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Allegheny Front
From Wikipedia, the free encyclopedia
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 Allegheny Mountains, separating them from the lower Ridge and Valley Appalachians to the east. While the entire escarpment 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.[1] In Maryland the front is known as Dan's Mountain. [2] The elevational change of the front ranges from less than 2,000 feet (600 meters) in Pennsylvania to nearly 3,000 feet in West Virginia.
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.[3] 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.[4]
- ^ Hobson, Archie (1995). The Cambridge Gazetteer of the United States and Canada: A Dictionary of Places. New York, NY: Cambridge University Press.
- ^ Campbell, John C. (1969 (original version 1921)). The Southern Highlander & His Homeland. Lexington, Kentucky: The University Press of Kentucky, 341. found at Google Books
- ^ Geophysics Study Committee; Commission on Geosciences, Environment, and Resouces; National Research Council (1990). The Role of Fluids in Crustal Processes. Washington, D.C.: National Academy Press, 143. found at Google Books
- ^ Fichter, Lynn S.; Baedke, Steve J. (2003-01-20). The Geological Evolution of Virigina and the Mid-Atlantic Region: The Late Paleozoic Alleghanian Orogeny. James Madison University. Retrieved on 2006-09-08.