Allegheny Plateau, dissected plateau, western part of the Appalachian Mts., extending c.500 mi (800 km) SW from N Pa. to SW Va., rising to c.4,860 ft (1,480 m) at Spruce Knob, the highest peak in West Virginia. The E Allegheny Plateau, known as the Allegheny Mountains or the Alleghenies, has a steep eastward-facing escarpment often called the Allegheny Front (c.1,500–1,600 ft/460–490 m high) and is more rugged than the western portion. The plateau, formed by the folding of sedimentary rocks, has been subsequently reduced by erosion. The mountains, rich in coal and timber, also contain iron ore, petroleum, and natural gas.
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