Presenter: Mark Lundine (University of Delaware)

Description:
Carolina Bays are shallow, roughly circular to elliptical, and sandy-rimmed depressions found throughout the Atlantic Coastal Plain (ACP). Their origin has been debated for decades, producing many competing origin hypotheses. This study will synthesize a variety of field and laboratory investigations of Carolina Bays throughout the ACP. Over 23,000 Carolina Bays have been identified through a convolutional neural network trained on LiDAR-derived digital elevation models, resulting in a thorough description of the Bays’ morphology, land-use and land cover, and surface hydrology. Guided by the detection results, field investigations on the Bays’ sedimentology and stratigraphy were conducted using ground penetrating radar, sub-bottom profiles, sediment cores, and hand auger samples. These investigations showed that Bays typically have 1.5 m to 2.5 m thick sand rims that show a gradient in texture, with coarser sand at the bottom and finer sand and silt towards the top. Their basins were found to be 0.5 m to 2 m thick and showed a mix of clayey, silty, and sandy deposits. Last, four seasonal deployments of an acoustic doppler current profiler in a flooded Carolina Bay provided an understanding of the current and wave regimes in modern Carolina Bays. In synthesis, these findings complement past descriptions of Carolina Bays and provide strong evidence towards aeolian and lacustrine beginnings for these enigmatic features.