Geologic Time Period
lower Paleozoic

Piedmont Unit

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.

Coarse- to very coarse-grained granitic pegmatite with tourmaline crystals locally. Where outcrop is present, pegmatite is tabular and concordant with the regional trend of the underlying Wissahickon Formation. Lenticular xenoliths of Wissahickon gneisses occur locally in the pegmatite.