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The Munson-Nygren slide is a large compound slide located between Munson and Nygren Canyons below 1900 m depth on the Continental Slope off Georges Bank. Its structural and morphological features are recognized in high-resolution seismic-reflection profiles. The slide comprises an axial trough which has a relief as great as 325 m and a width of 6-10 km. The trough is flanked by displaced and disrupted strata for a total lateral extent of approximately 20 km and a downslope extent of at least 35 km. The slide is unrelated genetically to the adjacent canyons and may postdate Munson Canyon. There is evidence of plastic deformation at the base of the section subjected to sliding. Certain features of the slide complex...
Categories: Publication; Types: Citation; Tags: Marine Geology
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In 1996 a major flood occurred in the Saguenay region, Quebec, Canada, delivering several km3 of sediment to the Saguenay Fjord. Such sediments covered large areas of the, until then, largely contaminated fjord bottom, thus providing a natural capping layer. Recent swath bathymetry data have also shown that sediment landslides are widely present in the upper section of the Saguenay Fjord, and therefore, should a new event occur, it would probably expose the old contaminated sediments. Landslides in the Upper Saguenay Fjord are most probably due to earthquakes given its proximity to the Charlevoix seismic region and to that of the 1988 Saguenay earthquake. In consequence, this study tries to characterize the permanent...
Categories: Publication; Types: Citation; Tags: Marine Geology
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A diverse suite of geochemical tracers, including 87Sr/86Sr and 143Nd/144Nd isotope ratios, the rare earth elements (REEs), and select trace elements were used to determine sand-sized sediment provenance and transport pathways within the San Francisco Bay coastal system. This study complements a large interdisciplinary effort (Barnard et al., 2012) that seeks to better understand recent geomorphic change in a highly urbanized and dynamic estuarine-coastal setting. Sand-sized sediment provenance in this geologically complex system is important to estuarine resource managers and was assessed by examining the geographic distribution of this suite of geochemical tracers from the primary sources (fluvial and rock) throughout...
Categories: Publication; Types: Citation; Tags: Marine Geology
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The impact of multi-decadal, large-scale deflation (76 million m3 of sediment loss) and contraction (~ 1 km) of a 150 km2 ebb-tidal delta on hydrodynamics and sediment transport at adjacent Ocean Beach in San Francisco, CA (USA), is examined using a coupled wave and circulation model. The model is forced with representative wave and tidal conditions using recent (2005) and historic (1956) ebb-tidal delta bathymetry data sets. Comparison of the simulations indicates that along north/south trending Ocean Beach the contraction and deflation of the ebb-tidal delta have resulted in significant differences in the flow and sediment dynamics. Between 1956 and 2005 the transverse bar (the shallow attachment point of the...
Categories: Publication; Types: Citation; Tags: Marine Geology
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Sediment exchange at large energetic inlets is often difficult to quantify due complex flows, massive amounts of water and sediment exchange, and environmental conditions limiting long-term data collection. In an effort to better quantify such exchange this study investigated the use of suspended sediment concentrations (SSC) measured at an offsite location as a surrogate for sediment exchange at the tidally dominated Golden Gate inlet in San Francisco, CA. A numerical model was calibrated and validated against water and suspended sediment flux measured during a spring–neap tide cycle across the Golden Gate. The model was then run for five months and net exchange was calculated on a tidal time-scale and compared...
Categories: Publication; Types: Citation; Tags: Marine Geology
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Necker Ridge, Horizon Guyot and S.P. Lee Guyot in the Central Pacific were sampled, seismically surveyed, and photographed by bottom cameras in order to better understand the distribution, origin, and evolution of ferromanganese crusts. Necker Ridge is over 600 km long with a rugged crest, pods of sediment to 146 m thick, slopes that average 12° to 20°, and debris aprons that cover some of the lower flanks. Substrate lithologies are mostly hyaloclastite, volcaniclastic breccia, and minor alkalic basalt. Horizon Guyot, 300 km long and 75 km wide, is capped by at least 160 m of sediment, which buries stepped terraces. Substrate lithologies are similar to those on Necker Ridge, although previous workers sampled much...
