These seismic data were collected to infer the paleodepositional environment of Pulley Ridge through seismic facies analysis. Without actual rock cores, remote sensing is the next best tool. It was uncertain if Pulley Ridge represented a drowned reef or paleoshoreline. Through seismic imaging, it was determined from the high-amplitude, level-bedded nature of material in the sub-surface that Pulley Ridge represents several stages of barrier-island development.

These seismic data were collected to infer the paleodepositional environment of Pulley Ridge through seismic facies analysis. Without actual rock cores, remote sensing is the next best tool. It was uncertain if Pulley Ridge represented a drowned reef or paleoshoreline. Through seismic imaging, it was determined from the high-amplitude, level-bedded nature of material in the sub-surface that Pulley Ridge represents several stages of barrier-island development.

These seismic data were collected to infer the paleodepositional environment of Pulley Ridge through seismic facies analysis. Without actual rock cores, remote sensing is the next best tool. It was uncertain if Pulley Ridge represented a drowned reef or paleoshoreline. Through seismic imaging, it was determined from the high-amplitude, level-bedded nature of material in the sub-surface that Pulley Ridge represents several stages of barrier-island development.

These seismic data were collected to infer the paleodepositional environment of Pulley Ridge through seismic facies analysis. Without actual rock cores, remote sensing is the next best tool. It was uncertain if Pulley Ridge represented a drowned reef or paleoshoreline. Through seismic imaging, it was determined from the high-amplitude, level-bedded nature of material in the sub-surface that Pulley Ridge represents several stages of barrier-island development.

These seismic data were collected to infer the paleodepositional environment of Pulley Ridge through seismic facies analysis. Without actual rock cores, remote sensing is the next best tool. It was uncertain if Pulley Ridge represented a drowned reef or paleoshoreline. Through seismic imaging, it was determined from the high-amplitude, level-bedded nature of material in the sub-surface that Pulley Ridge represents several stages of barrier-island development.

This GIS overlay is a component of the U.S. Geological Survey, Woods Hole Science Center's, Gulf of Mexico GIS database. The Gulf of Mexico GIS database is intended to organize and display USGS held data and provide on-line (WWW) access to the data and/or metadata. A two week cruise aboard the R/V GYRE focused on mapping surficial sedimentary processes and their connection to the subsurface geology. The study area was on the upper continental slope in the northwestern Gulf of Mexico; an area of active hydrocarbon exploration. Active salt movement, hydrocarbon movement up faults, the presence of gas hydrates associated with biogenic and thermogenic methane, and overpressured sand deposits all present hazards to oil exploration in this area. This study used sidescan sonar and high-resolution chirp subbottom profiling techniques to map the surficial and shallow subsurface expression of these processes in two areas roughly 15 by 25 km in size. High-resolution multi-channel seismic-reflection data were collected simultaneously with the sidescan imagery to provide a link to the deeper subsurface. Additional multi-channel and Huntec seismic data were collected along regional lines between the detailed study areas to tie these studies to other areas of known hydrates and to wells where shallow overpressured sands have been drilled. The detailed studies attempted to map entire geological systems in this upper slope environment to provide a broader perspective than can be seen from studying a single lease block. One study area focused on two adjacent salt withdrawal basins to assess the processes that are shaping the flanks of the basins, the processes affecting sedimentation in the basin floors, and to compare the deeper structures and surficial processes between the basins. The second study area focused on three salt domes, the processes associated with them, and how they affect the shallow subsurface stratigraphy. Initial observations suggest that most of the surface and shallow subsurface geohazards are associated with the flanks of salt structures. Here active salt movement generates faults along which hydrocarbons can escape to the seafloor, and tectonic oversteepenning generates slope failures.

