A PRELIMINARY REPORT ON CLAYS OV VLORIDA 189

mately forty feet. Water transportation via the St. Marys River is available at this point.
 Other brick plants have been operated about seven miles east of Callahan, at Yulee, and at Fernandina.

 OKALOOSA COUNTY
 Okaloosa County is located in western Florida and extends from the Florida-Alabama line to the Gulf of Mexico. The formations consist of the Alum Bluff in the northeast corner and undifferentiated sands and marls in the remainder of the county. Much of the surface is covered by a sand-clay mantle. No clays adapted to manufacturing uses are known in the county.

 OKEECHOBEE COUNTY
 Okeechobee County lies just north of Lake Okeechobee and east of the Kissimmee River. Pleistocene sands and marls form the surface materials. No clays of commercial importance are known to.be present.

 ORANGE COUNTY
 Orange County is situated in the east-central part of the peninsula and lies within the Lake Region. Its surface formations are Alum Bluff and Pleistocene sands and marls. Reddish and brownish sandy clays suitable only for sand-clay roads are of widespread distribution in the county.
 A bluish-gray clay occurring about two miles east of Clarcona has been washed and found fairly satisfactory for some grades of work at the Orlando potteries. The overburden ranges from one to five feet of sand and the clay averages abouf three feet in thickness. The nearest railway is about two miles. The unwashed clay has the following physical properties:
 Physical Properties of the Clarcona Clay (Lab. No. o-6o).
 Plasticity, judged by feel........... Excellent.
 W ater of plasticity................. 22.50%
 Pore water ........................ 0.16%
 Shrinkage water .................. 22.34%
 Linear air shrinkage............... 6.90%
 Volume air shrinkage............... 19.80%
 Modulus of rupture, average........ 133.1 pounds per square inch.
 Slaking test ....................... 3 days.