Allegheny Plateau


 
 
The Allegheny Plateau
 
This province is found only in the southwestern portion of Virginia, although much of West Virginia is composed of the plateau. The rocks here are sedimentary, flat lying, and topographically higher relative to the rest of the state. They have a characteristic dendritic drainage pattern. For example, go to the Cumberland Map covering parts of northern Virginia and West Virginia. The area mostly in green to the west (left) is the Allegheny plateau in West Virginia, and although some drainages appear organized, in many places they follow no particular pattern, especially in the southwest (lower left).
 
The exposed rocks are late Paleozoic in age (DevonianMississippianPennsylvanian, and in parts of West Virginia, Permian). These rocks were deposited at a time when most of Virginia to the east contained major mountain ranges (TaconicAcadian and Alleghenian orogenies). Underneath the Devonian rocks are additional flat lying sedimentary rocks of Cambrian,Ordovician and Silurian age. Finally at the bottom of the pile are igneous and metamorphic Grenville Basement Rocks (1.1 billion years and older.) 
 
Contributed by Lynn Fichter 
Thursday, July 24, 2014
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