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.* 
Tho 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.f 
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. 47—82. 
t Agassiz, A., “ Reconnaissance of Bahamas,” p. 7. 
