The Allegheny Front is a portion of the escarpment that delineates the eastern edge of the Appalachian Plateau (locally called the Allegheny Plateau) and the higher ranges of the Allegheny Mountains, separating them from the lower Alleghenies to the east. It is a part of the Ridge and Valley Appalachians and is conterminous with the Eastern Continental Divide in this region.

Geography

While the entire escarpment of which the Allegheny Front is a part stretches from New York (the Helderbergs) to Tennessee (Cumberland Mountain and Waldens Ridge), the portion known as the Allegheny Front extends southwesterly from south-central Pennsylvania, through western Maryland and eastern West Virginia to a portion of the West Virginia/Virginia border. In Maryland the front is known as Dan's Mountain. The elevational change of the front ranges from less than in Pennsylvania to almost above the North Fork South Branch Potomac River near Hopeville, West Virginia.

Geology

Historically, the front was the edge of a salt evaporite basin formed at the end of the Silurian period, which created significant differences in the erosionary properties of rocks to either side of the front. The terrain differences to either side are also partially caused by the Alleghenian orogeny, in which Gondwana (modern Africa) impacted and overrode part of what is now the North American crustal plate, thrusting and piling up the ridge mountains of the physiographic regions to the east.

See also

• Geology of the Appalachians
• Horseshoe Curve

References