17 Surficial Geology and Geomorphology of the Southeastern Lower and Middle Atlantic Coastal Plain and Continental Shelf

Friday, 11 April 2008
8:20 AM - 12:00 PM

GEOMORPHOLOGY AND RADARSTRATIGRAPHY OF THE CAINHOY RIDGE BARRIER SYSTEM, GEORGETOWN, SOUTH CAROLINA

Paper number: 17-9
Program: SYMPOSIA SESSIONS
Time: 11:00 AM – 11:20 AM

Authors

Abstract

The Coastal Plain of South Carolina consists of a series of linear to sublinear ridges separated by systems of terraces that are shore and river parallel in nature. The lower and middle Coastal Plain contains a variety of these landforms, which from their geomorphic position and surficial geometry, appear to have originated as barrier islands. This study focuses on the Cainhoy ridge situated just seaward to the shore-parallel jog of the Black River, 20 km from Georgetown, SC. The well-defined, assymetric ridge extends 10 km parallel to the modern coastline and appears to be coincident with the Conway Barrier to the north. The maximum elevation is approximately16m, with a mean ridge-crest height of approximately 12m.

This study utilizes primarily ground penetrating radar, with LiDAR data from Georgetown County GIS to better understand the internal architecture of this landform. About 30 km of 200 MHz GPR line were collected, processed with RADAN, and surface-corrected with the LiDAR. Penetration typically exceeded 250 nS with some signal return at times greater than 350 nS.

Overall, the internal geometry can be subdivided into three dominant facies, which are interpreted to be related to paleochannels, paleochannel infill, and dipping beds typical to barrier island progradation. These results are typical to those found elsewhere in SC using GPR, including the Conway, Maybank, and Legareville barrier systems. The next step is to sample and attempt to gather age control for the deposits.