NATURAL HISTORY OF THE BERMUDAS. 395 



This foundation proves to be a sub-marine mountain, 

 rising abruptly from a base of only 120 miles in 

 diameter, as verified by the visit of H.M.S. " Challen- 

 ger" in 1876. "This peak," says Sir Wyville Thomp- 

 son, in his " Voyage of the ' Challenger,' " " runs up, a 

 solitary cone, to a height about equal to that of Mont 

 Blanc, possibly a volcanic mountain, comparable in charac- 

 ter with Pico in the Azores, or the Pic of Teneriffe." 



The " Challenger," between Halifax and Madeira, took 

 four soundings in the Atlantic, the deepest being off the 

 Bermudas, where the lead sank four and a half miles. 



The southern margin of the reef lies in north latitude 

 32° 85', and west longitude 64 51'. 



How many centuries rolled into the past while this 

 stupendous monument of coral was being built we have no 

 evidence to guide us. Innumerable sea birds were probably 

 the only occupants of the reef at this period ; while mollusca 

 and other shell-fish would abound upon its ample surface. 

 Such must have been the existing state of this marine 

 prodigy at this time. 



We now approach the wonderful changes caused by 

 nature : of tropical storms, passing from the equator to 

 arctic regions, revolving on their onward course, as at the 

 present day, and causing tremendous seas to break, first 

 upon the southern margin of the reef, and veering with the 

 gale to other points of the compass, taking their departure 

 with mighty breakers upon the northern barrier of the 

 reef. 



In these violent disturbances of nature, millions upon 

 millions of Crustacea perished ; their shells being pulverised 

 by the heavy seas, and their particles washed upon the reef 

 would assume the form of small heaps. These would dry 

 under the powerful influence of the sun, and be driven by 

 passing winds in various directions, particularly towards the 

 southern margin of the reef. 



