A PRELIMINARY REPORT ON CLAYS OF FLORIDA 185

 Chemical Analysis of W. J. McLaughlin Clays, A. M. Henry, Analyst.
 Lab. Numbers.
 0-19 0-72
 Silica (Si02) ....................................... 54.95 34.55
 Iron and Aluminum oxides.......................... 11.54 5.75
 Calcium oxide (CaO) ............................. 9.10 24.40
 M agnesium oxide (MgO) ........................... 5.54 6.63
 M oisture at 100*C. .................................. 4.37 1.70
 Both samples contain considerable organic matter.
 85.50 73.03

 The Bartow clay occurs in the northeastern part of the county. (For a discussion of Bartow clay see Polk County, page 195.) This
 area, however, is not accessible to transportation.
 Fuller's earth occurs in the Alum Bluff formation and is mined at Ellenton on the north side of the Manatee River.

 MARION COUNTY
 Marion County is situated in the central part of the peninsula. Its western half is underlain chiefly by the Ocala and the eastern half by the Alum Bluff formation. Numerous outliers of the Alum Bluff and Alachua formations are found in the Ocala formation. The eastern part of the county extends to Lake George in the St. Johns River valley and includes flood-plain deposits. Marion County is partly in the Lake Region, and numerous lacustrine deposits, chiefly in sink-holes, are found locally.
 Residual clays from the Ocala limestone are of common occurrence but few of them are of commercial importance. The losses from warping and cracking in drying and firing these clays are often excessive. In the northwestern part of the county, just across the county line from Williston in Levy County, are some residual clays having the same properties as the Williston School clay. (See Levy County, page 180.) Calcareous residual clays are found near Dunnellon, Summerfield, and Kendrick.
 Sedimentary clays underlie extensive areas in the eastern part of the county. One of these is found in the region about Burbank. Here the clay is over eighteen feet deep and overlain by about one foot of sandy soil. The exact depth of the clay is not known.
 This clay is red-burning, has good plasticity, works well and dries without difficulty. It may be used for common brick, hollow-block ware,