MACROPALEONTOLOGY OF THE HOPEGATE FORMATION, JAMAICA, AN UPPER PLIOCENE RAISED REEF

The Hopegate Formation has been the least attractive unit for paleontological investigation in the Cenozoic of Jamaica, despite being a rare example of a Pliocene raised reef in the Caribbean. This is due to its extreme lithification and dolomitization, making collecting difficult; most scleractinians and benthic molluscs are moldic. Further, the formation was formerly considered to be Pleistocene, making the more friable rocks of the overlying Falmouth Formation a more encouraging prospect for any collector. However, scleractinians collected in the present study include typical Pliocene taxa, confirming strontium isotope determinations and disproving earlier suggestions of a penultimate interglacial age.

New and extensive exposures of the Hopegate Formation have become available since 2002 as the main north coast road has been re-engineered in central north Jamaica. Hitherto, few names of macrofossils from the unit have been published. Preliminary determinations from the current study include 23 genera of scleractinians, an estimated 60+ species of benthic molluscs, four species of decapod crustaceans, six species of echinoids and five ichnogenera (borings). Together, these provide a unique insight into life in Caribbean reefs in the late Pliocene, an interval more commonly known from non-reefal deposits. This research was supported by National Geographic Society grant #7278-02.