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Sea-floor geology in central Rhode Island Sound south of Sakonnet Point, Rhode Island

Open-File Report 2012-1004

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Abstract

The U.S. Geological Survey (USGS) and the National Oceanic and Atmospheric Administration (NOAA) are working together to study the sea floor along the northeastern coast of the United States. NOAA collected multibeam-echosounder data during hydrographic survey H11995 in a 63-square-kilometer area in central Rhode Island Sound, south of Sakonnet Point, Rhode Island. The USGS collected sediment samples, bottom video, and still photographs from 27 stations in this study area to verify an interpretation of the bathymetric data. Collected data are used to map areas of scour depressions and erosional outliers, megaripples, boulders, and relatively undisturbed modern marine sediments. In general, much of the eastern part of the study area, a submerged segment of the Harbor Hill-Roanoke Point-Charlestown-Buzzards Bay moraine, is bouldery. Bottom photography shows boulders are generally encrusted with hydrozoans, algae, and anemone. Scour depressions, presumably formed by long-period storm waves, and erosional outliers of Holocene sediments dominate the western part of the study area and several large areas in the east. The scour depressions tend to have coarser grained sediment than intervening erosional outliers. The coarseness likely creates turbulence in the water over these areas, which prevents fine-grained sediment deposition. Several small areas of megaripples are visible in the bathymetry data in the west. Other sandy areas are typically rippled, with burrows, worm tubes, and starfish present.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Sea-floor geology in central Rhode Island Sound south of Sakonnet Point, Rhode Island
Series title:
Open-File Report
Series number:
2012-1004
Year Published:
2012
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
Woods Hole Coastal and Marine Science Center
Description:
HTML Document
Country:
United States
State:
Rhode Island
Other Geospatial:
Rhode Island Sound
Online Only (Y/N):
N
Additional Online Files(Y/N):
Y