Investigating the origin and dynamics of Carolina Bays

This study compiles a myriad of previously published and novel results from field-based and remote sensing investigations of Carolina Bays (shallow, circular to elliptic, sandy-rimmed, coastal plain depressions), aiming at identifying possible origin mechanisms as well as future research avenues. These investigations include neural network-based detection and morphometric analysis of over 20,000 Carolina Bays across the Atlantic Coastal Plain from digital elevation models; sedimentological investigations at Bays in Delaware, Virginia, North Carolina, and South Carolina; satellite-based surface water mapping of Bay lakes in North Carolina; a compilation of published geochronological data extracted from Carolina Bay sediments; collection of hydrodynamic data from a Carolina Bay pond; and geologic and geomorphic comparisons between Bays and similar depressions found in North America. This synthesis shows that Carolina Bays and similar depressions are widespread on unglaciated provinces composed of unconsolidated sediments, where wind was likely the main forcing mechanism which initially scoured out the depressions. Wave processes likely produced the Bays' characteristic round to ovate planform shape, with water-level fluctuations leaving behind sand rims as paleoshorelines. Holocene warming, increased humidity, and an increase in vegetation cover has induced more benign geomorphic conditions within Carolina Bays, during which finer sediment and organic matter has filled in these depressions. Modern observations of Carolina Bays and related features show little modern geomorphic activity. Geochronological data shows that Bays originated and underwent geomorphic modification from Marine Isotope Stage 5 to Marine Isotope Stage 1, coeval with the growth and decay of the Laurentide Ice Sheet, as well as with the development of nearby sand dunes. The available geochronological evidence is not compatible with an impact origin for the Bays, particularly one related to the Younger Dryas impact hypothesis or one related to Australasian tektites dating to 788 ka. The results of this synthesis should encourage future research into field-based, modeling, and synthetic investigations of Bays and similar depressions.