88 FLORIDA GEOLOGICAL SURVEY ELEVENTH ANNUAL REPORT. 
The following table includes a summary of the formations of 
this area as they are at present defined. All of these formations 
fall within the latest of the large divisions of geologic time, the 
Cenozoic. The earliest or oldest formation is placed at the bot- 
tom of the table, the latest at the top. 
Pleistocene. The presence of Pleistocene formations has not been dem- 
onstrated, although deposits of this age may come in near 
the coast. 
Pliocene. The presence of fossiliferous marine Pliocene has not been de- 
termined within this area. 
Pliocene-Miocene. Uppermost formation of a part of this area consist- 
ing of coarse sands and streaks and lenses of clay. 
Miocene. Choctawhatchee formation: Shell marls and sands. 
Alum Bluff formation : Calcareous sands, clays and shell marls. 
Oligocene. Chattahoochee formation : Impure clayey limestones. 
Marianna formation : Chiefly pure limestones. 
Eocene. Ocala formation : Pure white limestones. 
Claiborne formation : Glauconitic sands. 
DESCRIPTION OF FORMATIONS. 
EOCENE. 
CLAIBORNE FORMATION. 
Deposits of Claiborne age which are extensively developed in 
Alabama and Georgia are regarded as probably extending a short 
distance into Florida. If so these are the oldest formations ex- 
posed at the surface in the State. The extension of the Claiborne 
to the Florida State line on the Choctawhatchee River was re- 
corded by Dr. E. A. Smith in 1894.* The exposures on this 
river were examined by the writers in 1915. On the left bank of 
the Choctawhatchee River for a short distance below the Florida- 
Alabama State line there is exposed a green glauconitic sandy lime- 
stone. As much as about 8 feet of this rock shows at low water 
stage, the upper five feet being more sandy than that at a lower 
level. Fossils in this rock are rare, the only species obtained in 
Florida being a small Pecten. Lithologically this rock is similar 
to the much more fossiliferous Claiborne deposits exposed at Gen- 
eva, Alabama, on both the Choctawhatchee and Pea rivers, and 
* Report on the Geology of the Coastal Plains of Alabama, Geol. Surv. of 
Alabama, 1894, pp. 673-675. 
