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At least 433 records · Page 24Linked to original sources
USGS2000

Geologic and geophysical characterization studies of Yucca Mountain, Nevada, a potential high-level radioactive-waste repository

In recognition of a critical national need for permanent radioactive-waste storage, Yucca Mountain in southwestern Nevada has been investigated by Federal agencies since the 1970's, as a potential geologic disposal site. In 1987, Congress selected Yucca Mountain for an expanded and more detailed site characterization effort. As an integral part of this program, the U.S. Geological Survey began a series of detailed geologic, geophysical, and related investigations designed to characterize the tectonic setting, fault behavior, and seismicity of the Yucca Mountain area. This document presents the results of 13 studies of the tectonic environment of Yucca Mountain, in support of a broad goal to assess the effects of future seismic and fault activity in the area on design, long-term performance, and safe operation of the potential surface and subsurface repository facilities.

Nevada↗
USGS2000

Isostatic gravity map of the Battle Mountain 30 x 60 minute quadrangle, north central Nevada

Gravity investigations of the Battle Mountain 30 x 60 minute quadrangle were begun as part of an interagency effort by the U.S. Geological Survey (USGS) and the Bureau of Land Management to help characterize the geology, mineral resources, hydrology, and ecology of the Humboldt River Basin in north-central Nevada. The Battle Mountain quadrangle is located between 40°30' and 41°N. lat. and 116° and 117°W. long. This isostatic gravity map of the Battle Mountain quadrangle was prepared from data from about 1,180 gravity stations. Most of these data are publicly available on a CD-ROM of gravity data of Nevada (Ponce, 1997) and in a published report (Jewel and others, 1997). Data from about 780 gravity stations were collected by the U.S. Geological Survey since 1996; data from about 245 of these are unpublished (USGS, unpub. data, 1998). Data collected from the 400 gravity stations prior to 1996 are a subset of a gravity data compilation of the Winnemucca 1:250,000-scale quadrangle described in great detail by Wagini (1985) and Sikora (1991). This detailed information includes gravity meters used, dates of collection, sources, descriptions of base stations, plots of data, and a list of principal facts. A digital version of the entire data set for the Battle Mountain quadrangle is available on the World Wide Web at: http://wrgis.wr.usgs.gov/docs/gump/gump.html

Nevada↗
USGS1981

Map showing mineral-resource potential of the King Range and Chemise Mountain Instant Study Areas, Humboldt and Mendocino counties, California

The potential for economic development of energy-related or metallic mineral resources in the King Range and Chemise Mountain Instant Study Areas is low to moderate as indicated by geologic, geophysical, and geochemical investigations. No oil or gas seeps or coal seams were detected within the King Range or Chemise Mountain Study Area. The low porosity and permeability of the Franciscan sandstones that underlie these areas indicate a very low potential for oil or gas. The geothermal resource potential of these areas also is low. Minor manganese resources occur adjacent to the southeast corner of the King Range Instant Study Area near Queen Peak. The manganese forms small stratabound deposits associated with radiolarian chert and pillow basalt. The known deposits are too small and the manganese too low in concentration for further economic exploitation. Similar manganese mineralization may be within the belt of melange in the southeast corner of the King Range area and within the Chemise Mountain Instant Study Area, but economic deposits are unlikely. Although there has been historical base- and precious-metal exploration activity north of the King Range in the Mattole River drainage, our geologic and geochemical field data indicate almost no gold potential and low potentials for lead, zinc, copper, and silver. During this investigation, one high-grade vein and several minor veins containing lead, zinc, copper, and silver were discovered at Point Delgada immediately south of the King Range Instant Study Area. The vein mineralization is Miocene and cuts Cretaceous basalt flows, dikes, flow breccia, and younger overlying sedimentary rocks of the King Range. The vein mineralization at Point Delgada could be remobilized from more extensive unexposed stratabound base-metal mineralization at depth. Traces of lead and zinc detected within the King Range Instant Study Area may have similar stratabound or vein origins, but no resource potential is indicated. Minor copper mineralization with associated lead, zinc, and manganese anomalies within the Chemise Mountain Instant Study Area is of low economic potential because of the shearing, isolation, and lenticularity of the basaltic and cherty rocks within the melange mineralization.

