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At least 919 records · Page 51Linked to original sources
USGS2000

Geologic map of the Wildcat Lake 7.5' quadrangle, Kitsap and Mason Counties, Washington

The Wildcat Lake quadrangle lies in the forearc of the Cascadia subduction zone, about 20-km east of the Cascadia accretionary complex exposed in the Olympic Mountains (Tabor and Cady, 1978),and about 100-km west of the axis of the Cascades volcanic arc. The quadrangle lies near the middle of the Puget Lowland, which typically has elevations less than 600 feet (183 m), but on Gold Mountain, in the center of the quadrangle, the elevation rises to 1761 feet (537 m). This anomalously high topography also provides a glimpse of the deeper crust beneath the Lowland. Exposed on Green and Gold Mountains are rocks related to the Coast Range basalt terrane. This terrane consists of Eocene submarine and subaerial tholeiitic basalt of the Crescent Formation, which probably accreted to the continental margin in Eocene time (Snavely and others, 1968). The Coast Range basalt terrane may have originated as an oceanic plateau or by oblique marginal rifting (Babcock and others, 1992), but its subsequent emplacement history is complex (Wells and others, 1984). In southern Oregon, onlapping strata constrain the suturing to have occurred by 50 Ma; but on southern Vancouver Island where the terrane-bounding Leech River fault is exposed, Brandon and Vance (1992) concluded suturing to North America occurred in the broad interval between 42 and 24 Ma. After emplacement of the Coast Range basalt terrane, the Cascadia accretionary complex,exposed in the Olympic Mountains west of the quadrangle,developed by frontal accretion and underplating (e.g., Clowes and others, 1987). The Seattle basin, part of which lies to the north of Green Mountain, also began to develop in late Eocene time due to forced flexural subsidence along the Seattle fault zone (Johnson and others, 1994). Domal uplift of the accretionary complex beneath the Olympic Mountains occurred after approximately 18 million years ago (Brandon and others, 1998). Ice-sheet glaciation during Quaternary time reshaped the topography of the quadrangle, and approximately two-thirds of the map area is covered with Quaternary deposits related to the last glaciation. Geophysical studies and regional mapping indicate the Seattle fault lies north of Green Mountain. This fault produced a large earthquake about 1000 years ago and may pose a significant earthquake hazard (Bucknam and others, 1992; Atwater and Moore, 1992; Karlin and Abella,1992; Schuster and others, 1992; Jacoby and others, 1992). We found no evidence of Holocene faulting in the Wildcat Lake quadrangle. Geologic mapping within and marginal to the quadrangle began with Willis (1898), who described glacial deposits in Puget Sound. Weaver (1937) correlated volcanic rocks in the quadrangle to the Eocene Metchosin Volcanics on Vancouver Island. Sceva (1957), Garling and Moleenar (1965), and Deeter (1978) all focused on mapping and understanding the Quaternary stratigraphy of the Kitsap Peninsula, but they also examined bedrock in the quadrangle. Reeve (1979) was the first to examine the igneous rocks on Green and Gold Mountains in some detail, and Clark (1989) significantly improved Reeve's (1979) mapping. Clark's (1989) mapping was conducted soon after extensive logging on the mountains. A surficial geologic map of the Seattle 1:100,000-scale quadrangle, which includes the Wildcat Lake 1:24,000-scale quadrangle, was published by Yount and others (1993). Yount and Gower (1991) also published a bedrock geologic map of the Seattle quadrangle. Geologic mapping for this report was conducted by Haeussler in the spring and summer of 1998 and in the winter of 1999. We could not substantially improve upon the bedrock mapping of Clark (1989) and thus it is incorporated into this map. Well data in the southeastern corner of the map area also helped to constrain the surficial mapping (Geomatrix Consultants, 1997). In addition, 1995 vintage 1:12,000-scale aerial photographs were used in mapping Quaternary deposits. Geologic time scale is that of Berggeren and others (1995).

