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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 865 records · Page 48Linked to original sources
USGS1980

Minisparker profiles from Jeffreys Ledge and adjacent areas in the western Gulf of Maine

A total of 250 kilometers of single-channel seismic-reflection data (28 minisparker profiles) were collected in the coastal waters of Massachusetts, north of and immediately south of Cape Ann, and on the western flank of Jeffreys Ledge, western Gulf of Maine, during the September 1978 cruise of the R/V ASTERIAS. The survey was conducted by the U.S. Geological Survey as part of the Massachusetts Cooperative Marine Geologic Program. The seismic systems used included a 1Del Norte minisparker and streamer, an Energy International Streamer, and EPC 3200 and 4100 recorders. Navigational control was established by Radar and Loran-C. The Loran-C navigation data were recorded on a Northstar 6000 system. The purpose of the cruise was to discover the significance and extent of the folded and faulted internal reflections that were first noticed on the esternmost tip of Jeffreys Ledge in line 14 of esternmost tip of Jeffreys Ledge in line 14 of rninisparker data from the 1976 R/V FAY 023 cruise. Sixteen northwest-trending lines were run off Cape Ann to investigate the deformed reflectors, now thought to represent a moraine formed by readvance of continental ice over the last glacial marine Presurnpscot Formation. Lines north and south of Cape Ann were run to locate the offshore extension of the Clinton-Newbury and Bloody Bluff fault systems. The original records can be studied at the U.S. Geological Survey offices at Woods Hole, Mass. Microfilm copies of the records can be purchased only from the National Geophysical and Solar-Terrestrial Data Center, NOAA/EDIS/NGSDC, Code D621, 325 Broadway; Boulder, CO 80303 (303-497-6338)

Open-File Report↗
USGS1984

Map showing outcrops of granitic rocks, Basin and Range Province, Nevada

This map report is one of a series of geologic and hydrologic maps covering all or parts of States within the Basin and Range province of the western United States. The map reports contain information on subjects that characterize the geohydrology of the province, including the ground-water hydrology, ground-water quality, surface distribution of selected rock types, tectonic conditions, areal geophysics, Pleistocene lakes and marshes, and mineral and energy resources. This work is a part of the U.S. Geological Survey's program for geologic and hydrologic evaluation of the Basin and Range province to identify potentially suitable regions for further study relative to isolation of high-level nuclear waste (Bedinger, Sargent, and Reed, 1984). Data for this report were taken largely from Spengler and others (1979), supplemented by data from individual geologic maps and reports, following the project guidelines as defined in Sargent and Bedinger (1984). As used in this report, granitic rocks include granodiorite, quartz monzonite, and granite, and locally associated mafic rocks such as diorite and gabbro. In the Snake Range and Ruby Mountains, Stewart (1980) has recognized large areas as metamorphic core complexes, and in these complexes some plutonic masses may not extend to great depth because of lateral displacement along low-angle faults subsequent to intrusion. The Description of Map Units includes the sources of data, the geologic, and if available, the radiometric age, lithologic character, type of intrusive body and relation to rock units, where known, for the granitic rocks within outlined and numbered areas in each county of the study area. The radiometric ages of the rock units are only those which are available and do not necessarily represent the entire age range of the geologic units.

Nevada↗
USGS2022

Updates to and applications of the USGS National Crustal Model for seismic hazard studies

