188 FLORIDA state geological survey. 
holes and hollows. The holes, which communicate with underground 
solution channels, are of all sizes, varying from those not over an inch 
across to those twenty feet or more in diameter. Their depths ranged 
from three to over ten feet. Besides the sharply outlined holes, there 
are throughout the pineland countless shallow hollows one to three 
feet deep and ten to one hundred feet across. A few of these hollows 
may owe their origin to original conditions of deposition, some may 
be due to the overturning of trees and consequent upheaval of the 
rocks loosened by roots, while others have been caused by the falling 
in of the roofs of subterranean water courses. Few of the holes and 
hollows are large enough to be termed sinks. The large vertically- 
walled holes running down to permanent water level form natural 
wells, the shallow hollows are best denominated potholes. The writer 
has heard of only one rock-rimmed opening in southern Florida that 
resembles the great sinks in the country to the north. That is Deep 
Lake, near the west coast, twelve miles east of Everglade postoffice. 
The lake, about four acres in'extent, has a nearly circular shore line 
and no surface outlet; its reported greatest depth is ninety feet, fully 
seventy feet below sea level. 
While there is danger of exaggerating the activity of underground 
and surface water in eating away the soft limestone of the east coast, 
yet there is plentiful evidence of solution. The potholes and the hol¬ 
low-sounding areas of rock, perhaps twenty-five feet across, with as 
many as six or seven holes a foot or so in diameter showing the water 
beneath, that are found along the edges of the southern Everglades, 
the springs below tide level at Cocoanut Grove, and other points on 
the shore of Biscayne Bay, the Punch Bowl, a spring basin, the deep 
holes in New River, and the shallow gorge of Arch Creek with its 
low rock bridge all bear witness to the work being done. 
SWAMPS. 
As before stated the swamp land of southern Florida includes the 
great saw-grass morass of the Everglades, the cypress swamps and 
strands around its edges or intermingled with the pineland and the salt 
meadows and mangrove swamps of the coast. The very slight dif¬ 
ferences in elevation over long stretches of the mainland, the gradual 
slope of the rock surface below tide water level, the rock ridges on the 
southeast, the configuration of the upper surface of the bed rock and 
the rapid growth of grasses and sedges, are all factors in the distribu¬ 
tion of land which is permanently wet and that which is, for a part 
of every year, dry. 
