110 
FLORIDA GEOLOGICAL SURVEY-I4TH ANNUAL REPORT 
Johns River, is found Pliocene shell marls, Nashua formation. Un¬ 
derneath these surface materials the Miocene is probably represented 
by shell marls, clays and sands. The Eocene is probably present, al¬ 
though thin, and at less than 200 feet, probably 160 feet at Eustis, the 
Cretaceous is entered. The water wells of this county vary from less 
than 100 to over 500 feet in depth. 
LEE COUNTY 
Lee County, in southern Florida, borders the Gulf of Mexico and 
extends east to the Everglades. In the northern part of the county, 
on the Caloosahatchee River, the Pliocene shell marls (Caloosahatchee 
marls) are exposed. Farther to the south and east, including most of 
the county, the surface formations are Pleistocene sands and fresh¬ 
water limestones. This county extends west and includes the keys and 
islands at the entrance to Charlotte Harbor. On these islands the Alum 
Bluff formation probably lies rather near the surface, being concealed 
by surface materials. The log of a well drilled at Ft. Myers has already 
been given. (See Ft. Myers Area.) 
The dip of the formations in this county is in general to the southeast. 
Some mild folding later than the Pliocene is seen in the marl beds on the 
Caloosahatchee River. 
LEON COUNTY 
Leon County is located in north Florida, east of the Ocklocknee River. 
The oldest formation exposed in this county is the Chattahoochee 
limestone. This formation lies at the surface in the southern part of 
the county and is occasionally exposed in sinks, stream beds, and lake 
basins to the north county line. Overlying the Chattahoochee limestone 
in the northern part of the county are the Alum Bluff sands and clays, 
and this formation in turn is to some extent concealed by surface mate¬ 
rials consisting of red sands and sandy clays of undetermined age. In 
the southwestern part of the county, at Jackson Bluff and elsewhere, 
the Upper Miocene shell marls (Choctawhatchee formation) come into 
the section. 
Water wells have been drilled at Tallahassee to a depth of about 700 
feet. Following is a log of the deepest of these wells. Some samples of 
cuttings from this well are preserved in the Walker Library at Talla¬ 
hassee : 
