Investigation of the Neogene and Quaternary geology of the Milford and Mispillion River quadrangles has identified six formations: the Calvert, Choptank, and St. Marys formations of the Chesapeake Group, the Columbia Formation, and the Lynch Heights and Scotts Comers formations of the Delaware Bay Group. Stream, swamp, marsh, shoreline, and estuarine and bay deposits of Holocene age are also recognized. The Calvert, Choptank, and St. Marys formations were deposited in inner shelf marine environments during the early to late Miocene.
The hydraulic properties of the Piney Point (Eocene) aquifer and overlying basal silt of the Chesapeake Group (Miocene) were determined by a 23-day aquifer test conducted at the Danner Farm Well Field of the City of Dover, Delaware. During the test, head changes were monitored continuously in the Piney Point aquifer, overlying Cheswold (Miocene) aquifer, and the intervening confining bed.
The geology of Delaware includes parts of two geologic provinces: the Appalachian Piedmont Province and the Atlantic Coastal Plain Province. The Piedmont occurs in the hilly northernmost part of the state and is composed of crystalline metamorphic and igneous rocks. This chart summarizes the age and distribution of the geologic units that are recognized in the state by the Delaware Geological Survey.
Analyses of drillers' and geophysical logs, cuttings, and 29 core samples from well Nc13-3 near Greenwood, Sussex County, Delaware indicate that the 1500-foot section penetrated by the drill can be divided into seven rock-stratigraphic units: Matawan Formation, Monmouth Formation, unit A, Piney Point Formation, Chesapeake Group (undifferentiated), Staytonville unit, and the Columbia Formation. The rock units are identified on the basis of texture, mineralogy, color, and interpretation of electric and gamma-ray logs.
Geohydrology of the Milford, Delaware area.
Geohydrology of the Dover Aera, Delaware