A +20 m middle Pleistocene sea-level highstand (Bermuda and the Bahamas) due to partial collapse of Antarctic ice

P. J. Hearty, P. Kindler, H. Cheng, R. L. Edwards

Research output: Contribution to journalArticlepeer-review

174 Scopus citations

Abstract

Marine deposits at +20 ± 3 m on the tectonically stable coastlines of Bermuda and the Bahamas support the hypothesis of a partial collapse of the Antarctic ice sheet during the middle Pleistocene. Beach sediments fill a sea cave at +22 m in Bermuda, and horizontal, fenestrae-filled beds crop out on platforms at two sites as high as +21 m in Eleuthera, Bahamas. Carbonate beach sands are bound by an early generation of isopachous fibrous cement that is characteristic of a phreatic marine environment. Amino acid racemization and TIMS (thermal-ionization mass spectrometry) dates constrain the age of the deposits to between 390 and 550 ka, while proxy evidence supports a correlation with oxygen isotope stage 11. This direct geologic evidence of a 20% decrease in polar ice during the middle Pleistocene has important implications for the stability of ice sheets during warm interglaciations.

Original languageEnglish (US)
Pages (from-to)375-378
Number of pages4
JournalGeology
Volume27
Issue number4
DOIs
StatePublished - Apr 1999

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