The island of Saint-Barthélemy is part of the French Lesser Antilles. Located at the northern end of the Caribbean arc, between the Caribbean and Atlantic plates, it lies on the easternmost inactive arc.
Saint-Barthélemy is one of the main landforms on the Banc d'Anguilla, along with the islands of Saint-Martin, Tintamarre, Anguilla and their outlying islets.
Geological studies reveal that the substratum is Middle to Upper Eocene and Oligocene in age (between 51 and 24 million years). This substrate combines marine formations, volcanic formations and superficial detrital deposits (Westercamp and Andreieff, 1983).
18,000 years ago, sea level was 100 m lower than it is today. It was then that the island of Banc d'Anguilla, almost twice the size of Guadeloupe, took shape. This geological configuration helps explain the presence of endemic* herpetological flora and fauna.
Vocabulary:
Exogenous: A species that does not occur naturally on the island, but has been voluntarily or involuntarily introduced by humans. Exotic is a synonym.
Native: A species that occurs naturally over a large geographical area. In Saint Barth, typically American species with a fairly wide distribution, including the Caribbean, are considered indigenous. Native is a synonym.
Endemic: This is a species native to a limited geological entity (e.g. endemic to the Lesser Antilles), and which is not naturally present elsewhere. In Saint Barthélemy we have species endemic to the Banc d'Anguilla, i.e. present only in Saint Martin, Anguilla, Saint Barthélemy and their satellite islets around the world.
