308 E. A. Smith—G@eology of Florida. 
from swiftly flowing to nearly stagnant waters, might have 
been interrupted by such subordinated and local oscillations as 
would have caused the formation of deposits like the Port 
Hudson and the Leess. 
6th. Following the submergence during the Champlain 
period, was a re-elevation, which brought up the peninsula 
with La ianiee ed its present configuration. 
Evidences on this point are to be found in the Post-Pliocene 
deposits described by Conrad, Tuomey and others, as border- 
ing more or less uniformly, the eastern, southern and western 
eae which has been advanced in connection with the geo- 
ogical history of the Gulf region. ; 
In view of the absence of marine formations of Middle and 
Upper Tertiary age along the Gulf coasts of Mississippi, Louisi- 
ana and Texas, and to account for the formation of the beds of 
the Grand Gulf group, without remains of marine life, which 
overlie the Eocene of those coasts, Professor Hilgard has 
been brought to the conclusion that during a part or the whole 
of the interval between the Vicksburg and Champlain periods, 
the Gulf was by some means isolated from the Atlantic, and 
thus converted into a fresh- or brackish-water basin, and he also 
further suggested that this was brought about by a land con- 
nection between Florida and Yucatan. 
is hypothesis has been freely discussed in this Journal and 
elsewhere, and a further discussion of it would be to some ex- 
tent foreign to this article, since the facts observed by me and 
recorded above, beyond proving that Florida during the Mid- 
dle and later Tertiary periods, was part of the firm land of the 
continent, and was probably then nearly twice its present 
* We can only speculate as to when and how the change from the broad penin- 
sula of the Middle and later Tertiary periods, to the present narrow form took 
: o possibilities suggest themselves, viz: 1. At the beginning of the 
Champlain period, a more profound depression of the western as compared with 
eastern half of the broad Tertiary peninsula; or 2. At the end of the period 
of submergence, the shifting of the main axis of elevation eastward, would have 
brought about this result, 
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