The Geological and Paleogeomorphological Evolution of a Spit System and Its Associated Coastal Environments: Cape Henlopen Spit, Delaware

Abstract

ABSTRACT Cape Healopen is a simple spit located at the confluence of the large estuary, Delaware Bay, and the Atlantic Ocean on the northeast coast of the United States of America. Examination of surface and subsurface elements of the present and ancestral spit area and associated coastal environments over a sixty square kilometer area shows that Cape Henlopen was formerly a recurved spit building northward from an eroding Pleistocene headland. It has been possible to delineate the areal distribution of estuarine, spit, beach, nearshore-marine, dune, marsh, and lagoon environments of the spit complex from middle Holocene time to present based on data obtained from an intensive drilling program. As relative sea-level rise and coastal erosion continue, the upper portion of the stratigraphic record formed by the spit complex is being destroyed. The remainder is covered by a thin veneer of shallow marine sands and gravels. Vertical sedimentary sequences in the spit complex include regressive sequences in which coastal environments migrate over marine environments as well as transgressive sequences in which marine and barrier environments overlie lagoon and marsh environments.