surfaces with no debris-flow deposition during the late Wisconsin. Seven cores up to 12 meters long, taken along the axis of Leidy Creek fan, have been correlated by radiocarbon dates, tephra layers, and stratigraphy. Radiocarbon ages and tephra layers indicate a record of peat deposition spanning the last 12,000 years and fluvial sedimentation extending to at least 24,240 yr B.P. Recent mapping in Fish Lake Valley (Reheis, 1991, 1992; Reheis and others, 1993) documents a Pliocene to middle Pleistocene pluvial lake in Fish Lake Valley whose 770-ka shoreline has been vertically offset across the Furnace Creek fault zone as much as 240 m (Reheis and McKee, 1991). CORING AND LOGGING METHODS Core samples were collected from seven drill sites (fig. 2), including four sites from the distal part of the Leidy Creek fan, two sites from a peat bog at the toe of the fan, and a site within marsh deposits adjacent to the peat bog. The sites were cored using a 10-ton truck mounted drill rig, hollow-stem augers, and 3-foot long, 3-inch diameter sampling barrels to obtain a continuous record. Sediment records as long as 12 meters were recovered at the site. Overall core recovery was 96 percent. A 5 meter-wide, 5 meter-long trench was excavated by backhoe on the distal part of the Leidy Creek fan, about 0.5 km southeast of site 5 (fig. 2). The trench was mapped using a 1-meter grid system, placed over the trench wall. Each core consists of segments representing each separate drive into the borehole. The depth of the top of each segment is determined by the driller's depth for that segment. Selected core segments were extruded on site with a piston extruder into a hard plastic casing that had been split lengthwise. Each extruded core segment was wrapped in plastic film to * Depths are approximate due to channeling and depositional irregularities in unit contacts. %or core samples, analysis was determined by Loss on ignition;-, not determined. Determined by Chittick method. 4Clay size is < 0.5 microns for core samples. For trench samples refers to fine silt and cky (clay fractions not analyzed due to lab error). *Sieve analysis by phi (0) scale.
Lineaments and faults in Quaternary and late Tertiary deposits in the southern part of the Walker... more Lineaments and faults in Quaternary and late Tertiary deposits in the southern part of the Walker Lane are potentially active and form patterns that are anomalous with respect to the typical fault patterns in most of the Great Basin. Little work has been done to identify and characterize these faults, with the exception of those in the Death Valley-Furnace Creek fault zone (DVFCFZ) and those in and near the Nevada Test Site. This report includes two quadrangle maps and portions of four others at a scale of 1:100,000; these maps complete a project (previous maps include U.S.G.S. Open-File Reports 90-41 and 90-500) to summarize the existing knowledge about these lineaments and faults within 100 km of the potential high-level nuclear waste repository at Yucca Mountain, based on extensive aerial-photo interpretation, limited field investigations, and published geologic maps. The map area can be divided into two areas. The principal area, covering all of the map area except the southeast corner in the Las Vegas quadrangle, contains mainly northtrending lineaments and faults with a lesser number of east-to northeast-trending faults and a few inactive northwest-trending faults. The north-trending features include rangebounding faults and scarps, faults within volcanic plateaus (Pahute Mesa), and some clusters of faults and scarps on valley floors. The orientations and sense of slip within this domain indicate that the least principal stress direction is northwest-southeast. In the southeastern area, faults and lineaments associated with the Pahrump fault zone trend northwest and north; in this domain, the least principal stress direction is about east-west. Most of the area, and particularly the eastern part of the principal area, has previously been considered to be tectonically inactive, at least since the late Miocene. The abundance of steep straight range-front segments and scarps in Quaternary deposits, however, indicates that faulting and extension in this area are still active. 117°-37° 30' ,-36° 30' Figure l.-Sketch map showing physiography, geographic features, principal fault zones, and boundaries of plates.
Table 11. Arithmetic mean, observed range, geometric mean, and geometric deviation of ash content... more Table 11. Arithmetic mean, observed range, geometric mean, and geometric deviation of ash content and contents of 10 major and minor oxides in the laboratory ash of coal samples from the Williams Fork Formation, northwestern Colorado 93 12. Arithmetic mean, observed range, geometric mean, and geometric deviation of 37 elements in 100 coal samples from the Williams Fork Formation, northwestern Colorado 94 vii EXPLANATION OF FIGURES 2 AND 3
ABSTRACT Arid and semi-arid regions constitute over 35% of global lands. The utilization of these... more ABSTRACT Arid and semi-arid regions constitute over 35% of global lands. The utilization of these areas is increasing rapidly in response to rising human populations and attendant food needs. In addition, they are also foci for activities associated with energy production, mineral extraction, military training and conflict, and recreation. The resultant disturbance reduces the protective cover of plants and physical and biological soil crusts. This leads to accelerated soil loss by both wind and water, across a wide range of parent materials, textures, or soil surface ages. Further vulnerability to soil erosion is expected with predicted future drier and hotter climates, as plant cover declines and fires increase. Synergistic effects, such as surface disturbance occurring during drought periods in plant communities dominated by annual weeds, can exacerbate the situation further. At a local scale, the redistribution of soil by wind and water results in nutrients being more heterogeneously distributed, subsequently altering abundance and distribution of plants, animals, and rates of biogeochemical cycling. Particles transported by wind from disturbed settings can be deposited in washes, subsequently entering streams and rivers.Particles saltating across the soil surface are also frequently deposited in washes, subsequently entering streams and rivers. This process represents a local loss of soil fertility and a local and regional decrease in water quality, as sediment and salts enter water bodies. At the larger watershed scale, dust is deposited on nearby snow cover, darkening the snow and increasing melt rates. Increased melt rates decrease the length of the snow-cover season, increasing water losses to evapotranspiration and thus the amount of water entering streams and rivers. As water quantity decreases, salts and sediments are concentrated, thereby further decreasing water quality. As water becomes scarcer in drylands around the world, the diminishing integrity of the soil surface is likely to become a major issue for land managers. In addition, the spatial decoupling between the people engaged in the upstream activities that lower water availability/quality and the downstream users facing water shortages will likely result in new combinations of interest groups and the need for novel ways to address their differences. The science of ecohydrology has an important role to play in these conversations.
