THE BAHAMA ISLANDS 7 



process is extremely slow at best, and can only be detected by careful measure- 

 ment extending over long periods of time." 



Prom this resume it will be seen that four views have been held at various 

 times by those who have studied the geology of the Bahamas. Nelson con- 

 cluded that the Islands were stationary; Northrop, that they were probably 

 rising ; Agassiz, that they had been depressed ; and lastly, Shattuck and Miller, 

 that the Islands had undergone a former elevation ; followed by a more recent 

 depression, which in turn had given place to a still later elevation; but as to 

 whether the Islands are now stationary or experiencing a change in level no 

 opinion was expressed. 



PHYSIOGRAPHIC FEATURES. 



The physiographic features of the Bahama Islands fall into two groups, a 

 submarine and a subaerial. Those belonging to the first division are largely 

 hidden from direct observation, beneath the surface of the ocean, and have been 

 only roughly ascertained by means of the sounding-line. Those of the second 

 division are everywhere open to observation and constitute the topographic fea- 

 tures of the Islands. 



Submarine Division. 



The Bahama Islands rest on a submerged platform which rises on all sides 

 abruptly from the surrounding depths of the ocean. This platform is the most 

 significant physiographic feature of the Bahama Islands, and will be considered 

 first in relation to surrounding regions ; second, in regard to its own contour 

 and slope; and third, in regard to the character of its surface. 



Relation with surrounding regions. — Between the great land-masses of 

 North and South America there is a region of land and water including southern 

 Mexico, Central America, the islands of the West Indies, the Gulf of Mexico 

 and the Caribbean Sea, which has long been a puzzle to geographers and geolo- 

 gists. As a result of a vast amount of tedious sounding it has finally been 

 ascertained that the American Mediterranean, as this region is appropriately 

 called, is divisible into three great basins. In the northwestern portion is a 

 huge depression which is filled by the Gulf of Mexico; in the southeast a still 

 greater one is occupied by the Caribbean sea; while between them a third, 

 deeper than either of the others, holds the waters which lie between Yucatan' 

 and Cuba. These three basins not only are separated from each other by broad 

 banks which rise like partitions between them, but they are also cut off from 



