This vector data set contains the rock unit polygons for the surficial geology in the Delaware Coastal Plain covered by DGS Geologic Map Series No. 27 (Elkton, Saint Georges, and Delaware City Quadrangles). The geology of the map area reflects a complex history with a cut and fill geometry where the Pleistocene-aged deposits incised into older units. The Tertiary deposits were modified by erosion and deposition of the Columbia Formation during the early Pleistocene and again by the Lynch Heights and Scotts Corners Formations as a result of sea-level fluctuations during the middle to late Pleistocene. The geology is further complicated by periglacial activity that produced Carolina Bay deposits in the map area, which modified the land surface. This map supersedes this portion of Geology of the Chesapeake and Delaware Canal Area, Delaware: Delaware Geological Survey Geologic Map Series No. 1 (Pickett, 1970) and Geologic Map of New Castle County, Delaware: Delaware Geological Survey Geologic Map Series No. 13 (Ramsey, 2005).