158 FLORIDA GEOLOGICAL SURVEY-I5TH ANNUAL REPORT

 Fire tests:
Temperature. Linear Shr. Absorption. Porosity. Color.
 Per Cent. Per Cent. Per Cent.
 9500C. 0.5 12.86 31.50 Brick red.
 1050 0.5 12.20 30.50 Brick red.
 1150 0.5 11.36 29.70 Brick red.
 1190 0.5 11.27 29.40 Brick red.
 1230 0.5 10.75 28.30 Brick red.
 1310 1.0 10.15 28.20 Brick red.


 FRANKLIN COUNTY

 Franklin County borders the Gulf of Mexico and lies between the Apalachicola and Ocklocknee rivers. The surface exposures consist of sands and marls, but no clays of any commercial importance are known.
 GADSDEN COUNTY
 Gadsden County lies in the northwestern part of the State between the Apalachicola and Ocklocknee rivers and the formations exposed are the Chattahoochee, Alum Bluff, and a surface mantle of Pleistocene or Recent. The Chattahoochee, while primarily a limestone, contains some interbedded clays and residual clays also abound in this formation. The Alum Bluff consists of beds of sand, clay and fuller's earth. In addition to these clays there are some more recent flood-plain clays along the Apalachicola and Ocklocknee rivers.
 Deposits of sand-clay road material are common in the county and essentially all the roads in the county are made of this material.
 Very few of the Chattahoochee formation clays, either the sedimentary or the residual ones, are of any value for manufactured products. In general their working qualities are poor. Most of them are calcareous, have a high shrinkage, warp and crack badly and have poor plasticity. A sample which may be considered as illustrative of the great mass of Chattahoochee clays in the county was taken at an exposure in the roadside about two miles east of the State Hospital near Chattahoochee. This is a grayish-green jointed clay of low plasticity, containing a few flint concretions and geodes. It is worked only with difficulty. This clay is not appreciably calcareous. In a burned condition it is suited only for railroad ballast. A few of its physical properties are: