170 
ORIGIN OF LIFE IN AMERICA 
the tropical flora had gained admission to southern Florida 
during its supposed land connection with the West Indies 
in lower Pleistocene times, it would have been all destroyed 
again subsequently. If Dr. Spencer’s theory were substan¬ 
tiated, the tropical flora of Florida should owe its origin to 
accidental transport. 
When Dr. E. A. Smith * visited Florida in 1880 he made 
some geological notes on the peninsula which do not bear out 
Dr. Spencer’s views. He maintains that Florida was elevated 
nearly to its present height above sea-level after the deposi¬ 
tion of the Vicksburg limestone, that is to say, after the 
Eocene Period, and that this elevation persisted until the 
Pleistocene, when the country was partly submerged. 
No one, however, has done more practical geological work 
on the peninsula than Dr. Dall,f who, in his monumental 
treatises on the Tertiary fauna of Florida, presented us with 
a masterly survey of the past life of that portion of the United. 
States. His opinion on the geological history of Florida 
deserves, therefore, most serious consideration, and it may be 
stated at onc'e that he is strongly opposed to Dr. Spencer’s 
views, declaring them to be “ incompatible with every geologic 
and palaeontologic fact of South Florida which has come to 
my knowledge.” 
As the result of his researches Dr. Dali expresses the 
opinion that the peninsula of Florida, together with the larger 
Antillean Islands and the Middle American highlands, were 
uplifted, and the two Americas thus united in Oligoeene 
times, that is to say, during the early part of the Tertiary 
Era. 
Professor Gregory ij; had a similar idea, except that he did 
not specify any geological period. 
When Florida again became disconnected from this Antil¬ 
lean continent is not clearly stated, but Dr. Dali thought 
that it formed a peninsula of the southern continent as it 
does now of the northern. Florida, according to the same 
author, became definitely united to North America towards 
* Smith, E. A., “ Geology of Florida,” p. 306. 
t Dali, W. H., “Tertiary Fauna of Florida,” IV., p. 1546. 
t Gregory, J. W., “Geology of West Indies,” p. 305. 
