Overfilling of Accommodation in a Modern Ooid Sand Body—A Record of Climate (Storm Frequency) Change

Our ongoing examination of South Joulter Cay, an important component of the large modern ooid sand body lying directly north of Andros Island on Great Bahama Bank, targets a better delineation of the processes and timing that formed the island. High resolution imagery, a DEM constructed from a drone survey, field evidence, and radiocarbon dating of ooids and meteoric cements forward the hypothesis that island geomorphology comprising ridges associated with three distinct island growth stages results from punctuated intervals of local hurricane activity over the last ~1800 years, which in turn changed the local hydrodynamic and depositional conditions.

Indeed, millennial-scale Atlantic paleo hurricane compilations broadly inform hurricane-climate dynamics, which reveal centennial-scale intervals of elevated Atlantic hurricane activity relative to the instrumental period. A scenario for island development emphasizes active sand bars locally building to beaches and back-beach dune ridges forming repeatedly, with variations in dispersal of ooid sands driven by tidal channels, wind and wave energy, and longshore and storm-related currents. We suggest that intervals of elevated storm activity proximal to Joulters and delivering east to west energy and sediment transport are most likely to have played a role in island development, and radiocarbon dating, although limited, suggests a correspondence between island growth stages and the periods of elevated storm activity documented from Bahamian storm compilation. Given the absence of a local paleo hurricane reconstruction from Northern Andros and that local hurricane histories may deviate from basin-wide compilations, the Joulters geomorphology may be informing local paleo hurricane activity.