372 



humboldt's cuba. 



tiary limestone of the peninsula of Araya, near 

 Cumana, but of a more recent formation. The 

 inequalities of these coral rocks, are filled with the 

 detritus of shells and madrepore. All that rises 

 above the surface of the sea is composed of broken 

 lumps cemented by carbonate of lime, in which 

 grains of quartz sands are held. I do not know if, 

 under this fragmentary coral rock, structures of 

 living polypus are to be found, at a great depth, and 

 whether they adhere to the Jurassic formation. 



Mariners believe that the sea gradually diminishes 

 in depth in this vicinity, perhaps because they per- 

 ceive the cays to grow and rise up, either from the 

 sandbanks which the beating of the waves forms, or 

 by successive agglutinations. Besides, it might not 

 be impossible, that the widening of the Bahama 

 channel, through which the waters of the Gulf 

 Stream emerge, should cause in the lapse of time, 

 a slight lowering of the level of the sea on the south 

 side of Cuba, and particularly of the Gulf of Mexico, 

 the centre of the great whirlpool of that pelagian 

 river which washes the shores of the United States, 

 and casts the fruits of tropical plants on the coasts 

 of Norway. 



The form of the coasts, the direction, force, and 

 duration of certain currents, and certain winds, and 

 the variations they experience from the changeable 



