GEOMORPHOLOGY OF THE SOUTH CAROLINA COASTAL PLAIN AND CONTINENTAL SHELF: STRATIGRAPHIC HETEROGENEITY AND DEVELOPMENTAL INFLUENCES THROUGHOUT THE QUATERNARY

The deposits beneath the outer Coastal Plain and inner Continental Shelf represent the culmination of physical processes interacting with factors that vary in space through time. This paper presents recent methods and thought on the factors that influence the spatial and temporal distribution of these highly variable, heterogeneous Quaternary deposits. The morphology of the lower Coastal Plain and inner Continental Shelf of South Carolina is discussed with respect to the various influencing factors.

The geomorphology and stratigraphy in this region has been studied since the 1790's (Bartram, 1791). The first regional geologic studies of Shattuck and Cooke provided a basis of understanding for the dominance of the cyclic deposits later described by Colquhoun (1965, 1969). More recently, Colquhoun (1995) clearly describes the nature and dimensions of the cyclic deposits in South Carolina.

The dominant processes acting on and forming the depositional sequences range from riverine and lacustrine to estuarine and open ocean. Waves, tides, wind, sea level, and to a lesser degree tectonics (at this scale), act upon a myriad of variables to construct and destroy morphology and and the stratigraphic framework. These factors include sediment supply (fluvial and reworked/eroded), geomorphology (antecedent topography, proximity to capes, paleochannels, paleovalleys, etc.), stratigraphic variability (fabric and mechanical competency, heterogeneity), and sedimentary cover over "bedrock." Along the South Carolina Coastal zone, these variables can be recognized as more or less important at different periods and in different regions. Patterns developed earlier in the Quaternary history continue, change, and are modified due to changes in these variables across and beneath the entire lower Coastal Plain and Continental Shelf.