California↗
USGS2001

Selected ground-water data for Yucca Mountain region, southern Nevada and eastern California, through December 1999

The U.S. Geological Survey, in support of the U.S. Department of Energy, Yucca Mountain Site Characterization Project, collects, compiles, and summarizes hydrologic data in the Yucca Mountain region. The data are collected to allow assessments of ground-water resources during studies to determine the potential suitability of Yucca Mountain for storing high-level nuclear waste. Data on ground-water levels at 34 wells and a fissure (Devils Hole), ground-water discharge at 5 springs and a flowing well, and total reported ground-water withdrawals within Crater Flat, Jackass Flats, Mercury Valley, and the Amargosa Desert are presented for calendar year 1999. Data collected prior to 1999 are graphically presented and data collected by other agencies (or as part of other Geological Survey programs) are included to further indicate variations of ground-water levels, discharges, and withdrawals through time. A statistical summary of ground-water levels at seven wells in Jackass Flats is presented to indicate potential effects of ground-water withdrawals associated with U.S. Department of Energy activities near Yucca Mountain. The statistical summary includes the number of measurements, the maximum, minimum, and median water-level altitudes, and the average deviation of measured water-level altitudes for selected baseline periods and for calendar years 1992-99. At two water-supply wells median water levels for calendar year 1999 were unchanged from their respective baseline periods. At a nearby observation well, the 1999 median water level was slightly lower (0.1 foot) than its baseline period. At the remaining four wells in Jackass Flats, median water levels for 1999 were slightly higher (0.2 foot to 1.6 feet) than for their respective baseline periods.

Open-File Report↗
USGS2003

Principal facts for 408 gravity stations in the vicinity of the Talkeetna Mountains, south-central Alaska

Gravity data were collected between 1999 and 2002 along transects in the Talkeetna Mountains of south-central Alaska as part of a geological and geophysical study of the framework geology of the region. The study area lies between 61° 30’ and 63° 45’ N. latitude and 145° and 151° W. longitude. This data set includes 408 gravity stations. These data, combined with the pre-existing 3,286 stations, brings the total data in this area to 3,694 gravity stations. Principal facts for the 408 new gravity stations and the 15 gravity base stations used for control are listed in this report. During the summer of 1999, a gravity survey was conducted in the western Talkeetna Mountains. Measurements at 55 gravity stations were made. One gravity base station was used for control for this survey. This base station, STEP, is located at the Stephan Lake Lodge on Stephan Lake. The observed gravity of this station was calculated based on an indirect tie to base station ANCL in Anchorage. The temporary base used to tie between STEP and ANCL was REGL in Anchorage. During the summer of 2000, a gravity survey was conducted in the western Talkeetna Mountains. Measurements at 56 gravity stations were made. One gravity base station was used for control for this survey. This base station, GRHS, is located at the Gracious House Lodge on the Denali Highway. The observed gravity of this station was calculated based on multiple ties to base stations D87, and D57 along the Denali Highway. During the summer of 2001, a gravity survey was conducted in the western Talkeetna Mountains. Measurements at 90 gravity stations were made. One gravity base station was used for control for this survey. This base station, HLML, is located at the High Lake Lodge. The observed gravity of this station was calculated based on multiple ties to base stations ANCU in Anchorage, PALH in Palmer, WASA in Wasilla, and TLKM in Talkeetna. Also during the summer of 2001, a gravity survey was conducted in the vicinity of Tangle Lakes. Measurements at 86 gravity stations were made. The Tangle Lakes area is located about 25 km west of Paxson and north of the Denali Highway. One gravity base station was used for control for this survey. This base station, TLIN, is located at the Tangle Lakes Inn. The observed gravity of this station was calculated based on multiple ties to base stations ANCU in Anchorage, PALH in Palmer, BD27 in Gulkana, B-07 on the Richardson Highway, and base stations D42, and D57 along the Denali Highway. During the summer of 2002, measurements at an additional 107 gravity stations were made in the vicinity of Tangle Lakes. Base station TLIN at the Tangle Lakes Inn was again used for control. Additional ties to base stations ANCU and B-07 were made.

