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In spring and summer 2017, the U.S. Geological Survey’s Gas Hydrates Project conducted two cruises aboard the research vessel Hugh R. Sharp to explore the geology, chemistry, ecology, physics, and oceanography of sea-floor methane seeps and water column gas plumes on the northern U.S. Atlantic margin between the Baltimore and Keller Canyons. Split-beam and multibeam echo sounders and a chirp subbottom profiler were deployed during the cruises to map water column backscatter, sea-floor bathymetry and backscatter, and subsurface stratigraphy associated with known and undiscovered sea-floor methane seeps. The first cruise, known as the Interagency Mission for Methane Research on Seafloor Seeps and designated as field...
Categories: Data; Types: Downloadable, Map Service, OGC WFS Layer, OGC WMS Layer, Shapefile; Tags: Accomac Canyon, Applied Acoustics, Atlantic Margin, Atlantic Ocean, Baltimore Canyon, All tags...
This dataset contains information on the probabilities of storm-induced erosion (collision, inundation and overwash) for each 100-meter (m) section of the United States Pacific coast for return period storm scenarios. The analysis is based on a storm-impact scaling model that uses observations of beach morphology combined with sophisticated hydrodynamic models to predict how the coast will respond to the hydrodynamic forcing. Storm-induced water levels, due to both surge and waves, are compared to coastal elevations to determine the probabilities of three types of coastal change: collision (dune erosion), overwash, and inundation. Data on morphology (dune crest and toe elevation) and hydrodynamics (storm surge,...
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High-resolution multichannel minisparker, multichannel boomer and chirp seismic-reflection data were collected by the U.S. Geological Survey and the University of Washington in February of 2017 west of Seattle in Puget Sound and in Lake Washington, Washington. Data were collected aboard University of Washington’s R/V Clifford A. Barnes during USGS field activity 2017-612-FA. Sub-bottom acoustic penetration spans several hundreds of meters and is variable by location. Data were collected to characterize recent deformation and estimate earthquake recurrence on the Seattle Fault zone. These data and information are intended for science researchers, students from elementary through college, policy makers, and general...
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This data release contains 25 multichannel minisparker seismic reflection (MCS) profiles and 41 chirp sub-bottom profiles that were collected in February of 2016 from the Catalina Basin offshore southern California by the U.S. Geological Survey Pacific and Coastal Marine Science Center in cooperation with the University of Washington. Data were collected aboard the University of Washington’s R/V Thomas G. Thompson on USGS cruise 2016-616-FA. MCS profiles were collected to image the Catalina and San Clemente fault systems as well as the San Gabriel Canyon and Channel system.
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Two marine geological surveys were conducted in Nantucket Sound, Massachusetts, in May 2016 and May 2017 by the U.S. Geological Survey as part of an agreement with the Massachusetts Office of Coastal Zone Management to map the geology of the sea floor offshore of Massachusetts. Samples of surficial sediment and photographs of the sea floor were collected at 76 sampling sites within the survey area, and sea-floor videos were collected at 75 of the sites. The sediment data and the observations from the photos and videos are used to explore the nature of the sea floor; in conjunction with high-resolution geophysical data, the observations are used to make interpretive maps of sedimentary environments and validate acoustic...
Categories: Data; Types: Downloadable, Map Service, OGC WFS Layer, OGC WMS Layer, Shapefile; Tags: Atlantic Ocean, CMHRP, CZM, Coastal and Marine Hazards and Resources Program, MA CZM, All tags...
Transport of material in an estuary is important for water quality and hazards concern. We studied these processes in the Hudson River Estuary, located along the northeast coast of the U.S. using the COAWST numerical modeling system. A skill assessment of the COAWST model for the 3-D salinity structure of the estuary has been successfully studied in the past, and the present research extended that understanding to look at both physical and numerical mixing. The model grid extends from the south at the Battery, NY to the north in Troy, NY. The simulation is performed from March 25 to July 11, 2005 (111 days). For more information see: https://doi.org/10.5066/P95E8LAS.
Categories: Data; Types: Map Service, NetCDF OPeNDAP Service, OGC WMS Layer; Tags: CMG_Portal, Earth Science > Human Dimensions > Natural Hazards > Floods, Earth Science > Oceans > Marine Sediments >Sediment Transport, Earth Science > Oceans > Ocean Circulation > Ocean Currents, Earth Science > Oceans > Ocean Temperature > Potential Temperature, All tags...
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This part of DS 781 presents data for the isopachs of the Point Sur to Point Arguello, California, region. The vector data file is included in the “Isopachs_PointSurToPointArguello.zip,” which is accessible from https://doi.org/10.5066/P97CZ0T7. As part of the USGS's California State Waters Mapping Project, a 50-m grid of sediment thickness for the seafloor within the 3-nautical mile limit between Point Sur and Point Arguello was generated from seismic-reflection data collected between 2008 and 2014, and supplemented with geologic structure (fault and fold) information following the methodology of Wong (2012). Reference Cited: Wong, F. L., Phillips, E.L., Johnson, S.Y., and Sliter, R.W., 2012, Modeling of depth...
