U.S. Geological Survey Open-File Report 2011–1005
Surficial Geology of the Sea Floor in Central Rhode Island Sound Southeast of Point Judith, Rhode Island
Multibeam echosounder data from NOAA survey H11996 combined with sediment and bottom photography data from a USGS cruise are used to outline sea-floor features in this area of Rhode Island Sound, southeast of Point Judith, R.I. Sea-floor features include scour depressions, sand waves, trawl marks, and dredge spoils. Bottom currents likely control the formation and maintenance of scour depressions and sand waves. Scour depressions cover much of the bathymetric highs, with widths up to several hundred meters wide and depths of about 0.5 meters. The floors of the depressions have more rippled and coarser sand than the surrounding sea floor, which probably helps to keep them maintained. Sand waves with wavelengths of several meters to more than 40 meters are located mostly in the southwest. Trawl marks are located in the northern parts of the study area. Disposal site 69b, located in the western part of the study area, contains distinct mounds of dredge spoils. Sand and silty sand covers much of the study area, while gravel and gravelly sediment were found at eight of the stations. Bottom photography shows sandy areas tend to be burrowed and have scattered shells, amphipod communities, and worm tubes, while coarse gravel tends to be overgrown with hydrozoans and anemones.