The U.S. Geological Survey (USGS) National Crustal Model (NCM) is being developed to assist in the modeling of seismic hazards across the conterminous United States. The NCM is composed of a grid of geophysical profiles, extending from the Earth’s surface into the upper mantle. It is constructed from a 3D geologic framework and geophysical rules defined by: (1) a petrologic and mineral physics database; (2) a 3D temperature model; and (3) a calibrated rock type- and age-dependent porosity model. Parameters needed to estimate site response for existing ground motion models (GMMs), including the time-averaged velocity in the upper 30 meters ( V S 30 ) and the depths to 1.0 and 2.5 km/s shear-wave velocity ( Z 1.0 and Z 2.5 ), can be extracted from the NCM. As GMMs develop, other metrics could also be extracted or derived from the NCM such as sediment thickness and travel times, fundamental frequency, a fully frequency-dependent site response function, or 3D geophysical volumes for wavefield simulations. Application of the NCM may also benefit other aspects of seismic hazard analysis including better accounting for path-dependent attenuation and geometric spreading, more accurate estimation of earthquake source properties such as hypocentral location and stress drop, and calculation of crustal strength profiles that inform estimates of the base of seismicity.

Conference Paper↗
USGS2002

Geology, Geochemistry and Geophysics of Sedimentary Rock-Hosted Au Deposits in P.R. China

This is the second report concerning results of a joint project between the U.S. Geological Survey and the Tianjin Geological Academy to study sedimentary rock-hosted Au deposits in P.R. China. Since the 1980s, Chinese geologists have devoted a large-scale exploration and research effort to the deposits. As a result, there are more than 20 million oz of proven Au reserves in sedimentary rock-hosted Au deposits in P.R. China. Additional estimated and inferred resources are present in over 160 deposits and occurrences, which are undergoing exploration. This makes China second to Nevada in contained ounces of Au in Carlin-type deposits. It is likely that many of the Carlin-type Au ore districts in China, when fully developed, could have resource potential comparable to the multi-1,000-tonne Au resource in northern Nevada. The six chapters of this report describe sedimentary rock-hosted Au deposits that were visited during the project. Chapters 1 and 2 provide an overview of sedimentary rock-hosted Au deposits and Carlin-type Au deposits and also provide a working classification for the sedimentary rock-hosted Au deposits. Chapters 3, 4, and 5 provide descriptions that were compiled from the literature in China in three main areas: the Dian-Qian-Gui, the Qinling fold belt, and Middle-Lower Yangtze River areas. Chapter 6 contains a weights-of-evidence (WofE), GIS-based mineral assessment of sedimentary rock-hosted Au deposits in the Qinling fold belt and Dian-Qian-Gui areas. Appendices contain scanned aeromagnetic (Appendix I) and gravity (Appendix II) geophysical maps of south and central China. Data tables of the deposits (Appendix III) also are available in the first report as an interactive database at http://geopubs.wr.usgs.gov/open-file/of98-466/. Geochemical analysis of ore samples from the deposits visited are contained in Appendix IV.

Open-File Report↗
USGS2014

Salt‐water intrusion in the Connecticut River

The intrusion of salt water in the lower Connecticut River Basin was studied during October 1, 1934, to June 30, 1939. The field‐ and laboratory‐work was done as a project of the Works Progress Administration under the sponsorship of the State Water Commission of the State of Connecticut. Some technical assistance was given by the Geological Survey through cooperation with the State Water Commission.

Connecticut↗
USGS2014

Runoff in the Santa Ynez River Basin, California, following the excessive rainfall of 1940–41

This paper reports briefly on the runoff‐characteristics of the Santa Ynez River in Santa Barbara County, California, following the excessive rainfall in the winter of 1940–41; also, it contrasts these conditions of 1940–41 with earlier years of less rainfall. The data for this report were compiled in connection with an investigation of the water‐resources of Santa Barbara County which is being conducted by the United States Geological Survey in cooperation with the County of Santa Barbara.

