First State Geology has been the newsletter of DGS for over 25 years. 
The following description is published in GM10 Bedrock Geologic Map of The Piedmont of Delaware and the Adjacent Pennsylvania, Schenck, W.S., Plank, M.O., and Srogi, L., 2000.
Massive fine-grained dark to light yellow-green serpentinite. Contacts with the Wissahickon Formation are not exposed.
