22 
FLORIDA GEOLOGICAL SURVEY. 
ties. It is exposed locally throughout an area extending 
from Pasco County to South Columbia County and locally 
west to the Suwannee River. The largest exposed areas 
lie in Pasco, Hernando, Marion and Levy Counties. 
Lying upon the Orbitoidal limestone and probably con¬ 
formable with it is a thin limestone of similar character 
known as the Ocala Limestone from its typical exposure 
at the Meffert lime kiln at Ocala. These two formations 
make up the Lower Oligocene of Florida. 
The Upper Oligocene formation consists of limestones 
and clays. Over much of the north central and western 
part of the State, these deposits lie at or near the surface, 
forming a thin coating which rests unconformably upon 
an eroded surface of the older limestone. The Suwan¬ 
nee River cuts across them between Hamilton, Columbia 
and Suwannee Counties. They are also cut by the Apa¬ 
lachicola River from Chattahoochee to Bristol. South of 
the Orbitoidal limestone area these late Oligocene forma¬ 
tions crop out along the Hillsboro River, Tampa Bay 
and elsewhere. They doubtless also extend to the east in 
that direction underlying later formations. 
The Miocene deposits, next above, lie along the east 
side of the peninsula from Jacksonville to Lake Worth. 
Deposits representing the same time interval occur in 
west Florida from Tallahassee to Pensacola, lying be¬ 
tween the Oligocene and the coast. Marine Pliocene 
deposits, consisting of marls and shell beds, occur over 
much of the southern end of the peninsula, being best 
exposed along the Caloosahatchee River. Residual and 
river-formed Pleistocene deposits are to be expected 
locally throughout the State. A Marine Pleistocene shell 
rock occurs along North Creek, near Osprey. Similar 
deposits have been reported from other localities. The 
Miami Oolite limestone is apparently the most extensive 
marine Pleistocene deposit in the State. This Oolitic 
limestone is known to reach north to or beyond Ft. Lau¬ 
derdale, forming the eastern boundary of the Everglades 
and dipping to the west. Miami, New River, and other 
