EASTERN AND SOUTHERN UNITED STATES. 
137 
Florida. 
The geological relations of the rocks of this State, as well as the history of .then- 
exploration, are clearly set forth in a paper by Prof Eugene A. Smith, entitled : “ On 
the Geology of Florida,” and published in the American Journal of Science, 3d series, 
vol. 21. It is there conclusively shown that the -views entertained by Louis Agassiz 
and Joseph Le Conte as to the recent and coralline formation of the peninsula are 
essentially erroneous, and that, as a matter of fact, the greater portion of the peninsula 
dates back to the Oligocene period, or to the period of the Orbitoitic limestone. 
Substantial proof of this fact is afforded by the numerous localities where fossils — 
very largely the genus Orhitoides itself, with the species 0. Mantelli, and others — dis- 
tinctive of the Orbitoitic formation have been discovered, as in the stretch betw-een 
Tampa Bay, where they were first identified by Conrad nearly forty years ago, and 
the Georgia line. Beside the localities where fossils of this class were determined by 
me to characterize the rock formation, to which reference is made by Dr. Smith, 
other areas of a like nature have since been discovered, and most notably, perhaps, 
the territory about Cedar Keys, where, from rock specimens submitted to me by Mr. 
Joseph M'illcox, I was enabled to detect the existence of a true Nummulitic rock, or 
a rock made up very largely of the united tests of principally one form of Nummulite.* 
This rock, which is found in the immediate neighborhood of the Cheeshowiska River, 
in Hernando County, about four miles from the coast, contains in addition to the mass 
of Nummulites of which it is so largely made up, a sufficient abundance of Orhitoides, 
and also the foraminiferal form which Conrad described as Cristellaria rotella, but 
which I have referred to Opercidina.f From a locality further to the north, Waca- 
sassa in I.cvy Co., rock specimens submitted to me were found to contain a number 
of Echinoids of the genus Euspatangns,X referable specifically to the forms described 
by Cotteau from the Oligocene deposits of the island of St. Bartholomew, as E. Clevei 
and E. AntiUarum.% 
From what has preceded, taken in connection with the observations that have been 
made in western as well as in northern Florida, it may safely be conceded that the 
underlying rock of the greater portion, if not of nearly the entire State, is of Oligocene 
age, and therefore no countenance is given to the theory which assumes a recent for- 
“ Claibomian ” ao'p The Miocene tract, whose rock masses are stated to closely resemble the Grand Gulf sand- 
stone of the Gulf '’states, is claimed to have a much broader extension than we have above indicated, for if the 
outcrops observed in Irvin and Dodge Coimties really belong to the period in question, which m.ay perhaps still 
be considered as not yet satisfactorily established, then the imier boundarj' of the formation will be removed 
from the coast by about 130 miles. [The Miocene area on the map is according to Loughndge.] The rocks 
have a slight dip to the southeast, and on the Oconee, where they have been traced for a distance of 00 nnles, 
their develoinneiit is stated to be 200 feet. . t^i .i i xr. a 
* Nummuhtes milroxi. Heilprin, “On the Occurrence of Nummulitic Deposits m Florida, and the Asso- 
ciation of Nummulites with a Fresh-water Faima,” Proc. A. N. S., July, 1883. 
t Tlic .species is not impossibly identical with 0. cmnplanata. 
t The generic determination kindly made for me by Prof. Alexander Agassiz. 
§ K. Svens. Vet.-Akad. Ilandl., 1874. 
