Bermuda is an isolated oceanic island situated 1000 km ESE of Cape Hatteras, North Carolina (Fig. 1, inset). Its volcanic core, last active during the Oligocene (Reynolds & Aumento, 1974), was probably subaerial for some of its existence because rare basaltic pebbles and a small percentage of volcanic grains have been found in surface deposits. Apart from the initial volcanic origin of Bermuda,...