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Humboldt Slide is a large, complex slide zone located on the northern California continental margin. Its three-dimensional architecture has been imaged by a combination of multibeam bathymetry, Huntec Deep-Tow seismic profiling, and sidescan sonar. The slide is interpreted to be Late Pleistocene to early Holocene in age and was caused by a combination of factors. The area of the slide is a local depocenter with high accumulation rates of organic-rich sediment; there has been local steepening of slopes by tectonic uplifts; and the entire area is one of high seismicity. Overall, the failure occurred by retrogressive, shear-dominated, minimum movement apparently as a sequence of events. Failure initially occurred by...
Categories: Publication; Types: Citation; Tags: Marine Geology
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Samples from four geographically and tectonically discrete cold seeps named Clam Flat, Clamfield, Horseshoe Scarp South, and Tubeworm City, within the Monterey Bay National Marine Sanctuary were analyzed for their hydrocarbon content. The sediment contains gaseous hydrocarbons and CO2, as well as high molecular weight aliphatic and aromatic hydrocarbons with various combinations of thermogenic and biogenic contributions from petroleum, marine, and terrigenous sources. Of particular interest is the cold seep site at Clamfield which is characterized by the presence of thermogenic hydrocarbons including oil that can likely be correlated with oil-saturated strata at Majors Creek near Davenport, CA, USA. At Clam Flat,...
Categories: Publication; Types: Citation; Tags: Marine Geology
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A large amphitheater-shaped scarp, approximately 55 km across, was imaged on the northern insular slope of Puerto Rico using long-range sidescan sonar and bathymetric data. This scarp results from the removal of more than 1500 km3 of Tertiary strata. A review of seismic-reflection profiles, stratigraphic data, and subsidence models of the northern insular margin of Puerto Rico were used to infer that large-scale slope failure was induced by the tectonic oversteepening of the insular slope and was responsible for the formation of the scarp. The oversteepening probably was caused by the most recent episode of convergence of the Caribbean and North American plates, which began between approximately 4 and 2.5 m.y. ago....
Categories: Publication; Types: Citation; Tags: Marine Geology
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We really appreciate the interest and comments regarding our manuscript. We hope we address all the lingering issues in this reply. This also gives us the opportunity of publishing an update on our dataset that will complete the original manuscript (see Table 1). We have followed the author pattern in our answers: 1-Gas sampling procedure, 2-Reported gas concentrations results, 3-General remarks, 4-Conclusions.
Categories: Publication; Types: Citation; Tags: Marine Geology
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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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Sea-floor drainage features of Cascadia Basin and the adjacent continental slope include canyons, primary fan valleys, deep-sea valleys, and remnant valley segments. Long-range sidescan sonographs and associated seismic-reflection profiles indicate that the canyons may originate along a mid-slope escarpment and grow upslope by mass wasting and downslope by valley erosion or aggradation. Most canyons are partly filled with sediment, and Quillayute Canyon is almost completely filled. Under normal growth conditions, the larger canyons connect with primary fan valleys or deep-sea valleys in Cascadia Basin, but development of accretionary ridges blocks or re-routes most canyons, forcing abandonment of the associated...
Categories: Publication; Types: Citation; Tags: Marine Geology
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A circuit has been developed to allow the writing of up to 192 digits of user-selectable data on a portion of tape called extended header, which is always available for use before each DFS-V seismic record is written. Such data could include navigation information, air gun and streamer depth and shot times.
Categories: Publication; Types: Citation; Tags: Marine Geology
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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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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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RBRduo pressure and temperature sensors, mounted on aluminum frames, were moored in shallow (< 6 m) water depths in Skagit and Bellingham Bays, Washington, USA, from December 2017 to February 2018, to capture wave heights and periods. Continuous pressure fluctuations are transformed into surface-wave observations of wave heights, periods, and frequency spectra at 30-minute intervals.
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Scientists from the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center investigated the sedimentary and geochemical properties of the lower reaches of the Pascagoula River along the Mississippi coast of the Gulf of Mexico by collecting estuarine, riverine and marsh sediments. This was done in order to increase understanding of the region's environmental history, describe the long-term (millennial-scale) depositional history, and identify sedimentary intervals associated with extreme marine intrusions. To this end, the group obtained long sediment cores, shovel-dug sediment slabs and marsh and riverine channel/estuarine surface samples from a north-south transect along the river edge from...
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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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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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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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The natural resiliency of the New Jersey barrier island system, and the efficacy of management efforts to reduce vulnerability, depends on the ability of the system to recover and maintain equilibrium in response to storms and persistent coastal change. This resiliency is largely dependent on the availability of sand in the beach system. In an effort to better understand the system's sand budget and processes in which this system evolves, high-resolution geophysical mapping of the sea floor in Little Egg Inlet and along the southern end of Long Beach Island near Beach Haven, New Jersey was conducted from May 31 to June 10, 2018, followed by a sea floor sampling survey conducted from October 22 to 23, 2018, as part...


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 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) Sedimentary data from the lower Pascagoula River, Mississippi, USA Wave observations from nearshore bottom-mounted pressure sensors in Skagit and Bellingham Bays, Washington, USA from Dec 2017 to Feb 2018 Chirp seismic reflection data from the Edgetech 512i collected in Little Egg Inlet and offshore the southern end of Long Beach Island, NJ, during USGS field activity 2018-001-FA (shotpoints point shapefile, survey trackline shapefile, PNG profile images, and SEG-Y trace data). 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) Chirp seismic reflection data from the Edgetech 512i collected in Little Egg Inlet and offshore the southern end of Long Beach Island, NJ, during USGS field activity 2018-001-FA (shotpoints point shapefile, survey trackline shapefile, PNG profile images, and SEG-Y trace data). The use of modeling and suspended sediment concentration measurements for quantifying net suspended sediment transport through a large tidally dominated inlet Wave observations from nearshore bottom-mounted pressure sensors in Skagit and Bellingham Bays, Washington, USA from Dec 2017 to Feb 2018 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