64 
FLORIDA STATE GEOLOGICAL SURVEY. 
Rock Phosphate Belt, The Middle Florida Hammock Belt, and 
The Fake Region. 
Immediately adjacent to the Gulf coast, in northern Peninsular 
Florida and for a few miles inland, the limestone lies at or very 
close to the surface. The underground water level is near the 
surface, and numerous large springs of limestone water emerge 
from the rock and flow to the ocean. This coastal strip contains' 
numerous extensive calcareous hammocks and is known as the 
Gulf Hammock section of Florida. If formations later than the 
Oligocene limestones were formerly 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 Suwan¬ 
nee River, is underlaid by the Upper Oligocene limestones, while 
east of the Suwannee River the underlying formation is chiefly 
the Tower Oligocene limestone. 
Inland from the Gulf Hammock area, in Peninsular Florida, is 
found a strip of country over which formations of later age than 
the Tower Oligocene were clearly present in former times, 
although there now remains of these scarcely more than the 
mixed and complex residue. The strip of country of this type 
extends in well marked development from the southern part of 
Suwannee 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 explained 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 sur¬ 
face contour is rolling, there being no regularity of hills or valleys. 
Inland from the hard rock phosphate belt is found areas less 
affected by erosion, in which more or less of the formations that 
originally overlaid the Vicksburg Timestone may be identified 
in position. This type of country is known as the Middle Florida 
