A PRELIMINARY REPORT ON CLAYS OE FLORIDA 
111 
outcrops in Jackson and Holmes counties where again it forms local 
residual clay deposits. These residual clays are variable in their physical 
properties. They range in color from a gray or greenish-gray to a 
brown, tan or light buff. Sometimes this range of color will be found in 
a single deposit with the lighter colors at the bottom. They are usually 
fairly plastic though at times somewhat stiff at the surface, becoming 
more plastic with depth. In places they are quite sandy and at times 
contain flint and limestone fragments or calcareous or ferruginous con¬ 
cretions. Red or dark brown-burning clays are the rule, though buff 
ones are found. Most of these clays have a high air- and fire-shrinkage 
and also crack and warp badly in drying and burning. The resulting 
losses are high. The deposits range in depth from a few inches to as 
much as twenty feet, with a slight overburden, and in lateral extent 
often cover as much as sixty or eighty acres or more. Some of these 
clays found in eastern Levy and western Marion and Alachua counties 
are suitable for common brick. None of the Ocala clays are now being 
utilized. 
The Marianna formation (Oligocene) is a thin limestone of limited 
extent in Jackson County. Some very small and local residual clay 
deposits occur in this area. They will not be treated here, however, on 
account of their insufficient size and their calcareous character. 
The Chattahoochee formation, also of Oligocene age, occupies an 
area in the vicinity of the Suwannee and Aucilla rivers, a small area 
on the Ocklocknee River, and a belt in west Florida extending westward 
from the Apalachicola River to beyond the Choctawhatchee River. It 
consists essentially of a very impure, soft argillaceous limestone with 
some interbedded clays and marls. Residual clays result from the weath¬ 
ering of this formation and hence are frequently found in the.areas 
where it is exposed. The clays interbedded with the limestone are 
usually calcareous, greenish to gray in color, break with a slight con- 
choidal fracture, are fairly plastic, but at times stiff and often very 
sticky. The residual clay resulting from the decomposition of the Chat¬ 
tahoochee limestone is a plastic joint clay containing some calcareous 
concretions and geodes. Numerous deposits of it are located in 
Suwannee and Hamilton counties, in western Gadsden County, and in 
Jackson and Holmes counties. None of the Chattahoochee clay is now 
being utilized, although brick plants have formerly been operated near 