This GIS overlay is a component of the U.S. Geological Survey, Woods Hole Science Center's, Gulf of Mexico GIS database. The Gulf of Mexico GIS database is intended to organize and display USGS held data and provide on-line (WWW) access to the data and/or metadata. A two week cruise aboard the R/V GYRE focused on mapping surficial sedimentary processes and their connection to the subsurface geology. The study area was on the upper continental slope in the northwestern Gulf of Mexico; an area of active hydrocarbon exploration. Active salt movement, hydrocarbon movement up faults, the presence of gas hydrates associated with biogenic and thermogenic methane, and overpressured sand deposits all present hazards to oil exploration in this area. This study used sidescan sonar and high-resolution chirp subbottom profiling techniques to map the surficial and shallow subsurface expression of these processes in two areas roughly 15 by 25 km in size. High-resolution multi-channel seismic-reflection data were collected simultaneously with the sidescan imagery to provide a link to the deeper subsurface. Additional multi-channel and Huntec seismic data were collected along regional lines between the detailed study areas to tie these studies to other areas of known hydrates and to wells where shallow overpressured sands have been drilled. The detailed studies attempted to map entire geological systems in this upper slope environment to provide a broader perspective than can be seen from studying a single lease block. One study area focused on two adjacent salt withdrawal basins to assess the processes that are shaping the flanks of the basins, the processes affecting sedimentation in the basin floors, and to compare the deeper structures and surficial processes between the basins. The second study area focused on three salt domes, the processes associated with them, and how they affect the shallow subsurface stratigraphy. Initial observations suggest that most of the surface and shallow subsurface geohazards are associated with the flanks of salt structures. Here active salt movement generates faults along which hydrocarbons can escape to the seafloor, and tectonic oversteepenning generates slope failures.

Two 21-day field operations were conducted in 1997 and 1998 in the estuaries and on the inner continental shelf off the northern Oregon and southern Washington coast. These cruises aboard the R/V Corliss were run in order to generate reconnaissance maps of the seafloor geology and the shallow subsurface stratigraphy using sidescan sonar and seismic-reflection mapping techniques. The 1998 cruise also collected sediment grab samples, bottom photographs, and video images to verify the sidescan-sonar imagery and to document the seafloor geology. The combination of these data with previously collected sediment sample data (Robert, 1974; Nittrouer, 1978; and Smith et. al., 1980) has been used to define the extent and lithology of shelf sediments associated with the Columbia River littoral cell. This work is one component of a larger project studying the erosion of the Washington and Oregon coast and is being coordinated by the U.S. Geological Survey and the Washington State Department of Ecology. The reason for collecting these data is to provide a regional synthesis of the offshore geology to support a wide variety of management decisions and to provide a basis for further process-oriented investigations.

Two 21-day field operations were conducted in 1997 and 1998 in the estuaries and on the inner continental shelf off the northern Oregon and southern Washington coast. These cruises aboard the R/V Corliss were run in order to generate reconnaissance maps of the seafloor geology and the shallow subsurface stratigraphy using sidescan sonar and seismic-reflection mapping techniques. The 1998 cruise also collected sediment grab samples, bottom photographs, and video images to verify the sidescan-sonar imagery and to document the seafloor geology. The combination of these data with previously collected sediment sample data (Robert, 1974; Nittrouer, 1978; and Smith et. al., 1980) has been used to define the extent and lithology of shelf sediments associated with the Columbia River littoral cell. This work is one component of a larger project studying the erosion of the Washington and Oregon coast and is being coordinated by the U.S. Geological Survey and the Washington State Department of Ecology. The reason for collecting these data is to provide a regional synthesis of the offshore geology to support a wide variety of management decisions and to provide a basis for further process-oriented investigations.

The point shapefile contains the shotpoint navigation for the Keathley Canyon multichannel seismic survey collected during USGS cruise G1-03-GM aboard the R/V Gyre in the Gulf of Mexico in May, 2003. The purpose of this cruise was to collect multichannel seismic data in support of USGS and Department of Energy gas hydrate studies. About 786 km of data were collected along 59 lines in and around lease block Keathley Canyon 195.