90 FLORIDA GEOLOGICAL SURVEY-THIRD ANNUAL REPORT.
Covered and sloping ......................................... 5 feet
Sloping, some sticky clay exposed ............................. 5 feet
Y ellow 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 observed at any one place along Black Creek.
The following section was observed in the pit of the Jacksonville 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 St. Johns River about five miles north of the Atlantic Coast Line bridge in Volusia County. Pliocene beds were also recognized from a well near Kissimmee. From
the exposures thus recognized it is evident that Pliocene beds underlie a considerable area of eastern Florida.
SSmith. F. A., On the Geology of Florida. Amer. Journ. cci. 3d Ser., V )1. XXI, pp. 302-303.
t~la. Geol. Surv. Sec. Ann. Rpt., pp. 128-133, 19o9.