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Interpretation of reflection profiles across the Washington continental margin suggests deformation of Cascadia basin strata against the continental slope. Individual reflecting horizons can be traced across the slope-basin boundary. The sense of offset along faults on the continental slope is predominantly, but not entirely, west side up. Two faults of small displacement are seen to be west-dipping reverse faults. Magnetic anomalies on the Juan de Fuca plate can be traced 40-100 km eastward under the slope, and structural interpretation combined with calculated rates of subduction suggests that approximately 50 km of the outer continental slope may have been formed in Pleistocene time. Rocks of Pleistocene age...
Categories: Publication; Types: Citation; Tags: Marine Geology
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A review of recent data on the velocity of bottom currents, the frequency of bottom-sediment movement, the kinds and amounts of suspended sediments in near-bottom waters, and the acoustic and sedimentary features of subbottom strata indicates that the characteristics of the ubiquitous sand sheet on the Atlantic outer continental shelf of the United States have been controlled by a variety of past and present processes. Although these processes collectively have had a widespread effect on the characteristics of the sand sheet, the relative importance of each process changes geographically. On Georges Bank, late Pleistocene glaciations along with modern tidal currents and the regional circulation pattern have played...
Categories: Publication; Types: Citation; Tags: Marine Geology
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Dune erosion is shown to occur at the embayment of beach mega-cusps O(200 m alongshore) that are associated with rip currents. The beach is the narrowest at the embayment of the mega-cusps allowing the swash of large storm waves coincident with high tides to reach the toe of the dune, to undercut the dune and to cause dune erosion. Field measurements of dune, beach, and rip current morphology are acquired along an 18 km shoreline in southern Monterey Bay, California. This section of the bay consists of a sandy shoreline backed by extensive dunes, rising to heights exceeding 40 m. There is a large increase in wave height going from small wave heights in the shadow of a headland, to the center of the bay where convergence...
Categories: Publication; Types: Citation; Tags: Marine Geology
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Acoustic swath-mapping of the greater Monterey Bay area continental shelf from Point An??o Nuevo to Point Sur reveals complex patterns of rock outcrops on the shelf, and coarse-sand bodies that occur in distinct depressions on the inner and mid-shelves. Most of the rock outcrops are erosional cuestas of dipping Tertiary rocks that make up the bedrock of the surrounding lands. A mid-shelf mud belt of Holocene sediment buries the Tertiary rocks in a continuous, 6-km-wide zone on the northern Monterey Bay shelf. Rock exposures occur on the inner shelf, near tectonically uplifting highlands, and on the outer shelf, beyond the reach of the mud depositing on the mid-shelf since the Holocene sea-level rise. The sediment-starved...
Categories: Publication; Types: Citation; Tags: Marine Geology
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The Santa Rosa-Cortes Ridge is an 1800 m high, 180 km long feature lying approximately 90 km off the coast of southern California and directly south of the northern group of Channel Islands. Geophysical profiling and sampling cruises to the northern part of the ridge, an area of recent and future lease sales for petroleum development, provide a strong data base for interpretation of structural and sedimentary patterns and their relation to potential geologic hazards. The northern part of the ridge is a complexly folded and faulted northwest-trending anticlinorium composed mostly of lower and middle Miocene shale and mudstone. Erosional remnants of upper Miocene and Pliocene rocks unconformably overlie highly folded...
Categories: Publication; Types: Citation; Tags: Marine Geology
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Time-exposure intensity (averaged) images are commonly used to locate the nearshore sandbar position (xb), based on the cross-shore locations of maximum pixel intensity (xi) of the bright bands in the images. It is not known, however, how the breaking patterns seen in Variance images (i.e. those created through standard deviation of pixel intensity over time) are related to the sandbar locations. We investigated the suitability of both Time-exposure and Variance images for sandbar detection within a multiple bar system on the southern coast of Brazil, and verified the relation between wave breaking patterns, observed as bands of high intensity in these images and cross-shore profiles of modeled wave energy dissipation...
Categories: Publication; Types: Citation; Tags: Marine Geology
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Assessment of the probability for destructive landslide-generated tsunamis depends on the knowledge of the number, size, and frequency of large submarine landslides. This paper investigates the size distribution of submarine landslides along the U.S. Atlantic continental slope and rise using the size of the landslide source regions (landslide failure scars). Landslide scars along the margin identified in a detailed bathymetric Digital Elevation Model (DEM) have areas that range between 0.89??km2 and 2410??km2 and volumes between 0.002??km3 and 179??km3. The area to volume relationship of these failure scars is almost linear (inverse power-law exponent close to 1), suggesting a fairly uniform failure thickness of...
Categories: Publication; Types: Citation; Tags: Marine Geology
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Mass movement has influenced in varying degrees the morphology of the United States east coast continental margin seaward of the Baltimore Canyon trough as revealed by detailed geophysical studies using high-resolution 3.5-kHz, and seismic reflection data. Each of three areas studied is along the slope within a distance of 225 km, and is seaward of a nonglaciated shelf but near major land drainage systems. Thick sequences of material believed to be Pleistocene were deposited on the slope in all three areas. Sediment failure in the form of large block movement involving block thicknesses of more than 100 m, however, has taken place in only two of the areas. A factor common to the two areas where failure took place,...
