Shore of South Carolina: Geomorphology and coastal processes

摘要

The South Carolina Coast, owing to its location along a wide coastal plain on the trailing edge of the North American Plate, as well as to its moderate-sized waves (breaker heights that average 60 cm [2 ft]) and spring tides that approach 3 m (10 ft), is a depo-sitional, mixed-energy coast with: a) short, drumstick-shaped barrier islands; b) numerous tidal flats and coastal wetlands; and c) abundant tidal inlets with large ebb-tidal deltas and small, to non-existent, flood-tidal deltas. The shoreline is composed of four distinct geomorphological compartments (from north to south) - Grand Strand, Delta, Barrier Islands, and Low Country. The Grand Strand, which includes the highly populated Myrtle Beach area, is for the most part a slightly erosional shoreline arc that abuts the Pleistocene mainland. The Delta compartment is composed of the seaward bulge of the largest river delta on the east coast of the United States, the Santee/Pee Dee Delta.rnThe Barrier Islands compartment consists of a combination of relatively short, landward migrating (transgressive) barrier islands and longer, prograding barrier islands that typically have a drumstick configuration, primarily because of the accretion on their northern ends of large swash bars of sand derived from the adjacent massive ebb-tidal deltas. Ebb-tidal deltas contain 77% of all the sand in the shore zone of the state. The Barrier Islands compartment is also the site of a project carried out in 1983 (and repeated in 1996) that relocated a rapidly migrating tidal inlet, Captain Sams Inlet, a distance of 1,200 m (4,000 ft) updrift (northeast), which resulted in the accretion of 300 m (1000 ft) of sand on a highly erosional beach downdrift of the old inlet. The Low Country compartment contains massive estuarine systems with extensive intertidal flats and marshes and huge and diverse offshore sand shoals.