TOPOGRAPnY OF THE EASTEEN COAST. 105 



Islands, rising from twelve to sixteen thousand feet above the 

 bottom of the Eastern Caribbean, with the many passes between 

 them, — the sieve through which the warm surface water of 

 a great part of the equatorial current is forced by the trade- 

 winds ? 



We may imagine for a moment that we are taking a bird's-eye 

 view of this whole district, and look down upon the compara- 

 tively level plains of the Atlantic to the eastward of the Barba- 

 dos. These plains rise from a depth of three thousand fathoms 

 to the hundred-fathom line in a distance varying from three 

 hundred and fifty to two hundred miles on the eastward of the 

 Windward Islands ; the highest summits of these islands (five 

 thousand feet) are only separated by narrow passages, and thus 

 form a more or less continuous chain of volcanic peaks. On 

 the westward, toward the Caribbean, the slope is more rapid; 

 a depth of one thousand to fifteen hundred fathoms is reached 

 at a comparatively short distance to the leeward of the Lesser 

 Antilles. The chain is narrowest between Martinique and Do- 

 minica, widening gradually towards Grenada and Tobago to the 

 south, and somewhat? faster towards the Virgin Islands, which 

 are separated from the Santa Cruz, Saba and Sombrero banks 

 by a deep basin opening into a narrow canon of about one 

 thousand fathoms, with a shallow connecting ridge between 

 Santa Cruz and Porto Rico. 



The mountain chain, of which San Domingo, Porto Rico, and 

 the Virgin Islands form the summit, has a steep slope to the 

 north, dropping at the eastern extremity, at a distance of less 

 than one hundred miles, to a depth of three thousand fathoms. 

 The two-thousand-fathom line runs alono^ the eastern edg-e of 

 the Bahama Bank, a distance of less than fifteen miles, and 

 forms a steep edge to that face of the bank, while the thousand- 

 fathom line cuts off a few isolated outside patches, and extend- 

 ing far to the westward, beyond the Windward Passage, forms 

 the mouth of the funnel of the old Bahama Channel. 



The southern slope of this part of the West India Islands 

 chain is fully as steep as the northern. At the western ex- 

 tremity of San Domingo, the southern line of mountains extends 

 toward Jamaica, and that part of the chain is deflected to the 



