Geologic history

The Grenadine Islands and Carriacou represent the exposed summits of peaks on a single narrow bank of submerged volcanic mountains. The Island of Grenada is separated from Carriacou by a channel 600 feet deep.

The Grenadine Islands came into existence in the late Oligocene period, sank or eroded away during the Pliocene and were completely submerged during the Pleistocene period. Since that time, a regional uplifting of the sea floor has raised the Islands above sea level (Howard, 1950).

The diversity of the geological formation of the Grenadines is fascinating. Bequia is characterized by pyroclastic rocks preponderant over massive. Some islands have red and white clays due to laterization and kaolinization of the volcanic andesites in situ. Other islands are weathered rugged volcanic rocks and agglomerates.

Carriacou, an Island of 34 square kilometers has been studied by geologists since the 19th century. The most recent studies have indicated fossiliferous limestone formation ranging in age from upper Eocene to Pleistocene.

The Island can be divided into two zones:

(i) The Fossiliferous limestone area which is mainly of the miocene age with outcroppings in the eastern part. This non-volcanic formation is characterized by continuous stratifications of calcareous, clastic and volcanic lithofacies; and

(ii) The volcanic area which covers about two thirds of the Island. This section consists of lava flows, lava domes and volcanoclastic products ranging in age from Miocene to the Pliocene (Briden et al., 1979).