A preliminary report on clays oe elorida 
177 
LEON COUNTY 
Leon County is located in north Florida east of the Ocklocknee 
River. The Chattahoochee, Alum Bluff, Choctawhatchee and Pleistocene 
formations are exposed at the surface. A surface mantle of a jointed 
sandy clay, probably Pleistocene, covers the entire county. Flood-plain 
clays occur at some points along the Ocklocknee River and lacustrine 
clays are also found in several places. 
Many years ago, before there were railroads to bring better material 
from other localities, bricks were made from sandy red clay just north of 
Tallahassee, and the remains of the yards can still be seen. 
The surface mantle clays occupying the northwestern half of the 
county and roughly co-extensive with the Alum Bluff formation contain 
much coarse sand and some gravel. This material is well suited for 
sand-clay road material. 
The surface material in the southeastern part of the county and 
essentially co-extensive with the Chattahoochee formation contains a 
high percentage of clay. 
An exposure of this clay occurs in a road-clay pit about six miles 
south of Tallahassee on the Woodville road and just north of the Wakul¬ 
la Hammock. The thickness of this deposit is not known, but more than 
five feet are exposed. It is overlain by about eighteen inches of surface 
sand and soil. This clay may be used for a fair grade of common brick, 
but as it retains a porous texture even at cone 16 , it cannot be used for 
a vitrified product. It has the following physical properties: 
Physical Properties of the Woodville Road Clay (Lab. No. 0 - 5 ). 
Plasticity, judged by feel... 
Water of plasticity.. 
Pore water. 
Shrinkage water. 
Linear air shrinkage. 
Volume air shrinkage. 
Modulus of rupture, average 
Slaking test. 
Fair. 
31.40% 
1.33% 
30.07% 
11.3 % 
29.8 % 
225.6 pounds per square inch. 
24 hours. 
Fire tests: 
T emperature. 
Linear Shr. 
Per Cent. 
A bsorption. 
Per Cent. 
Porosity. 
Per Cent. 
Color. 
950°C. 
1.2 
17.30 
35.00 
Buff. 
1050 
1.7 
18.20 
35.00 
Buff. 
1150 
4.7 
14.00 
27.80 
Buff. 
1190 
5.7 
13.20 
27.80 
Buff. 
1230 
6.2 
11.40 
25.90 
Gray. 
1310 
6.7 
10.00 
19.30 
Gray. 
1370 
6.7 
9.20 
19.90 
Gray. 
1430 
7.7 
8.50 
18.60 
Gray. 