Washington↗
USGS2001

Geologic map of the Tucson and Nogales quadrangles (Arizona, scale 1:250,000): A digital database

The geologic map of the Tucson-Nogales 1:250,000 scale quadrangle (Peterson and others, 1990) was digitized by U.S. Geological Survey staff and University of Arizona contractors at the Southwest Field Office, Tucson, Arizona, in 2000 for input into a geographic information system (GIS). The database was created for use as a basemap in a decision support system designed by the National Industrial Minerals and Surface Processes project. The resulting digital geologic map database can be queried in many ways to produce a variety of geologic maps. Digital base map data files (topography, roads, towns, rivers and lakes, etc.) are not included; they may be obtained from a variety of commercial and government sources. Additionally, point features, such as strike and dip, were not captured from the original paper map and are not included in the database. This database is not meant to be used or displayed at any scale larger than 1:250,000 (for example, 1:100,000 or 1:24,000). The digital geologic map graphics and plot files that are provided in the digital package are representations of the digital database. They are not designed to be cartographic products.

Arizona↗
USGS2003

Geologic map of the Winchester quadrangle, Frederick County, Virginia

The Winchester 1:24,000-scale quadrangle is one of several quadrangles in Frederick County, Virginia being mapped by geologists from the U.S. Geological Survey in Reston, VA with funding from the National Cooperative Geologic Mapping Program. This work is part of a project being lead by the U.S. Geological Survey Water Resources Discipline, Virginia District, to investigate the geologic framework and groundwater resources of Frederick County as well as other areas in the northern Shenandoah Valley of Virginia and West Virginia. For more information about the Project see: http://geology.er.usgs.gov/eespteam/Karst/index.html for Geologic Discipline efforts and http://va.water.usgs.gov/va134/index.htm for Water Resources Discipline efforts.

Open-File Report↗
USGS2004

Bedrock geologic map of the Port Wing, Solon Springs, and parts of the Duluth and Sandstone 30' X 60' quadrangles, Wisconsin

This Open-File Report provides digital data (shapefiles and .e00 files) for the bedrock geology in the Port Wing, Solon Springs, and parts of the Duluth and Sandstone quadrangles in Wisconsin. A Miscellaneous Investigations Series map (I map) is currently in review with analogous data in paper format. This map portrays the geology of part of the Midcontinent rift system (MRS) along the southern extension of the Lake Superior syncline in northern Wisconsin. The map area contains the St. Croix horst, a rift graben filled with Mesoproterozoic rocks of the Keweenawan Supergroup that was subsequently inverted. The horst exposes about 15 - 20 km of strata that record the opening of the Midcontinent rift, its subsequent transition to a thermal subsidence basin, and eventual inversion. About 3 km of underlying Mesoproterozoic strata, including the Gogebic iron range, and about 10 km of Neoarchean rocks, exposed in the southernmost part of the map area lie to the southeast of the horst. The nearly flat-lying continental red beds of the Oronto and Bayfield Groups, the youngest strata of the Keweenawan Supergroup, overlie the volcanic rocks. A wealth of geologic data exists for the area as a result of many individual studies over the last hundred years, but much has remained unpublished in theses, dissertations, and other reports of limited availability. This map has incorporated most of that data (see list of data sources) and includes results of our investigations conducted from 1992 to 2000. Our studies were designed to fill gaps in existing data and reconcile conflicting interpretations on some aspects of the geology of the region. The purpose of this map is to complete digital coverage of quadrangles with significant exposure of rocks of the Midcontinent rift in Wisconsin and Michigan at a scale of 1:100,000. Other maps in this series include the bedrock geologic maps of the Ontonagon-Wakefield, the Ashland-Ironwood, and the Keweenaw Peninsula areas (USGS Open-File Reports 01-088 , 99-546 , and 99-149 , respectively).

Open-File Report↗
USGS2006

High-resolution geologic mapping of the inner continental shelf: Nahant to Gloucester, Massachusetts

