442 MEXICO, CENTRAL Aî^tERICA, WEST INDIES. 



forming either straits or sounds, such as Providence Channel, and farther south 

 those of Crooked Island, the Caicos and Turks grouj)s, or else land-locked inlets 

 such as Exuma Bay and the Tongue of the Ocean east of Andros. These long 

 lines of solid rock, whose form and disposition depend on the action of fleeting 

 waters, are one of the most remarkable phenomena of physical geography. 



In the direction from east to west, that is, from the Atlantic towards the 

 entrance to the Gulf of Mexico, the Baharaan plateau decreases in altitude ; the 

 upraised lands grow' less numerous, the shallows more extensive, until at last 

 the whole submarine bank becomes separated from Haiti and Cuba by a profound 

 trouo-h with abysses of over 2,000 fathoms in the east. But towards the west 

 it aoain shoals a little to form the Old Bahama Channel, and farther on the 

 Santarem Channel, continued northwards by the ]S"ew Bahama Channel, better 

 known as Florida Strait. 



"West of Santarem Channel, quite beyond the Great Bahama Bank, and 

 midway between Cuba and the Florida reefs, is situated the triangular plateau of 

 Cay Salt Bank (Salt Cay or Key),* which is everywhere encircled by marine 

 waters over 300 and towards the west over 600 fathoms deep. This bank aiïects 

 somewhat the form of a saucer, with depths of from 4 to 6 fathoms in the central 

 parts, which are enclosed by an outer rim either of submarine shoals or of 

 upheaved reefs, some bare, others covered with moving sandhills. The encircling 

 reefs, formed of corals and shells fused in a conglomerate mass by a calcareous 

 cement, receive the deposit of tine sands washed up by winds and waves, and 

 develop little dunes 15 to 20 feet high wherever the reefs offer a sufiiciently 

 broad foundation. A curious effect is produced by these isolated sandhills rising 

 in the very midst of the marine waters, those of recent formation resembling 

 ships under sail, but the majority already bound fast, anchored so to say, by 

 trailing plants and lianas {batatas UttoraJis), which spread their firm network of 

 green meshes over the shifting sands. The bank takes its name from Salt Cay, 

 the largest of the group, so called from a salt-water lagoon in the centre. This 

 lagoon takes a slight orange tinge from a little seaweed w'hich grows in dense 

 masses round the margin, and which resembles putrid flesh both in appearance 

 and odour. 



Being formed like Yucatan of fissured coralline limestones with numerous caves 

 or cavities, the upraised parts of the Great Bahama Bank are destitute of springs 

 or running waters. Andros alone, on the west side of the Tongue of Ocean, has a 

 few brooklets, or rather marshy rills. At high water this island becomes divided 

 into three separate fragments. As in Yucatan, the rainwater is collected in under- 

 ground reservoirs, though in many places the neighbouring marine waters filter 

 through and render the lacustrine basins quite brackish. In some of the islands 

 the tides penetrate into the wells under the fresh water, causing a slight rise and 

 fall with flow and ebb. Before these wells were sunk the early settlers still found 

 sufiicient potable water in a plant of the mistletoe family [viscum caryophylloides) , 



* The Spanish eaijo takes the form of caij in English and l-eij in American geographical nomen- 

 clature ; hence Salt Cay and Key, Key -West, Marquesas Keys, kc. 



