GEOLOGY BETWEEN APALACHICOLA AND OCKLOCKNEE RIVERS. 5 1 
sible that the similar materials of this area may be included in that 
formation. If not referable to the Altamaha formation, possibly 
these materials may be referred to the Citronelle formation, al- 
though this should not be done until fossils can be. obtained or con- 
tinuity of deposition with the Citronelle formation can be deter- 
mined. If these materials can be referred to neither of these forma- 
tions, they may be known as the Bristol formation from their typ- 
ical exposure in the vicinity of Bristol, Florida, where they are 
known to lie stratigraphically above the Choctawhatchee Miocene. 
STRUCTURE. 
A study of the structure of this formation is made difficult by 
the fact that only occasionally can the base of the. formation be 
located. Approximate levels indicate, however, that the deposits 
dip to the south. At Alum Bluff, as already noted, the base of this 
formation is 61 feet above, water level, or about ioi feet above sea. 
At Rock Bluff the base of the formation, assuming that it extends 
to the north, cannot be less than ioo feet above water level, or about 
142 feet above sea. At Chattahoochee Landing, materials referred 
to the Alum Bluff formation were exposed at the time the published 
section was made, to a level of 103 feet above the. river, or about 
154 feet above sea, above this being covered. Recently the cut on 
the public road has been deepened, and exposures of the Alum 
Bluff formation may now be recognized up to an elevation of 12 1 
feet above the river, or 172 feet above sea. If this formation is 
present in this section, therefore, it lies at a greater elevation than 
172 feet above sea. On the public road one mile southeast of River 
Junction the fullers earth horizon is exposed at 212 feet above sea. 
At Hosford, 12 miles, east of Alum Bluff, where the red sands 
of this formation lie above the. Choctawhatchee marl, the base of 
the formation, as seen in the railroad cuts, appears to lie about no 
feet above sea. 
From such approximate elevations on this formation as have 
been obtained it appears that the formation dips to the south, the 
rate of dip being approximately the same as that of the underlying 
formation. 
