56 
FLORIDA STATE GEOLOGICAL SURVEY. 
from Ocala, by Le Conte, as early as 1861, 1 and subsequently the observation has 
been confirmed by Smith. Specimens of this rock have been collected by Will- 
cox at Martin station, Marion County, about 8 miles north of Ocala, where the 
rock is very cherty; and at Jarves’ Spring, on the southern border of Pasco 
County; at Fort Foster, on the North fork of the Hillsboro River, where, as in 
many other places, relics of the old Miocene beds overlie it. Several of the 
localities referred to by Heilprin must remain for the present on the doubtful 
list, but among them should hardly be counted the islet at the mouth of the 
Homosassa River, from which Mr. Willcox obtained the Pygorhynchus 
{Ravenelia) gouldii Bouve, a small echinoderm originally described from the 
buhrstone (ante-Claibornian) of Georgia. 
It will be seen from this quotation that later investigations indicate 
that the limestone at some of the localities mentioned by Smith is not 
all of Vicksburgian age. However, this should not be regarded as 
detracting from the value of the earlier work, for with the increase 
of knowledge it is inevitable that formation lines should be shifted 
and that new formations should be discriminated. 
Miss Maury’s 2 summary of the Vicksburgian indicates that it 
forms a large part of the country rock in north central Florida, and 
she cites many of the localities mentioned by Dali and Bailey. She 
mentions especially the exposures seen in the vicinity of Gainesville, 
which are surrounded by rocks belonging to the subdivision here 
called Apalachicola group. Attention is also called to the occurrence 
of gypsum, which is regarded as the result of the action of sulphur 
on calcium carbonate, and the occurrence of phosphate rock resulting 
from an analogous chemical action. 
During the progress of recent field work the occurrence of the 
Marianna limestone was noted at Natural Bridge in north central 
Walton County, but there is no indication that it reaches the surface 
west of this county; indeed, from well records and exposures of other 
formations, there is every reason to believe that in Escambia and Santa 
Rosa Counties, this formation lies some hundreds of feet below the 
surface of the upland. 
East of Marianna the formation is exposed at several localities 
where it presents considerable variation in its lithologic characteristics. 
At some of these localities it is a soft, porous, white limestone, while 
in other places it is a tough, dense, gray limestone. However, some 
of this difference in texture may be accounted for by the fact that 
the rock hardens upon exposure to the air, and it is perhaps a sig¬ 
nificant fact that the hard, gray limestone usually occurs at natural ex¬ 
posures while the soft, porous rock is seen in the quarries. 
1 Am. Jour. Sci., 2nd ser., 1861, vol. xxi, pp. 1-12. 
? Maury, Carlotta Joaquina. The Oligocene of western Europe and southern 
United States. Bull. Amer. Paleont., vol. iii, No. 15, 1902, pp. 45-46. 