California↗
USGS2006

Two-dimensional magnetotelluric model of deep resistivity structure in the Bodie-Aurora district of California

Introduction: Magnetotelluric data were acquired during October 2001 by the U.S. Geological Survey (USGS) as part of a study to examine the structural nature of basins in the transition zone between the Sierra Nevada Mountains of California and the Basin and Range province of Nevada. Magnetotelluric (MT) geophysical studies assist the mapping of geologic structure and the inference of lithologic packages that are concealed beneath the Earth's surface. The Basin and Range province has a complicated geologic history, which includes extension and compression of the Earth's crust to form the basins and ranges that blanket much of Nevada. The basins and ranges in the vicinity of this study trend northeastward and are bounded by steeply dipping strike slip faults. Interestingly, deep east-west magnetic trends occur in the aeromagnetic data of this study area indicating that the northeast-trending basins and ranges represent only thin-skinned deformation at the surface with an underlying east-west structure. To investigate this issue, MT data were acquired at seven stations in eastern California, 20 km east of Mono Lake. The purpose of this report is to present a two-dimensional apparent resistivity model of the MT data acquired for this study.

Open-File Report↗
USGS2009

Results and Interpretations of U.S. Geological Survey Data Collected In and Around the Tuba City Open Dump, Arizona

This Open-File Report was originally an Administrative Report presentation to the Bureau of Indian Affairs based on U.S. Geological Survey data that has been collected and presented in four previous reports (Open-File Reports 2009-1020, 2008-1380, and 2008-1374, and an Administrative Report on geophysical data). This presentation was given at a technical meeting requested by the BIA on March 3 and 4, 2009, in Phoenix, Arizona. The idea for this meeting was for all the technical people working on issues related to the Tuba City Open Dump site to come together and share their data collection procedures, results, interpretations, and working hypotheses. The meeting goal was to have a clear record of each party's interpretations and a summary of additional data that would be needed to solve differences of opinion. The intention of this presentation is not to provide an exhaustive summary of U.S. Geological Survey efforts at the Tuba City Open Dump site given in the four previously published Open-File Reports listed above, since these reports have already been made available. This presentation briefly summarizes the data collected for those reports and provides results, interpretations, and working hypotheses relating to the data available in these reports. The major questions about the Tuba City Open Dump addressed by the U.S. Geological Survey are (1) what are the sources for uranium and other constituents found in the ground water in and around the Tuba City Open Dump, (2) what is the current distribution of ground water contaminants away from the Tuba City Open Dump (can plume limits be delineated), and (3) what controls the mobility of uranium and other constituents in and around the Tuba City Open Dump? Data collection, results, and interpretations by the U.S. Geological Survey that address these questions are presented herein.

Open-File Report↗
USGS2004

Hydrogeology and Extent of Saltwater Intrusion in the Northern Part of the Town of Oyster Bay, Nassau County, New York: 1995–98

The Oyster Bay study area, in the northern part of Nassau County, N.Y., is underlain by unconsolidated deposits that form a sequence of aquifers and confining units. At least one production well has been affected by the intrusion of saltwater from Hempstead Harbor, Long Island Sound, and Cold Spring Harbor. Nineteen boreholes were drilled during 1995-98 for the collection of hydrogeologic, geochemical, and geophysical data to delineate the subsurface geology and the extent of saltwater intrusion. Continuous high-resolution marine-seismic-reflection surveys in the surrounding embayments of the Oyster Bay study area were conducted in 1996. New drill-core data indicate two hydrogeologic units—the North Shore aquifer and the North Shore confining unit—where the Lloyd aquifer, the Raritan confining unit, and the Magothy aquifer have been completely removed by glacial erosion. Water levels at 95 observation wells were measured quarterly during 1995–98. These data and continuous water-level records indicated that (1) the upper glacial (water-table) and Magothy aquifers are hydraulically connected and that their water levels did not respond to tidal fluctuations, and (2) the Lloyd and North Shore aquifers are hydraulically connected and their water levels responded to pumping and to tidal fluctuations. Marine seismic-reflection surveys in the surrounding embayments indicate at least four glacially eroded buried valleys with subhorizontal, parallel reflectors indicative of draped bedding that is interpreted as infilling by silt and clay. The buried valleys (1) truncate the surrounding coarse-grained deposits, (2) are asymmetrical and steep sided, (3) trend northwest-southeast, (4) are several miles long and about 1 mile wide, and (5) extend to more than 500 feet below sea level. Water samples taken during 1995–98 from three production wells and six observation wells screened in the upper glacial and Magothy aquifers contained volatile organic compounds in concentrations that exceeded the New York State Department of Health Drinking Water Maximum Contaminant Levels. High iron or nitrate concentrations were detected in water samples taken in 1997–98 from 39 observation wells. Previous high concentrations resulted in the shutdown of two production wells. Four distinct areas of saltwater intrusion in the Oyster Bay study area were delineated—three were in the upper glacial aquifer, and the fourth was in the Lloyd aquifer. Borehole-geophysical-logging data indicated that three of these saltwater "wedges" ranged from a few feet thick to more than 100 feet thick and had sharp freshwater-saltwater interfaces. Chloride concentrations in water from eight observation wells within these wedges in 1997 ranged from 125 to 13,750 milligrams per liter. One production well in Bayville has been shut down as of 1996 and others in the area may be affected by these saltwater wedges.

