Caves as paleo-water table indicators in the unconfined Upper Floridan aquifer

Caves and associated dissolution features provide a valuable resource and geological record for paleo-water table elevations in the Upper Floridan aquifer. The water table has migrated up and down in response to sea level fluctuations, and laterally extensive regions of enhanced porosity, including caves, have formed during periods of paleo-water table stability. Because water table elevations controlled cave formation, cave development was more widespread during periods of low sea level, when unconfined aquifer conditions were more widespread and more of the Florida platform was exposed. By contrast, during periods of high sea level, less of the platform was exposed and confined aquifer conditions in the peninsula interior prevented cave development. Paleo-cave data provide evidence that an increase in sea level is likely to shift the elevation of the water table higher in the unconfined Upper Floridan aquifer up by a similar amount. Areas of Florida where the Upper Floridan aquifer is unconfined and where the water table is within a meter or so of the surface may flood in response to predicted sea level rise by the year 2100, regardless of distance from the coast. Therefore, paleo-water level markers may be used as a method of predicting the impacts of future sea level rise