The Bahama Banks are the submerged

carbonate platform A carbonate platform is a sedimentary body which possesses topographic relief, and is composed of autochthonic calcareous deposits. Platform growth is mediated by sessile organisms whose skeletons build up the reef or by organisms (usually micr ...

s that make up much of the

Bahama The Bahamas (), officially the Commonwealth of The Bahamas, is an island country within the Lucayan Archipelago of the West Indies in the North Atlantic. It takes up 97% of the Lucayan Archipelago's land area and is home to 88% of the arch ...

Archipelago. The term is usually applied in referring to either the Great Bahama Bank around

Andros Island Andros Island is an archipelago within the Bahamas, the largest of the Bahamian Islands. Politically considered a single island, Andros in total has an area greater than all the other 700 Bahamian islands combined. The land area of Andros consis ...

, or the Little Bahama Bank of

Grand Bahama Grand Bahama is the northernmost of the islands of the Bahamas, with the town of West End located east of Palm Beach, Florida. It is the third largest island in the Bahamas island chain of approximately 700 islands and 2,400 cays. The island i ...

Island and

Great Abaco Great may refer to: Descriptions or measurements * Great, a relative measurement in physical space, see Size * Greatness, being divine, majestic, superior, majestic, or transcendent People * List of people known as "the Great" *Artel Great (born ...

, which are the largest of the platforms, and the

Cay Sal Bank Cay Sal Bank ( es, Placer de los Roques) is the third largest (after Great Bahama Bank and Little Bahama Bank) and the westernmost of the Bahama Banks. It is located between 23º27'N - 24º10'N and 079º25'W – 080º35'W. In a geographical se ...

north of

Cuba Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is an island country comprising the island of Cuba, as well as Isla de la Juventud and several minor archipelagos. Cuba is located where the northern Caribbea ...

. The islands of these banks are politically part of the Bahamas. Other banks are the three banks of the

Turks and Caicos Islands The Turks and Caicos Islands (abbreviated TCI; and ) are a British Overseas Territory consisting of the larger Caicos Islands and smaller Turks Islands, two groups of tropical islands in the Lucayan Archipelago of the Atlantic Ocean and n ...

, namely the Caicos Bank of the Caicos Islands, the bank of the

Turks Islands The Turks and Caicos Islands (abbreviated TCI; and ) are a British Overseas Territory consisting of the larger Caicos Islands and smaller Turks Islands, two groups of tropical islands in the Lucayan Archipelago of the Atlantic Ocean and no ...

, and wholly submerged Mouchoir Bank. Farther southeast are the equally wholly submerged Silver Bank and Navidad Bank north of the

Dominican Republic The Dominican Republic ( ; es, República Dominicana, ) is a country located on the island of Hispaniola in the Greater Antilles archipelago of the Caribbean region. It occupies the eastern five-eighths of the island, which it shares with ...

Geologic history and structure

The

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

that comprises the Banks has been accumulating since at least the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

period, and perhaps as early as the

Jurassic The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...

; today the total thickness under the Great Bahama Bank is over 4.5 kilometres (2.8 miles). As the limestone was deposited in shallow water, the only way to explain this massive column is to estimate that the entire platform has subsided under its own weight at a rate of roughly 3.6 centimetres (2 inches) per 1,000 years. The waters of the Bahama Banks are very shallow; on the Great Bahama Bank they are generally no deeper than 25 meters (80 feet).Stephen K. Boss, "Geological Research on the Great Bahama Bank" (Accessed 3/9/06)
The slopes around them however, such as the border of the

Tongue of the Ocean The Tongue of the Ocean (TOTO) is the name of a region of much deeper water in the Bahamas separating the islands of Andros and New Providence. Features The TOTO is a U-shaped, relatively flat-bottomed trench measuring approximately . Its depth ...

in the Great Bahama Bank, are very steep. The Banks were dry land during past

ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gre ...

s, when sea level was as much as 120 meters (390 feet) lower than at present; the area of the Bahamas today thus represents only a small fraction of their prehistoric extent. When they were exposed to the atmosphere, the limestone structure was subjected to

chemical weathering Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement ...

that created the

caves A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word ''cave'' can refer to smaller openings such as sea ...

and

sinkholes A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are locally also known as ''vrtače'' and shakeholes, and to openi ...

common to karst terrain, resulting in structures like

blue hole A blue hole is a large marine cavern or sinkhole, which is open to the surface and has developed in a bank or island composed of a carbonate bedrock ( limestone or coral reef). Their existence was discovered in the late 20th century by fishe ...

References

External links

European Space Agency: ''Earth From Space: The Great Bahamas Bank'', on http://spaceref.com, December 20, 2014 11:00 AM
{{coord, 24.046464, N, 77.651367, W, source:dewiki_region:BS-FC_type:isle, format=dms, display=title Undersea banks of the Atlantic Ocean Landforms of the Bahamas Landforms of the Caribbean Cretaceous Caribbean Jurassic Caribbean Early Cretaceous North America Late Jurassic North America

Geologic history and structure

See also

References

Further reading

External links