154 
FLORIDA GEOLOGICAL SURVEY—THIRD ANNUAL REPORT. 
210 feet above sea. Newburg and Brooklyn, 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 Clav 
County. In the pit of Union Brick Company at Middleburg the 
following section was observed: 
Loose sand and soil . 1 foot 
Sandy clays oxidized red ... 7 feet 
Blue sticky clay, comparatively free from sand. 10 feet 
Light-colored sands ... 3 feet 
The clav exposed in this pit is probably the same as the clays 
in the clay pit near Jacksonville (p. 90). Beneath these clays, as 
indicated 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 Landing, 
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 forma¬ 
tion. A bluff at the mouth of the south fork shows twenty-five 
feet of the Jacksonville formation. A bluff on the north bank of the 
north fork one and one-half miles from Middleburg, shows three 
feet of the Jacksonville formation. 
AREA OF ARTESIAN FLOW IN CLAY COUNTY. 
The area of artesian flow in Clay County is confined to that 
portion bordering the St Johns River and its tributaries. As has 