Sediment cores taken near extant springs along the western margin of Soda Lake playa, as well as ... more Sediment cores taken near extant springs along the western margin of Soda Lake playa, as well as from the playa center, reveal dramatic hydrologic changes that occurred in the central Mojave Desert during the late Quaternary. Results of stratigraphic, chronologic, physical, chemical, and microfossil analyses of seven cores, ranging in length from 5 to 23 m, help refine the timing and character of the final stages of pluvial Lake Mojave during the late Pleistocene and define distinct periods of wetland development in the early and late Holocene. Evidence shows that an incipient lake occupied the central Soda Lake basin by at least 25.0 ka (ka ¼ thousands of calibrated 14 C years before present), and a fully developed Lake Mojave was present between 20.5 and 12.8 ka, before receding and ultimately yielding to playa conditions by 11.0 ka. Organic-rich "black mats" appear in several cores along the playa margin between 10.7 and 9.0 ka, suggesting that spring-fed wetlands persisted in this area long after the lake had regressed. The basin remained relatively dry throughout most of the Holocene until wetland ecosystems expanded along the margins between 0.73 and 0.18 ka, coincident with part of the Medieval Climate Anomaly and Little Ice Age. Overall, our results demonstrate that buried sediments surrounding extant and extinct springs can be used to reconstruct past hydrologic conditions in desert environments on a variety of spatial and temporal scales, and provide important baseline information for effective management of limited desert resources.
The Las Vegas Formation (LVF) is a well-characterized sequence of groundwater discharge (GWD) dep... more The Las Vegas Formation (LVF) is a well-characterized sequence of groundwater discharge (GWD) deposits exposed in and around the Las Vegas Valley in southern Nevada. Nearly monolithologic bedrock surrounds the valley, which provides an excellent opportunity to test the hypothesis that GWD deposits include an aeolian component. Mineralogical data indicate that the LVF sediments are dominated by carbonate minerals, similar to the local bedrock, but silicate minerals are also present. The median particle size is ~35 μm, consistent with modern dust in the region, and magnetic properties contrast strongly with local bedrock, implying an extralocal origin. By combining geochemical data from the LVF sediments and modern dust, we found that an average of ~25% of the LVF deposits were introduced by aeolian processes. The remainder consists primarily of authigenic groundwater carbonate as well as minor amounts of alluvial material and soil carbonate. Our data also show that the aeolian sediments accumulated in spring ecosystems in the Las Vegas Valley in a manner that was independent of both time and the specific hydrologic environment. These results have broad implications for investigations of GWD deposits located elsewhere in the southwestern U.S. and worldwide.
This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey e... more This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards and stratigraphic nomenclature. Any use of trade names is for descriptive purposes only and does not imply endorsement by the USGS.
Thin loess deposits on the uplands of the southeastern Colorado Plateau have previously not been ... more Thin loess deposits on the uplands of the southeastern Colorado Plateau have previously not been well studied. We sampled deposits and soils from trenches on Hatch Point mesa near Canyonlands National Park, Utah, and from two outcrops in Mesa Verde National Park, Colorado. At Hatch Point, the oldest buried unit yielded two OSL ages of 10,370 and 7,555 yr; the middle unit yielded 10 OSL ages from 6220 to 1385 yr; and the youngest unit has a single age of 1740 yr. At Mesa Verde, three loess units are preserved in the two outcrops we examined; six OSL ages range from 51 to 17 ka. At least one buried soil is present between two units with ages of about 50 and 40 ka. The ages of the loess units in both study areas correspond well with OSL-dated dune sands in Canyonlands National Park and with dune sands on Black Mesa, Arizona. Particle size distribution combined with chemical and magnetic data indicate that Hatch Point loess was derived mostly from nearby sandstone sources with a small component of far-traveled atmospheric dust, whereas Mesa Verde loess was sourced both from the nearby sandstone and the San Juan River and its tributaries.
Uploads
Papers by Marith Reheis