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At least 991 records · Page 55Linked to original sources
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↗
USGS1989

Summary and interpretation of geochemical maps for stream sediment and heavy mineral concentrate samples, Mount Hayes Quadrangle, eastern Alaska Range, Alaska

This report and accompanying maps summarize the results of geochemical exploration studies in the Mount Hayes quadrangle, Alaska. This is one of a series of maps and reports on the geological, geochemical, and geophysical studies of the quadrangle prepared as part of the Alaskan Mineral Resource Assessment Program (AMRAP) of the U.S. Geological Survey. These maps are part of the Mount Hayes l:250,000-scale folio. The geochemical studies were made in order to identify and define mineralized areas in the quadrangle and to aid in characterizing the nature of the mineral occurrences within these areas. The studies included the collection of composite samples of stream sediment or glacial debris and preparation of these samples, as described by O'Leary and others (1982), to yield a minus-80-mesh (0.2-mm) fraction and nonmagnetic heavy-mineral-concentrate fraction consisting of mineral grains having a specific gravity greater than 2.85. Samples were collected at 911 sites either from tributary streams or tributary glaciers with drainage basins ranging from 1 to 5 sq mi in area. The samples were analyzed for 30 elements by semiquantitative emission spectrography (O'Leary and others, 1982). The stream-sediment and glacial-debris samples also were analyzed for zinc by an atomic absorption method (Ward and others, 1969), and those results were used in preparing map A. The maps in this report show drainage basins in which the stream sediment or glacial debris contained anomalously high amounts of selected metals. The geologic base map aids in showing the geologic terranes of the quadrangle. The accompanying tables give frequencies and cumulative percents of the selected metals for all major geologic terranes within the quadrangle.

Alaska↗
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↗
USGS2009

Geophysical Studies in the Vicinity of the Warner Mountains and Surprise Valley, Northeast California, Northwest Nevada, and Southern Oregon

From May 2006 to August 2007, the U.S. Geological Survey (USGS) collected 793 gravity stations, about 102 line-kilometers of truck-towed and ground magnetometer data, and about 325 physical-property measurements in northeastern California, northwestern Nevada, and southern Oregon. Gravity, magnetic, and physical-property data were collected to study regional crustal structures and geology as an aid to understanding the geologic framework of the Surprise Valley geothermal area and, in general, geothermal systems throughout the Great Basin. The Warner Mountains and Surprise Valley mark the transition from the extended Basin and Range province to the unextended Modoc Plateau. This transition zone, in the northwestern corner of the Basin and Range, is relatively diffuse compared to other, more distinct boundaries, such as the Wasatch front in Utah and the eastern Sierran range front. In addition, this transition zone is the site of a geothermal system with potential for development, and previous studies have revealed a complex structural setting consisting of several obliquely oriented fault sets. As a result, this region has been the subject of several recent geological and geophysical investigations. The gravity and magnetic data presented here support and supplement those studies, and although the study area is composed predominantly of Tertiary volcanic rocks of the Modoc Plateau rocks, the physical properties of these and others rocks create a distinguishable pattern of gravity and magnetic anomalies that can be used to infer subsurface geologic structure.

Open-File Report↗
USGS2001

Delineation of tidal scour through marine geophysical techniques at Sloop Channel and Goose Creek bridges, Jones Beach State Park, Long Island, New York

Inspection of the Goose Creek Bridge in southeastern Nassau County in April 1998 by the New York State Department of Transportation (NYSDOT) indicated a separation of bridge piers from the road bed as a result of pier instability due to apparent seabed scouring by tidal currents. This prompted a cooperative study by the U.S. Geological Survey with the NYSDOT to delineate the extent of tidal scour at this bridge and at the Sloop Channel Bridge, about 0.5 mile to the south, through several marine- geophysical techniques. These techniques included use of a narrow-beam, 200-kilohertz, research-grade fathometer, a global positioning system accurate to within 3 feet, a 3.5 to 7-kilohertz seismic-reflection profiler, and an acoustic Doppler current profiler (ADCP). The ADCP was used only at the Sloop Channel Bridge; the other techniques were used at both bridges. Results indicate extensive tidal scour at both bridges. The fathometer data indicate two major scour holes nearly parallel to the Sloop Channel Bridge—one along the east side, and one along the west side (bridge is oriented north-south). The scour-hole depths are as much as 47 feet below sea level and average more than 40 feet below sea level; these scour holes also appear to have begun to connect beneath the bridge. The deepest scour is at the north end of the bridge beneath the westernmost piers. The east-west symmetry of scour at Sloop Channel Bridge suggests that flood and ebb tides produce extensive scour. The thickness of sediment that has settled within scour holes could not be interpreted from fathometer data alone because fathometer frequencies cannot penetrate beneath the sea-floor surface. The lower frequencies used in seismic-reflection profiling can penetrate the sea floor and underlying sediments, and indicate the amount of infilling of scour holes, the extent of riprap under the bridge, and the assemblages of clay, sand, and silt beneath the sea floor. The seismic- reflection surveys detected 2 to 5 feet of sediment filling the scour holes at both bridges; this indicates that the fathometer surveys were undermeasuring the effective depth of bridge scour by 2 to 5 feet through their inability to penetrate the infilled sediment. Several clay layers with thicknesses of 3 to 5 feet were detected beneath the sea floor at both bridges. Most of the piers beneath Sloop Channel Bridge appear to be surrounded by riprap, but, in several areas the riprap appears to be slumping or sliding into adjacent scour holes. Similar slumping was indicated at the Goose Creek Bridge. Most of the sediment underlying the sea floor at both bridges is interpreted as a fine-grained, cross-bedded sand. ADCP data from Sloop Channel indicate that the constricted flow beneath the bridge increases the horizontal current velocities from 2 to 6 feet per second. Total measured discharge beneath Sloop Channel Bridge was 41,800 cubic feet per second at flood tide and 27,600 cubic feet per second at ebb tide.

