PALEOECOLOGY AND SEDIMENTOLOGY OF THE FALMOUTH FORMATION (EEMIAN, JAMAICA): EVIDENCE FOR SEA-LEVEL CHANGES DURING THE LAST INTERGLACIAL

The Falmouth Formation is an Eemian limestone well exposed on the north coast of Jamaica. It consists primarily of shallow water reef facies, with framework corals dominated by Montastrea "annularis", Acropora palmata, Porites sp., and Diploria strigosa. The back-reef facies are rich in bivalves, especially Arcopagia spp. and Arca spp., and echinoderms. Rhodoliths are abundant in the high-energy facies, such as tidal channels between reef cores. Most rhodoliths were constructed around coral debris and consist mostly of calcareous red algae, juvenile corals, vermetid gastropods, and serpulid worm tubes. They show a complicated history of burial and reactivation. The sediment matrix of the Falmouth is mostly coral, mollusk, echinoderm, foraminiferal and calcareous algal debris, along with micritic, pelleted and radial cement generations. The Falmouth rests on a bored and encrusted erosional surface cut into the underlying Hope Gate Formation (Middle Pleistocene), and is topped by an extensive caliche surface. Near the middle of the Falmouth is a laterally extensive, undulating surface which truncates corals and is heavily marked by terra rosa. This may be an erosion surface cut during the Devil’s Point Event (White et al., 2001), which was a sharp drop in global sea-level followed by a rapid rise again approximately 125,000 years ago. This Falmouth surface is unusual, though, because it does not apparently have the deep bivalve and sponge borings which characterize this unconformity in the Bahamas, Florida, and other places where coral facies record the event. This may be because of deep weathering of the limestone during its brief exposure in Jamaica. Another extensive surface is present lower in the Falmouth, but we believe it is the base of a tempestite. Further work on the Falmouth may show that its paleoecological and sedimentological diversity is especially valuable for further study of the character of the Devil’s Point Event.