Coastal Plain - Primarily Surficial Unit
The following description was published in GM13 Geologic Map of New Castle County, Delaware, Ramsey, K.W., 2005:
Reddish-brown to brown clayey silt, silty sand to sandy silt, and medium to coarse quartz sand with pebbles (Ramsey, 2005). Rock fragments of mica or sillimanite quartzose schist are common sand fraction. At land surface, a gray to grayish-brown clayey silt is present. Sands are cross-bedded with laminae of muscovite or heavy minerals defining the cross-sets. Silty beds tend to be structureless, or in the gray clayey silt beds, heavily bioturbated by roots. No fossils other than pollen have been recovered. Pollen indicate a cold climate during deposition of the upper clayey silt unit (unpublished DGS data). Stratigraphic relationships indicate either slightly younger than or contemporaneous with the Columbia Formation. Ranges from 5 to 40 ft in thickness.
Ramsey, K.W., 2005, <a href="/publications/ri69-geology-old-college-formation-along-fall-zone-delaware">Geology of the Old College Formation along the Fall Zone of Delaware: Delaware Geological Survey Report of Investigations No. 55</a>, 40 p.