These data were collected under a cooperative agreement between the Massachusetts Office of Coastal Zone Management (CZM) and the U.S. Geological Survey (USGS), Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center (WHCMSC). Initiated in 2003, the primary objective of this program is to develop regional geologic framework information for the management of coastal and marine resources. Accurate data and maps of seafloor geology are important first steps toward protecting fish habitat, delineating marine resources, and assessing environmental changes due to natural or human impacts. The project is focused on the inshore waters of coastal Massachusetts, primarily in water depths of 2-30 meters. Data collected for the mapping cooperative have been released in a series of USGS Open-File Reports (https://woodshole.er.usgs.gov/project-pages/coastal_mass/). The data collected in this study area are located in both Buzzards Bay and Vineyard Sound and are primarily in the shallow water areas around the eastern Elizabeth Islands and Martha's Vineyard, Massachusetts. The data include high resolution bathymetry, acoustic-backscatter intensity, sound velocity in water, seismic-reflection profiles, and navigation data. These data were collected during several cruises between 2007 and 2011 onboard the R/V Rafael using the following equipment: an SEA Ltd SwathPlus interferometric sonar (234 kHz), Klein 3000 dual frequency sidescan sonar, a boomer source and Geometrics 8-channel GeoEel streamer, a Knudsen 3200 subbottom profiling system, and 4 GPS antennae. More information about the cruises conducted as part of the project: Geologic Mapping of the Seafloor Offshore of Massachusetts can be found on the Woods Hole Coastal and Marine Science Center Field Activity webpages: https://cmgds.marine.usgs.gov/fan_info.php?fan=2011-013-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2009-068-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2007-039-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2010-100-FA, and https://cmgds.marine.usgs.gov/fan_info.php?fan=2010-047-FA.

These data were collected under a cooperative agreement between the Massachusetts Office of Coastal Zone Management (CZM) and the U.S. Geological Survey (USGS), Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center (WHCMSC). Initiated in 2003, the primary objective of this program is to develop regional geologic framework information for the management of coastal and marine resources. Accurate data and maps of seafloor geology are important first steps toward protecting fish habitat, delineating marine resources, and assessing environmental changes due to natural or human impacts. The project is focused on the inshore waters of coastal Massachusetts, primarily in water depths of 2-30 meters. Data collected for the mapping cooperative have been released in a series of USGS Open-File Reports (https://woodshole.er.usgs.gov/project-pages/coastal_mass/). The data collected in this study area are located in both Buzzards Bay and Vineyard Sound and are primarily in the shallow water areas around the eastern Elizabeth Islands and Martha's Vineyard, Massachusetts. The data include high resolution bathymetry, acoustic-backscatter intensity, sound velocity in water, seismic-reflection profiles, and navigation data. These data were collected during several cruises between 2007 and 2011 onboard the R/V Rafael using the following equipment: an SEA Ltd SwathPlus interferometric sonar (234 kHz), Klein 3000 dual frequency sidescan sonar, a boomer source and Geometrics 8-channel GeoEel streamer, a Knudsen 3200 subbottom profiling system, and 4 GPS antennae. More information about the cruises conducted as part of the project: Geologic Mapping of the Seafloor Offshore of Massachusetts can be found on the Woods Hole Coastal and Marine Science Center Field Activity webpages: https://cmgds.marine.usgs.gov/fan_info.php?fan=2011-013-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2009-068-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2007-039-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2010-100-FA, and https://cmgds.marine.usgs.gov/fan_info.php?fan=2010-047-FA.

