REGIONAL-SCALE SEDIMENT MAPS OF U.S. CONTINENTAL MARGINS: INSIGHTS TO SEDIMENTARY CHARACTER AND PROCESSES, AGGREGATE RESOURCES

Continental margins are dynamic sedimentary landforms that serve many important functions: benthic habitats, navigation/national defense and engineering. Coastal margins also contain resources such as sand and gravel, increasingly important for beach nourishment to mitigate coastal erosion. Existing products depicting seafloor and sub-bottom sedimentary character, morphology, texture, composition, and other seafloor properties are not available for all regions, not inclusive of datasets collected during the past several decades, and not in digital formats. New maps, based on unified national datasets, showing the sedimentary character of continental margins are critical for better understanding the geologic history and processes of US continental margins.

Most existing seafloor maps are decades old and don’t include recent data from sea floor mapping, sampling and observation. Because shelf margins are increasingly important, comprehensive and integrated databases are needed to produce GIS digital base maps displaying information such as seafloor geology, sediment character, texture and distribution. To meet the need for a unified database of seafloor sedimentary character, the USGS is conducting the Marine Aggregate Resources and Processes Project, a national assessment with federal, state, and academic partners.

The main objectives of MARP are: increase scientific understanding of Quaternary shelf history and sand budgets for coastal-shelf systems; and, better understand the character and distribution of offshore sand and gravel resources. MARP combines the dbSEABED system and the hugh usSEABED data collection to implement a series of regional assessments (NY Bight, ME, LA) that will result in a national mapping of seafloor sedimentary character and assessment of marine aggregate resources and provide fresh insights into the geologic character of US coastal margins.