PETROLEUM POSSIBILITIES OE ELORIDA 
63 
The shell marl deposits of this formation in west Florida have re¬ 
ceived distinctive names as members of this formation. The marl near 
the base of the formation seen exposed at Bailey’s Ferry on the Chipola 
River, at Alum Bluff on the Apalachicola River, and at Jackson Bluff 
on the Ocklocknee River is known as the Chipola marl. Another mem¬ 
ber, the Oak Grove sand, is seen on Yellow River in west Florida. Some¬ 
what higher In the formation is the Shoal River member, seen on Shoal 
River. 1 
JACKSONVILLE FORMATION 
The Jacksonville formation was named from exposures seen in exca¬ 
vations at Jacksonville, which unfortunately are not available for exam¬ 
ination at the present time. Subsequently the term was applied to de¬ 
posits exposed on Black Creek, in Clay County. The Clay County de¬ 
posits are lithologically very similar to certain phases of the Alum Bluff 
formation, consisting of phosphatic marls, prevailingly yellow in color, 
the phosphate being for the most part in the form of small, round peb¬ 
bles. The fauna, however, is supposed to indicate a later age than that 
of the Alum Bluff formation. 
1 Fla. Geol. Surv., 2nd Ann. Rept., 1909. 
Fig. 9. The Apalachicola River showing Alum Bluff. 
