Geology on the Allegheny Highlands Trail

The rock formations between Garrett and Rockwood are the source of geology lessons for students and other trail users.

The Casselman River cut a 700-foot gorge through the Negro Mountain, revealing 200 million years of history and exposing bedrock for study. Those who stop by to take a close look might even find fossils as they examine exposed coal seams, sandstone, and limestone. Boulders of sandstone mark the Pennsylvania Period, a geologic time interval from 300 million years ago. The Negro Mountain anticline was formed 200 million years ago when layers of rock were pushed up during the event known as the Alleghanian orogeny.

Because the formations are easily accessible, they have become the focus of field trips and a curriculum written by Jim Shaulis, senior geologist with the PA Department of Conservation and Natural Resources (DCNR), and Tom Jones, an educator in the Rockwood Area School District.

"Through the identification of geologic features found along these pathways, there exists the potential for these former roads of rails to connect us to an educational resource, one that remains to help us better understand our earth and our history," the two have written in Pennsylvania Geology magazine. "Thus, in addition to the pursuit of fitness and fun, the trials link us to knowledge and udnerstanding of our physical world and environment."

The Rockwood Borough Water Authority excavated a site in 1999 now used to teach trail users of the local geology. Layers of fossils are exposed in the Wymps Gap Limestone, where students can search for marine fossils, even though they are 1,920 feet above sea level. The excavation was done in cooperation with the Somerset County Parks and Recreation Board.

Acid mine drainage from the Lower Kittanning coal seam seeps from the rock surfaces, also providing an opportunity to learn. Coal was deep mined from the site in the early 1900's and burned in a nearby power plant.

Shaulis and Jones developed "Rails to Rocks" workshops that were sponsored by the University of Pittsburgh at Johnstown Center for Mathematics and Science Education.

For more information on the project, go to Pennsylvania Geology magazine and Click on Vol. 31, No. 1. Note: You will need Adobe Acrobat Reader.

For more information on fossils, go to U.S. Geological Survey Fossils, Rocks and Time or explore Paleontology at the U.S. Geological Survey.

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This page last updated August 19, 2007.