The marine geology of the Bahama Escarpment

A stratigraphic section (2050 to 3960 m) of the Bahama Escarpment off Cat island, measured with DSRV A/vin, consists of lower and Middle Cretaceous peritidal, lagoonal, patchreef and backreef limestones unconformably overlain by an intermittent cover of lithified Maastrichtian and Eocene pelagic linestone above 2540 m. Additional dive traverses and dredging elsewhere indicate that sequences similar in age and lithology to the Cat Island section occur along the entire 800 km of escarpment southeast of Cat Island. Reef and forereef debris which constituted the original Bahama Escarpment is absent due to erosion, and the present Bahama Escarpment is therefore an erosional feature. Erosion occurs intermittently (pre-Maastrichtian, Paleocence and Oligocene erosional events) as recorded by the unconformable forereef and pelagic cover. Erosion of the lower escarpment is effected at present by spallation of joint blocks. Jointing may result from (1) lithostatic pressure at four or five km depth exceeding the strength of the linestone comprising the platform, or (2) decompression of previously deeply buried following exposure on the seafloor.