Alaska↗
USGS2003

Selected ground-water data for Yucca Mountain region, southern Nevada and eastern California, January 2000-December 2002

The U.S. Geological Survey, in support of the U.S. Department of Energy, Yucca Mountain Project, collects, compiles, and summarizes hydrologic data in the Yucca Mountain region. The data are collected to allow assessments of ground-water resources during activities to determine the potential suitability or development of Yucca Mountain for storing high-level nuclear waste. Data on ground-water levels at 35 wells and a fissure (Devils Hole), ground-water discharge at 5 springs and a flowing well, and total reported ground-water withdrawals within Crater Flat, Jackass Flats, Mercury Valley, and the Amargosa Desert are tabulated from January 2000 through December 2002. Historical data on water levels, discharges, and withdrawals are graphically presented to indicate variations through time. A statistical summary of ground-water levels at seven wells in Jackass Flats is presented for 1992-2002 to indicate potential effects of ground-water withdrawals associated with U.S. Department of Energy activities near Yucca Mountain. The statistical summary includes the annual number of measurements, maximum, minimum, and median water-level altitudes, and average deviation of measured water-level altitudes compared to selected baseline periods. Baseline periods varied for 1985-93. At six of the seven wells in Jackass Flats, the median water levels for 2002 were slightly higher (0.3-2.4 feet) than for their respective baseline periods. At the remaining well, data for 2002 was not summarized statistically but median water-level altitude in 2001 was 0.7 foot higher than that in its baseline period.

California, Nevada↗
USGS2006

A Preliminary Investigation of The Structure of Southern Yucca Flat, Massachusetts Mountain, and CP Basin, Nevada Test Site, Nevada, Based on Geophysical Modeling

New gravity and magnetic data collected in the vicinity of Massachusetts Mountain and CP basin (Nevada Test Site, NV) provides a more complex view of the structural relationships present in the vicinity of CP basin than previous geologic models, helps define the position and extent of structures in southern Yucca Flat and CP basin, and better constrains the configuration of the basement structure separating CP basin and Frenchman Flat. The density and gravity modeling indicates that CP basin is a shallow, oval-shaped basin which trends north-northeast and contains ~800 m of basin-filling rocks and sediment at its deepest point in the northeast. CP basin is separated from the deeper Frenchman Flat basin by a subsurface ridge that may represent a Tertiary erosion surface at the top of the Paleozoic strata. The magnetic modeling indicates that the Cane Spring fault appears to merge with faults in northwest Massachusetts Mountain, rather than cut through to Yucca Flat basin and that the basin is downed-dropped relative to Massachusetts Mountain. The magnetic modeling indicates volcanic units within Yucca Flat basin are down-dropped on the west and supports the interpretations of Phelps and KcKee (1999). The magnetic data indicate that the only faults that appear to be through-going from Yucca Flat into either Frenchman Flat or CP basin are the faults that bound the CP hogback. In general, the north-trending faults present along the length of Yucca Flat bend, merge, and disappear before reaching CP hogback and Massachusetts Mountain or French Peak.

