geologic sections across the everglades. 69 
the surface.* This data is consistent with other data available indi¬ 
cating a general south and east dip of the formations. The Oli- 
gocene and Miocene formations are somewhat difficult to recog¬ 
nize in well samples, but the fact that these formations lie at the 
surface along the Gulf coast as far south as Polk and Manatee 
counties, and are also believed to be represented in the wells on 
the Atlantic coast, leads to the reasonable conclusion that they 
also underlie the Everglades although at a considerable depth. The 
depth at which these formations are to be expected is a matter 
of importance to the agricultural and industrial development of 
the Everglades country, since the limestones include the principal 
water bearing strata of the State, and supply the greater part of 
the artesian water of peninsula Florida. 
At Palm Beach on the east coast Miocene deposits are believed 
to have been rcognized at a depth of 400 feet, while in a well at 
Knights Key the Miocene appeared to be present at from about 
180 to 420 feet.* From its known distribution on the Atlantic 
coast it seems probable that the Miocene underlies the Everglades 
resting upon the Eocene or Oligocene. In this connection also it 
should be noted that the Miocene has been somewhat doubtfully 
identified as occurring near Caloosa, on the Caloosahatchee River 
west of the Everglades.f 
SURFACE FORMATIONS OF THE EVERGLADES. 
CALOOSAHATCHEE MARL 
With the possible exception of the Miocene exposure near 
Caloosa, the oldest deposits in the section here described are the 
Pliocene deposits known as the Caloosahatchee marl, the surface 
outcrop of which is found along the Caloosahatchee River and 
hence west of the Everglades. This formation, being readily ac¬ 
cessible, has long been known to geologists and has been fully 
described in earlier papers.ff Angelo Heilprin, who in company 
*Fla. State Geol. Sur. Second Annual Report, pp. 204-206, 1909. 
fFla. Geol. Survey, Sec. Ann. Rept., p. 122, 1909. 
ff Heilprin, Wagner Free Inst., Vol. 1, p. 32, 1887. Dali Wm. H. U. S. Geol. 
Bull. 84, p. 147, 1892. Matson and Clapp, Fla. State Geol. Surv. Second Annual 
Report, p. 126, 1909. 
