Geologic Development and Sand Accumulation Within a Northeastern South Carolina Spit
Abstract
As part of the USGS-South Carolina Sea Grant Consortium Coastal Erosion Program, this continuing study examines the geologic development and evolution of the North Island spit, located seaward of Winyah Bay in northeastern South Carolina. This prominent Holocene spit, which is over 5 km in length and 1 km in width, has developed as a series of southward prograding, recurved shorelines located at the southern end of the 75 km long Grand Strand coastline. Measurements of sediment thickness and rate of shoreline progradation of this feature will not only allow for a better understanding of regional sediment transport along the Grand Strand system but also the geologic processes active in spit formation. To determine geologic architecture, ground-penetrating radar data were collected along the length of the spit and along three shore-normal transects. Fifteen vibracores and several newer deeper auger cores have been collected to ground truth the GPR data and to determine age control. Cores were split, photographed, visually described, and subsampled for textural and component analysis. To determine shoreline age, luminescence age estimates have now been obtained on basal or near basal dune sands along the length of the spit. Except for a small paleo-channel at the northern end of the spit, GPR records indicate continuous spit progradation to the south. Uneven GPR reflectors, recorded in the upper 2-6 m, are composed of fine sand. This upper unit is interpreted as part of the spit platform. Underling this upper unit, southward steeply dipping reflectors extending beyond 10 m depth are composed of bedded shelly sands. This lower unit is interpreted as channel infill. Major boundaries within the lower unit appear to be tied to geomorphic shorelines. The most prominent of these shorelines are dated at ~150, ~300 and > ~650 years ago. This study will allow for a better understanding of regional sedimentary transport and processes affecting the Grand Strand as well as other coastal systems.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2002
- Bibcode:
- 2002AGUFMOS71B0275W
- Keywords:
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- 3020 Littoral processes;
- 4200 OCEANOGRAPHY: GENERAL