Palaeontology and caves in Jamaica

Stephen K Donovan (The Netherlands). Although it has a rock record that only extends back to the Early Cretaceous, the geology of Jamaica is sufficiently diverse to satisfy most appetites (Donovan & Jackson, 2012a, b). It lies within the North Caribbean Plate Boundary Zone and displays a range of geological structures, commonly faults, both ancient and modern. There are about 25 Cretaceous inliers, from small to large, each including a sequence of volcanic and/or sedimentary rocks that are rarely metamorphosed. The half-graben Wagwater Belt in the east, flanking the western margin of the Blue Mountain inlier, is a Paleogene succession of terrestrial red beds, shallow to deep water siliciclastics and volcanics. These older rocks are draped by thick sequences of Eocene and younger rocks, which are mainly sedimentary (Robinson, 1994). Of the sedimentary rocks, limestones from the Cretaceous to the Quaternary are particularly widespread (Fig. 1), covering about two-thirds of the island’s surface. Although only subaerially exposed for about the last ten million years, these limestones have been strongly karstified under conditions of tropical high temperatures and seasonal extreme precipitation (Donovan, 2002). This has produced widespread, and magnificent, karst topography. Fig. 1. Simplified geological map of Jamaica, showing the principal stratigraphical units (after Donovan, 1993, fig. 1). Key: B=Blue Mountain inlier; C=Central inlier. Stratigraphy of principal Cenozoic units: granodiorite=Upper Cretaceous to Paleocene; Wagwater Formation, Newcastle Volcanics=Paleocene; Richmond Formation=Paleocene to Lower Eocene; Yellow Limestone Group=Lower to Middle Eocene; White Limestone Group=Middle Eocene to Upper Miocene; Coastal Group=Upper Miocene to Quaternary; alluvium=Quaternary. … Read More
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