The Bahamas - Geography

The islands are surface projections of two oceanic banks, the Little Bahama Bank and the Great Bahama Bank. The highest point is only sixty-three meters above sea level on Cat Island; the island of New Providence, where the capital city of Nassau is located, reaches a maximum elevation of only thirty-seven meters.

The Bahamas is an archipelagic nation of more than 700 islands and cays that cover a geographical region approximately equivalent in scale to the state of California. At its closest point, The Bahamas is only 50 miles from the US. As a result, the country is considered the “third border” of the US.

The Commonwealth of The Bahamas comprises the majority of an extensive archipelago of carbonate islands and shallow banks in the western North Atlantic Ocean (21°to 27°30'N and 69° to 80030'W). The southeastern portion of the same archipelago consists of the Turks and Caicos Islands (British West Indies), and the submerged Mouchoir, Silver, and Navidad banks.

It is a remarkable fact that, except in the island of Andros, no streams of running water are to be found in the whole group. The inhabitants derive their water supply from wells. As a result of the porosity of the rock, many of the wells feel the influence of the sea and exhibit an ebb and flow. There is an extensive swampy lagoon in Eleuthera, the water of which is fresh or nearly so; and brackish lagoons also occur, as in Watling Island. An artificial lake in New Providence, constructed for the use of the turtle-catchers, is noted as exhibiting an extraordinary degree of phosphorescence.

A remarkable natural phenomenon is that of the so-called "banana holes," which frequently occur in the limestone. Their formation had been attributed to the effect of rotting vegetation on the rock, but without certainty. These holes are of various depths up to about 40 ft., and of curiously regular form. The Mermaid's Pool in New Providence, which is deeper still, is partly filled with water.

The Bahamian archipelago covers 300,000 km2, of which 136,000 km2 is shallow bank, and 11,400 km2 is land. The banks are generally less than 10m deep and are bounded by near-vertical declivities into very deep water. The Bahamas consists of 29 land masses referred to as islands, 661 cays (pronounced "keys", generally minor islands), and 2,387 rocks.

Great Bahama Bank is embayed by two deep troughs: Tongue of the Ocean (TOTO) in the center (1400-2000 m), and Exuma Sound to the east (1700-2000 m). Little Bahama Bank is separated from Great Bahama Bank by Northwest and Northeast Providence Channels.

The land on the Bahamas has a foundation of fossil coral, but much of the rock is oolitic limestone; the stone is derived from the disintegration of coral reefs and seashells. The rock on the surface is as hard as flint, but underneath it gradually softens and furnishes an admirable stone for building which can be sawn into blocks of any size, hardening on exposure to the atmosphere.

The crust underlying the carbonates of the Bahamas was a product of the processes associated with rifting of Pangea and the opening of the North Atlantic basin in the late Middle Jurassic. The basement rocks in the northwestern Bahamas, under the Florida Straits, the Northwest Providence Channel, and the northernmost Tongue of the Ocean (TOTO) is "intermediate" or "transitional" rift crust, com- posed of tilted fault blocks of Jurassic volcaniclastics. Southeast of that region, the Bahamas are underlain by oceanic crust.

The Great Bahama Bank is a massive underwater hill underlying Andros Island in the west, Eleuthera Island in the east, and multiple islands in between. To the north, another bank underlies another set of islands, including Grand Bahama. The varied colors of these banks suggest their surfaces are somewhat uneven. The banks’ distinct contours, sharply outlined in dark blue, indicate that the ocean floor drops dramatically around them. In fact, over the banks, the water depth is often less than 10 meters (30 feet), but the surrounding basin plunges to depths as low as 4,000 meters (13,000 feet).

The Bahamas are referred to as carbonate islands, which is due to the formation of carbonate banks. This megabank formed in the Late Jurassic and is evidence of an absence of deep water at the time of formation due to the type of rock formed. Carbonates are more likely to form in shallower waters, thus the formation of two major carbonate banks in the Bahamas shows that there was an absence of deep water.

At meeting place of the deep waters of the Tongue of the Ocean and the much shallower, completely submerged Grand Bahama Bank, the platform reef drops off quickly into the branch of the Great Bahama submarine canyon that because of its shape is called the Tongue of the Ocean. The vertical rock walls of the Canyon rise 14,000 feet from their greatest depth to the surrounding seabed, which is why the water is so dark in color compared to the reef. The shallowest parts of the reef are no more than three to seven feet deep; so shallow, in fact, that in the northeast corner of the image you can zoom in and see large wave-sized ripples of sand on the bottom. Like so many other biological structures, the ribbon-like form of the reef maximizes surface area and thus the number of organisms that can colonize the structure. The closest land is the Bahama Islands of Great Exuma, less than 16 miles to the east, and Andros about 27 miles to the west.

There are approximately 19 inhabited family islands in the archipelagic chain of the Bahamas. Some of them are more developed than others, but they all have one thing in common: beautiful beaches with pink and white sands whose powdery quality defies description. The crystal clear water surrounding the islands change colours at the blink of an eye.

When the sea is calm the waves make a soft rhythmic sound as they lap the shore. When rough, they become tumultuous. The terminology, "Family of Islands," has a romantic ring to it. Although each island has its own distinct character, there is a sense of similarity among the inhabitants.

The Abacos have blue holes which contain the relics of creatures that lived here centuries ago. Bimini and The Exumas are noted for sport fishing and deep-sea diving. Inagua claims flamingos and other exotic birds. Cat Island boasts the highest point in the archipelago. Comer Hill or Mount Alvernia, as it is named, has an unforgettable history dating from the early 1940’s when a Catholic Priest came to the island and built a monastery at the summit. It has become a famous tourist attraction.