IOO FLORIDA GEOLOGICAL SURVEY-NINTH ANNUAL REPORT. 
through the removal of these overlying materials by erosion that the 
rock of this formation has at places become exposed at the surface. 
In the eastern part of Wakulla County, and the southern part of 
Jefferson County, there is a large area over which this formation 
lies at or very near to the surface. The following localities in Leon 
County may be recorded at which this formation may be seen at the 
surface. The large area in Wakulla and Jefferson Counties over 
which it is found at the surface is indicated on the map. (Fig. 3). 
SURFACE EXPOSURES OF THE CHATTAHOOCHEE LIMESTONE. 
In addition to these surface exposures the limestone rock is 
reached occasionally by dug wells and usually by drilled wells. A 
well dug on the Griscom plantation on the south side of Lake 
Iamonia (Sec. 32, T. 3 N., R. 1 E.) reached the limestone at a 
depth of 60 feet or less. In the southern part of Leon County the 
surface elevation drops off to a much lower level, and in this area 
the limestone is comparatively near the surface. Approaching the 
Wakulla County line in the eastern half of the county, limestone 
rock lies at the surface, where it has been quarried for road pur¬ 
poses. 
An exposure of limestone rock, which probably represents the 
Chattahoochee formation, is found on the Meridian Road near the 
Georgia-Florida line, the rock, which is found in a depression in a 
field at the side of the road, is hard and compact A few miles 
further east a similar limestone, was seen in a sink known locally as 
the “Cascades.” 
The basins of the large lakes of Leon County, including Iamonia, 
Jackson, Miccosukee and Lafayette, all of which are solution basins, 
are reduced to or below the level of the limestone. The writer was 
fortunate in having an opportunity in the fall of 1909 of examining 
these basins at an exceptionally low stage of water. The basins are 
drained by sinkholes, which are in fact openings into the limestone. 
The principal sink of Lake Iamonia is found adjoining the bluff at 
the north side. Limestone rock is exposed near the bottom of this 
sink. A similar limestone was observed at the bottom of a sink 
in Lake Jackson. In Lake Lafayette basin the limestone rock is 
seen at the sink near the northwest corner of the lake. The prin¬ 
cipal sink of Lake Miccosukee is at the west side of the lake near the 
north end. The limestone at this sink is a compact, chalky white 
