Geology in Barbados
Sitting at a very unique location in the Atlantic Ocean to the east of the other West Indies islands and boasting a Latitude 13º10' N and Longitude 59º 32' W, the island of Barbados is the most eastern island of the English Caribbean chain of islands (Lesser Antilles).
The birth of Barbados came about as a result of a natural impact that occurred between the Atlantic and Caribbean plates. Over a period of about a million years, was born of the gradual accumulation of the oceanic sediments and regular tectonic uplifts caused by the Atlantic plate being pushed under the Caribbean plate which literally forced Barbados to surface.
The island however, did not take its present shape all at once. Barbados presented as a gradual rising (over some 500,000 years) when coral reefs were created in clear, shallow waters which surrounded the exposed part of the Barbados ridge. At different intervals between 500,000 to 120,000 years ago, Barbados became enlarged by tectonic uplifts which pushed these reefs out of the water. These sea reefs are now 'inland reefs' which present as terraces and cliffs that can be seen as you drive around the island.
The unique activity of Barbados' geology also explains why we have so many caves, the most fascinating and beautiful of which is the popular Harrison’s Caves. Simply put, the caves came about as a result of continued rain and ground water eroding the surface and structure of underground coral beds. The porosity of coral limestone bedrock also acts as a natural filter for rain water which is tapped in reservoirs and pumped throughout the island as excellent potable water to Barbadians.
The Scotland District in St. Andrew is home to the oldest rocks on the island and consists of thick-bedded sandstones, coarse grits, bituminous sandstones and shales, dark-grey and mottled clays with nodules of ironstone. Bent into numerous flexures and curves, these beds are broken by quite a few faults of greater or less magnitude that make it quite an arduous task to accurately estimate their true thickness. Apparently, there are approximately 550 to 600 feet of them exposed on the island. However, due to the fact that the base is hidden it is not possible to precisely determine the thickness of them all. Except for the highlands, the deformed Tertiary strata are overlain by a succession of Pleistocene, tectonically little affected, reef terraces that topographically downstep toward the northern, eastern and southern coastlines almost concentrically becoming younger toward the coastline. The Upper Reef Terrace is older than 600 000 years whereas the youngest reef terrace submerged off the Lower Reef Terrace is of Holocene-Recent age. The terraces formed in response to tectonic uplift and eustatic sea-level fluctuations that resulted in several episodes of relative sea-level drop.