Coral growth was greater through the Tertiary, until the start of the ice ages, and hence those deposits are more abundant below a depth of . In fact, an ancient extinct reef exists half a km seaward of the present one,  below sea level. Oolites form when oceanic water penetrate the shallow banks, increasing the temperature about  and the salinity by 0.5 per cent. Cemented ooids are referred to as grapestone. Additionally, giant stromatolites are found off the Exuma Cays.