Document Type

Article

Publication Date

2016

Abstract

Anyone who has driven across West Virginia has noticed major changes in the lay of the land. In the western portion of the State the landscape belongs to the Appalachian Plateaus Physiographic Province. But what constitutes a plateau? According to the Glossary of Geology, a plateau is a dissected (stream carved) upland underlain by horizontal strata. In the case of the Appalachian Plateau, it is a relatively flat to gently rolling surface with an average elevation of about 900 feet underlain by gently folded to flat-lying sedimentary rocks. But what is a physiographic province? Again, according to the Glossary of Geology, a physiographic province is "a region of which all parts are similar in geologic structure and climate and which has consistently had a uniform geomorphic history". What that means is that it's a region whose geologic characteristics are significantly different from the adjoining regions. Note, however, that the province is called the Appalachian Plateaus Physiographic Province indicating that the region consists of two or more plateaus. In fact, there are five different plateaus (Figure xx). Because most of West Virginia is located in the Un-glaciated Plateau, we will only consider the one plateau. The Un-glaciated Plateau is in subdivided into a Low Plateau and a High Plateau largely based on elevation and topography. For example, Morgantown is located in the easternmost portion of the Low Plateau. From Morgantown to the westernmost edge of the low plateau in eastern Ohio, the topography consists of gently rolling hills and essentially horizontal sedimentary rocks. The boundary between the Low and High plateaus is Immediately east of Morgantown. Within the High Plateau, the sedimentary rocks have been folded to the point of creating anticlinal ridges and synclinal valleys. An anticline is a convex upward fold while a syncline is a concave downward fold (Figure xx). The westernmost anticlinal ridge of the High Plateau, the Chestnut Ridge Anticline, is immediately east of Morgantown and extends from Uniontown, Pennsylvania southward to Weston, West Virginia, with an average elevation along its summit of 1,900 feet. As we continue eastward to the eastern edge of the High Plateau, the elevation rises progressively to about 5,000 feet (Figure xx). In West Virginia, the eastern edge of the High Plateau is known as the Allegheny Structural Front (Figure xx). At that point, one enters the Appalachian Mountain Section of the Valley and Ridge Physiographic Province (Tom: this is the correct terminology), the major topic of the discussion to follow. Individuals find it interesting that the average elevations of 3,000 feet along the summits of the ridges in the Appalachian Mountains are generally lower that that at the eastern edge of the plateau. Before we finish our discussion, you will understand why. East of the Appalachian Mountain Section, one enters the Great Valley Section of the Valley and Ridge Physiographic Province. As the name implies, the section is characterized by a broad valley. At this point, the average elevation has dropped to about 1,000 feet (Figure xx).

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