Permian (?) or older crystalline limestone, banded and ribbon chert, and minor siltstone form a metasedimentary wedge in diorite. Pyrite is common in the carbonate. The area is faulted and folded and bedding attitudes change quickly from gentle to nearly vertical.

A band, 300 metres wide, of intermixed white and pale blue- calcium limestone and dolomite strikes 120 degrees and dips steeply southwest. About 2.4 kilometres to the northwest, a 30 metre band of similar rock strikes 127 degrees for 150 metres, dipping vertically.