50 On the Gulf Stream and the Keys of Florida. 
f ‘Tampa are Eocene Tertiary. Supposing this to be a fact, 
it 
more than sixty or seventy feet thick: To this may be added in 
the case of coral islands from ten to fifteen feet for material accu- 
mulated above the sea level by the agency of waves. If there 
is no subsidence, therefore no coral formation can be more 
than eighty feet in thickness. Now, nothing can be more certain - 
than that there has been no subsidence whatever of the sea- 
bottom upon which grow the reefs of Florida, for otherwise the 
extension of the peninsula by means of coral agency would have 
en impossible. It necessarily follows, therefore, that the coral 
formation of Florida, whether upon the main land, or upon the 
eys, or upon the living reef, can no where be more than seventy 
or eighty feet thick. In other words, it is evident that Florida 
and the keys are only faced or encrusted with coral formation. 
Tf, then, corals have been the only agents in this work, if the sea 
bottom has remained substantially unchanged during the whole 
time the coral work was progressing, it is evident that the sea, 
for the enormous distance of five degrees of latitude, viz: from 
St. Augustine to the present reef, was nowhere more than sixty 
or seventy feet in depth, and Florida must have been represented 
_ by a tongue of shoal water three hundred miles in length—a cir- 
cumstance possible, certainly, but so improbable that it behoves 
those who maintain the theory that coral alone has formed the 
peninsula to account for it. . 
