Fayette County can be divided into two parts corresponding to the two sections of the Appalachian Plateau Province.
The eastern half of the County forms part of the Allegheny Mountain Section and is mountainous with Chestnut Ridge rising to heights of more than 2,900 feet. This area is sparsely populated and is physiographically different from the western half of the County. Municipalities in this area include:
The Boroughs of Ohiopyle and Markleysburg
The eastern corners of Dunbar, North Union, Georges, and Springhill Townships
The western half of the County lies in the Pittsburgh Low Plateau Section of the Appalachian Plateau Province. This area, west of Chestnut Ridge, is a rolling and hilly plateau.
Most of natural features information was abstracted from:
The Fayette County Soil survey, prepared by United States Department of Agriculture (USDA), SCS 1991
The County Report Number 26, Pennsylvania Geologic Survey, Fourth Series, 1973
The Subdivision and Land Development Ordinance of Fayette County
The Geology of Pennsylvania, Pittsburgh Geological Society, 1999