Evidence of An Archaic Dam In A Carolina Bay: The Sewee Shell Ring, South Carolina

Abstract

Abstract The Sewee shell ring is part of a complex water gathering system built in a Carolina bay designated as Oak Bay. The seaward boundary of the shell ring, the sand rim of Oak Bay, and a surface exposed aquiclude/aquitard stratum are concordant. A Slough, adjacent to the Sewee shell ring structure, is characterized by a perennial freshwater stream flowing into it. A Slough shell structure is located near the seaward end of the Slough. This shell structure is perpendicular to the long axis of the Slough. It was built on the aquiclude/aquitard stratum of Oak Bay. Measurement of unconfined sub-surface water heights, seaward of the Slough shell structure, indicated no trends in retention of freshwater at low or high tide during sequential drought and rainy periods, Water heights, in contrast, landward of the Slough shell structure at low and high tide were higher during the rainy, compared to the drought period. Salinities of unconfined sub-surface water samples also indicated retention of freshwater landward of the Slough shell structure, but not seaward of it. These findings indicate that the Slough shell structure could have been part of an archaic dam, designed and located to retain surface and sub-surface freshwater in the Slough. This freshwater then flowed across a series of weirs and into an Arena-tank.