Geomorphic boundaries of marine Pleistocene terraces (toes of scarps) in South Carolina were examined on 1:24,000 topographic maps, aerial photographs, and new 1:24,000 STATEMAP geologic maps. Did the Dorchester Scarp at its type location face a Pleistocene estuary or the Pleistocene Atlantic Ocean? Colquhoun (1962) interpreted the Dorchester Scarp as formed by a marine Pleistocene highstand at 75 ft elevation and as the boundary between the Wicomico and Penholoway terraces. Colquhoun (1962) also interpreted the Summerville Scarp as formed by a marine Pleistocene highstand at approximately 75 ft elevation and as the boundary between the Penholoway and Talbot terraces. Relationships show: 1) that the Dorchester Scarp at Four Hole Swamp is the boundary between older barrier-island deposits beneath the Wicomico terrace and younger estuarine deposits of the Penholoway terrace; 2) that the Summerville Scarp at Lincolnville is the boundary between older beach deposits beneath the Wicomico terrace and the younger beach deposits beneath the Penholoway terrace; and 3) that a barrier island core separated the two scarps formed during the same Pleistocene highstand. A modern analog is Hilton Head Island. It contains two Pleistocene barrier-island cores separated by successively lower scarps formed during successively lower highstands. The mainland behind the island has two estuarine shoreline scarps in the back-barrier system. Both barrier-island and estuarine scarps were formed during the same highstands, with successive reoccupation of the back-barrier estuarine systems.