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. 23 (Seaford West and Seaford East Quadrangles). The geological history of the surficial units of the Seaford East Quadrangle and the Delaware portion of the Seaford West Quadrangle was the result of deposition of the Beaverdam Formation and its subsequent modification by erosion and deposition related to the sea-level fluctuations during the Pleistocene. The geology reflects this complex history by the cut and fill geometry of the middle and late Pleistocene deposits into the Beaverdam Formation. The geology is further complicated by periglacial activity that produced dune deposits and the Carolina Bays in the map area, which modified the land surface. Mapping was conducted using field maps at a scale of 1:12,000 with 2-ft contours. Stratigraphic boundaries drawn at topographic breaks reflect detailed mapping using contours not shown on this map. This map is an update of the surficial geology of DGS Geologic Map No. 9: Geology of the Seaford Area, Delaware (Andres and Ramsey, 1995), and is based on new field data in the map area and the mapping of adjacent quadrangles. The purpose of the update is to provide continuity of surficial stratigraphic units in adjacent quadrangles in light of additional data, such as LiDAR data not available in 1995 and revisions to the Quaternary stratigraphy of Sussex County (Ramsey, 2010a). Geologic interpretations of subsurface stratigraphy in Andres and Ramsey (1995), Andres, Ramsey, and Groot (1996), and Andres, Ramsey, and Schenck (1995) have not been revised. Surficial stratigraphic units depicted on this map supersede those of Andres and Ramsey (1995).
This data is accessible as a map service on Delaware FirstMap.
Additionally, this and other services are available in the ArcGIS Online DGS Map Viewer
+/- 1 foot. Drill holes and hand auger holes have been averaged together to get this value.
+/- 20 feet. Boring sites are located on topographic base maps and aerial photography. Spot checking of these locations using GPS has verified this accuracy.