REMARKS: A large igneous intrusive sheet (Haycock Sheet, Triassic age) of diabase has weathered unevenly, leaving high peaks; The Lookout and Rock Hill (348)(East Rockhill Township) are examples. The diabase is a dark-gray to black, coarse-grained, igneous rock predominantly containing pyroxene and plagioclase minerals.
REMARKS: Shales, siltstones, and sandstones of the Brunswick Formation (Triassic age) were eroded by the Delaware River. These rocks form near-vertical cliffs because they have been partially metamorphosed by the nearby Coffman Hill diabase sheet and are therefore denser, harder, and more resistant than similar rocks to the northwest of Kintnersville. The cliffs are a spectacular scenic geologic site along the Delaware River.
REFERENCES: Drake, A. A., Jr., McLaughlin, D. B., and Davis, R. E. [1967], Geologic map of the Riegelsville quadrangle, Pennsylvania-New Jersey, U. S. Geological Survey Geologic Survey Geologic Quadrangle Map GQ-593.
REMARKS: A diabase boulder field where the various boulders have different sounds when hit with a hammer; a tune may be played on the rocks. This is the largest "ringing-rock" boulder field in the East.
REFERENCES: Faas, R. W., and Flocks, J. M. [1966], Some acoustic properties of the Ringing Rocks diabase, Kintnersville, Pennsylvania [abs.], Pennsylvania Academy of Science Proceedings, v. 40, no. 1, p. 12.
Fackenthal, B. F., Jr. [1932], Ringing Rocks of Bridgeton Township, Bucks County, Pennsylvania, Bucks County Historical Society, Papers 5, p. 212-221.
Redmond, Andrew [1976], Ringing Rocks, Bucks County Department of Parks and Recreation, Langhorne, Pennsylvania, 8 p.