Abstract
Cape Romain, South Carolina, a barrier island-cuspate foreland just south of the Santee delta, shows a classic transgressive stratigraphic sequence. The island has eroded landward 150 m in the past 30 years. Today, 75% of the island shoreline is manifest as narrow washover fans and coalesced terraces migrating landward under the influence of normal spring high tides and storm events. The remainder of the island is occupied by eroding ridge and swale topography. Landward of the barrier is a lagoon-marsh system 11 km wide which abuts and overlies the Pleistocene mainland. Using a modified concrete compactor, 40 vibracores 5 to 9 m long were taken from three transects across the island. The coring system permits an undisturbed (preserved primary sedimentary structures and bioturbation) core 7.6 cm in diameter to be removed from any unconsolidated sediment. Cores have been taken in compacted clays, fine to coarse sands, shell lags, and oyster reefs. Recovery ranges from 90 to 100%. Additional data were obtained from box cores and short (1 to 2 m) vibracores taken by divers in specific subtidal locations. Eight meters under the present berm crest is a relict barrier-marsh complex overlain by a shell storm lag. Overlying the shell lag are flaser-bedded sands and muds of a very shallow-water high-energy lagoonal facies which grades upward into highly bioturbated sandy muds of a deeper water lagoonal facies. A tidal-flat oyster reef complex lies above, grading upward into a fringing marsh. The sequence is capped by washover sands and shells, beachface sands, and/or dunes of the present barrier. This sequence indicates a general rise in sea level during the Holocene through a combination of eustatic rise and a relatively high subsidence rate. The sequence shows a barrier island overtopped by the rising sea level. At some later time, another barrier was developed seaward on the shelf. This barrier transgressed landward to occupy the present position of Cape Romain. End_of_Article - Last_Page 518------------
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