90 
FLORIDA GEOLOGICAL SURVEY—THIRD ANNUAL REPORT. 
Covered and sloping. 5 feet 
Sloping, some sticky clay exposed . 5 feet 
Yellow sand . 8 feet 
Buff colored sandy limestone, containing a small proportion of 
black phosphatic pebbles .12 feet 
Same, with greater amount of phosphate . 5 feet 
Same, with some phosphate.12 feet 
This is the thickest exposure of the Jacksonville formation ob¬ 
served at any one place along Black Creek. 
The following section was observed in the pit of the Jackson¬ 
ville Brick Company two miles southwest of Jacksonville: 
Incoherent sand and soil. 2.4 feet 
Sandy clays, the top 5 or 6 feet oxidized yellow.16 feet 
Bluish fossiliferous marl . 4 feet 
Beneath this marl as shown by numerous well drillings the 
sandy limestones of the Jacksonville formation occur. 
Miocene deposits in Florida were first recognized by Dr. E. A. 
Smith,* at Rock Springs in the northwestern part of Orange 
County. The limestone exposed here is a light sandy fossiliferous 
limestone and is probably of the Jacksonville formation. 
PLIOCENE. 
Pliocene is known to occur in eastern Florida, although the 
extent and distribution of the deposits have been but imperfectly 
determined. The shell deposits of this period occurring in the St. 
Johns valley and along the east coast have been described by 
Messrs. Matson and Clapp.t Localities mentioned by them are 
Nashua on the St. Johns River in Putman County and at DeLand 
and near Daytona in Volusia County. Other localities at which 
these deposits were observed to be exposed are one-half mile above 
the Atlantic Coast Line bridge over the St. Johns River in Putnam 
County; on the east side of the S't. Johns River about five miles 
north of the Atlantic Coast Line bridge in Volusia County. Plio¬ 
cene beds were also recognized from a well near Kissimmee. From 
the exposures thus recognized it is evident that Pliocene beds under¬ 
lie a considerable area of eastern Florida. 
* Smith, E. A., On the Geology of Florida. Amer. Journ. sci. 3d Ser., V A. 
XXI, pp. 302-303. 
fFla. Geol. Surv. Sec. Ann. Rpt., pp. 128-133, 1909. 
