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L.J. Poppe

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The U.S. Geological Survey, the National Oceanic and Atmospheric Administration (NOAA), and the Connecticut Department of Environmental Protection are mapping the sea floor in coastal areas of the northeastern United States. As part of the project, more than 100 square kilometers of multibeam-echosounder data, 23 sediment samples, bottom video, and 86 still photographs were obtained from an area in Long Island Sound north of Duck Pond Point, New York, in the study area of NOAA survey H11999. This report delineates the sediment types and sea-floor features found within this area in order to better understand the sea-floor processes occurring in this part of Long Island Sound. The sea floor in the study area is dominated...
Categories: Publication; Types: Citation; Tags: Open-File Report
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High biogenic productivity, strong tidal currents, shoal topography, and short transport distances combine to favor shell-bed formation along the lower flanks of a cape-associated shoal off Herod Point on Long Island, New York. This shell bed has a densely packed, clast-supported fabric composed largely of undegraded surf clam (Spisula solidissima) valves. It is widest along the central part of the western flank of the shoal where topographic gradients are steep and a stronger flood tide results in residual flow. The bed is narrower and thinner toward the landward margins where currents are too weak to transport larger valves and topographic gradients are gentle, limiting bed-load transport mechanisms by which the...
Categories: Publication; Types: Citation; Tags: Journal of Coastal Research
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This fraction, which is enriched in heavy minerals relative to the sand fraction, is mainly detrital but contains a strong authigenic component. The authigenic silt heavy-mineral fraction is largely a product of the lateritic weathering and dominated by iron oxides and alterites. Grains of bladed rutile and leached ilmenite are common. Spatial variability in silt-fraction mineralogy is considerable. Within the Rio Cibuco system variability is related to compositional differences in rapidly eroding source rocks. On the shelf, silt heavy-mineral abundances are greatest at the river mouths and decrease seaward. Variability in the shelf samples is controlled primarily by source rivers and shelf sorting processes.
Categories: Publication; Types: Citation; Tags: Sedimentary Geology
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This report releases echosounder data from the northern part of the National Oceanic and Atmospheric Administration (NOAA) hydrographic survey H11044 in Long Island Sound, off Milford, Connecticut. The data have been interpolated and regridded into a complete-coverage data set and image of the sea floor. The grid produced as a result of the interpolation is at 10-m resolution. These data extend an already published set of reprocessed bathymetric data from the southern part of survey H11044. In Long Island Sound, the U.S. Geological Survey, in cooperation with NOAA and the Connecticut Department of Environmental Protection, is producing detailed maps of the sea floor. Part of the current phase of research involves...
Categories: Publication; Types: Citation; Tags: Open-File Report
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The U.S. Geological Survey (USGS), the National Oceanic and Atmospheric Administration (NOAA), and the Connecticut Department of Environmental Protection (CT DEP) are working cooperatively to map and interpret features of the sea floor along the northeastern coast of the United States. This report presents multibeam bathymetry and sidescan-sonar data obtained during NOAA survey H11446, which was conducted in a 12-km2 area in Long Island Sound offshore of Orient Point, NY. In addition, sediment and photographic data from 26 stations obtained during a USGS verification cruise are presented. Overall, the sea floor slopes gently seaward, but topography is more complex in sand-wave and boulder areas, which are evident...
Categories: Publication; Types: Citation; Tags: Open-File Report
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