Park Geology

Park Geology. Scripture Rocks Heritage Park. , The Scripture Rocks are a type of rock called sandstone. Sandstone is composed of rounded grains of river sand that became cemented together to make a hard durable stone. This sand was deposited 320 million years ago when western Pennsylvania was a tropical river delta along an inland sea. The sand was carried by the river from high mountains that then occupied portions of eastern Pennsylvania. Ripple marks formed by the river’s current can be seen on the surface of the Veil-Lifting Rock. The river fed vast swamps that contained a luscious growth of tree-like plants called lepidodendron., Examples of lepidodendron fossils can be found on several rocks throughout the park. In the succeeding millennia, tectonic forces uplifted the Appalachian Plateaus of western Pennsylvania. Today, our streams and rivers are slowly eroding our hills and rolling mountains. The strata newer than the Pennsylvanian Period has been carried downriver and deposited in the Mississippi delta as sand and silt (see diagram on the right).