A PRELIMINARY REPORT ON CLAYS OE ELORIDA 
221 
GEOLOGIC AGE 
The age of the sedimentary kaolin is not known. Matson 1 places 
it provisionally in the Pliocene with a query. Ries 2 lists it under the 
Oligocene clays, but explains that its position in the Tertiary system is 
not known. Watkins 3 says, “geologically, this area belongs to the Apa¬ 
lachicola group of Oligocene age.” The formations in the general re¬ 
gion about the sedimentary kaolin occurrences were formerly included 
in the Apalachicola group of Oligocene age. At present, however, the 
Alum Bluff formation, formerly considered a part of the Apalachi¬ 
cola group, is regarded as Miocene. This does not necessarily mean 
that the sedimentary kaolin is of the same age. 
Sellards 4 says: “The place of the clay-bearing formation in the 
geologic time-scale is difficult to determine owing to the complete 
absence of fossils. It overlies the Oligocene limestones. There is also 
some reason for believing that it lies at a stratigraphic level higher 
than the fuller’s earth beds and hence is not older than the Miocene. 
However, inasmuch as no one of the later formations is found over- 
lying this formation, it is not possible to fix its age more definitely.” 
The fact that the clay formation is found overlying the fuller’s 
earth confirms the belief that it is at least younger than that stage of 
the Alum Bluff when the fuller’s earth was deposited. 
ORIGIN 
The origin of the sedimentary kaolin has not as yet been satis¬ 
factorily explained. The beds are, without doubt, sedimentary, as is 
indicated by the cross-bedding within the clay-bearing sand; by the fact 
that the various substances, such as green clay, fuller’s earth, lime¬ 
stone, etc., underlie the sand; and by the conglomeratic texture and the 
presence of water-worn pebbles in the material itself. This formation 
is apparently everywhere separated from the underlying formations 
by an unconformity. 
1 Matson, G. C., The Clays of Florida, U. S. Geol. Survey Bull. 380, p. 353, 1909. 
2 Ries, H., High Grade Clavs of the Eastern United States, U. S'. Geol. Survey 
Bull. 708, p. 289, 1922. 
3 Watkins, Joel H., White-Burning Clays of the Southern United States, Trans. 
A. I. M. E., Vol. 51, p. 481, 1916. 
4 Sellards, E. H., The Clays of Florida, Journal American Ceramic Society, 
Vol. I, p. 318, 1918. 
