Sea Level Events and Pleistocene Coral Ages in the Northern Bahamas

Abstract

Emergent Pleistocene sea level indicators in the northern Bahamas include: a bioerosional notch at +5.3 to 5.9 m; sea caves, notches, and marine terraces at about +4.3 m; and lithified coral rubble and reef deposits between 0 and 3 m. Thorium 230 dates of the fossil corals, which were deposited as these features were being produced, span the age range from 100 to 145 thousand years BP with a majority falling between 115 and 130 thousand years BP. The notch at about +5.6 m is interpreted to be the product of a sea level stand 125 thousand years BP, while the features at +4.3 m are believed to be formed sometime later as sea level fell from the higher position. Part of the age span is inherent in the dating technique and possible sample alteration. Another cause of the spread may be mixing of corals of different ages into a single deposit.