GEOLOGY OF BERMUDA 185 



depths, yet indicating that they represent a range of drowned 

 mountains. 



According to Professor Verrill it is now generally admitted 

 that Bermuda is the flattened and greatly eroded summit of a 

 vast submarine volcano, and he thinks it most reasonable to 

 suppose that its last activity corresponded in time with the 

 last great volcanic eruptions of the nearest American main- 

 land. This, as he remarks, would imply that the Bermuda 

 volcano was formed or completed during the Triassic Period 

 or at its close. Immense outbursts of volcanic material took 

 place all along the eastern coast of America at that time, 

 giving rise to enormous trap-dykes. In Nova Scotia these 

 dykes have a nearly north and south direction, and they may 

 have had some direct relation with the volcano of Bermuda. 

 It is estimated that the latter had a height of about 15,000 feet.* 



The whole surface structure of Bermuda reminds us vividly 

 of the Bahamas. The latter owe their configuration to the 

 same process of waste which has been going on during their 

 subsidence. The coral reefs surrounding the Bahamas form 

 but an insignificant part of the topography of the islands. 

 The same aeolian rocks as in Bermuda cover all the visible 

 parts of the Bahamas, and we find an intercalation of similar 

 red earth. Altogether there is, as Professor Agassiz points 

 out, clear evidence of the comparatively recent subsidence 

 of at least three hundred feet of the Bahama Bank.j- 



A slightly greater elevation would have had the effect of 

 shutting out the Gulf Stream from the northern Atlantic, 

 for it now pursues its swift northern course through the 

 shallow channel lying between the Bahama Bank and Florida. 

 Now it is interesting to note that the ancestral Gulf Stream 

 did not flow where it does now, but across northern Florida, 

 thus separating the northern from the southern portion of the 

 peninsula. Not only were northern Florida and Georgia sub- 

 merged. Tertiary marine deposits are known even as far north 

 as New Jersey. The sea covered a vast area of the present 

 southern Atlantic States. That a strong current flowed 

 through the channel of north Florida is evidenced by the fact 



* Verrill, A. E., "Bermuda Islands Geology," XII., pp. 4782. 

 t Agassiz, A., " Eeconnaissance of Bahamas," p. 7. 



