184 
FLORIDA STATE GEOLOGICAL SURVEY. 
a short distance east of Hurds, a level of thirty-six feet. From 
East Palatka south information regarding elevation is unfortu¬ 
nately very deficient. From the fact that such wells as have been 
put down at Dinner Island, Espanola, Bunnell and Dupont, are 
non-flowing, it is probable that this part of the county is above 
the twenty-five-foot contour line, and parts of this area may, in 
fact, approach or exceed the fifty-foot contour. Along the west 
side of the county bordering the St. Johns River areas varying 
in width from 3 to 10 or more miles lie below the twenty-five- 
foot contour line. 
WATER-BEARING FORMATIONS. 
The Vicksburg Limestone is the chief source of the artesian 
water supply of St. Johns County, although a small flow is prob¬ 
ably obtained before reaching this formation. The Vicksburg 
Limestone consists of alternating hard and soft fossiliferous 
strata and is usually easily recognized. At St. Augustine, accord¬ 
ing to determinations made by Dr. W. H. Dali,* fossils charac¬ 
teristic of this formation were obtained from a depth of 224 feet. 
At Hastings, 17 miles southwest of St. Augustine, well records 
indicate that a limestone similar in character to the Vicksburg is 
reached at a depth of from 175 to 200 feet. At Orange Mills, in 
Putnam County, 3 miles southwest of Hastings, Orbitoides, ap¬ 
parently representing some member of the Vicksburg group, 
were obtained at a depth reported at 110 feet. At the time the 
sample was received the well was drilled to a total depth of only 
130 feet. Toward the northern part of St. Johns County the 
Vicksburg Limestone probably dips deeper, since, at Jacksonville, 
this formation is first reached at a depth of about 524 feet. 
The superficial material in this county is largely Pleistocene 
and recent sands together with Pleistocene and recent shell de¬ 
posits. Oscillations of level have affected the surface elevation, 
and consequently the relative extent of land and water area in 
this county within comparatively recent time. That this part of 
the State stood at a lower level during a part of Pleistocene time 
is evident from the occurrence of marine shell deposits of Pleisto- 
