210 FLORIDA GEOLOGICAL SURVEY-I5TH ANNUAL REPORT

 Fire tests:
 Temperature. Linear Shr. Absorption. Porosity. Color.
 Per Cent. Per Cent. Per Cent.
 950*C. 1.2 18.95 38.00 Cream.
 1050 1.3 19 78 38.50 Cream
 1150 1.3 17.30 38.30 Cream.
 1190 1.2 17.42 38.50 Cream.
 1230 1.3 18.22 35.75 Cream.
 1310 1.3 15.20 35.00 Cream.
 1430 1.7 15.58 34.80 Cream.

 A brick plant was formerly operated about one-half mile south of the station at DeLeon Springs. The Volusia County Commissioners have opened a pit to obtain marl in the same deposit, one-quarter mile farther southward. The deposit consists of two feet of sand, four feet of gray, plastic clay. The clay is underlain by marl. It underlies an extensive area in the vicinity of DeLeon Springs. This clay may be used for a good grade of common structural materials. It has the following physical properties:
 Physical Properties of Folusia County Shell and Marl Clay, DeLeon Springs (Lab. No. 0-70).
 Plasticity, judged by feel........... Excellent.
 W ater of plasticity................. 20.10%
 Pore water ....................... 1.90%
 Shrinkage water .................. 18.20%
 Linear air shrinkage............... 8.0 %
 Volume air shrinkage.............. 25.7 %
 Modulus of rupture, average........ 532.3 pounds per square inch.
 Slaking test ....................... 5 m inutes.

 Fire tests:
Temperature. Linear Shr. Absorption. Porosity. Color.
 Per Cent. Per Cent. Per Cent.
 950'C. 0.5 14.69 34.50 Brick red.
 1050 0.5 14.30 34.00 Brick red.
 1150 1.0 14.29 32.70 Brick red.
 1190 1.0 14.33 31.10 Brick red.
 1230 1.5 13.09 31.80 Brick red.
 1370 1.5 12.16 32.25 Brick red.

 The same conditions prevail a half-mile southward on the property of George LaFevre, except that the clay has a thickness of five feet and an overburden of only a few inches. The quality of the clay is the same. Several pits have been opened and a railway spur built to them. The clay is now being removed as an overburden in working the marl.
 Another brick plant was formerly operated at Deep Creek, three miles north of DeLeon Springs. This deposit consists of an overburden