Geologic Map of the Frederica and Bennetts Pier Quadrangles, Delaware

Abstract

Geologic mapping was conducted at 1:12,000 with a 1-ft contour basemap. In some instances, stratigraphic boundaries drawn at topographic breaks and highs reflect detailed mapping using LiDAR data. Elevations of stratigraphic contacts along stream valleys are projected from subsurface data. Except for a few erosional bluffs, these contacts are covered by colluvium. Carolina Bay deposits were visually identified using a hillshade digital elevation model (DEM). This map supersedes Geology of the South-Central Kent County Area, Delaware: Delaware Geological Survey Geologic Map Series No. 7 (Pickett and Benson, 1986) and Geologic Map of Kent County, Delaware: Delaware Geological Survey Geologic Map Series No. 14 (Ramsey, 2007).

The geological history of the surficial units of the Frederica and Bennetts Pier Quadrangles is the result of erosion of the Choptank and Beaverdam Formations by glacial dam burst events during the early Pleistocene. These periods of erosion were followed by fluvial and estuarine deposition associated with multiple sea-level fluctuations during the middle to late Pleistocene. Periglacial activity that followed produced Carolina Bay deposits and freeze-thaw features on the land surface. Marsh sediments deposited during the Holocene further modified the geology.