How did Barbados form geologically?

Barbados is geologically distinct from the nearby Lesser Antilles archipelago. Its formation began approximately 70 million years ago with the accumulation of sedimentary deposits, including thick layers of shales, clays, sands, and conglomerates.12

Over these foundational rocks, chalky deposits accumulated. Subsequently, the island was capped with coral before it eventually rose to the surface. Today, a layer of coral limestone—reaching up to 300 feet (90 metres) in thickness—covers most of the island. The only exception is the Scotland District in the northeast, where erosion has stripped away the coral cap, exposing the older underlying sedimentary rocks.2