Abstract
The Carolina Sandhills are a tertiary body of unlithified surficial sand on the upper coastal plain of the Carolinas, just west of the Orangeburg Scarp. Much of the sand is part of the Pinehurst Formation. Conventional interpretations indicate several different depositional environments, including eolian, subtidal sandwaves, intertidal, fluvial, and deltaic. Ten samples of sand were collected and analyzed, including samples from "Sugarloaf Mountain" and "Horseshoe Mountain," which are barchan-shaped dunes (with south- and southwest dipping cross beds) in Chesterfield County, South Carolina. In this area many mound-shaped accumulations like this occur, which are up to 35 m high. Outcrop observations, bulk sieve analysis, and thin section studies all show the sand is poorly sorted, angular, and immature. Grain sizes range from clay to large granules. We propose that a large post-Flood hurricane(s) or hypercane(s) may be able to explain the unusual mix of features. The Orangeburg Scarp may represent a wave-cut cliff, cut by the high-standing post-Flood Atlantic Ocean (before the Ice Age). The angular, unsorted, and overall immature nature of the sand suggests deposition soon after erosion, close to its source (igneous and metamorphic rocks to the west). It is conceivable that the sand may have been eroded and deposited during the same storm. The unusual, poorly sorted nature of these dunes may suggest catastrophic windblown processes during a large storm, leaving little time for sorting. Cross bed direction might be explained due to counterclockwise circulation around a storm causing strong north or northeast winds. The confusing mix of so many depositional environments may be due to continental erosion processes coalescing with storm surge and strong coastal winds during a large storm. Perhaps the reason this formation has been so poorly understood is that it did not form by conventional means. This study is being undertaken as part of the Flood-Activated Sedimentation and Tectonics (FAST) project of the Coconino Sandstone funded by the National Creation Science Foundation (NCSF) and Calgary Rock and Materials Services. We thank them for their generous support.