Open-File Report↗
USGS2006

Structure and Velocities of the Northeastern Santa Cruz Mountains and the Western Santa Clara Valley, California, from the SCSI-LR Seismic Survey

Introduction: The Santa Clara Valley is located in the southern San Francisco Bay area of California and generally includes the area south of the San Francisco Bay between the Santa Cruz Mountains on the southwest and the Diablo Ranges on the northeast. The area has a population of approximately 1.7 million including the city of San Jose, numerous smaller cities, and much of the high-technology manufacturing and research area commonly referred to as the Silicon Valley. Major active strands of the San Andreas Fault system bound the Santa Clara Valley, including the San Andreas fault to the southwest and the Hayward and Calaveras faults to the northeast; related faults likely underlie the alluvium of the valley. This report focuses on subsurface structures of the western Santa Clara Valley and the northeastern Santa Cruz Mountains and their potential effects on earthquake hazards and ground-water resource management in the area. Earthquake hazards and ground-water resources in the Santa Clara Valley are important considerations to California and the Nation because of the valley's preeminence as a major technical and industrial center, proximity to major earthquakes faults, and large population. To assess the earthquake hazards of the Santa Clara Valley better, the U.S. Geological Survey (USGS) has undertaken a program to evaluate potential earthquake sources and potential effects of strong ground shaking within the valley. As part of that program, and to better assess water resources of the valley, the USGS and the Santa Clara Valley Water District (SCVWD) began conducting collaborative studies to characterize the faults, stratigraphy, and structures beneath the alluvial cover of the Santa Clara Valley in the year 2000. Such geologic features are important to both agencies because they directly influence the availability and management of groundwater resources in the valley, and they affect the severity and distribution of strong shaking from local or regional earthquakes sources. As one component of these joint studies, the U. S. Geological Survey acquired more than 28 km of combined seismic reflection/refraction data from the Santa Cruz Mountains to the central Santa Clara Valley in December 2000. The seismic investigation included both high-resolution (~5-m shot and sensor spacing) and relatively lower-resolution (~50-m sensor) seismic surveys from the central Santa Cruz Mountains to the central part of the valley. Collectively, we refer to these seismic investigations as the 2000 western Santa Clara Seismic Investigations (SCSI).

Open-File Report↗
USGS2006

Preliminary geologic map of the Black Mountain area northeast of Victorville, San Bernardino County, California

The Black Mountain area is in the Mojave Desert about 20 km northeast of Victorville, California. The geology of this area is of interest primarily for its excellent exposures of the early Mesozoic Fairview Valley Formation, a sequence of weakly metamorphosed sedimentary rocks including a thick, commercially important unit of limestone conglomerate that has been mined for cement at Black Mountain Quarry for several decades. Recent geochronologic work has shown that the Fairview Valley Formation is probably of Early Jurassic age. This preliminary geologic map of the Black Mountain area depicts the stratigraphic and structural relations of the Fairview Valley Formation and the associated rocks, most notably the overlying Sidewinder Volcanics of Early(?), Middle, and Late(?) Jurassic age. The map is based on new field studies by the author designed to clarify details of the stratigraphy and structure unresolved by previous investigations. The map is considered preliminary because the ages of some geologic units critical for a satisfactory understanding of the stratigraphic and structural framework remain unknown. The map area also includes a segment of the Helendale Fault, one of several faults of known or inferred late Cenozoic right-lateral displacement that make up the Eastern California Shear Zone. The fault is marked by aligned northeast-facing scarps in Pleistocene or older alluvial deposits and the underlying bedrock units. Relations in the map area suggest that right-lateral displacement on the Helendale Fault probably does not exceed 2 km, a conclusion compatible with previous estimates of displacement on this fault based on relations both within and outside the Black Mountain area.

