The Rocks of Penny's Bend -

Triassic Sedimentary Rocks

Triassic sediments in the Penny's Bend area consist of interlayered sandstones and siltstones. Both rock types are relatively easy to erode compared to diabase, but the sandstone is a little more resistant to erosion. (Photograph from Martha's Chapel on shore of Jordan Lake.)
Sandstone - The Triassic sandstone typically is composed of sand-sized grains of quartz and feldspar with some mica (muscovite and/or biotite).
Siltstone - The Triassic siltstone often contains gray areas that are interpreted by geologists to have been caused by plant roots or burrowing animals. Geologist call these features bioturbation. (Photograph from Martha's Chapel on shore of Jordan Lake.)
Triassic sediments that are in contact with diabase typically display a dark brown color and are even more easily eroded than Triassic sediments away from diabase. The dark brown coloration is a result of the sediments being "baked" by the hot intruding diabase. (Photograph of "baked" Triassic sediments from the former Nello Teer Quarry adjacent to the Eno River in Durham, NC.)

Please remember that rock and mineral collecting is STRICTLY PROHIBITTED on protected land!

Want to learn more about the geology of the Eno River area?

You may be interested in A Geologic Adventure Along the Eno River - A richly illustrated publication from the North Carolina Geological Survey.