1500 B.C. Amorite Lead Mines Still Visible in Pennsylvania
Historical Collection of Pennsylvania, 1843
A remarkable, irregular trench, the vestiges of which can yet be seen, with occasional interruptions, runs from the upper lead mines to the neighborhood of the lower; it is at least six miles in length. It was found there by the earliest emigrants, and thirty years ago, stout trees grew on the banks of earth thrown out in excavating it. It was there, it is said, and ancient in its appearance, when Roberdeau erected or commanded the fort at the upper lead mines.