New York↗
USGS2020

River channel response to dam removals on the lower Penobscot River, Maine, United States

Most geomorphology studies of dam removals have focused on sites with appreciable quantities of stored sediments. There is great interest in channel responses to sediment releases because of potential effects on aquatic and riparian habitats and human uses of these areas. Yet, behind many dams in the Northeast U.S. and other regions of the world only minor accumulations of sediment are present because of small impoundments, run‐of‐river dam design and management (inflow ≈ outflow), low watershed sediment yield, and/or channel beds dominated by coarse sediment and/or bedrock. The two lowermost dams on the Penobscot River in Maine, United States, removed in 2012–2013, exemplified those conditions. Great Works and Veazie dams were about 6 and 10 m high, respectively. Pre‐project geophysical surveys showed coarse substrates dominated the reservoir beds and little sediment was stored in either impoundment—functions of reach geology, late Quaternary history, and upstream dams. Repeat cross‐section surveys in each impoundment, as well as the upstream and downstream reaches, were completed from 2009 to 2015 to evaluate channel morphology responses to the removals. Bed‐sediment grain size and turbidity were also measured to characterize changes in bed texture and suspended sediment. Pre‐ and post‐removal survey comparisons confirmed the expectation that bed elevations, channel shapes, and channel positions would not change substantially. Changes were often within, or close to, our estimated random measurement error. Our study shows that large‐scale physical changes are likely to be minimal when impoundments storing relatively little sediment are removed from erosion‐resistant streambeds. Many dams eligible for removal have these characteristics, making these observations an important case study that is largely unrepresented in the dam removal literature.

Maine↗
USGS2011

Modeling hazardous mass flows Geoflows09: Mathematical and computational aspects of modeling hazardous geophysical mass flows; Seattle, Washington, 9–11 March 2009

A recent workshop at the University of Washington focused on mathematical and computational aspects of modeling the dynamics of dense, gravity-driven mass movements such as rock avalanches and debris flows. About 30 participants came from seven countries and brought diverse backgrounds in geophysics; geology; physics; applied and computational mathematics; and civil, mechanical, and geotechnical engineering. The workshop was cosponsored by the U.S. Geological Survey Volcano Hazards Program, by the U.S. National Science Foundation through a Vertical Integration of Research and Education (VIGRE) in the Mathematical Sciences grant to the University of Washington, and by the Pacific Institute for the Mathematical Sciences. It began with a day of lectures open to the academic community at large and concluded with 2 days of focused discussions and collaborative work among the participants.

