Coastal Plain - Primarily Subsurface Unit
The following description was published in GM13 Geologic Map of New Castle County, Delaware, Ramsey, K.W., 2005:
Glauconitic clayey silt and clay, with some glauconite sand and fine glauconitic quartz sand. Deposited in the middle Eocene (Benson and Spoljaric, 1996), and is generally 60 to 70 ft thick. Based on the microfossils (unpublished DGS file data), it can be characterized as an open shelf deposit.
Benson, R.N., and Spoljaric, N., 1996, <a href="/publications/b20-stratigraphy-post-potomac-cretaceous-tertiary-rocks-central-delaware">Stratigraphy of the Post-Potomac Cretaceous-Tertiary Rocks of Central Delaware: Delaware Geological Survey Bulletin 20</a>, 28 p.