A PRELIMINARY REPORT ON CLAYS OF FLORIDA 113

 The Alum Bluff formation of Miocene age is probably the most widely distributed of any of the formations exposed in Florida, extending in a belt of variable width from northern Okaloosa County eastward to the northern part of the peninsula, thence southward to the Manatee River and the northern margin of the Everglades. It consists chiefly of interbedded sands, gravels, marls and clays, including the fuller's earth, each of variable thickness and extent. These sediments are often cross-bedded indicating conflicting currents. They represent terrestrial, fresh-water and marine shallow-water conditions of sedimentation. The clays are usually thin, sandy, and variable in lateral extent. The Alum Bluff formation doubtless represents conditions of sedimentation not very different from those in operation in Florida at the present time.
 The fuller's earth deposits are confined to 'a limited area in Gadsden and Leon counties, a smaller area in Manatee County, and isolated deposits in Marion and Alachua counties.
 Overlying much of the fuller's earth in Gadsden County are two strata of clay. A section in one of the Floridin Company's mines near Quincy shows the following:

 Soil and surface sand ......................................... 5 feet
 U nconform ity ... ...........................................
 C lay, green, plastic ........................................... 3 feet
 Apparent unconformity ...................................
 Clay, greenish, sandy ......................................... 8 feet
 F uller's earth ................................................

 An exposure on the highway about one mile east of Quincy, however, exhibits only one stratum of clay. This is greenish in color and plastic. In other localities the clays above the fuller's earth are absent. In the vicinity of Quincy this clay has formerly been used for the manufacture of common brick and is very suitable for that purpose.
 In the vicinity of White Springs the Alum Bluff clays are prominent. At the bridge across the Suwannee River the following section was observed:
 Sand and soil (Pleistocene) ................................... 6 feet
 Unconformity ............................................
 G reen, plastic, jointed clay .. ................................. 8 feet
 Sand and m arls .............................................. ?

 An exposure on the White Springs-Lake City highway, about two miles northwest of Lake City, exhibited the following sections: