Controls on carbonate island formation and evolution: South Joulter Cay, Great Bahama Bank

Abstract Islands in active carbonate depositional systems can profoundly impact local wave, wind and tidal energy distributions, affecting sediment factories and facies distributions. Island development and facies were investigated for South Joulter Cay, located within the modern Joulters ooid sandbody of Great Bahama Bank, using high‐resolution imagery, a digital elevation model, field observations and radiocarbon dating of weakly cemented rock samples. Island ridge morphology exhibits three distinct developmental stages spanning the last 1400 years, with differences in ooid sand distribution, tidal channels, wind, waves and longshore currents driving island development. Radiocarbon dating suggests that the nucleation and development of South Joulter Cay occurred in stages over the last 1400 years. Island development started with linear ridges oriented SE‐NW and extending approximately 2 km, and this was followed by a second stage of arcuate ridges influenced by local tidal channels. The third stage consisted of triangular cuspate ridges driven by longshore currents and bidirectional winds and waves. Storm activity and associated shifts in local hydrodynamics appear to have played an important role in forming the initial ridges and those created during transitions between growth stages. Although a single storm event is unlikely to cause lasting changes, prolonged periods of intense storm activity over decades are more probably to drive the island's changes and development. Periods with elevated hurricane activity in the northern Bahamas during the Medieval Climate Anomaly or Little Ice Age may be a possible control on the punctuated development of South Joulter Cay.