This report presents high-resolution maps of the seafloor offshore of Massachusetts, from Nahant to Gloucester. Approximately 134 km² of the inner shelf were mapped with a focus on the nearshore region in water depths less than 40 m (fig. 1.1). The maps were prepared as part of a cooperative mapping program between the U.S. Geological Survey (USGS) and the Massachusetts Office of Coastal Zone Management (CZM). They are based on marine geophysical data, sediment sampling, and bottom photography obtained on two research cruises carried out in 2003 and 2004. The primary objective of this program is to develop a suite of seafloor maps that provide geologic information for management of coastal and marine resources. Accurate maps of seafloor geology are important first steps toward protecting fish habitat, delineating marine reserves, and assessing environmental changes due to natural or human impacts. The maps also provide a geologic framework for scientific research, industry and the public. The organization of this report is outlined in the navigation bar along the left-hand margin of the page. This is section 1, the introduction. Section 2 briefly describes the mapping products contained in this report and has links to large-format map sheets, that can be viewed on line or downloaded. Section 3 is a description of the data collection, processing, and analysis procedures used to create the map products. Section 4 examines the geologic framework and late Quaternary evolution of the region, and presents two different strategies for mapping the complex seafloor. This report also contains four appendices that include GIS layers of all data collected in this study, and copies of the sample and photographic data used to validate the interpretations.

Massachusetts↗
USGS2009

Geology and Nonfuel Mineral Deposits of Africa and the Middle East

A nation's endowment of nonfuel mineral resources, relative to the world's endowment, is a fundamental consideration in decisions related to a nation's economic and environmental well being and security. Knowledge of the worldwide abundance, distribution, and general geologic setting of mineral commodities provides a framework within which a nation can make decisions about economic development of its own resources, and the economic and environmental consequences of those decisions, in a global perspective. The information in this report is part of a U.S. Geological Survey (USGS) endeavor to evaluate the global endowment of both identified and undiscovered nonfuel mineral resources. The results will delineate areas of the world that are geologically permissive for the occurrence of undiscovered selected nonfuel mineral resources together with estimates of the quantity and quality of the resources. The results will be published as a series of regional reports; this one provides basic data on the identified resources and geologic setting, together with a brief appraisal of the potential for undiscovered mineral resources in Africa and the Middle East. Additional information, such as production statistics, economic factors that affect the mineral industries of the region, and historical information, is available in U.S. Geological Survey publications such as the Minerals Yearbook and the annual Mineral Commodity Summaries (available at http://minerals.usgs.gov/minerals).

Open-File Report↗
USGS2006

Geologic interpretation and multibeam bathymetry of the sea floor in southeastern Long Island Sound

Digital terrain models (DTMs) produced from multibeam echosounder (MBES) bathymetric data provide valuable base maps for marine geological interpretations (e.g. Todd and others, 1999; Mosher and Thomson, 2002; ten Brink and others, 2004; Poppe and others, 2006a,b). These maps help define the geological variability of the sea floor (one of the primary controls of benthic habitat diversity); improve our understanding of the processes that control the distribution and transport of bottom sediments, the distribution of benthic habitats and associated infaunal community structures; and provide a detailed framework for future research, monitoring, and management activities. The bathymetric survey interpreted herein (National Oceanic and Atmospheric Administration (NOAA) survey H11255) covers roughly 95 km? of sea floor in southeastern Long Island Sound (fig. 1). This bathymetry has been examined in relation to seismic reflection data collected concurrently, as well as archived seismic profiles acquired as part of a long-standing geologic mapping partnership between the State of Connecticut and the U.S. Geological Survey (USGS). The objective of this work was to use these geophysical data sets to interpret geomorphological attributes of the sea floor in terms of the Quaternary geologic history and modern sedimentary processes within Long Island Sound.

Open-File Report↗
USGS2006

Preliminary surficial geologic map of a Calico Mountains piedmont and part of Coyote Lake, Mojave desert, San Bernardino County, California

