112 THREE CRUISES OF THE " BLAKE." 



St. Eustatius to Nevis, and Barbuda to Antigua, and thence 

 extends south so as to include Guadeloupe, Marie-Galante, and 

 Dominica.^ The five - hundred - fathom line thus forms one 

 bank of the, northern islands, and leaves but a narrow channel 

 between it and the eastern end of the five-hundred-fathom line 

 running round Santa Cruz. Santa Cruz is separated from St. 

 Thomas by a channel of forty miles, which thus forms a basin 

 with a maximum depth of over twenty-four hundred fathoms. 

 It is united with Porto Rico by a submarine ridge with a depth 

 of about nine hundred fathoms. This plainly shows its con- 

 nection with the northern islands of the Caribbean group, 

 rather than with St. Thomas ; yet, as is also well shown by the 

 geographical relations of its mollusca, their affinities are rather 

 with Porto Rico and that group of islands than with the Carib- 

 bean Islands. This may be explained by the existence of an 

 easterly current setting along the shore, or of a former land 

 connection with Porto Rico, still indicated by a ridge discovered 

 by the " Albatross," running from Santa Cruz to Porto Rico, 

 having a maximum depth of nine hundred fathoms. The five- 

 hundred-fathom line again unites, in one huge spit extending 

 northerly from the mouth of the Orinoco, all the islands to the 

 south of Martinique, leaving Barbados to the east, and a narrow 

 passage between Martinique and the islands of Dominica and 

 St. Lucia. 



At the time of this connection, if it existed, the Caribbean 

 Sea was connected with the Atlantic only by a narrow passage 

 of a few miles in width between St. Lucia and Martinique, by 

 one somewhat wider and slightly deeper between Martinique 

 and Dominica, by another between Sombrero and the Virgin 

 Islands, and by a comparatively narrow passage between Jamaica 

 and Hayti. The hundred-fathom line connects the Bahamas 

 with the north-eastern end of Cuba ; the five-hundred-fathom 

 line unites them not only with Cuba, but also with Florida. 

 The Caribbean Sea, therefore, must have been a gulf of the 

 Pacific, or have been connected with it by wide passages, of 

 which we find the traces in the tertiary and cretaceous deposits 



^ Between Martinique and Dominica a peak in raid-ciianuel was found within 

 eighty-five fathoms of the surface. 



