Caribbean Islands: the Lesser Antilles

Virgin Islands

The Virgin Islands is an archipelago located in the northern part of the Lesser Antilles, in the Caribbean Sea. To the east lies the Atlantic Ocean and to the west the Caribbean. This archipelago comprises of three main islands: Saint Thomas (St. Thomas), Saint John (San Juan), and Water Island and other smaller islands.

The Virgin Islands are located on the edge of the Caribbean and North American plates, therefore, most of the islands are volcanoes with propensity to experience occurrences of natural phenomena such as earthquakes, hurricanes and tsunamis. There are bountiful deposits of limestones of coral origin, and corals. The highest peak is Mount Crown (474 m) in St. Thomas. The soil is mostly clay and the islands are rugged and mountainous. Higher elevations are present in the island of Saint Thomas Mount Crown, with 474 meters.

Saint Croix is one of the Lesser Antilles. Is about 84 square miles and it is approximately 22 miles long. The terrain is similar to its neighboring islands; rocky and arid. It is crossed by several streams and in its center flaunts beautiful beaches. In the east, its vegetation consists of short grassy hillsides and cactus. The west end of the island, consists of elevated areas, and it boasts verdant vegetation with fruit trees. St. Croix’s highest peak, Mount Eagle, is 1,088 feet high. From its elevated region, the land slopes to flatlands on the southern side of the island. St. Croix also has natural harbors and protected bays.

As a result of the eastward Caribbean Plate movement, and the North American plated subduction (one tectonic plate moving beneath the other) the formation of igneous rock from magma maintained a continuous indication of its formation from the late Cretaceous to Paleogene Ages.   Its complex volcanic-arc Aves Ridge records changes from the Eocene to the Holocene in the Lesser Antilles arc (Rankin, D.)

Windward Islands

The Windward Islands comprise de southern arc of the Lesser Islands in the east of the Caribbean. The northern part is made up of two parallel arcs of islands. Its limestone characterizes the outer arc. The complex geological makeup of the Windward Islands denotes its volcanic and sedimentary strata of Oligocene age, from Pleistocene coral limestone and alluvium.

The inner arc of the Lesser Antilles is longer than the outer islands. Its formation is exclusively volcanic and originates in the Eocene Age.

Trinidad is also part of the Lesser Antilles and structurally is part of northern South America region and studies indicate that at some point in prehistoric times there was land connecting with Venezuela. The similarity with the Venezuelan coastal cordillera is obvious in its mountainous ridges of metamorphosed sedimentary rocks with igneous intrusions dating to the lower Cretaceous age with their igneous intrusions.

Leeward Antilles

These islands form two groups:

One group of islands is located on the continental shelf of Venezuela, among them are Margarita, Coche, Cubagua and Testigos. The geological formation of these islands is similar to that of the Venezuelan coastal mountain range, Cordillera de la Costa. The island of Margarita is the most important of this group of islands, covers an area of approximately 578 square miles.

The Margarita island is formed by the presence of two rocky cores, connected by a barrier island or sandbar which causes an inner lagoon, known as Laguna de la Restinga. The rocky core forms the eastern and western Copey Pico takes the name of Macanao.

The Leewards’ Offshore islands are located off the continental shelf and owe their origin to the existence of coral reefs, among them are The Birds, Los Roques, La Orchila, La Blanquilla and Los Hermanos.

Besides these two groups of islands the Leewards’ also reach the aptly named, for its geostrategic importance, Bird Island and the archipelago of The Monks located off the Gulf of Venezuela.

The ABC islands, also part of the Leewards, are off the coast of Venezuela.   These comprise Aruba, Curacao and Bonaire, a string of islands blocks raised with positive gravimetric expression, in the northern coast Venezuela. This platform, which was probably a primitive magmatic arc, limits with the basin of Los Roques on its northern margin and its southern flank by a series of basins along the Venezuelan border including the Falcon-Bonaire basins and Trench Cariaco to the east.

The Virgin Islands – References

Wikipedia – Retrieved on 1/13/2012 from

http://en.wikipedia.org/wiki/United_States_Virgin_Islands

Rankin, D., Geology of St. John, U.S. Virgin Islands. Retrieved on 1/13/2012 from

http://pubs.usgs.gov/pp/p1631/P1631-tag.pdf

The Windward Islands – References

Wikipedia – Retrieved on 1/13/2012 from      http://en.wikipedia.org/wiki/Windward_Islands

Encyclopedia Britannica Retrieved on 1/13/2012 from

http://www.britannica.com/EBchecked/topic/645259/Windward-     Islands

The Leeward Islands

Wikipedia – Retrieved on 1/13/2012 from

http://en.wikipedia.org/wiki/Volcanic_arc

Wikipedia – Retrieved on 1/13/2012 from

http://en.wikipedia.org/wiki/Leeward_Islands

Wikipedia – Retrieved on 1/13/2012 from

http://en.wikipedia.org/wiki/Leeward_Antilles

van der Lelif, R., and Spikings, R., Kounov, A., Cosca, M., Chew, D., (not known but recent) Thermal and tectonic history of the Leeward Antilles: Aruba and Bonaire.

Retrieved on 1/13/2012 from http://www.tcd.ie/Geology/staff/chewd/publications/Other/Thermal%20and%20Tectonic%20History%20of%20the%20Leeward%20Antilles.pdf

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