These data were collected under a cooperative agreement between the Massachusetts Office of Coastal Zone Management (CZM) and the U.S. Geological Survey (USGS), Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center (WHCMSC). Initiated in 2003, the primary objective of this program is to develop regional geologic framework information for the management of coastal and marine resources. Accurate data and maps of seafloor geology are important first steps toward protecting fish habitat, delineating marine resources, and assessing environmental changes due to natural or human impacts. The project is focused on the inshore waters of coastal Massachusetts, primarily in water depths of 2-30 meters. Data collected for the mapping cooperative have been released in a series of USGS Open-File Reports (https://woodshole.er.usgs.gov/project-pages/coastal_mass/). The data collected in this study area are located in both Buzzards Bay and Vineyard Sound and are primarily in the shallow water areas around the eastern Elizabeth Islands and Martha's Vineyard, Massachusetts. The data include high resolution bathymetry, acoustic-backscatter intensity, sound velocity in water, seismic-reflection profiles, and navigation data. These data were collected during several cruises between 2007 and 2011 onboard the R/V Rafael using the following equipment: an SEA Ltd SwathPlus interferometric sonar (234 kHz), Klein 3000 dual frequency sidescan sonar, a boomer source and Geometrics 8-channel GeoEel streamer, a Knudsen 3200 subbottom profiling system, and 4 GPS antennae. More information about the cruises conducted as part of the project: Geologic Mapping of the Seafloor Offshore of Massachusetts can be found on the Woods Hole Coastal and Marine Science Center Field Activity webpages: https://cmgds.marine.usgs.gov/fan_info.php?fan=2011-013-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2009-068-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2007-039-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2010-100-FA, and https://cmgds.marine.usgs.gov/fan_info.php?fan=2010-047-FA.

These data were collected under a cooperative agreement between the Massachusetts Office of Coastal Zone Management (CZM) and the U.S. Geological Survey (USGS), Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center (WHCMSC). Initiated in 2003, the primary objective of this program is to develop regional geologic framework information for the management of coastal and marine resources. Accurate data and maps of seafloor geology are important first steps toward protecting fish habitat, delineating marine resources, and assessing environmental changes due to natural or human impacts. The project is focused on the inshore waters of coastal Massachusetts, primarily in water depths of 2-30 meters. Data collected for the mapping cooperative have been released in a series of USGS Open-File Reports (https://woodshole.er.usgs.gov/project-pages/coastal_mass/). The data collected in this study area are located in both Buzzards Bay and Vineyard Sound and are primarily in the shallow water areas around the eastern Elizabeth Islands and Martha's Vineyard, Massachusetts. The data include high resolution bathymetry, acoustic-backscatter intensity, sound velocity in water, seismic-reflection profiles, and navigation data. These data were collected during several cruises between 2007 and 2011 onboard the R/V Rafael using the following equipment: an SEA Ltd SwathPlus interferometric sonar (234 kHz), Klein 3000 dual frequency sidescan sonar, a boomer source and Geometrics 8-channel GeoEel streamer, a Knudsen 3200 subbottom profiling system, and 4 GPS antennae. More information about the cruises conducted as part of the project: Geologic Mapping of the Seafloor Offshore of Massachusetts can be found on the Woods Hole Coastal and Marine Science Center Field Activity webpages: https://cmgds.marine.usgs.gov/fan_info.php?fan=2011-013-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2009-068-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2007-039-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2010-100-FA, and https://cmgds.marine.usgs.gov/fan_info.php?fan=2010-047-FA.

These data were collected under a cooperative agreement between the Massachusetts Office of Coastal Zone Management (CZM) and the U.S. Geological Survey (USGS), Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center (WHCMSC). Initiated in 2003, the primary objective of this program is to develop regional geologic framework information for the management of coastal and marine resources. Accurate data and maps of seafloor geology are important first steps toward protecting fish habitat, delineating marine resources, and assessing environmental changes due to natural or human impacts. The project is focused on the inshore waters of coastal Massachusetts, primarily in water depths of 2-30 meters. Data collected for the mapping cooperative have been released in a series of USGS Open-File Reports (https://woodshole.er.usgs.gov/project-pages/coastal_mass/). The data collected in this study area are located in both Buzzards Bay and Vineyard Sound and are primarily in the shallow water areas around the eastern Elizabeth Islands and Martha's Vineyard, Massachusetts. The data include high resolution bathymetry, acoustic-backscatter intensity, sound velocity in water, seismic-reflection profiles, and navigation data. These data were collected during several cruises between 2007 and 2011 onboard the R/V Rafael using the following equipment: an SEA Ltd SwathPlus interferometric sonar (234 kHz), Klein 3000 dual frequency sidescan sonar, a boomer source and Geometrics 8-channel GeoEel streamer, a Knudsen 3200 subbottom profiling system, and 4 GPS antennae. More information about the cruises conducted as part of the project: Geologic Mapping of the Seafloor Offshore of Massachusetts can be found on the Woods Hole Coastal and Marine Science Center Field Activity webpages: https://cmgds.marine.usgs.gov/fan_info.php?fan=2011-013-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2009-068-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2007-039-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2010-100-FA, and https://cmgds.marine.usgs.gov/fan_info.php?fan=2010-047-FA.

