Allegheny Front

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. [ cite book | last = Hobson | first = Archie | title = The Cambridge Gazetteer of the United States and Canada: A Dictionary of Places | publisher = Cambridge University Press | date = 1995 | location = New York, NY ] In Maryland the front is known as Dan's Mountain. [ cite book | last = Campbell | first = John C. | title = The Southern Highlander & His Homeland | publisher = The University Press of Kentucky | date = 1969 (original version 1921) | location = Lexington, Kentucky | pages = 341 found at [http://books.google.com/books?vid=ISBN0813190789&id=NvDjQqggh-wC&pg=PA341&lpg=PA341&dq=%22Allegheny+Front%22&sig=97Bfc9PtvxOoc9Qrqrg9FukHRak Google Books] ] The elevational change of the front ranges from less than 2,000 feet (600 meters) in Pennsylvania to nearly 3,000 feet (900 meters) in 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. [ cite book | last = Geophysics Study Committee; Commission on Geosciences, Environment, and Resources; National Research Council | title = The Role of Fluids in Crustal Processes | publisher = National Academy Press | date = 1990 | location = Washington, D.C. | pages = 143 found at [http://books.google.com/books?vid=ISBN030904037X&id=3xWHZLqOGyoC&pg=PA143&lpg=PA143&dq=%22Allegheny+Front%22&sig=ZT7xtqkq6z1eruNWh_VMmBYBARI Google Books] ] 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. [ cite web | last = Fichter | first = Lynn S. | coauthors = Baedke, Steve J. | title = The Geological Evolution of Virigina and the Mid-Atlantic Region: The Late Paleozoic Alleghanian Orogeny | publisher = James Madison University | date = 2003-01-20 | url = http://csmres.jmu.edu/geollab/vageol/vahist/K-LatPal.html | accessdate = 2006-09-08 ]

See also

* Geology of the Appalachians

References