Virginia is divided into several physiographic provinces based on their geologic history. Each province is unique in topography, soil pH, soil depth, elevation, availability of light, and hydrology. These characteristics all combine to influence the species of plants and animals found there. Virginia is unique, encompassing parts of five of these provinces, and thus a greater variety of natural landscapes than any other eastern state. For the purposes of this list, we have grouped the physiographic provinces into three regions: Coastal Plain, Piedmont, and Mountain.
Virginia's Coastal Plain is bordered by the Fall Line to the west and by the Atlantic Ocean, the Chesapeake Bay and its tributaries to the east. This is the youngest of the physiographic provinces, formed by sediments eroded from the Appalachian Highlands and deposited along the Atlantic shoreline. The Coastal Plain varies in topography from north to south. The northern Coastal Plain consists of the three peninsulas formed between the four major tributaries of the Chesapeake Bay; the Potomac, the Rappahannock, the York, and the James Rivers. In the north, the Northern Neck is somewhat hilly and well drained. As you move southward across the Middle Peninsula and Lower Peninsula the topography flattens until south of the James River the landscape is basically level. The Eastern Shore, separated from the mainland by the Chesapeake Bay, exhibits little topographic relief. These subtle differences in topography and the variety of fresh, brackish, and saltwater systems from ocean and inland bay to rivers, ponds, and bogs, have contributed to the great variety of natural communities found on the Coastal Plain.
Virginia's Piedmont Plateau province is a gently rolling upland bounded on the east by the Fall line and the west by the Blue Ridge Mountains. The western boundary of the Piedmont is characterized by distinct peaks and ridges, comprising the foothills of the Blue Ridge Mountains. To the east, the Piedmont continues to slope more gently toward the Fall Line. The Fall Line marks the zone of transition from the hard, resistant bedrock underlying the Piedmont to the softer sediments underlying the Coastal Plain. Streams are able to cut more easily through the sands, gravels, and clays of the Coastal Plain, and rivers widen as the topography flattens. In the northern part of the state this boundary is sharply delineated by falls and rapids. From foothills to rapids, these varying site conditions support a mosaic of plant communities.
The Mountain region of Virginia actually includes parts of three provinces; the Blue Ridge, the Ridge and Valley, and the Appalachian Plateau Physiographic Provinces. The Blue Ridge encompasses the Blue Ridge Mountains, a wedge of ancient rock that was uplifted over younger rocks when the Appalachian Mountains were formed. A narrow system of peaks in the north, the Blue Ridge widens south of Roanoke Gap into a broad plateau topped by the highest peaks in Virginia--Mount Rogers and Whitetop. The Ridge and Valley Province is characterized by long, even-crested, parallel ridges rising above intervening valleys of various size. The Valley of Virginia is included in this province, encompassing the large Shenandoah Valley, as well as the James, Roanoke, New River and the Clinch, Powell and Holston River valleys. The ridges of the Appalachian Plateau in far southwestern Virginia were not as folded and faulted as those of the Ridge and Valley, but formed from a high, unified plateau of nearly horizontal rock layers. The modern mountainous topography was created by streams cutting deeply through the plateau, forming an intricate network of narrow, steep valleys. The diversity in topography and geologic history of the Mountain region of Virginia gives rise to a rich array of natural communities and native species.