Lake Mead is a large interstate reservoir located in the Mojave Desert of southeastern Nevada and northwestern Arizona. It was impounded in 1935 by the construction of Hoover Dam and is one of a series of multi-purpose reservoirs on the Colorado River. The lake extends 183 km from the mouth of the Grand Canyon to Black Canyon, the site of Hoover Dam, and provides water for residential, commercial, industrial, recreational, and other non-agricultural users in communities across the southwestern United States. Extensive research has been conducted on Lake Mead, but a majority of the studies have involved determining levels of anthropogenic contaminants such as synthetic organic compounds, heavy metals and dissolved ions, furans/dioxins, and nutrient loading in lake water, sediment, and biota (Preissler, et al., 1998; Bevans et al, 1996; Bevans et al., 1998; Covay and Leiker, 1998; LaBounty and Horn, 1997; Paulson, 1981). By contrast, little work has focused on the sediments in the lake and the processes of deposition (Gould, 1951). To address these questions, sidescan-sonar imagery and high-resolution seismic-reflection profiles were collected throughout Lake Mead by the USGS in cooperation with researchers from University of Nevada Las Vegas (UNLV). These data allow a detailed mapping of the surficial geology and the distribution and thickness of sediment that has accumulated in the lake since the completion of Hoover Dam. Results indicate that the accumulation of post-impoundment sediment is primarily restricted to former river and stream beds that are now submerged below the lake while the margins of the lake appear to be devoid of post-impoundment sediment. The sediment cover along the original Colorado River bed is continuous and is typically greater than 10 m thick through much of its length. Sediment thickness in some areas exceeds 35 m while the smaller tributary valleys typically are filled with less than 4 m of sediment. Away from the river beds that are now covered with post-impoundment sediment, pre-impoundment alluvial deposits and rock outcrops are still exposed on the lake floor.

In September 2018, the U.S. Geological Survey, in collaboration with the U.S. Army Corps of Engineers, conducted high-resolution geophysical mapping and sediment sampling to determine the distribution of historical mine tailings on the floor of Lake Superior. Large amounts of waste material from copper mining, locally known as “stamp sands,” were dumped into the lake in the early 20th century, with wide-reaching consequences that have continued into the present. Mapping was focused offshore of the town of Gay on the Keweenaw Peninsula of Michigan, where ongoing erosion and re-deposition of the stamp sands has buried miles of native, white-sand beaches. Stamp sands are also encroaching onto Buffalo Reef, a large area of cobble/boulder substrate that supports productive fisheries in the lake. The objectives of this cooperative mapping project are to develop a framework for scientific research and provide baseline information required for management of resources within the coastal zone of northern Michigan. High-resolution bathymetry and backscatter data reveal the irregular topography of the shallow, cobble-covered Buffalo Reef and the relatively smooth surface of finer-grained sediment that covers adjacent, deeper parts of the lake floor. Previous research used numerous sediment samples to determine the general distribution of mine tailings on the lake floor in this area, but little information exists on the extent and thickness of the surficial deposits. The main priority of this project is to image the near-surface stratigraphy, specifically the thickness of surficial sand and mud that threaten to cover the reef, with seismic-reflection profiling systems. In addition to continuous coverage of bathymetric and backscatter data, this report includes a dense grid of closely spaced seismic profiles, which will guide efforts to mitigate the environmental impacts of the shifting stamp sands.