34 FLORIDA GEOLOGICAL SURVEY TENTH ANNUAL REPORT. 
T 2 N, R 7 W), limestone rock which probably represents the 
Chattahoochee formation, was thrown out from the bottom of a 
well. The well is near the mouth of Sweetwater creek, and the 
rock which was reached at a depth of io or 12 feet, appears to lie 
somewhat below water level in the river, or probably at an actual 
elevation of approximately 40 feet above sea. 
This locality on Sweetwater creek is the last known occurrence 
of the Chattahoochee limestone on this river above water le.vel. 
The distance from Chattahoochee Landing, where the top of the 
formation is 136 feet above, sea, to this locality in a direct line is 
about 15 miles. The dip of this formation in the direction of the 
flow of the river, which in this part of its course is southwest, is 
therefore 96 feet in 15 miles, or approximately an average of 6.4 
feet per mile. The writers’ former estimate of the rate of dip of 
this formation was 7 feet per mile.* If the dip of the limestone is 
computed from mile south of River Junction, where the Chat- 
tahoochee formation appears to reach an elevation of 148 feet, the 
dip amounts to 105 feet in about 14 miles, or 7.5 fe.et per mile. 
The actual average dip is probably close to the estimate formerly 
given of 7 feet per mile. Minor folds in this formation which re- 
sult in pronounced dips over limited areas have previously been de- 
scribed.* Elevations on the top surface of this formation are in- 
dicated on the sketch map, figure 2. 
Limestone rock, which probably represents Chattahoochee for- 
mation, is exposed on the east bank of the Ocklocknee river, about 
1 mile above the Fairbanks bridge near the Georgia-Florida State 
line (S 12, T 3 N, R 1 W). In a bluff facing an abandoned chan- 
nel of the river this rock was found in place at an elevation of 13 
feet above water level. The water level in the river at this place 
was estimated by its relation to Lake Iamonia, the level of which is 
known to be about 95 feet above sea. Accordingly, the top surface 
of the rock at this place is about 108 feet above, sea. A similar 
rock is exposed in a sink on Parrott’s Mill creek about three- 
fourths of a mile west of Fairbanks bridge on the Ocklocknee river 
(S 15, T 3 N. R 1 W). The le.vel of the top surface of the rock at 
this exposure is 5 feet above the water in the river or about 100 
feet above sea level. In a sink on Ponto creek about three-fourths 
* Fla. Geol. Surv., 2nd Ann. Rpt., pp. 277-278, 1909. 
