Eastward, the southern boundary follows the northern extremity of the Pelham Escarpment separating the Fall Line Hills from the Tifton Upland. The southern boundary then closely follows the northernmost occurrence of the undifferentiated Neogene geologic unit, which underlies the Vidalia Upland. The Fall Line Hills District is highly dissected with little level land except the marshy floodplains and their better drained, narrow stream terraces. Stream valleys lie 50 to 250 feet below the adjacent ridgetops. Stream dissection seems to be greatest in the East Gulf portion of this district.
Relief gradually diminishes to the south and east.
Maximum elevations are approximately 760 feet between Columbus and Macon and gradually diminish to a minimum elevation of 150 feet south of Augusta. FVP Fort Valley Plateau District. An anomalous area within the Fall Line Hills is known as the Fort Valley Plateau. This area is distinct from the Fall Line Hills in that the broad, flat-topped interfluves are the dominant feature, there are fewer streams, and there is less local relief. The area is less dissected than the Fall Line Hills because it is underlain by the more clayey units of undifferentiated Eocene, Paleocene, and possible Cretaceous age sediments.