294 Ei. A. Smith— Geology of Florida. 
clear distinction between the marl beds near the shore and the 
more ancient marls, and limestones occurring farther inland, 
although he does not undertake to decide upon the geological 
age of either. 
His remarks upon the distribution of the more ancient lime- 
stone in the interior, where it forms ‘the bottoms of the many 
ponds and lakes,” are particularly interesting, in the light of 
my recent observations. 
We come next to an important paper by T. A. C 
“ Observations on the Geology of a part of East Florida 
In this, the author describes certain Post-Pliocene deposits on 
the St. Johns River and at Tampa Bay, occurring ten or fifteen 
feet above high tide; proving a considerable elevation of the 
whole Florida peninsula in the Post-Pliocene period, a move- 
ment which clearly raised all the Florida Keys above water. 
The greater part of the paper is devoted to a description of the 
Keys, with notices of the shells occurring on them and in the 
neighboring waters. At Tampa Bay and southward along the 
shore, he notices the Post-Pliocene deposits, but calls attention 
also to an underlying limestone occurring at Fort Brooke and 
as far inland as the Falls of Hillsboro River. This limestone 
onrad : 
NX 
, &e. 
ry 
probably the prevalent limestone of Florida will be included in 
this division.”+ This rock, he states, extends throughout the 
peninsula, as far south as Tampa Bay; and both the eastern 
and western shores are covered with a Pleistocene formation 0 
recent species of shells, and remains of mammalia. The eleva- 
tion of East Florida above the sea level is so inconsiderable 
that all or nearly all of it must have been submerged at the 
time the Post Pliocene species were existing, and therefore 1ts 
elevation was contemporaneous with that of the Keys, which 
line its eastern, western and southern shores.” ; 
We have here the first definite attempt at the determination 
of the age of the Florida limestone. js 
n volume ii of this Journal, 2d series, p. 399, Conrad gives 
“Descriptions of new species of Organic remains from the 
Upper Eocene Limestone of Tampa Bay.” In this article he 
* This Journal, IT, ii, 36 et seq. 
+ In more recent papers by Conrad these views are slightly modified. 
+ In this connection, see table of altitudes appended to the present article, and 
Dr. Burnett’s letter below. 
