Elevated marine terraces from Eleuthera (Bahamas) and Bermuda: sedimentological, petrographic and geochronological evidence for important deglaciation events during the middle Pleistocene

Sedimentological, petrographic and geochronological (uranium series and amino acid racemization dating) study of middle Pleistocene deposits from the archipelagos of Bermuda and The Bahamas revealed the occurrence of marine terraces of possible stage 11 age at +2, +7 and over 20 m above mean sea level. Considering the tectonic stability of the investigated regions, these elevated deposits likely correspond to three discrete, higher than present sea levels during this time period, which is regarded by many as the warmest interglacial of the late Quaternary. It follows that warmer than present climatic conditions might profoundly modify water distribution between the cryosphere and the oceans. The punctuated nature of our stratigraphy further suggests that future deglaciation might not be a smooth process, but could be marked by rapid ice-sheet breakdown leading to abrupt, meter-scale sea-level rises. Given the long period of warm climate and stable sea level of the past few thousands of years and CO2 loading of the atmosphere, the probability of a rapid eustatic rise must be seriously considered. (C) 2000 Elsevier Science B.V. All rights reserved.