This three hundred eighty foot slice into Sideling Hill exposes a sweep of geologic time spanning about twenty million years, from the dark gray marine rocks at the far end of the north slope, about thirty-six million years old, to the white continental sandstones at the top of the cut, about three hundred forty million years old, where seas, rivers, and marshes left behind sediments in a layered story of the earth’s formation and reformation.

Photo: J. J. Prats

Photo: Devry Becker Jones

Photo: J. J. Prats

Union Township, Pennsylvania · USA