PEBBLE PHOSPHATE DEPOSITS. 
83 
BLACK CREEK. 
The pebble phosphates on Black Creek in Clay County are de¬ 
rived from the phosphatic marls through which the stream has cut 
its channels. This marl, as previously stated, has been referred, on 
the basis of the invertebrate fossils, to the Jacksonville formation. 
OLUSTEE CREEK. 
Pebble phosphate is found on some of the tributaries of Qlustee 
Creek in Bradford and Columbia counties, and probably in the 
creek itself. The pebble is derived from phosphatic marls which 
probably represent the Alum Bluff formation. 
ALLAPAHA RIVER. 
A limited amount of pebble phosphate is found on the Allapaha 
River near Jennings in Hamilton County. This pebble is derived 
without doubt from the Alum Bluff formation. 
SOPCHOPPY RIVER. 
Pebble phosphate has been found to some extent in the valley of 
Sopchoppy River and some other streams in Wakulla County, the 
pebble being derived from the Alum Bluff formation. The local 
beds of phosphate in Wakulla County were among the first reported 
in Florida, having been described by Dr. J. Kost in his report to 
Governor Perry in 1887. 
Fig. 11 .—Ostrea from the Pembroke mine of the Coronet Phosphate Com¬ 
pany. Silicified oysters are found at this locality in considerable abundance 
within about two feet of the top of the workable phosphate bed (Bone Valley 
formation). 