Eos, Earth and Space Science News↗
USGS2006

Sea floor topography and backscatter intensity of the Hudson Canyon region offshore of New York and New Jersey

These maps show the sea floor topography and backscatter intensity of the Hudson Canyon region on the continental slope and rise offshore of New Jersey and New York (fig. 1 and fig. 2). Sheet 1 shows sea floor topography as shaded relief. Sheet 2 shows sea floor topography as shaded relief with backscatter intensity superimposed in color. Both sheets are at a scale of 1:300,000 and also show smoothed topographic contours at selected intervals. The maps are based on new multibeam echo-sounder data collected on an 18-day cruise carried out aboard the National Oceanic and Atmospheric Administration (NOAA) Ship Ronald H. Brown during August and September 2002. Additional multibeam data of the Hudson Canyon collected by the Woods Hole Oceanographic Institution (WHOI), on the continental shelf collected by the STRATAFORM project (Goff and others, 1999), and a survey of the Hudson Shelf Valley (Butman and others, 2003), and a compilation of bathymetric data from the National Geophysical Data Center (NGDC) Coastal Relief Model provide coverage of areas surrounding Hudson Canyon (fig. 2). Interpretations of the surficial geology also utilize widely spaced 3.5- and 10-kiloHertz (kHz) high-resolution seismic profiles collected by the U.S. Geological Survey (fig.2).

New Jersey, New York↗
USGS1979

Mid-Atlantic Single-channel seismic reflection profiles collected over the Baltimore Canyon Trough area

Available are 377km of mini sparker data collected during the September 1977 cruise of the research vessel Annandale over the Baltimore Canyon Trough area. The prime purpose of the cruise was to obtain vibracores at selected locations across the Continental Shelf. The samples and seismic profiles were collected to study the origin and possible geologic hazards of a broad sedimentary terrace that lies just south of the Hudson Channel. Information about the cruise can be obtained from Dr. Harley J. Knebel, U.S. Geological Survey, Woods Hole, Massachusetts 02543. The original records are on file at the U.S. Geological Survey's Data Library in Woods Hole. Microfilm copies of the seismic profiles may be purchased from the National Geophysical and Solar Terrestrial Data Center (NGSDC), in Boulder, Colorado 80302.

Open-File Report↗
USGS1980

High-resolution seismic-reflection profiles collected by the R/V Columbus Iselin, cruise CI 7807-1, in the Baltimore Canyon outer continental shelf area, offshore New Jersey

High-resolution seismic-reflection profiles were collected by the U.S. Geological Survey (USGS) aboard R/V COLUMBUS ISELIN, cruise 7807-1, from 18 August to 4 September 1978 over the Continental Slope of the Eastern United States between Wilmington and Hudson Canyons. These data were acquired as part of a study to determine potential geologic hazards to petroleum development of the Baltimore Canyon trough area. On this cruise, the Continental Slope between Lindenkohl and Carteret Canyons was surveyed along lines spaced one-half nautical mile apart to study the size and distribution of mass-wasting features as a guide to assess the importance of mass wasting processes on the Continental Slope. The seismic-reflection profiles were placed to complement other data gathered previously by the USGS. Track-line distances totaled 2,050 km of 40-in3 air-gun (with wave shaper) profiles, 2,100 km of 800-J sparker data, and 2,100 km of 3 .5-kHz data. The air-gun and sparker profiles are of high quality, but the 3.5-kHz system did not function well and achieved no subbottom penetration. The side-scan sonar system was operated along the uppermost Continental Slope to investigate its potential for use in this environment. Data were acquired over 22 km of ship's track. Navigation was by Loran-C (5-minute fix interval). The original records can be examined at the U.S. Geological Survey offices in Woods Hole, Massachusetts 02543. Microfilm copies of the data are available for purchase from the National Geophysical and Solar-Terrestrial Data Center (NGSDC), Boulder, Colorado 80303.