Open-File Report↗
USGS2009

Emergency Assessment of Postfire Debris-Flow Hazards for the 2009 Station Fire, San Gabriel Mountains, Southern California

This report presents an emergency assessment of potential debris-flow hazards from basins burned by the 2009 Station fire in Los Angeles County, southern California. Statistical-empirical models developed for postfire debris flows are used to estimate the probability and volume of debris-flow production from 678 drainage basins within the burned area and to generate maps of areas that may be inundated along the San Gabriel mountain front by the estimated volume of material. Debris-flow probabilities and volumes are estimated as combined functions of different measures of basin burned extent, gradient, and material properties in response to both a 3-hour-duration, 1-year-recurrence thunderstorm and to a 12-hour-duration, 2-year recurrence storm. Debris-flow inundation areas are mapped for scenarios where all sediment-retention basins are empty and where the basins are all completely full. This assessment provides critical information for issuing warnings, locating and designing mitigation measures, and planning evacuation timing and routes within the first two winters following the fire. Tributary basins that drain into Pacoima Canyon, Big Tujunga Canyon, Arroyo Seco, West Fork of the San Gabriel River, and Devils Canyon were identified as having probabilities of debris-flow occurrence greater than 80 percent, the potential to produce debris flows with volumes greater than 100,000 m3, and the highest Combined Relative Debris-Flow Hazard Ranking in response to both storms. The predicted high probability and large magnitude of the response to such short-recurrence storms indicates the potential for significant debris-flow impacts to any buildings, roads, bridges, culverts, and reservoirs located both within these drainages and downstream from the burned area. These areas will require appropriate debris-flow mitigation and warning efforts. Probabilities of debris-flow occurrence greater than 80 percent, debris-flow volumes between 10,000 and 100,000 m3, and high Combined Relative Debris-Flow Hazard Rankings were estimated in response to both short recurrence-interval (1- and 2-year) storms for all but the smallest basins along the San Gabriel mountain front between Big Tujunga Canyon and Arroyo Seco. The combination of high probabilities and large magnitudes determined for these basins indicates significant debris-flow hazards for neighborhoods along the mountain front. When the capacity of sediment-retention basins is exceeded, debris flows may be deposited in neighborhoods and streets and impact infrastructure between the mountain front and Foothill Boulevard. In addition, debris flows may be deposited in neighborhoods immediately below unprotected basins. Hazards to neighborhoods and structures at risk from these events will require appropriate debris-flow mitigation and warning efforts.

Open-File Report↗
USGS2021

A geologic field guide to S P Mountain and its lava flow, San Francisco Volcanic Field, Arizona

Introduction We created this guide to introduce the user to the San Francisco Volcanic Field as a terrestrial analog site for planetary volcanic processes. For decades, the San Francisco Volcanic Field has been used to teach scientists to recognize the products of common types of volcanic eruptions and associated volcanic features. The volcanic processes and products observed in this volcanic field are like those observed on lunar and Martian surfaces. As a result, this region has been a favored location for training National Aeronautics and Space Administration astronauts and engineers since the Apollo missions. Though the San Francisco Volcanic Field has more than 600 volcanic vents and flows, this guide will focus on S P Mountain (known locally as S P Crater, located ~30 miles north of Flagstaff, Arizona), one of the best preserved and most accessible of the volcanic cones and lava flows. S P Mountain presents both major types of basaltic eruptions—explosive and effusive—as well as some commonly associated tectonic landforms. We assume that the user has a basic understanding of geologic concepts and terminology. For more specialized terminology, we include tables showing the classification scheme for lava compositions, styles of eruptions, and tephra sizes (tables 1, 2, and 3). If a further introduction or refresher in volcanological terminology is desired, we suggest reviewing such terms on the U.S. Geological Survey Volcano Science Center’s online glossary ( https://volcanoes.usgs.gov/vsc/glossary/ ). One term requires clarification at the start of this guide—the term cinder. The terms cinder and cinder cone are widely used to describe the material and edifice produced by lava fountains. However, the term comes from the mining and construction industries and has no clear or formal definition. The international committees in geology and volcanology have chosen the term tephra to be the general term to describe pyroclasts (material ejected through a volcanic explosion or from a volcanic vent). Therefore, in this guide, we use the term tephra rather than cinder. This guide is outlined as follows: A brief tour of volcanism across the solar system A brief geologic history of the Colorado Plateau and San Francisco Volcanic Field Background on distributed volcanism and S P Mountain Driving directions and field stops Questions for discussion Each field stop includes a brief description, learning goals, tasks, and a summary of key points. At the end of the field guide are discussion points and questions that will ask the user to consider what they have observed and learned and how such knowledge can be used to better our understanding of geologic processes on other planetary bodies. Upon the completion of this field guide, we expect the user to: Have a basic understanding of the volcanic processes relevant to S P Mountain and its lava flow. Be able to identify different volcanic textures that are associated with tephra cones. Be aware of the different observations one can make at different scales (for example, observing lava flow morphology from aerial or satellite imagery versus tephra characteristics in the field).