This 1:24,000 scale detailed surficial geologic map and digital database of a Calico Mountains piedmont and part of Coyote Lake in south-central California depicts surficial deposits and generalized bedrock units. The mapping is part of a USGS project to investigate the spatial distribution of deposits linked to changes in climate, to provide framework geology for land use management (http://deserts.wr.usgs.gov), to understand the Quaternary tectonic history of the Mojave Desert, and to provide additional information on the history of Lake Manix, of which Coyote Lake is a sub-basin. Mapping is displayed on parts of four USGS 7.5 minute series topographic maps. The map area lies in the central Mojave Desert of California, northeast of Barstow, Calif. and south of Fort Irwin, Calif. and covers 258 sq.km. (99.5 sq.mi.). Geologic deposits in the area consist of Paleozoic metamorphic rocks, Mesozoic plutonic rocks, Miocene volcanic rocks, Pliocene-Pleistocene basin fill, and Quaternary surficial deposits. McCulloh (1960, 1965) conducted bedrock mapping and a generalized version of his maps are compiled into this map. McCulloh's maps contain many bedrock structures within the Calico Mountains that are not shown on the present map. This study resulted in several new findings, including the discovery of previously unrecognized faults, one of which is the Tin Can Alley fault. The north-striking Tin Can Alley fault is part of the Paradise fault zone (Miller and others, 2005), a potentially important feature for studying neo-tectonic strain in the Mojave Desert. Additionally, many Anodonta shells were collected in Coyote Lake lacustrine sediments for radiocarbon dating. Preliminary results support some of Meek's (1999) conclusions on the timing of Mojave River inflow into the Coyote Basin. The database includes information on geologic deposits, samples, and geochronology. The database is distributed in three parts: spatial map-based data, documentation, and printable map graphics of the database. Spatial data are distributed as an ArcInfo personal geodatabase, or as tabular data in the form of Microsoft Access Database (MDB) or dBase Format (DBF) file formats. Documentation includes this file, which provides a discussion of the surficial geology and describes the format and content of the map data, and Federal Geographic Data Committee (FGDC) metadata for the spatial map information. Map graphics files are distributed as Postscript and Adobe Acrobat Portable Document Format (PDF) files, and are appropriate for representing a view of the spatial database at the mapped scale.

Open-File Report↗
USGS2006

Preliminary geologic map of the White Sulphur Springs 30' x 60' Quadrangle, Montana

The geologic map of the White Sulphur Springs quadrangle, scale 1:100,000, was made as part of the Montana Investigations Project to provide new information on the stratigraphy, structure, and geologic history of the geologically complex area in west-central Montana. The quadrangle encompasses about 4,235 km2 (1,635 mi2), across part of the Smith River basin, the west end of the Little Belt Mountains, the Castle Mountains, and the upper parts of the basins of the North Forks of the Smith and Musselshell Rivers and the Judith River. Geologically the quadrangle extends across the eastern part of the Helena structural salient in the Rocky Mountain thrust belt, a segment of the Lewis and Clark tectonic zone, west end of the ancestral central Montana uplift, and the southwest edge of the Judith basin. Rocks and sediments in the White Sulphur Springs quadrangle are assigned to 88 map units on the basis of rock or sediment type and age. The oldest rock exposed is Neoarchean diorite that is infolded with Paleoproterozoic metamorphic rocks including gneiss, diorite, granite, amphibolite, schist, and mixed metamorphic rock types. A thick succession of the Mesoproterozoic Belt Supergroup unconformably overlies the metamorphic rocks and, in turn, is overlain unconformably by Phanerozoic sedimentary and volcanic rocks. Across most of the quadrangle, the pre-Tertiary stratigraphic succession is intruded by Eocene dikes, sills, and plutons. The central part of the Little Belt Mountains is generally underlain by laccoliths and sheet-like bodies of quartz monzonite or dacite. Oligocene andesitic basalt flows in the western and southern part of the quadrangle document both the configuration of the late Eocene erosional surfaces and the extent of extensional faulting younger than early Oligocene in the area. Pliocene, Miocene, and Oligocene strata, mapped as 11 units, consist generally of interbedded sand, gravel, and tuffaceous sedimentary rock. Quaternary and Quaternary-Tertiary sediments rest across the older Cenozoic deposits and across all older rocks. The Quaternary and Quaternary-Tertiary deposits generally are gravels that mantle broad erosional surfaces on the flanks of the mountains, gravels in stream channels, and colluvium and landslide deposits on hill sides. Glacial deposits, representing at least two stages of glaciation, are present in the northern part of the Little Belt Mountains. The geologic structure of much of the northwest part of the quadrangle is a broad uplift, in the core of which the Paleoproterozoic and Neoarchean metamorphic rocks are exposed. Down plunge to the east, the succession of Phanerozoic sedimentary rocks define an east-trending arch, cored locally by Mesoproterozoic strata of the Belt Supergroup. The north flank of the arch dips steeply north as a monocline. Stratigraphic relations among Mississippian, Pennsylvanian, and Jurassic strata document the recurrent uplift and erosion on that north flank. The broader arch of the Little Belt Mountains reflects the west plunge of the ancestral Central Montana uplift. The eastern extension of the Lewis and Clark tectonic zone is exposed in the southern half of the quadrangle where the Volcano Valley fault zone curves from west to southeast as a reverse fault along which the latest movement is up on the south side. The fault zone ends in an anticline in the south-central margin of the quadrangle. Stratigraphic overlap of Phanerozoic strata over the truncated edges of Mesoproterozoic units documents that the area of the eastern terminus of the fault zone was tectonically recurrently active. Northeast trending strike-slip faults displace Mesoproterozoic rocks in the northwest and south-central parts of the quadrangle. Several of those faults are overlain unconformably by the Middle Cambrian Flathead Sandstone. Other north-east and west-trending faults across the central part of the quadrangle are intruded by middle Eocene plutons. You