Open-File Report↗
USGS1981

Seismic-reflection and sidescan-sonar data collected off eastern Cape Cod, Massachusetts, during April 1979

The U.S. Geological Survey collected 98 line kilometers of single-channel seismic-reflection profiles and sidescan sonar records on the inner shelf of eastern Cape Cod, Massachusetts, during April 1979. The data were obtained during cruise NE-1-79 of the R/V NEECHO. The purposes of the survey were: (1) to study the development of barrier islands; (2) to document the frequency and rate of migration of inlets that breach barrier islands; and (3) to define the characteristics of shoreface ridges on a barrier island. he survey uti I ized two acoustic systems. Information about the bottom was obtained by using an EDO Western model 606 sidescan-sonar system (100 kHz). Profiles of the subbottom were collected by an EG&G Uni boom transducer (400-4,000 Hz) and a Del Norte streamer. Positional control for al I track! ines was provided by a shore-based Miniranger system and by LORAN-C. The quality of the records generally is very good. However, subbottom penetration did vary somewhat from place to place during the survey due to the nature of the bottom sediments and to the presence or absence of buried channels. The original records may be examined at the U.S. Geological Survey, Woods Hole, MA 02543. Microfilm copies of the data are avai I able for purchase from the National Geophysical pnd Solar-Terrestrial Data Center, NOAA/EDIS/NGSDC, Code D621, 325 Broadway, Boulder, CO 80303 (303-497-6338).

Open-File Report↗
USGS2006

The Cerrillos Uplift, the La Bajada Constriction, and Hydrogeologic Framework of the Santo Domingo Basin, Rio Grande Rift, New Mexico

The geologic, geophysical, and hydrogeologic properties of the La Bajada constriction and Santo Domingo Basin, northern New Mexico, result from tectonic and volcanic processes of the late Tertiary and Quaternary Rio Grande rift. An integrated geologic and geophysical assessment in the La Bajada constriction allows development of a geologic framework that can provide input for regional ground-water flow models. These models then can provide better estimates of future water supplies in a region that largely subsists on aquifers in Rio Grande rift basins. The combination of surface geologic investigations (stratigraphic and structural studies; chapters A, B, C, and E), airborne geophysics (aeromagnetic and time-domain electromagnetic surveys; chapters D and F), ground geophysical measurements (gravity and magnetotelluric surveys; chapters D and F), and data from the few wells in the area (chapter G) provides new constraints on the hydrogeologic framework of this area. Summary results of our investigations are synthesized in chapter G. Through-going aquifers consisting of ancestral Rio Grande axial-river sand and gravel and of coarse western-piedmont gravel form the predominant ground-water pathways through the partly buried structural trough defining the La Bajada constriction between Española and Santo Domingo Basins. Thick, clay-rich Cretaceous marine shales of low hydraulic conductivity form a pervasive regional confining unit within the Cerrillos uplift on the southeast flank of the constriction. Numerous, dominantly north-northwest-striking, intrabasin faults that project part way across the La Bajada constriction create a matrix of laterally and vertically variable hydrogeologic compartments that locally partition and deflect ground-water flow parallel to faults.

New Mexico↗
USGS1983

Preliminary lithologic, geotechnical, and geophysical data from drill hole CW-81-2, Chuitna West coal field, Cook Inlet region, Alaska

The drilling and logging activity described in this report was undertaken in July 1981, as part of the Energy Lands program of the U.S. Geological Survey. The general objectives of the project of which this work is a part are to provide an understanding of the nature, location, and extent of the engineering geology and environmental geology concerns in areas of potential coal development in the Cook Inlet region, Alaska. The lithologic, geotechnical, and geophysical data presented in this report include some of the data needed to evaluate geologic hazards, and to predict the response of geologic materials to large-scale coal mining and related development in the Chuitna West coal field of the Beluga coal resource area. Specifically, the information may be used in evaluation of natural- and cut-slope stability, spoil-pile stability, ground response to seismic activity, blasting effects, excavatability, ground-water conditions, and erosion potential. The drill site (fig. 1, point C), located on the edge of a small, gently sloping basin draining northwestward into the Chuitna River, is approximately 90 km, (55 mi) west of Anchorage, Alaska, and 29 km (18 mi) northwest of Tyonek, a native village on the northwest side of Cook Inlet.

Alaska↗