(1) the South Atlantic Coastal Plain--As the name suggests, this region extends along the coast from the Atlantic Ocean to the Fall Line Zone. The Fall Line Zone refers to a section where the streams pass from the rocky areas of the mountain region or high land to the level area or low land; at such points, falls or rapids develop. The Great Falls of the Potomac in Maryland and in Virginia, the Falls of the Rappahannock at Fredericksburg, the rapids of the James River at Richmond and the Falls of the Appomattox at Petersburg illustrate the concept of the Fall Line. Consequently, the so-called Fall Line extends from Washington, D. C., through Alexandria, Fredericksburg, Richmond, Petersburg and Emporia in Virginia. Thus, the South Atlantic Coastal Plain region of Virginia is located along the Atlantic seacoast from the Potomac River at Alexandria to the North Carolina boundary line and as far west as the Fall Line Zone. The width of this area varies from 35 miles to 120 miles. This region is also called "Tidewater" Virginia because the level land here is so low that the ocean tides may often be seen in the inland streams. "Tidewater" Virginia includes five peninsulas formed by the Chesapeake Bay, the Potomac, the Rappahannock, the York and the James Rivers. These five peninsulas are: a. the Eastern Shore--Although most of Tidewater Virginia is located on the western side of the Chesapeake Bay, a unique peninsula called the Eastern Shore extends southward from Maryland and is separated from the rest of Virginia by the Chesapeake Bay. Thus, in order to travel by land from the mainland of eastern Virginia to the Eastern Shore, it is necessary to travel via Maryland. b. the Northern Neck--This peninsula lies between the Potomac and the Rappahannock Rivers and is only 22 miles at its widest point. c. the Middle Peninsula--This peninsula lies between the Rappahannock and the York Rivers. d. the Peninsula of the Lower York-James Peninsula or the Williamsburg Peninsula--This peninsula is located between the York and James Rivers.