THE SOILS OP FLORIDA. 
29 
the rainfall passes readily into the limestone. The underground 
water level is near the surface, and numerous large springs of lime¬ 
stone water emerge from the rock and flow to the ocean. This coas¬ 
tal strip contains numerous extensive calcareous hammocks and is 
known as the Gulf Hammock section of Florida.* If formations 
later than the Oligocene limestones were present over the Gulf Ham¬ 
mock area they have, with the exception of a slight residue of sand, 
disappeared. The Gulf Hammock section west of the Suwannee 
River is underlaid by Upper Oligocene limestones, while east of the 
Suwannee River the underlying formation is chiefly the Lower Oli¬ 
gocene limestone. Isolated areas of essentially similar country are 
found in the vicinity of Ocala in Marion County, and near Sumter 
ville in Sumter County. 
THE HARD ROCK PHOSPHATE BELT. 
Inland from the Gulf Hammock area in peninsular Florida and 
to a lesser extent in that part of Florida west of the Suwannee 
River, is found a strip of country over which formations of later 
age than the Oligocene were clearly present in former times, 
although there now remains of these scarcely more than the mixed 
and complex residue. The formations that have gone to decay over 
this area include deposits of Pliocene age as shown by the fossils, 
and probably also marine formations of Miocene age. It is probable 
also that the Upper Oligocene formations were formerly present, 
although in this area in peninsular Florida these formations have dis¬ 
integrated. The strip of country of this type extends in well marked 
development from the southern part of Sirwannee and Columbia 
Counties roughly paralleling the Gulf Coast to Hernando and Pasco 
Counties. This area includes the hard rock phosphate deposits, 
these deposits having accumulated by the processes elsewhere ex¬ 
plained during the period of erosion through which this section has 
passed. Few lakes or streams are found in the hard rock phosphate 
belt, as the rainfall enters through the loose surface material and 
passes directly into the underlying limestone. The underground 
water level, lies, as a rule at a greater depth beneath the surface 
than in the Gulf Hammock country. Numerous sinks form, giving 
evidence of the continued active erosion by underground solution. 
The surface contour is rolling, there being no regularity of hills 
or valleys. West of the Suwannee River workable phosphate beds 
have not yet been developed. Some phosphate, however, occurs in 
this section and larger deposits may yet be found. 
*E. A. Smith, U. S. 10th Census, Report on Cotton Production, Pt. 2, 1884. 
