SAND SOURCES FOR THE TRANSGRESSIVE BARRIER COAST OF LONG ISLAND, NEW YORK: EVIDENCE FOR LANDWARD TRANSPORT OF SHELF SEDIMENTS.

During investigations of the regional geologic framework of Long Island shelf by means of seismic-reflection profiles and cores, Williams (1976) identified a rather limited area on the shelf off Jones Beach where Upper Cretaceous or early Tertiary age glauconite-rich lithosomes subcrop at the seabed, seaward of the shoreface. A suite of beach samples from Montauk Point to Rockaway Beach, cores from the shelf that penetrated the glauconitic strata, and grab samples along a shore-normal transect from the shelf to the beach were analyzed to determine if shelf sediments are being eroded and transported landward, and are contributing to the littoral sand budget along the Long Island coast. Results of this study using glauconite as a natural tracer of sediment transport show that under present oceanographic conditions, and probably throughout the Holocene transgression, the inner continental shelf has been an important source of sediment for the Long Island barrier beaches.