Arizona↗
USGS1978

Mineral potential of altered rocks near Blawn Mountain, Wah Wah Range, Utah

A mineralized area near Blawn Mountain in the southern Wah Wah Range has potential for deposits of lithophile metals, including uranium, tin, molybdenum, and beryllium. An area of iron oxide, alunite, and kaolinite alteration in rhyolite on Blawn Mountain overlaps southward with an area of fluorite, montmorillonite, and illite alteration in rhyolite and breccia near the Staats mine. The area on Blawn Mountain is largely depleted of metals other than iron, but the area near the Staats mine has produced some fluorspar and uranium and has anomalous amounts of tin, molybdenum, and beryllium in altered rock. Topaz rhyolites near the Staats mine and on The Tetons are similar to those in the Thomas Range of Utah, which are associated with deposits of fluorspar, uranium, and beryllium. Unmineralized topaz rhyolite in the Wah Wah Range contains anomalous traces of Be, Ga, Li, Mo, Nb, and Sn. Extensive areas of jasperoid with very low trace metal contents are associated with the areas of mineralization and alteration. The age of alteration and mineralization in the southern Wah Wah Range can De inferred from the age of host rocks. The rhyolite of Blawn Mountain, which is the host for alunite and kaolinite, is dated as 30.7?1.5 m.y. old. The intrusive topaz rhyolite of the Staats mine area, which with its altered breccia zone is the host and probable source of fluorine and lithophile metals, is 19.7?0.8 m.y. old. The overlap of both kaolinite and montmorillonite in altered breccia along the north side of the intrusive topaz rhyolite suggests that all of the alteration and mineralization may be younger than 19.7?0.8 m.y.

Open-File Report↗
USGS1979

Possible uranium mineralization, Mineral Mountains, Utah

The Mineral Mountains block in west-central Utah is a horst whose core stands structurally high relative to all nearby basin-and-range fault blocks. Rocks of the Mineral Mountains range from Precambrian to Quaternary in age, but mostly consist of Tertiary granitic rocks. The range lies with the Wah Wah-Tusher mineral belt. Lead, silver, gold, and tungsten have been mined commercially. During a geochemical survey conducted in the summer of 1978, 30 water samples and 29 stream-sediment samples were collected from the Mineral Mountains area. The interpretation of simple plots of uranium concentrations and the results of a Q-mode factor analysis indicate that potential exists for uranium mineral deposits within the Mineral Mountains. The most favorable areas are in the granitic pluton near its contacts with sedimentary and metamorphic rocks. The most likely source of the uranium anomalies is uraninite-bearing epigenic veins along faults and fractures within the pluton. Three hypothetical models are proposed to account for the uranium mineralization.

