San Salvador Island and the opening of a new karst frontier

Karst fieldwork began on San Salvador Island in 1977, and has continued for three-plus decades, as a result of the Gerace Research Centre (GRC). This karst research effort received the strong support of Don and Kathy Gerace at a time when such support was rare in the United States; the success of current karst research in the Bahamas is a result of the GRC's sustained efforts. The GRC's location on an isolated small carbonate island and bank, in a tectonically-stable setting that is 100% mid to late Quaternary carbonates provided time and space boundary conditions on cave and karst development. Such boundary conditions do not exist in the world's classic continental karst areas.

The early karst research on San Salvador attempted unsuccessfully to apply continental models, which considered old, diagenetically-mature carbonates with significant imposed structure and adjacent non-carbonate lithologies. The first breakthrough, the flank margin cave model, explained the largest caves of San Salvador as the result of water mixing at the fresh-water lens boundaries, in a laminar-flow environment within young, porous, diagenetically-immature carbonates. A Friends Of Karst meeting at the GRC in 1988, and a Karst Waters Institute Paleokarst meeting there in 1995 presented these ideas to the karst science community, opening a new karst frontier.

Island karst research has advanced to successively more complex island settings: Isla de Mona, Puerto Rico, an uplifted carbonate island; the Mariana Islands, tectonically active with mixed carbonate and non-carbonate lithologies; and to the New Zealand and Croatian coasts with diagenetically-mature coastal carbonates. The result has been the development of the Carbonate Island Karst Model (CIKM), which takes into account the complexities of tectonics, geochemistry, rock maturity, and non-carbonate lithologies to explain island caves and karst globally. The karst of San Salvador Island is the “gold standard” base line of the CIKM.