The Bahama Banks are the submerged

carbonate platform A carbonate platform is a Sedimentary rock, sedimentary body which possesses topographic relief, and is composed of Autochthon (geology), autochthonic calcareous deposits. Platform growth is mediated by Sessility (zoology), sessile organisms whose ...

s located in the

archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection of islands. An archipelago may be in an ocean, a sea, or a smaller body of water. Example archipelagos include the Aegean Islands (the o ...

The Bahamas The Bahamas, officially the Commonwealth of The Bahamas, is an Archipelagic state, archipelagic and island country within the Lucayan Archipelago of the Atlantic Ocean. It contains 97 per cent of the archipelago's land area and 88 per cent of ...

within the

Lucayan Archipelago The Lucayan Archipelago, also known as the Bahamian Archipelago, is an island group comprising the Commonwealth of The Bahamas and the British Overseas Territory of the Turks and Caicos Islands. The archipelago is in the western North Atlant ...

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

Andros Island Andros is an archipelago in 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 consists of hun ...

, or the Little Bahama Bank of

Grand Bahama Grand Bahama is the northernmost of the islands of the Bahamas. It is the third largest island in the Bahamas island chain of approximately 700 islands and 2,400 cays. The island is roughly in area and approximately long west to east and at it ...

Island and

Great Abaco The Abaco Islands lie in the north of The Bahamas, about 193 miles (167.7 nautical miles or 310.6 km) east of Miami, Florida, US. The main islands are Great Abaco and Little Abaco, which is just west of Great Abaco's northern tip. There are ...

, which are the largest of the platforms, and the

Cay Sal Bank Cay Sal Bank () 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, and is found between Cuba, the Great Bahama Ba ...

. 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 no ...

, namely the Caicos Bank of the Caicos island group, the Turks Bank of the Turks island group, and the submerged

Mouchoir Bank Mouchoir Bank, in Spanish language, Spanish also called ''Banco de Pañuelo Blanco'', is a submerged bank that is part of the Turks and Caicos Islands and falls within its exclusive economic zone. The bank, located southeast of the Turks islan ...

, and the two banks north of the

Dominican Republic The Dominican Republic is a country located on the island of Hispaniola in the Greater Antilles of the Caribbean Sea in the Atlantic Ocean, North Atlantic Ocean. It shares a Maritime boundary, maritime border with Puerto Rico to the east and ...

Hispaniola Hispaniola (, also ) is an island between Geography of Cuba, Cuba and Geography of Puerto Rico, Puerto Rico in the Greater Antilles of the Caribbean. Hispaniola is the most populous island in the West Indies, and the second-largest by List of C ...

, namely the submerged

Silver Bank Silver Bank () is a submerged bank in the Atlantic Ocean north of the Dominican Republic and southeast of the territory of Turks and Caicos Islands. It covers an area of . It is separated from Mouchoir Bank in the west by Silver Bank Passage, and ...

and

Navidad Bank Navidad Bank () is a submerged bank in the Atlantic Ocean north of the Dominican Republic and southeast of the Territory of Turks & Caicos. It is separated from Silver Bank by the wide Navidad Bank Passage. Geography Navidad Bank is a shallow und ...

, are geographically and

geologically Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth s ...

part of the Lucayan Archipleago, which entire

is often generally referred to as the ''Bahamas platform''.

Geologic history and structure

The

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

that comprises the Banks has been accumulating since at least the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

period, and perhaps as early as the

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

; 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 depression measuring approximately . Its d ...

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 g ...

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

atmosphere An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

, 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, sunlight, and biological organisms. It occurs ''in situ'' (on-site, with little or no movem ...

that created the

caves Caves or caverns are natural voids under the Earth's surface. Caves often form by the weathering of rock and often extend deep underground. Exogene caves are smaller openings that extend a relatively short distance underground (such as rock ...

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 also known as shakeholes, and to openings where surface water ...

common to

karst Karst () is a topography formed from the dissolution of soluble carbonate rocks such as limestone and Dolomite (rock), dolomite. It is characterized by features like poljes above and drainage systems with sinkholes and caves underground. Ther ...

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). Blue holes typically contain tidally influenced water of fresh, ma ...

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