Categories: Publication; Types: Citation; Tags: Marine Geology
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This part of DS 781 presents data for the sediment-thickness map of the Pigeon Point to Monterey, California, region. The raster data file is included in "SedimentThickness_PigeonPointToSouthMontereyBay.zip," which is accessible from http://dx.doi.org/10.5066/F7F47M6T 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 Pigeon Point and Monterey was generated from seismic-reflection data collected in 2009 and 2012 (USGS activities S-15-10-NC, S-06-11-MB and S-N1-09-MB) supplemented with outcrop and geologic structure from DS 781. The resulting grid covers an area of approximately 860 sq km. The volume of sediment...
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The Sandy Hook artificial reef, located on the sea floor offshore of Sandy Hook, New Jersey was built to create habitat for marine life. The reef was created by the placement of heavy materials on the sea floor; ninety-five percent of the material in the Sandy Hook reef is rock. In 2000, the U.S. Geological Survey surveyed the area using a Simrad EM1000 multibeam echosounder mounted on the Canadian Coast Guard (CCG) ship Frederick G. Creed. The purpose of this multibeam survey, done in cooperation with the U.S. Army Corps of Engineers when the Creed was in the New York region in April 2000, was to map the bathymetry and backscatter intensity of the sea floor in the area of the Sandy Hook artificial reef. The collected...
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The Sandy Hook artificial reef, located on the sea floor offshore of Sandy Hook, New Jersey was built to create habitat for marine life. The reef was created by the placement of heavy materials on the sea floor; ninety-five percent of the material in the Sandy Hook reef is rock. In 2000, the U.S. Geological Survey surveyed the area using a Simrad EM1000 multibeam echosounder mounted on the Canadian Coast Guard (CCG) ship Frederick G. Creed. The purpose of this multibeam survey, done in cooperation with the U.S. Army Corps of Engineers when the Creed was in the New York region in April 2000, was to map the bathymetry and backscatter intensity of the sea floor in the area of the Sandy Hook artificial reef. The collected...
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The increasing volume of multibeam bathymetry data collected along continental margins is providing new opportunities to study the feedbacks between sedimentary and oceanographic processes and seafloor morphology. Attempts to develop simple guidelines that describe the relationships between form and process often overlook the importance of inherited physiography in slope depositional systems. Here, we use multibeam bathymetry data and seismic reflection profiles spanning the U.S. Atlantic outer continental shelf, slope and rise from Cape Hatteras to New England to quantify the broad-scale, across-margin morphological variation. Morphometric analyses suggest the margin can be divided into four basic categories that...
Categories: Publication; Types: Citation; Tags: Marine Geology
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Submarine canyons are common features of continental margins worldwide. They are conduits that funnel vast quantities of sediment from the continents to the deep sea. Though it is known that submarine canyons form primarily from erosion induced by submarine sediment flows, we currently lack quantitative, empirically based expressions that describe the morphology of submarine canyon networks. Multibeam bathymetry data along the entire passive US Atlantic margin (USAM) and along the active central California margin near Monterey Bay provide an opportunity to examine the fine-scale morphology of 171 slope-sourced canyons. Log–log regression analyses of canyon thalweg gradient (S) versus up-canyon catchment area (A)...
Categories: Publication; Types: Citation; Tags: Marine Geology
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High resolution bathymetric, sea-floor backscatter, and seismic-reflection data were collected offshore of southeastern Louisiana aboard the research vessel Point Sur on May 19-26, 2017, in an effort to characterize mudflow hazards on the Mississippi River Delta front. As the initial field program of a research cooperative between the U.S. Geological Survey, the Bureau of Ocean Energy Management, and other Federal and academic partners, the primary objective of this cruise was to assess the suitability of sea-floor mapping and shallow subsurface imaging tools in the challenging environmental conditions found across delta fronts (for example, variably distributed water column stratification and widespread biogenic...
