THE CAROLINA SANDHILLS, THE PINEHURST FORMATION AND THE SANDY UPPER ATLANTIC COASTAL PLAIN: A RELIC PLEISTOCENE ERG? EXTENSIVE DESERT LANDFORMS IMAGED BY LIDAR MAPPING FROM HOKE AND SCOTLAND COUNTIES, NORTH CAROLINA.

The State of North Carolina geologic map shows a broad outcrop of Late Cretaceous clastic sedimentary rocks in south-central NC. Mapping of modern LiDAR data in Hoke and Scotland counties illuminates a veneer of remnant desert landforms draped over this substrate which includes barchan, longitudinal and parabolic dunes in addition to widespread sheet sands. This study proposes that these desert features are elements of a Pleistocene erg that overlies and obscures the underlying Mesozoic strata. This hypothesized erg includes what is mapped as the Pinehurst Formation and the area informally referred to as the Carolina Sandhills. This sand sea developed during glacial low-stand periods of cold and dry climatic conditions. Analysis of the dune morphology and orientation suggest two separate wind regimes: an older episode of winds from the southeast with a later phase of wind from the west-southwest. On the Coastal Plain, remnant barchans and their related Carolina Bays are ubiquitous. The barchans’ orientation indicates a wind field from the southeast; these are interpreted to have formed during low-stand glacial episodes. Parabolic dunes are found along the eastern margins of fluvial drainage courses and along the eastern rims of Carolina Bays. Northwest of the barchan dunes, longitudinal and parabolic dune fields occur in a belt along the forefront of the Piedmont uplands. These form an overprint upon the updip remnant barchans and sheet sands with an indicated wind field from the west-southwest. The proposed mechanism for this shift in wind direction is climatic change associated with the onset of warmer high-stand interglacial periods. A regional synopsis, mapping results, and LiDAR examples of the desert landforms will be presented.