WATER SUPPLY OP PASTERN AND SOUTHERN FLORIDA. 119 
similar in character to the Choctawhatchee marl of West Florida, 
and the clay used for brick making in Duval, Nassau and Putnam 
Counties is probably of Miocene age. 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.f Localities mentioned by them are 
Nashua, on the St. Johns River, in Putnam 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. 
In Southern Florida the Pliocene is well developed in the valley 
of the Caloosahatchee River. The land pebble phosphate de¬ 
posits are also believed to be Pliocene. 
PLEISTOCENE. 
The marine Pleistocene deposits have been recognized at sev¬ 
eral localities in Eastern and Southern Florida. Messrs. Matson 
*Smith, E. A., On the Geology of Florida. Amer. Journ. Sic. 3d Ser., 
Vol. XXI, pp. 302-303. 
tFla. Geol. Surv. Sec. Ann. Rpt., pp. 128-133, 1909. 
