174 
FLORIDA GEOLOGICAL SURVEY—I 5 TH ANNUAL REPORT 
In a series of tests made by the United States Bureau of Standards 
in 1914 a clay from near Thomas City was included. Its qualities indi¬ 
cate that it may be used for a common building-brick. Its physical 
properties are i 1 
Physical Properties of Thomas City Clay (Bureau of Standards Sample No. 21). 
Plasticity. Good. 
Water of plasticity. 28.9% 
Linear air shrinkage. 6.0% 
Fire tests: 
Temperature. 
Linear Shr. 
Per Cent. 
Porosity. 
Per Cent. 
Color. 
950°C. 
0.22 
35.6 
Buff. 
1020 
34.0 
Buff. 
1050 
32.2 
Buff. 
1080 
33.4 
Buff. 
1110 
1.09 
33.8 
Buff. 
1140 
33.6 
Buff. 
1170 
33.6 
Buff. 
1200 
33.7 
Buff. 
1230 
0.55 
32.8 
Buff. 
1260 
34.4 
Buff. 
1290 
33.7 
Buff. 
1320 
0.49 
33.5 
Buff. 
LAFAYETTE COUNTY 
Lafayette County lies in the northwestern part of the peninsula and 
is underlaid by the Ocala and Chattahoochee formations. Both of these 
contain clays to some extent but none that may be considered of com¬ 
mercial importance. 
lake county 
Lake County lies in the central part of the peninsula in the heart 
of the Lake Region. Its surface formations are essentially all sand-clays 
in which there is a high percentage of coarse, sharp, angular sand and 
some gravel with a good, reddish, clay bond. This material is very 
desirable for sand-clay road material, but is not adapted to other uses. 
Extensive deposits of sedimentary kaolins also occur in Lake Coun¬ 
ty and are discussed in detail in a subsequent chapter. (Chapter IX.) 
Numerous lacustrine deposits also occur in Lake County. These are 
usually of limited areal extent and relatively thin. 
One of these occurs on the property of B. H. Nuckolls near Umatilla 
(Sec. 1, Twp. 18 S., R. 26 E-)- "This is a blue clay with a bright-red mot- 
iSellards, E. H., Report of Clay Tests for Paving Brick, Florida Geological 
Survey Press Bulletin No. 7, 1915. 