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Vertical sediment fluxes and their dominant controlling processes in Hueneme and Mugu submarine canyons off south-central California were assessed using data from sediment traps and current meters on two moorings that were deployed for 6 months during the winter of 2007. The maxima of total particulate flux, which reached as high as 300+ g/m2/day in Hueneme Canyon, were recorded during winter storm events when high waves and river floods often coincided. During these winter storms, wave-induced resuspension of shelf sediment was a major source for the elevated sediment fluxes. Canyon rim morphology, rather than physical proximity to an adjacent river mouth, appeared to control the magnitude of sediment fluxes in...
Categories: Publication; Types: Citation; Tags: Marine Geology
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ORWA26_500UTM is a digital bathymetric surface grid of the seafloor offthe coast of Washington and Oregon. Grid cell spacing is 500m and theprojection is UTM Zone 10.The surface was produced by gridding National Ocean Service (NOS)Hydrographic Surveys collected between 1926 and 1974 (primarily1926 to 1930). This work includes the most recent bathymetric dataavailable on a regional scale over the inner to outer continental shelfoff the coast of Washington and Oregon. The results represent thebest available estimate of the seafloor morphology for the time periodcirca 1926.
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A high-resolution ultrasonic profiler has been developed which permits both laboratory and field studies of small-scale subaqueous bedforms. The device uses a 2.5-cm diameter piezoelectric ceramic crystal pulsed at a frequency of 4.5 MHz to obtain vertical accuracy and resolution of at least 1 mm. Compared to other small-scale profiling methods, this ultrasonic technique profiles the bottom more accurately and more rapidly without disturbing the bedforms. These characteristics are vital in wave-dominated nearshore zones where oscillatory flow and low visibility for the most part have stymied detailed bedform studies. In the laboratory the transducer is mounted directly to an instrument carriage. For field work the...
Categories: Publication; Types: Citation; Tags: Marine Geology
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Geophysical and geological survey data were collected off Town Neck Beach in Sandwich, Massachusetts, in May and July 2016. Approximately 130 linear kilometers of subbottom (seismic-reflection) and 234-kilohertz interferometric sonar (bathymetric and backscatter) data were collected along with sediment samples, sea floor photographs, and (or) video at 26 sites within the geophysical survey area. Sediment grab samples were collected at 19 of the 26 sampling sites and video and (or) photographic imagery of the sea floor were taken at all 26 sites. These survey data are used to characterize the sea floor by identifying sediment-texture, seabed morphology, and underlying geologic structure and stratigraphy. Data collected...
Categories: Data; Tags: Atlantic Ocean, CMGP, Cape Cod, Cape Cod Bay, Coastal and Marine Geology Program, All tags...
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High-resolution acoustic backscatter data, bathymetry data, single channel minisparker seismic-reflection data were collected by the U.S. Geological Survey (USGS) and the Alaska Department of Fish and Game in May of 2014 southwest of Chenega Island and southwest of Montague Island, Alaska. Data were collected aboard the Alaska Department of Fish and Game vessel, R/V Solstice, during USGS field activity 2014-622-FA, using a pole mounted 100-kHz Reson 7111 multibeam echosounder, a 500 Joule SIG 2-mille minisparker sound source and a single channel streamer.
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Fine-grained sediments, or “fines,” are nearly ubiquitous in natural sediments, even in the predominantly coarse-grained sediments that host gas hydrates. Fines within these sandy sediments can be mobilized and subsequently clog flow pathways while methane is being extracted from gas hydrate as an energy resource. Using two-dimensional (2D) micromodels to test the conditions in which clogging occurs provides insights for choosing production operation parameters that optimize methane recovery in the field. During methane extraction, several processes can alter the mobility and clogging potential of fines: (1) fluid flow as the formation is depressurized to release methane from gas hydrate, (2) shifting pore-fluid...
