GEOLOGY BETWEEN APALACHICOLA AND OCKLOCKNEE RIVERS. 23 
PHOSPHATE. 
No workable phosphate beds are known in this area. The 
Alum Bluff formation, however, carries some phosphate, although 
probably not in commercial quantities. The type locality of this 
formation is at Alum Bluff on the. Apalachicola river in Liberty 
county. The bluff here consists chiefly of gray phosphatic and cal- 
careous sands. A detailed section of this bluff will be found on 
page 45 of this report. Of special interest in connection with a 
discussion of phosphate in this area is the. fact that the Alum Bluff 
formation, the type locality of which is in Liberty county, forms 
the bed rock of the workable pebble phosphate deposits and is the 
parent formation from which the pebble, phosphate deposits were 
derived.* 
The following are analyses of the light gray calcareous and 
phosphatic sandstones of the Alum Bluff formation. Samples 
from which these analyses were made were collected by the writers 
in 1909 in connection with the preparation of a report on the 
fullers earth of Gadsden county and were reported upon in the 
Second Annual Report of this Survey, pages 275-276. No. 1 is 
from Rock Bluff; No. 2 is from Alum Bluff; No. 3 is from an 
exposure on a tributary to Sweet Water Creek on S. 5, T. 1 N., 
R. 7 W. 
Analyses made for the State Survey in the office of the State Chemist, 
B. H. Bridges, Analyst. 
Silica (Si 0 2 ) 
Calcium carbonate (CaC 0 3 ) 
Magnesium carbonate (MgCOs) 
Iron and Alumina (Fe 2 0 3 and A 1 2 0 3 ) 
Phosphoric acid (P 2 0 5 ) 
Sulphate ( SCh) 
Moisture (100 degrees F.) 
No. 1. 
No. 2. 
No. 3. 
48.44 
53-02 
34-03 
- 38.57 
38.57 
35-35 
1.68 
1.84 
26.00 
2.88 
3.96 
3-20 
Trace 
0.22 
Trace 
h Trace 
Trace 
Trace 
- L 37 
1.60 
1.32 
An additional sample of the gray phosphatic rock of this forma- 
tion collected in 1909 by E. H. Sellards was analyzed in the State 
Chemist’s office with the following result: 
Fla. Geol. Surv. Seventh Ann. Rept., pp. 34-35, 1915. 
