GEOLOGY BETWEEN APALACHICOLA AND OCKLOCKNEE RIVERS. 29 
Fig. 2. Sketch map to show geology between the Apalachicola and 
Ocklocknee Rivers. 1. Area in which the Alum Bluff formation is oc- 
casionally exposed. 2. Area in which the Chattahoochee formation is 
exposed. 3. Belt in which the Choctawhatchee formation lies near the 
surface, being exposed in the stream channels. 4. Undifferentiated Mio- 
cene or later. 
