Brown micritic crusts occur at an elevation of 32 m below sea level in a borehole on the central west coast of Barbados, West Indies. The crusts are developed throughout a 2- to 3-m-thick interval of fore-reef skeletal wackestone that formed as part of a reef complex 125,000 B.P. Overlying the crust-bearing section is quartz-bearing skeletal grainstone containing clasts of the crust.
The crusts formed in a subaerial environment during a low stand of sea level after deposition of the 125,000-B.P. reef. The overlying quartz-bearing grainstone is an ancient beach deposit that formed during the initial stages of the rise in sea level that culminated in the known 105,000-B.P. high stand.
We estimate that the elevation of the low-stand sea level between 125,000 and 105,000 B.P. was −71 ± 11 m relative to present sea level. A sea-level fluctuation of this magnitude must be associated with an intense glacial event.