Open-File Report↗
USGS1981

Reconnaissance of the Hot Springs Mountains and adjacent areas, Churchill County, Nevada

A geologic reconnaissance of the Hot Springs Mountains and adjacent areas, which include parts of the Brady-Hazen and the Stillwater-Soda Lake Known Geothermal Resource Areas, during June-December 1975, resulted in a reinterpretation of the nature and location of some Basin and Range faults. In addition, the late Cenozoic stratigraphy has been modified, chiefly on the basis of radiometric dates of volcanic rocks by U.S. Geological Survey personnel and others. The Hot Springs Mountains are in the western part of the Basin and Range province, which is characterized by east-west crustal extension and associated normal faulting. In the surrounding Trinity, West Humboldt, Stillwater, and Desert Mountains, Cenozoic rocks overlie ' basement ' rocks of the Paleozoic and Mesozoic age. A similar relation is inferred in the Hot Springs Mountains. Folding and faulting have taken place from the late Tertiary to the present. (USGS)

Nevada↗
USGS1984

Hydrology of Area 62, Northern Great Plains and Rocky Mountain Coal Provinces, New Mexico and Arizona

This report summarizes available hydrologic data for Area 62 and will aid leasing decisions, and the preparation and appraisal of environmental impact studies and mine-permit applications. Area 62 is located at the southern end of the Rocky Mountain Coal Province in parts of New Mexico and Arizona and includes approximately 9,500 square miles. Surface mining alters, at least temporarily, the environment; if the areas are unreclaimed, there can be long-term environmental consequences. The land-ownership pattern in Area 62 is complicated. The checkerboard pattern created by several types of ownership makes effective management of these lands difficult. The climate generally is semiarid with average annual precipitation ranging from 10 to 20 inches. Pinons, junipers, and grasslands cover most of the area, and much of it is used for grazing by livestock. Soils vary with landscape, differing from flood plains and hillslopes to mountain slopes. The major structural features of this area were largely developed during middle Tertiary time. The main structural features are the southern San Juan Basin and the Mogollon slope. Coal-bearing rocks are present in four Cretaceous rock units of the Mesaverde Group: the Gallup Sandstone, the Dileo Coal Member, and the Gibson Coal Member of the Crevasse Canyon Formation, and the Cleary Coal Member of the Menefee Formation. Area 62 is drained by Black Creek, the Puerco River, the Zuni River, Carrizo Wash-Largo Creek, and the Rio San Jose. Only at the headwaters of the Zuni River is the flow perennial. The streamflow-gaging station network consists of 25 stations operated for a variety of needs. Streamflow changes throughout the year with variation related directly to rainfall and snowmelt. Base flow in Area 62 is zero indicating no significant ground-water discharge. Mountainous areas contribute the highest mean annual runoff of 1.0 inch. Very few water-quality data are available for the surface-water stations. Of the nine surface-water stations that have water-quality data, only one has chemical analyses from more than 10 samples. Therefore, sufficient data to characterize the area in detail are not available. Suspended sediment data are available only for a few surface- water stations in the area. Erosion rates generally are less than 1 acre-foot per square mile per year. Greater erosion rates are found within the badland areas. Water levels are periodically measured at 21 selected wells in Area 62. These observation wells are located mostly along the Rio San Jose and northeast of Gallup, New Mexico. The recharge to ground-water aquifers generally coincide with areas of greater precipitation in the mountainous areas. Depth to water below land surface is generally less than 200 feet. Well yields of 100 gallons per minute are common in most of the area. Ground-water quality is variable both within each aquifer and between aquifers. Water quality generally is best near recharge areas. Historical and current data related to stream discharge, water quality, and suspended sediment are available from computer files in the U.S. Geological Survey's National Water Data Storage and Retrieval System (WATSTORE) and through the National Water Data Exchange (NAWDEX).

Open-File Report↗
USGS1988

Water levels in periodically measured wells in the Yucca Mountain area, Nye County, Nevada, 1981-87

This report contains data on groundwater levels beneath Yucca Mountain and adjacent areas, Nye County, Nevada. In addition to new data collected since 1983, the report contains data that has been updated from previous reports, including added explanations of the data. The data was collected in cooperation with the U.S. Department of Energy to help that agency evaluate the suitability of the area of storing high-level nuclear waste. The water table in the Yucca Mountain area occurs in ash-flow and air-fall tuff of Tertiary age. West of the crest of Yucca Mountain, water level altitudes are about 775 m above sea level. Along the eastern edge and southern end of Yucca Mountain, the potentiometric surface generally is nearly flat, ranging from about 730 to 728 m above sea level. (USGS)

