36 FLORIDA GEOLOGICAL SURVEY TENTH ANNUAL REPORT. 
of a mile west of this locality, the calcareous and phosphatic phase 
of the Alum Bluff sands, including silicified oysters, is found in 
place at an elevation of 10 feet above the water level of the river. 
In Leon county, north of Lake Iamonia, the Chattahoochee lime- 
stone was reached in a well at an elevation of 135 feet above sea, 
while at a place nearby known as the “Cascades,” the rock is ex- 
posed at an elevation of 127 feet above sea. This data indicates 
that the limestones of this formation lie at a higher level on the east 
side of the Ocklocknee river than immediately on the west side. 
The Chattahoochee limestone is well exposed on and near the 
public road one-half mile south of River Junction. The highest 
exposure, of the light-colored rock on this hill was found to be 165 
feet above sea. Upon examining the rock, however, it appeared 
probable that the uppermost part of the exposure, including about 
20 feet, represents an indurated phase of the Alum Bluff forma- 
tion. Accordingly, the top surface of the Chattahoochee limestone 
in this exposure is probably not more than 148 feet above sea. 
On the Apalachicola Northern railway about three and one- 
half miles southeast of River Junction is a rock exposure which is 
probably near the top of the Chattahoochee formation, or the base 
of the Alum Bluff formation. The. approximate level of the top 
surface of the rock at this place as determined from the profile of 
the Apalachicola Northern railway, is 120 feet above sea. 
On the Ocklocknee. river at the crossing of the Seaboard Air 
Line railway limestone rock which apparently represents the Chat- 
tahoochee formation is exposed at an elevation of 66 feet above 
sea. This exposure is about 28 miles east-southeast of River 
Junction. The dip of the formation in this direction, as deter- 
mined from these exposures, accordingly appears to be 79 feet in 
28 miles, or an average slightly less than 3 feet per mile. 
There is reason to believe, however, that the dip is actually more 
rapid than is indicated by these measurements'. At the public road 
crossing on Little river west of Midway the oyster shell marl 
phase of the Alum Bluff formation is exposed at water level. The 
level in the bed of Little river at the Georgia, Florida and Alabama 
railway crossing (Quincy Branch) about five miles up stream from 
this place is about 82 feet above sea. The fall of this stream ap- 
proximates 3 feet per mile. While the actual elevation of the ex- 
posure of shell marl near Midway is not known it may be safely 
