The Geology of Delaware

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Potomac Formation

Kpt
Geologic Time Period: 
Cretaceous
Coastal Plain - Primarily Subsurface Unit

The following description was published in GM13 Geologic Map of New Castle County, Delaware, Ramsey, K.W., 2005:

Dark-red, gray, pink, and white silty clay to clayey silt and very fine to medium sand beds. Beds of gray clayey silt to very fine sand that contain pieces of charcoal and lignite are common. Deposited in a fluvial setting in a tropical to subtropical environment as indicated by abundant paleosol horizons. Ranges from 20 ft updip to over 1600 ft thick in southern New Castle County.