Open-File Report↗
USGS1997

Level II scour analysis for Bridge 26 (JAMATH00010026) on Town Highway 1, crossing Ball Mountain Brook, Jamaica, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure JAMATH00010026 on Town Highway 1 crossing Ball Mountain Brook, Jamaica, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Green Mountain section of the New England physiographic province in southern Vermont. The 29.3-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forest. In the study area, Ball Mountain Brook has an incised, sinuous channel with a slope of approximately 0.02 ft/ft, an average channel top width of 74 ft and an average bank height of 6 ft. The channel bed material ranges from gravel to boulder with a median grain size (D 50 ) of 82.6 mm (0.271 ft). The geomorphic assessment at the time of the Level I and Level II site visit on August 12, 1996, indicated that the reach was stable. The Town Highway 1 crossing of Ball Mountain Brook is a 80-ft-long, two-lane bridge consisting of one 78-foot steel-beam span (Vermont Agency of Transportation, written communication, March 29, 1995). The opening length of the structure parallel to the bridge face is 75.7 ft. The bridge is supported by vertical, concrete abutments with wingwalls. A scour hole 2 ft deeper than the mean thalweg depth was observed along the right abutment during the Level I assessment. The scour protection measures at the site were type-4 stone fill (less than 60 inches diameter) along the left bank upstream and extending underneath the bridge and along the bank downstream and also along the right bank upstream tapering to type-3 stone fill (less than 48 inches diameter) at the upstream end of the upstream right wingwall. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and recommended rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a highway crossing is comprised of three components: 1) long-term streambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is the sum of the three components. Equations are available to compute depths for contraction and local scour and a summary of the results of these computations follows. Contraction scour for the modelled flows ranged from 1.0 to 2.7 ft. The worst-case contraction scour occurred at the incipient-overtopping discharge. Abutment scour ranged from 8.4 to 17.6 ft. The worst-case abutment scour for the right abutment occurred at the incipient-overtopping discharge. For the left abutment, the worst-case abutment scour occurred at the 500-year discharge. Additional information on scour depths and depths to armoring are included in the section titled “Scour Results”. Scoured-streambed elevations, based on the calculated scour depths, are presented in tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure 8. Scour depths were calculated assuming an infinite depth of erosive material and a homogeneous particle-size distribution. It is generally accepted that the Froehlich equation (abutment scour) gives “excessively conservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, computed scour depths are evaluated in combination with other information including (but not limited to) historical performance during flood events, the geomorphic stability assessment, existing scour protection measures, and the results of the hydraulic analyses. Therefore, scour depths adopted by VTAOT may differ from the computed values documented herein.

Vermont↗
USGS1998

Rotational and accretionary evolution of the Klamath Mountains, California and Oregon, from Devonian to present time

The purpose of this report is to show graphically how the Klamath Mountains grew from a relatively small nucleus in Early Devonian time to its present size while rotating clockwise approximately 110°. This growth occurred by the addition of large tectonic slices of oceanic lithosphere, volcanic arcs, and melange during a sequence of accretionary episodes. The Klamath Mountains province consists of eight lithotectonoic units called terranes, some of which are divided into subterranes. The Eastern Klamath terrane, which was the early Paleozoic nucleus of the province, is divided into the Yreka, Trinity, and Redding subterranes. Through tectonic plate motion, usually involving subduction, the other terranes joined the early Paleozoic nucleus during seven accretionary episodes ranging in age from Early Devonian to Late Jurassic. The active terrane suture is shown for each episode by a bold black line. Much of the western boundary of the Klamath Mountains is marked by the South Fork and correlative faults along which the Klamath terranes overrode the Coast Range rocks during an eighth accretionary episode, forming the South Fork Mountain Schist in Early Cretaceous time.

California, Oregon↗