<P> The formation of the plateau began during the Paleozoic Era . Regional uplift during this time caused the area to rise altogether without changing the topography of the land . The eastern side of the plateau appears as a mountain range . This false appearance is due to a very steep slope on the eastern side known as the Allegheny Front . The eastern edge is the highest part of the Appalachian Plateau . In Pennsylvania, the altitude ranges from 1,750 to 3,000 feet and continues to rise toward West Virginia, where the elevation is around 4,800 feet . From West Virginia to Tennessee, the elevation lowers to 3,000 feet and continues slanting downward to 1,000 feet in Alabama . On the western side of the plateau, the elevation is 900 feet in Ohio, increasing to about 2,000 feet in Kentucky . From Kentucky the elevation drops down to 500 feet in northwestern Alabama . The plateau has a slight slant towards the northwest, making it higher on the eastern side . </P> <P> A large portion of the plateau is a coalfield, which was formed approximately 320 million years ago during the Pennsylvanian Age . The plateau was subjected to glaciation during the Pleistocene ice age . As a result, the topography of this section of the plateau is relatively flat in comparison to the rest of the physiographic province . This portion of the plateau is marked with evidence of a glaciated past including bogs, lakes, and small hills of sand and gravel . The topography of the rest of the plateau was created mainly from stream erosion . The result is a rugged landscape, unlike many other plateaus, that includes many narrow stream valleys surrounded by steep ridges . </P> <P> A physiographic region is a large portion of land that is grouped together by several factors . Each region has similar geology, topography, and groups of plants and animals . There are eight physiographic regions in the United States . Each region is divided into provinces, there are 25 provinces in the United States . Each region is then divided into sections, creating 85 different physio - graphic sections in the United States . The Appalachian Plateau is a province of the physiographic region of the Appalachian Highlands . The Appalachian Plateau province is divided into seven physio - graphic sections: Mohawk, Catskill, Southern New York, Allegheny Mountains, Kanawha, Cumberland Plateau, and the Cumberland Mountains . Each section is classified under the Appalachian Plateau province because of its similarities in geologic makeup, topography, and wildlife . Likewise, the Appalachian Plateau falls under the classification of Appalachian Highlands because of those similar characteristics . </P> <P> The rock underlying the Appalachian Plateau consists of a base of Precambrian rock, overlain by sedimentary rock from the Paleozoic Era . On top of the basement is a thick layer, approximately 20,000 feet, of a mixture of Cambrian, Ordovician, and Middle Silurian rock . This rock consists of shale, siltstone, and sandstone . Above this layer is the Upper Silurian evaporate basin, or basin of chemically formed sedimentary rocks . The Plateau fold belt consists of structurally complex Paleozoic strata which were thrust faulted over the younger evaporates . </P>

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