Open-File Report 2015-1149
Multibeam echosounder data collected by the National Oceanic and Atmospheric Administration along with sediment and photographic data collected by the U.S. Geological Survey from southern Narragansett Bay, Rhode Island, were used to interpret sea-floor features and sedimentary environments. Rocky areas tend to be along the coasts and in the eastern part of the study area where exposed bedrock onshore continues on the sea floor. Scour depressions were found in the deep parts of the study area, where currents scour the sea floor in constricted areas, and in patches around rocky areas in the eastern part of the study area. The rocky and scoured areas of the sea floor are in sedimentary environments characterized by erosion and nondeposition. Bedforms such as sand waves and megaripples can mostly be found in East Passage, where environments characterized by coarse-grained bedload transport exist. Areas of the sea floor that lack these features have relatively low-energy environments characterized by sorting and reworking. Anthropogenic features are also visible in the bathymetric data; two shipwrecks are present in the study area.