Water-Resources Investigations Report↗
USGS1985

Selected test-well data from the MX-missile siting study, Tooele, Juab, Millard, Beaver, and Iron Counties, Utah

This report contains well data collected from 1979 to 1983 in a part of the Great Basin in western Utah (fig. 1). The area is characterized by a series of generally north-trending mountain ranges separated by alluviumfilled basins that are partially filled with sedimentary deposits eroded from the adjacent mountains and lacustrine sediments deposited by Lake Bonneville. Most of the intermountain basins are elongated in the northward direction, but some are almost equidimensional. This report was prepared as part of the Great Basin Regional AquiferSystem Analysis (RASA) program. The report is intended to make well data from the MX-missile siting study readily available to water-resource managers and the general public. It includes well data obtained in areas for which little or no such data have been published previously. Well-drilling and well-completion data were compiled by Ertec, Inc. (formerly Fugro National, Inc.) under contract with the U. S. Air Force. Those data along with aquifer test data, geophysical logs, and drillers1 or geologists1 logs were obtained from Ertec, Inc. under an agreement with the U.S. Air Force. The authors thank the officials of both Ertec, Inc. and the U.S. Air Force for their helpful cooperation. The U.S. Geological Survey obtained accurate locations of the test wells (pi. 1) and accurate water-level measurements in those wells (table 1). Chemical analyses of water samples collected from several of the test wells drilled in the Sevier Desert have been published in a report by Enright and Holmes (1982, table 5). Test drilling for the MX-missile siting study consisted of two parts, the verification phase and the water-resources phase. The verification jhase was designed to obtain information necessary for the design and construction of the MX-basing system. Numerous small diameter wells were bored with depths ranging from 92 to 205 feet. Two-inch diameter JVC casing with the bottom 20 feet perforated was installed in each borehole. The water-resources phase was designed to determine ground-water availibility and to estimate the effects of ground-water withdrawals required for the construction of the MX-basing system. Six large-diameter production test wells were drilled along with associated small-diameter observation wells. Depths ranged from 310 to 1,399 feet. Lithologic logs for selected production test wells or associated observation wells are listed in table 2. Geophysical logs and aquifer test data are available in the files of the U. S. Geological Survey, as indicated in table 1.

Utah↗
USGS2013

Archive of U.S. Geological Survey selected single-beam bathymetry datasets, 1969-2000

New national programs, as well as natural and man-made disasters, have raised awareness about the need to find new and improved ways to share information about the coastal and marine environment with a wide-ranging public audience. The U.S. Geological Survey (USGS) Coastal and Marine Geology Program (CMGP) has begun a large-scale effort to incorporate the program's published, digital geophysical data into a single point of access known as the Coastal and Marine Geoscience Data System (CMGDS) (http://cmgds.marine.usgs.gov/). To aid in data discovery, work is also being done to import CMGP data into highly visible data and information resources, such as the National Oceanic and Atmospheric Administration's (NOAA) National Geophysical Data Center (NGDC) and two widely used Earth-science tools, GeoMapApp (GMA) (http://www.geomapapp.org) and Virtual Ocean (VO) (http://www.virtualocean.org/). This task of the CMGP Integrated Data Management System project will help support information exchange with partners, regional planning groups, and the public, as well as facilitate integrated spatial-data analysis. Sharing USGS-CMGP geophysical data via CMGDS, NGDC, GMA, and VO will aid data discovery and enable the data to support new purposes beyond those for which the data were originally intended. In order to make data available to NGDC, and from there into GMA and VO, the data must be reformatted into a standard exchange format and published. In 1977, a group of geophysical data managers from the public and private sectors developed the MGD77 format as the standard exchange format for geophysical data. In 2010, a tab-delimited version of the format was added as MGD77T (Hittelman and others, 1977). The MGD77T geophysical data format can include bathymetry, magnetics, gravity, and seismic navigation data. It is used for the transmission of data between marine institutions, data centers, and can be used by various software programs as an exchange format. A header (documentation) file and data file are created for each survey (Hittelman and others, 1977). More details about the MGD77T format are available at http://www.ngdc.noaa.gov/mgg/dat/geodas/docs/mgd77.pdf (74MB PDF). This archive describes the detailed steps used to convert single-beam bathymetry and navigation files into the MGD77T format (Hittelman and others, 1977) for submission to NGDC and formal Federal Geographic Data Committee (FGDC) (http://www.fgdc.gov/metadata) metadata as a publication of these single-beam bathymetry datasets.