Montana↗
USGS2006

History of the Fort Collins Science Center, U.S. Geological Survey

The U.S. Geological Survey’s Fort Collins Science Center ("the Center") has been a nucleus of research, technology development, and associated scientific activities within the Department of the Interior for more than 30 years. The Center’s historical activities are deeply rooted in federal biological resources research and its supporting disciplines, particularly as they relate to the needs of the U.S. Department of the Interior and its resource management agencies. The organizational framework and activities of the Center have changed and adapted over the years in response to shifts in the scientific issues and challenges facing the U.S. Department of the Interior and with the development of new strategies to meet these challenges. Thus, the history of the Center has been dynamic. The Center has been nested within the U.S. Geological Survey since 1996. From 1993 to 1996 the Center was a major unit of the National Biological Service (named the National Biological Survey at its inception). This was a period of great organizational flux. During that time the Center comprised multiple field stations and science functions that prior to 1993 had been scattered among the U.S. Bureau of Land Management, the U.S. Bureau of Reclamation, the National Park Service, and the U.S. Fish and Wildlife Service. In 1993, certain biological research components of these agencies were assigned to join with the National Ecology Research Center, formerly one of the major research and development hubs of the U.S. Fish and Wildlife Service. This was the year when biological resources research in the U.S. Department of the Interior was consolidated by the Secretary of the Interior, who in an April 1993 memo explaining his intentions wrote, "Our Department has, without doubt, the best biologists in the world." Soon after formation of the new agency, the Center was re-named the Midcontinent Ecological Science Center, reflecting its geographic location within the new Midcontinent administrative region of the National Biological Service (the other three original administrative regions were the eastern, western, and southern). The change in name to the Fort Collins Science Center took place in 2002, soon after the center moved to new facilities on the Colorado State University Natural Resources Research Campus. At various times during the period when it was part of the National Biological Service (1993–96), the Center served as the administrative and programmatic home base for a wide number of science activities in numerous Western states (table 1). This reflected the previous fragmentation of biological and related science efforts across resource management agencies in the U.S. Department of the Interior. The organization of the 2 Center within the National Biological Service was a manifestation of the desire of the Secretary of the Interior to consolidate its biological science activities in administratively independent entities that would ensure that the science retained its objectivity. Congress later recognized the need to maintain a hierarchical independence between biological science and resource management in the Department. However, Congress also saw that the U.S. Geological Survey, with its long history of objective science support to the nation in geology, water resources, geography, and remote sensing, was a suitable alternative home for these biological science functions. Thus, in 1996 Congress transferred the biological resources functions of the National Biological Service to the U.S. Geological Survey. Detailed overviews and opinions about the history and policy issues surrounding the formation and subsequent fate of the National Biological Service can be found elsewhere (for example Cohn, 1993, 2005; Kaufman, 1993; Kreeger, 1994; Pulliam, 1995, 1998a,b; Reichhardt, 1994; Wagner, 1999)

Open-File Report↗
USGS2006

Response to memorandum by Rowley and Dixon regarding U.S. Geological Survey report titled "Characterization of Surface-Water Resources in the Great Basin National Park Area and Their Susceptibility to Ground-Water Withdrawals in Adjacent Valleys, White Pine County, Nevada"

