40 43' 26 N
75 33' 27 W

The Martinsburg formation consists of shales, sandstones, and slates. It extends along the base of the Appalachian Valley from the Hudson Valley to Tennessee. In the Lehigh Valley, the average surface elevation of the rocks is between 700 and 800 feet above sea level. Rivers and streams have carved away at the formation, creating steep valleys. The Lehigh River flows between the high cliffs of the Martinsburg formation. The cliffs on both sides of the river provide spectacular views.

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