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High resolution bathymetric, sea-floor backscatter, and seismic-reflection data were collected offshore of southeastern Louisiana aboard the research vessel Point Sur on May 19-26, 2017, in an effort to characterize mudflow hazards on the Mississippi River Delta front. As the initial field program of a research cooperative between the U.S. Geological Survey, the Bureau of Ocean Energy Management, and other Federal and academic partners, the primary objective of this cruise was to assess the suitability of sea-floor mapping and shallow subsurface imaging tools in the challenging environmental conditions found across delta fronts (for example, variably distributed water column stratification and widespread biogenic...
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This part of DS 781 presents data for the transgressive contours of the Punta Gorda to Point Arena, California, region. The vector data file is included in the "TransgressiveContours_PuntaGordaToPointArena.zip," which is accessible from https://doi.org/10.5066/P9PNNI9H. 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 Punta Gorda and Point Arena was generated from seismic-reflection data collected between 2010 and 2012, and supplemented with geologic structure (fault) information following the methodology of Wong (2012). Water depths determined from bathymetry data were added to the sediment thickness data to...


map background search result map search result map Geomorphic characterization of the U.S. Atlantic continental margin ORWA26_500UTM: Oregon/Washington 500 meter, 1926 Bathymetry Grid;UTM Projection A Sr-Nd isotopic study of sand-sized sediment provenance and transport for the San Francisco Bay coastal system Changes in surfzone morphodynamics driven by multi-decadel contraction of a large ebb-tidal delta The use of modeling and suspended sediment concentration measurements for quantifying net suspended sediment transport through a large tidally dominated inlet Sediment Thickness--Pigeon Point to Monterey, California GeoTIFF image of the backscatter intensity of the sea floor of the Sandy Hook artificial reef (2-m resolution, Mercator, WGS 84) Tracklines of a multibeam survey of the sea floor of the Sandy Hook artificial reef (polyline shapefile, geographic, WGS 84) High-resolution geophysical data collected along the Mississippi River Delta front offshore of southeastern Louisiana, U.S. Geological Survey Field Activity 2017-003-FA Multibeam Echosounder, Reson T-20P tracklines, USGS field activity 2017-003-FA, Mississippi River Delta front offshore of southeastern Louisiana (Esri polyline shapefile, GCS WGS 84) 2D micromodel studies of pore-throat clogging by pure fine-grained sediments and natural sediments from NGHP-02, offshore India Location of bottom photographs along with images collected in July 2016 by the U.S. Geological Survey off Town Neck Beach, Sandwich, Massachusetts, during field activity 2016-037-FA (JPEG images, point shapefile, and CSV file) Transgressive Contours--Punta Gorda to Point Arena, California Location of bottom photographs along with images collected in July 2016 by the U.S. Geological Survey off Town Neck Beach, Sandwich, Massachusetts, during field activity 2016-037-FA (JPEG images, point shapefile, and CSV file) Tracklines of a multibeam survey of the sea floor of the Sandy Hook artificial reef (polyline shapefile, geographic, WGS 84) GeoTIFF image of the backscatter intensity of the sea floor of the Sandy Hook artificial reef (2-m resolution, Mercator, WGS 84) The use of modeling and suspended sediment concentration measurements for quantifying net suspended sediment transport through a large tidally dominated inlet Multibeam Echosounder, Reson T-20P tracklines, USGS field activity 2017-003-FA, Mississippi River Delta front offshore of southeastern Louisiana (Esri polyline shapefile, GCS WGS 84) Sediment Thickness--Pigeon Point to Monterey, California High-resolution geophysical data collected along the Mississippi River Delta front offshore of southeastern Louisiana, U.S. Geological Survey Field Activity 2017-003-FA Transgressive Contours--Punta Gorda to Point Arena, California 2D micromodel studies of pore-throat clogging by pure fine-grained sediments and natural sediments from NGHP-02, offshore India Changes in surfzone morphodynamics driven by multi-decadel contraction of a large ebb-tidal delta A Sr-Nd isotopic study of sand-sized sediment provenance and transport for the San Francisco Bay coastal system ORWA26_500UTM: Oregon/Washington 500 meter, 1926 Bathymetry Grid;UTM Projection Geomorphic characterization of the U.S. Atlantic continental margin