Applications pending for permanent permits to pump large quantities of ground water in Spring and Snake Valleys adjacent to Great Basin National Park (the Park) prompted the National Park Service to request a study by the U.S. Geological Survey to evaluate the susceptibility of the Park's surface-water resources to pumping. The result of this study was published as U.S. Geological Survey Scientific Investigations Report 2006-5099 'Characterization of Surface-Water Resources in the Great Basin National Park Area and Their Susceptibility to Ground-Water Withdrawals in Adjacent Valleys, White Pine County, Nevada,' by P.E. Elliott, D.A. Beck, and D.E. Prudic. That report identified areas within the Park where surface-water resources are susceptible to ground-water pumping; results from the study showed that three streams and several springs near the eastern edge of the Park were susceptible. However, most of the Park's surface-water resources likely would not be affected by pumping because of either low-permeability rocks or because ground water is sufficiently deep as to not be directly in contact with the streambeds. A memorandum sent by Peter D. Rowley and Gary L. Dixon, Consulting Geologists, to the Southern Nevada Water Authority (SNWA) on June 29, 2006 was critical of the report. The memorandum by Rowley and Dixon was made available to the National Park Service, the U.S. Geological Survey, and the public during the Nevada State Engineer's 'Evidentiary Exchange' process for the recent hearing on applications for ground-water permits by SNWA in Spring Valley adjacent to Great Basin National Park. The U.S. Geological Survey was asked by the National Park Service to assess the validity of the concerns and comments contained in the Rowley and Dixon memorandum. An Administrative Letter Report responding to Rowley and Dixon's concerns and comments was released to the National Park Service on October 30, 2006. The National Park Service subsequently requested that the contents with three minor changes to the Administrative Letter Report be released to the public. The first paragraph was revised to better explain how the memorandum was brought to the attention of the National Park Service and the U.S. Geological Survey and the purpose of the Administrative Letter Report. The second and third changes were minor word changes to the end of the first sentence at the top of page 11 and in the Summary statement, respectively. The Administrative Letter Report with these minor changes is reproduced herein. Lastly, the National Park Service asked me to explain the difference between potentially and likely susceptible areas used in the report. Admittedly, the report did not clearly explain their usage. Potentially susceptible areas were used in the report to identify areas where (1) ground water interacts with water in the creeks but the connection between permeable rocks in the mountains with the basin fill is uncertain or where (2) ground-water interaction with water in the creeks is less certain but permeable rocks are connected with basin fill. Likely susceptible areas were used to identify areas in the mountains and valleys where ground-water interacts with water in the creeks or discharges as springs and permeable rocks are connected with basin fill. Likely susceptible areas are, therefore, more vulnerable to ground-water pumping.

Open-File Report↗
USGS2007

Preliminary Geologic Map of the Lake Mead 30' X 60' Quadrangle, Clark County, Nevada, and Mohave County, Arizona

Introduction The geologic map of the Lake Mead 30' x 60' quadrangle was completed for the U.S. Geological Survey's Las Vegas Urban Corridor Project and the National Parks Project, National Cooperative Geologic Mapping Program. Lake Mead, which occupies the northern part of the Lake Mead National Recreation Area (LAME), mostly lies within the Lake Mead quadrangle and provides recreation for about nine million visitors annually. The lake was formed by damming of the Colorado River by Hoover Dam in 1939. The recreation area and surrounding Bureau of Land Management lands face increasing public pressure from rapid urban growth in the Las Vegas area to the west. This report provides baseline earth science information that can be used in future studies of hazards, groundwater resources, mineral and aggregate resources, and of soils and vegetation distribution. The preliminary report presents a geologic map and GIS database of the Lake Mead quadrangle and a description and correlation of map units. The final report will include cross-sections and interpretive text. The geology was compiled from many sources, both published and unpublished, including significant new mapping that was conducted specifically for this compilation. Geochronologic data from published sources, as well as preliminary unpublished 40Ar/39Ar ages that were obtained for this report, have been used to refine the ages of formal Tertiary stratigraphic units and define new informal Tertiary sedimentary and volcanic units.