Categories: Publication; Types: Citation; Tags: Marine Geology
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The Toms Canyon structure [~20-22 km wide] is located on the New Jersey outer continental shelf beneath 80-100 m of water, and is buried by ~1 km of upper Eocene to Holocene sedimentary strata. The structure displays several characteristics typical of terrestrial impact craters (flat floor; upraised faulted rim: brecciated sedimentary fill), but several other characteristics are atypical (an unusually thin ejecta blanket; lack of an inner basin, peak ring, or central peak; bearing nearly completely filled with breccia). Seismostratigraphic and biostratigraphic analyses show that the structure formed during planktonic foraminiferal biochron P15 of the early to middle late Eocene. The fill unit is stratigraphically...
Categories: Publication; Types: Citation; Tags: Marine Geology
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High-frequency Quaternary glacioeustasy resulted in the incision of six moderate- to high-relief fluvial erosion surfaces beneath the Virginia inner shelf and coastal zone along the updip edges of the Atlantic continental margin. Fluvial valleys up to 5 km wide, with up to 37 m of relief and thalweg depths of up to 72 m below modern mean sea level, cut through underlying Pleistocene and Mio-Pliocene strata in response to drops in baselevel on the order of 100 m. Fluvially incised valleys were significantly modified during subsequent marine transgressions as fluvial drainage basins evolved into estuarine embayments (ancestral generations of the Chesapeake Bay). Complex incised-valley fill successions are bounded...
Categories: Publication; Types: Citation; Tags: Marine Geology
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The coast of Maine contains over 200 individual barrier-lagoon systems, most quite small, with an aggregate length of nearly 100 km. Although they represent less than 5% of the tidally influenced coastline of Maine, they are widely distributed and occur in a variety of dynamic regimes and physiographic regions. Their morphology and backbarrier stratigraphy are different from better studied coastal plain systems, and provide important clues to the Holocene evolution of the Maine coast. In a study of geomorphic form and backbarrier stratigraphy, inlet processes and Holocene sea-level rise have been identified as the principal controls on coarse-grained barrier stratigraphy. Barriers in Maine are found in five distinct...
Categories: Publication; Types: Citation; Tags: Marine Geology
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Estimating the likelihood of tsunamis occurring along the U.S. Atlantic coast critically depends on knowledge of tsunami source probability. We review available information on both earthquake and landslide probabilities from potential sources that could generate local and transoceanic tsunamis. Estimating source probability includes defining both size and recurrence distributions for earthquakes and landslides. For the former distribution, source sizes are often distributed according to a truncated or tapered power-law relationship. For the latter distribution, sources are often assumed to occur in time according to a Poisson process, simplifying the way tsunami probabilities from individual sources can be aggregated....
Categories: Publication; Types: Citation; Tags: Marine Geology
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Tropical and extratropical storms produce significant erosion on the barrier islands of Louisiana. Over the past 100 years, such storms have produced at least 2 km of northward beach-face retreat and the loss of 63% of the surface area of the Isles Dernieres, a low-lying barrier-island arc along the central Louisiana coast. Elevations on the islands within the arc are typically less than 2 m above mean sea level. The islands typically have a washover-flat topography with occasional, poorly developed, dune-terrace topography consisting of low-lying and broken dunes. The central part of the arc consists of salt-marsh deposits overlain by washover sands along the Gulf of Mexico shoreline. Sand thicknesses range from...
Categories: Publication; Types: Citation; Tags: Marine Geology


map background search result map search result map Isopachs—Point Sur to Point Arguello, California Numerical model of salinity transport and mixing in the Hudson River Estuary Ultra-short baseline - navigation points and tracklines for Applied Acoustics EasyTrack Nexus 2 USBL data collected for ROV Global Explorer during USGS field activity 2017-001-FA Multichannel minisparker and chirp seismic reflection data of USGS field activity 2016-616-FA collected in the Catalina Basin offshore southern California in February 2016 Modeled extreme total water levels along the U.S. west coast Sea-floor videos and location of bottom video tracklines collected in Nantucket Sound, Massachusetts, in May 2016 and May 2017 by the U.S. Geological Survey during field activities 2016-005-FA and 2017-022-FA (MP4 video files and polyline shapefile) Sea-floor videos and location of bottom video tracklines collected in Nantucket Sound, Massachusetts, in May 2016 and May 2017 by the U.S. Geological Survey during field activities 2016-005-FA and 2017-022-FA (MP4 video files and polyline shapefile) Ultra-short baseline - navigation points and tracklines for Applied Acoustics EasyTrack Nexus 2 USBL data collected for ROV Global Explorer during USGS field activity 2017-001-FA Numerical model of salinity transport and mixing in the Hudson River Estuary Isopachs—Point Sur to Point Arguello, California Multichannel minisparker and chirp seismic reflection data of USGS field activity 2016-616-FA collected in the Catalina Basin offshore southern California in February 2016 Modeled extreme total water levels along the U.S. west coast