OCKLOCKNEE AND AUCILLA RIVERS. 
IOI 
rock. The overflow from Lake Miccosukee passes to the south and 
enters the limestone through a sink a few miles south of the lake 
where the limestone is again exposed in Jefferson County. On the 
Ocklocknee River this limestone is exposed a short distance above 
the crossing of the Seaboard Air Line Railway. 
In Wakulla County this limestone lies at or near the surface 
throughout practically all the eastern half of the county. The 
western boundary of the limestone rock in this country, leaving the 
Gulf Coast near Shell Point, passes north probably a little east of 
Medart and west of Crawfordville, entering Leon County near or a 
little, east of Hilliardville. Although underlying the west half of 
the county, the limestone lies below the surface. The limestone 
rock in this area is for the most part hard and compact and is often 
found as boulders at the surface. 
Throughout the southern part of Jefferson County, the limestone 
lies at or very near the surface, while flinty and indurated phases of 
the rock which resist erosion frequently lie on the surface, and in 
places have, accumulated forming masses of surface rock. In the 
northern part of Jefferson County the conditions are similar to those 
of northern Leon County. The limestone is covered by later for¬ 
mations, and is exposed only in depressions and sinks, although it is 
frequently reached in well drilling. 
Although limited in extent, these exposures in Leon County and 
in the northern part of Jefferson County, together with the larger 
surface exposures in Wakulla County and in the southern part of 
Jefferson County are sufficient to show that the Chattahoochee 
limestone underlies the whole area at no great depth. 
STRUCTURE. 
As an aid in the study of structure it becomes important to 
record, so far as possible, the elevation of exposures of the succes¬ 
sive formations. Such data, however, must be regarded as ap¬ 
proximate. First of all a part of the formation may have been 
removed, either by solution or by mechanical erosion, so that what 
appears to be the top may in reality be somewhat or considerably' 
below the top. Moreover, the lack of a detailed topographic map, 
or other adequate series of exact levels adds to the difficulty of 
studies in the structure of the formations. 
Of the formations exposed within the area covered by this re- 
