Bald Eagle Mountain is a roughly 60-mile ridge in central Pennsylvania that forms major valley divides and reflects the folded geology of the Ridge-and-Valley Appalachians. Part of the same Paleozoic anticline as several neighboring mountains, it was shaped during the Alleghanian orogeny and exposes formations whose harder quartzite and sandstone created its distinctive double crest. Roads, streams, and highways cross the ridge through wind and water gaps, making it an important corridor as well as a barrier. The mountain is also a noted route for migrating golden eagles and a center for glider flying. Its pyrite-bearing sandstone has influenced modern highway construction because of acid-producing runoff risks.