Open-File Report↗
USGS2007

Geologic interpretation and multibeam bathymetry of the sea floor in the vicinity of the Race, eastern Long Island Sound

Digital terrain models (DTMs) produced from multibeam bathymetric data provide valuable base maps for marine geological interpretations (Todd and others, 1999; Mosher and Thomson, 2002; ten Brink and others, 2004; Poppe and others, 2006a, b, c, d). These maps help define the geological variability of the sea floor (one of the primary controls of benthic habitat diversity), improve our understanding of the processes that control the distribution and transport of bottom sediments and the distribution of benthic habitats and associated infaunal community structures, and provide a detailed framework for future research, monitoring, and management activities. The bathymetric survey interpreted herein (National Oceanic and Atmospheric Administration (NOAA) survey H11250) covers roughly 94 km² of sea floor in an area where a depression along the Orient Point-Fishers Island segment of the Harbor Hill-Roanoke Point-Charlestown Moraine forms the Race, the eastern opening to Long Island Sound. The Race also divides easternmost Long Island Sound from northwestern Block Island Sound (fig. 1). This bathymetry has been examined in relation to seismic reflection data collected concurrently, as well as archived seismic profiles acquired as part of a long-standing geologic mapping partnership between the State of Connecticut and the U.S. Geological Survey (USGS). The objective of this work was to use these acoustic data sets to interpret geomorphological attributes of the sea floor, and to use these interpretations to better understand the Quaternary geologic history and modern sedimentary processes.

Connecticut;New York↗
USGS2008

U.S. Geological Survey Science Support Strategy for Biscayne National Park and Surrounding Areas in Southeastern Florida

The U.S. Geological Survey conducts a wide range of research in and around the Biscayne National Park region of southern Florida. This research encompasses the biologic, ecologic, meteorologic, geologic, and hydrologic components of the system, including water-quality analyses, ground-water modeling, hydrogeologic-data collection, ecologic-habitat evaluations, wetlands characterizations, biogeochemistry of ecosystems, and paleo-ecologic analyses. Relevant information is provided herein for researchers and managers interested in the Biscayne Bay area and about current U.S. Geological Survey efforts that address important resource protection and management issues. Specifically, managers and scientists are provided with information on current and recently completed U.S. Geological Survey projects and a sample listing of potential U.S. Geological Survey research projects addressing relevant issues that face the study area.

Open-File Report↗
USGS2008

Sidescan-sonar imagery and surficial geologic interpretations of the sea floor in central Rhode Island Sound

The U.S. Geological Survey (USGS) has been working with the National Oceanic and Atmospheric Administration (NOAA) to interpret the surficial geology of areas along the northeastern coast of the United States. During 2004, the NOAA Ship RUDE conducted Hydrographic Survey H11321 in Rhode Island Sound. This sidescan-sonar and bathymetry survey covers an area of 93 km? located 12 km southeast of Brenton Point, RI in water depths of 28-39 m (fig. 1). The purpose of this report is to delineate sea floor features and sedimentary environments of this area in central Rhode Island Sound using sidescan-sonar and bathymetric data from NOAA Survey H11321 and seismic-reflection data from a previous USGS field study (Needell and others, 1983a). This is important for the study of benthic habitats and provides a framework for future research. Prior work in this area includes the mapping of surface sediments and surficial geology. McMaster (1960) collected sediment samples from Rhode Island Sound and Narragansett Bay and mapped our study area as having a sandy sea floor. In addition, one sample of sand from the National Ocean Service (NOS) Hydrographic Database came from a location in the northeast part of our study area in 1939 (fig. 2; Poppe and others, 2003). McMaster and others (1968) used seismic-reflection profiles to map the locations of a cuesta of Cretaceous sediments crossing Rhode Island Sound and post-Cretaceous drainage channels. Knebel and others (1982) identified sedimentary environments in Rhode Island Sound using sidescan sonographs. Needell and others (1983b) studied the Quaternary geology and mapped the structure, sedimentary environments, and geologic hazards in Rhode Island Sound using sidescan-sonar and seismic-reflection data. Sidescan-sonar and bathymetric data from NOAA Survey H11320, which overlaps the far eastern edge of our study area, was interpreted to consist of basins surrounded by a moraine and bathymetric highs composed of till with areas of rocks, sand waves, hummocks, glaciolacustrine erosional outliers, small scarps and elongate hills (fig. 1; McMullen and others, 2007). Some of those features extend into this study area.