Data Series↗
USGS2022

Historical development of the U.S. Geological Survey hydrological monitoring and investigative programs at the Idaho National Laboratory, Idaho, 2002–2020

This report summarizes the historical development and operations, from 2002 to 2020, of the U.S. Geological Survey’s (USGS) hydrologic monitoring and investigative programs at the Idaho National Laboratory in cooperation with the U.S. Department of Energy. The report covers the USGS’s programs for water-level monitoring, water-quality sampling, geochemical studies, geophysical logging, geologic framework development, groundwater-flow modeling, drilling, surface-water monitoring, and unsaturated zone studies. The report provides physical information about wells, information about changes and frequencies of sampling and measurements, and management decisions for changes. Brief summaries of USGS reports published from 2002 through 2020 (with U.S. Department of Energy report numbers) are provided in an appendix.

Idaho↗
USGS2024

Seabed maps showing topography, ruggedness, backscatter intensity, sediment mobility, and the distribution of geologic substrates in quadrangle 5 of the Stellwagen Bank National Marine Sanctuary region offshore of Boston, Massachusetts

The U.S. Geological Survey, in cooperation with the National Marine Sanctuary Program of the National Oceanic and Atmospheric Administration, has conducted seabed mapping and related research in the Stellwagen Bank National Marine Sanctuary (SBNMS) region since 1993. The area being mapped using geophysical and geological data includes the SBNMS and the surrounding region, which totals approximately 3,700 square kilometers (km 2 ) and is subdivided into 18 quadrangles. The seabed is a glaciated terrain that is topographically and texturally diverse. Quadrangle 5, the subject of this scientific investigations map, has an area of 211 km 2 and has water depths that range from 23 meters (m) on the Stellwagen Bank crest to 105 m in the Stellwagen Basin. Seven map types, each at a scale of 1:25,000, depict seabed topography, ruggedness, backscatter intensity, distribution of geologic substrates, sediment mobility, distribution of fine- and coarse-grained sand, and substrate mud content. These maps show the distribution of geologic substrates on the crest and western flank of the south-central part of Stellwagen Bank and in Stellwagen Basin to the west. Interpretations of multibeam sonar bathymetric and seabed backscatter imagery, photographs, video imagery, and grain-size analyses were used to create the geology-based maps. Data from 729 stations were analyzed, including 620 sediment samples. The geologic substrate maps of quadrangle 5 show the distribution of 20 substrates that represent a wide range of textures, such as mobile and rippled sand, immobile sand, sand that partially veneers gravel, boulder ridges, and mud. Mapped substrates are characterized by sediment grain-size composition, surface morphology, substrate layering, the mobility or immobility of substrate surfaces, and water depth range. This scientific investigations map portrays the major geological elements (substrates, topographic features, and processes) of environments in quadrangle 5. It is intended to provide a foundation for research into present and past sediment transport processes in a complex terrain, provide insights into the ecological requirements of invertebrate and vertebrate species that utilize the various substrates, and to support seabed management in the region.

Massachusetts↗
USGS2024

Seabed maps showing topography, ruggedness, backscatter intensity, sediment mobility, and the distribution of geologic substrates in quadrangle 2 of the Stellwagen Bank National Marine Sanctuary region offshore of Boston, Massachusetts

