Neogene and Holocene volcanism in the Lesser Antillean arc has been explosive in character, and bioherms and carbonate platforms are only slowly established on young volcanic islands. ilands inactive for more than several million years begin to develop massive carbonate platforms and the size and maturity of the eventual platforms depend in large part on the length of the quiescent period. the resulting platforms have been variously subjected to sea level changes, minor tectonic uplift or subsidence, and in a few cases renewed volcanism. Windward Holocene coral reefs up to 14 m thick and algal ridges up to 10 m thick are abundant of older island cores in the eastern caribbean. the Holocene bioherms are structurall of two types: bench and bank barrier. bench bioherms are predominantly coral or coralline framework and occur at present depths of less than 6 to 10 m on wave cut Pleistocene benches or other mound or edge features. they are most abundant on raised or emergent carbonate islands. bank-barrier reefs formed initially as elongate horseshore or spit shaped arcs of carbonate sand and rubble trapped by head corals. they are well developed where extensive carbonate shelves are found at present depths of 10 to 20 m. the cap facies of bank barriers are coral or coralline frameworks similar to those found in bench bioherms. the deeper layers of these bioherms (more than 6 to 10 m) are dominated by Montastrea annularis. Acropora cervicornis commonly is present in mid reef zones but it is not as important a framework builder here as it is in the central and western Caribbean. above 6 to 10 m, the reef framework consists mostly of Acropora palmata, Millepora or coralline algae, depending on wave energy. high island reefs with turbid coastal waters are characterized by reef crests coated with fleshy algae. although the crests of some shelf edge reefs in the Lesser Antilles are emergent and therefore barrier reefs, most shelf edge reefs lie at depths of 15 to 30 m and have little Holocene framework. extensive shelf edge barrier or atoll reefs are not present. the Lesser Antillean arc is similar to the seismically active island arcs of plate margins in the Indo-Pacific