Rhode Island↗
USGS2009

Quaternary Geologic Framework of the St. Clair River between Michigan and Ontario, Canada

Concern about the effect of geomorphic changes in the St. Clair River on water levels in the Upper Great Lakes resulted in the need for information on the geologic framework of the river. A geophysical survey of the Upper St. Clair River between Port Huron, MI, and Sarnia, Ontario, Canada, was conducted to determine the Quaternary geologic framework of the region. Previously available and new sediment samples and photographic and video data support the interpretation of the seismic stratigraphy and surficial geology. Three seismic stratigraphic units and two unconformities were identified. Glacial drift, consisting of interbedded till and glaciolacustrine deposits, overlies shale. Glaciofluvial and modern fluvial processes have eroded the glacial drift. Glaciofluvial, glaciolacustrine, fluvial, and lacustrine deposits overlie this unconformity. Seismic facies were interpreted to identify areas where these geologic facies exist; however, in the absence of distinct boundaries between facies, these deposits were mapped as one undifferentiated unit. This unit is thickest in the northernmost 3 kilometers of the river, where it consists of relatively coarse-grained fluvial, reworked glaciofluvial, and possibly glaciofluvial deposits. To the south, this coarse-grained unit thins or is absent. The undifferentiated unit comprises most of the surficial deposits in the northernmost river area. Some areas of glacial drift, predominantly till, are exposed at the lake and riverbed. The shale is not exposed anywhere in the region. Geophysical surveys at sites downriver, together with the results of previous studies, indicate that the geologic framework is similar to that in the northernmost river area except for the absence or reduced thickness of the coarse-grained fluvial deposits. Instead, glacial drift is exposed at the riverbed or is covered by a veneer of sediment. This information on the substrate is important for ongoing sediment transport studies.

Open-File Report↗
USGS2009

Geologic Map of the Carlton Quadrangle, Yamhill County, Oregon

The Carlton, Oregon, 7.5-minute quadrangle is located in northwestern Oregon, about 35 miles (57 km) southwest of Portland. It encompasses the towns of Yamhill and Carlton in the northwestern Willamette Valley and extends into the eastern flank of the Oregon Coast Range. The Carlton quadrangle is one of several dozen quadrangles being mapped by the U.S. Geological Survey (USGS) and the Oregon Department of Geology and Mineral Industries (DOGAMI) to provide a framework for earthquake- hazard assessments in the greater Portland, Oregon, metropolitan area. The focus of USGS mapping is on the structural setting of the northern Willamette Valley and its relation to the Coast Range uplift. Mapping was done in collaboration with soil scientists from the National Resource Conservation Service, and the distribution of geologic units is refined over earlier regional mapping (Schlicker and Deacon, 1967). Geologic mapping was done on 7.5-minute topographic base maps and digitized in ArcGIS to produce ArcGIS geodatabases and PDFs of the map and text. The geologic contacts are based on numerous observations and samples collected in 2002 and 2003, National Resource Conservation Service soils maps, and interpretations of 7.5-minute topography. The map was completed before new, high-resolution laser terrain mapping was flown for parts of the northern Willamette Valley in 2008.

Open-File Report↗
USGS2012

Preliminary geologic map of the Stanardsville 7.5' quadrangle, Greene and Madison Counties, Virginia

The Stanardsville 7.5-minute quadrangle is located about 30 kilometers north of Charlottesville, Virginia, in the eastern foothills of the Blue Ridge and within the Blue Ridge physiographic province. The quadrangle contains a small part of the eastern margin of Shenandoah National Park along Saddleback Mountain just north of Swift Run Gap and stretches of Swift Run and the South, Conway, and Rapidan Rivers. The broad valleys occupied by these southeast-draining streams alternate with ridges as much as 1,700 feet high to produce a varied topography, with the 3,000- to 4,000-foot-high Blue Ridge defining the western horizon. The bedrock geology of the quadrangle was mapped at a scale of 1:24,000 as part of the Geology of Shenandoah National Park Project (which was conducted from 1995 to 2008) of the U.S. Geological Survey National Cooperative Geologic Mapping Program. The results of the mapping were incorporated in the Geologic Map of the Shenandoah National Park Region, Virginia ( USGS Open-File Report 2009-1153 ).

Virginia↗