The U.S. Geological Survey, in cooperation with the National Marine Sanctuary Program of the National Oceanic and Atmospheric Administration, has conducted seabed mapping and related research in the Stellwagen Bank National Marine Sanctuary (SBNMS) region since 1993. The area being mapped using geophysical and geological data includes the SBNMS and the surrounding region, which totals approximately 3,700 square kilometers (km 2 ) and is subdivided into 18 quadrangles. The seabed is a glaciated terrain that is topographically and texturally diverse. Quadrangle 2, the subject of this scientific investigations map, has a mapped area of 209 km 2 and has water depths that range from about 19 meters (m) on the Stellwagen Bank crest to about 68 m in the Stellwagen Basin. Seven map types, each at a scale of 1:25,000, depict seabed topography, ruggedness, backscatter intensity, distribution of geologic substrates, sediment mobility, distribution of fine- and coarse-grained sand, and substrate mud content. These maps show the distribution of geologic substrates across the southwestern part of Stellwagen Bank, in Stellwagen Basin to the west and southwest of the bank, and in Little Stellwagen Basin and the western part of Race Point Channel to the south of the bank. Interpretations of multibeam sonar bathymetric and seabed backscatter imagery, photographs, video imagery, and grain-size analyses were used to create the geology-based maps. Data from 733 stations were analyzed, including 656 sediment samples. The geologic substrate maps of quadrangle 2 show the distribution of 19 geologic substrates that represent a wide range of textures, such as rippled and immobile sand, immobile muddy sand and sandy mud, sand that partially veneers gravel, and a boulder ridge. Mapped substrates are characterized by sediment grain-size composition, surface morphology, substrate layering, the mobility or immobility of substrate surfaces, and water depth range. This scientific investigations map portrays the major geological elements (substrates, topographic features, and processes) of environments in quadrangle 2. It is intended to provide a foundation for research into present and past sediment transport processes in a complex terrain, provide insights into the ecological requirements of invertebrate and vertebrate species that utilize the various substrates, and support seabed management in the region.

Massachusetts↗
USGS2026

Seabed maps showing topography, ruggedness, backscatter intensity, sediment mobility, and the distribution of geologic substrates in quadrangle 3 of the Stellwagen Bank National Marine Sanctuary region offshore of Boston, Massachusetts

The U.S. Geological Survey, in cooperation with the National Marine Sanctuary Program of the National Oceanic and Atmospheric Administration, has conducted seabed mapping and related research in the Stellwagen Bank National Marine Sanctuary (SBNMS) region since 1993. The area being mapped using geophysical and geological data includes the SBNMS and the surrounding region, which totals approximately 3,700 square kilometers (km 2 ) and is subdivided into 18 quadrangles. The seabed is a glaciated terrain that is topographically and texturally diverse. Quadrangle 3, the subject of this scientific investigations map, has a mapped area of 185 km 2 and has water depths that range from about 30 meters (m) on the Stellwagen Bank crest to about 135 m in a basin east of South Ninety Bank, which lies off the eastern margin of Stellwagen Bank. Seven map types, each at a scale of 1:25,000, depict seabed topography, ruggedness, backscatter intensity, distribution of geologic substrates, sediment mobility, distribution of fine- and coarse-grained sand, and substrate mud content. These maps show the distribution of geologic substrates on the southeastern part of Stellwagen Bank, on adjacent banks and basins in deeper water to the east, in the eastern part of Race Point Channel to the south of the bank, and on the northern slope of Cape Cod. Interpretations of multibeam sonar bathymetric and seabed backscatter imagery, photographs, video imagery, and grain-size analyses were used to create the geology-based maps. Data from 309 stations were analyzed, including 279 sediment samples. The geologic substrate maps of quadrangle 3 show the distribution of 21 geologic substrates that represent a wide range of textures, such as rippled sand, immobile sand, immobile muddy sand, sand that partially veneers gravel, and boulder ridges. Mapped substrates are characterized by sediment grain-size composition, surface morphology, substrate layering, the mobility or immobility of substrate surfaces, and water depth range. This scientific investigations map portrays the major geological elements (substrates, topographic features, and processes) of environments in quadrangle 3. It is intended to provide a foundation for research into present and past sediment transport processes in a complex terrain, provide insights into the ecological requirements of invertebrate and vertebrate species that use the various substrates, and support seabed management in the region.

Quadrangle 3 of the Stellwagen Bank National Marin↗
USGS1971

Application of borehole geophysics to water-resources investigations

This manual is intended to be a guide for hydrologists using borehole geophysics in ground-water studies. The emphasis is on the application and interpretation of geophysical well logs, and not on the operation of a logger. It describes in detail those logging techniques that have been utilized within the Water Resources Division of the U.S. Geological Survey, and those used in petroleum investigations that have potential application to hydrologic problems. Most of the logs described can be made by commercial logging service companies, and many can be made with small water-well loggers. The general principles of each technique and the rules of log interpretation are the same, regardless of differences in instrumentation. Geophysical well logs can be interpreted to determine the lithology, geometry, resistivity, formation factor, bulk density, porosity, permeability, moisture content, and specific yield of water-bearing rocks, and to define the source, movement, and chemical and physical characteristics of ground water. Numerous examples of logs are used to illustrate applications and interpretation in various ground-water environments. The interrelations between various types of logs are emphasized, and the following aspects are described for each of the important logging techniques: Principles and applications, instrumentation, calibration and standardization, radius of investigation, and extraneous effects.

Techniques of Water-Resources Investigations↗