PETROLEUM POSSIBILITIES OE FLORIDA 119 
Log of City IVell No. 6, Clearwater, Fla., Drilled by Porter May 
Depth in feet. 
Sand . 0- 16 
Blue clay . 16- 26 
White rock .. 26- 73 
Hard flint.. 73- 83 
White coral .......... 83- 94 
Hard, gray rock .. 94- 98 
Gravelly rock .............. 98-103 
Fuller’s earth ( ?). Casing set at 112 feet. . .. 103-112 
Hard, white rock .... 112-168 
Flinty rock ....... 168-176 
Blue clay rock .. 4 . 176-179 
Soft, white rock .... 179-183 
Coarse, porous rock .... 183-188 
Hard rock . 188-215 
Soft, gray rock . 215-238 
Hard rock . 238-245 
Gray, porous rock . 245-287 
Water rock 112 to 245. No increase in water after 245. 
. POLK COUNTY 
Polk is one of the large counties of southern Florida. The central 
part of this county is in the uplands of the Lake Region, while 
the western part of the county includes the principal phosphate-pro¬ 
ducing section of the state. The phosphate beds of commercial value 
are found chiefly in the Bone Valley formation, which is of Pliocene 
age. The Bone Valley formation in turn rests upon the Alum Bluff 
formation, which is here also more or less phosphate bearing. The 
phosphate of the Bone Valley formation, in fact, represents more or 
less enriched concentrates from the Alum Bluff formation. 1 In some 
of the stream beds are Pleistocene and Recent deposits containing phos¬ 
phate derived from the older formations. 
The surface material in the lake region, consisting of sands and sandy 
clays, are non-fossiliferous and are of undetermined age. In the east¬ 
ern part of the county, near the Kissimmee River, the Pleistocene beds 
of the Kissimmee Valley come into the section. 
The log of a well near (Tiger Bay) Ft. Meade, in this county, has 
already been given. (See Tampa Area.) 
1 Sellards, E. H., Fla. Geol. Surv., 7th Ann. Rept, p. 31, 1915. 
