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The surface of the Piedmont Plateau rises in elevation from approximately 200 feet above sea level at its eastern margin (the Fall Line) to a general base level of 1000 feet above sea level in the west. Individual peaks may rise to over 2000 feet in western parts of the province. Relief varies across the province, a fact which has led to the delineation of two subregions. The Outer Piedmont is characterized by low relief; the Inner Piedmont by high relief.
The Piedmont is underlain by metamorphic rocks of various origins that were folded during the Paleozoic as the North American and African plates converged. Later, in the Mesozoic, it was affected by rifting as Pangaea broke apart and the Atlantic Ocean formed. (See geologic cross-section.)
Physiographic Subregions of the Piedmont
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The Outer Piedmont is a gently rolling upland; erosion and deep weathering have long since obliterated surface indications of the folded bedrock beneath. It is in this subregion that long, narrow rift valleys formed during the Triassic period of the Mesozoic era. Today the valleys--called Triassic lowlands--are filled with sandstones and basalts and can scarcely be distinguished by a casual observer.
The Inner Piedmont is an area of rugged terrain where erosion has not yet leveled the most resistant of the metamorphic rocks. Softer materials have been worn away leaving a discontinuous belt of mountains, erosional remnants termed monadnocks.
| Physiographic Provinces |
Created by SLW, January 1997. Last updated August 10, 1999 by slw.
Inner Piedmont
Outer Piedmont 
Triassic Lowlands