198 
FLORIDA STATF GEOLOGICAL SURVEY. 
ing line. The country surrounding this lake stands at or about 
175 feet above sea. According to the levels made by the Seaboard 
Air Line Railway the town of Highland, in the northwestern part 
of the county, stands 210 feet above sea. Newburg and Brook¬ 
lyn, in the lake region of the southwestern part of the county, 
have elevations, as recorded by the Georgia Southern and Florida 
Railway, of 155 and 157 feet, respectively. 
WATER-BEARING FORMATIONS. 
Most of the flowing wells of Clay County terminate in the 
Vicksburg Limestone. The first flow at Green Cove Springs, in 
the eastern part of the county, is obtained at a depth of from 
325 to 400 feet. 
The Miocene formations underlie much if not all of Clay 
County. In the pit of Union Brick Company, at Middleburg, the 
following section was observed: 
Feet. 
Eoose sand and soil. 1 
Sandy clays oxidized red .. 7 
Blue sticky clay, comparatively free from sand. 10 
Eight-colored sands . 3 
The clay exposed in this pit is probably the same as the clays 
in the clay pit near Jacksonville. Beneath these clays, as indi¬ 
cated by well borings, calcareous and phosphatic Miocene rocks 
are encountered. This part of the Miocene, the Jacksonville for¬ 
mation, is exposed at many localities along Black Creek and its 
tributaries. The section exposed at High Bluff, on the south 
fork of Black Creek, about five miles above Middleburg, has 
already been given. 
Other exposures of this formation were noted at the following 
localities along the river. At Fowler’s Landing, on the south 
fork of Black Creek, three miles above Middleburg, fifteen feet 
of the Jacksonville formation is exposed. At Buddington’s Land¬ 
ing, one and one-half miles above Middleburg, seventeen feet of 
the Jacksonville formation is exposed. Hogan’s Landing, just 
below Middleburg, shows twenty-eight feet of the Jacksonville 
