388 
GEOGRAPHY OF THE SOUTHERN PENINSULA 
glades, so far as explored, but seems also to be present in the 
river beds to the south, tlirough which the water of the glades 
finds an outlet. 
To the north the water empties into lake Okeechobee; to the 
west, south, and east it flows through various rivers into the 
Atlantic and the Gulf. The evident elevation of the area above 
the east, west, and south coasts precludes the idea of drainage 
from surrounding areas, and we must look elsewhere for the 
sources of the water. These, I think, are found in part in precipi- 
tation, and, in part, in subterranean streams or springs. The 
rainfall over this vast area of three million acres must be very 
great. But when we remember that all the creeks and rivers 
lead out of and not into the glades, the rainfall, which possibly 
approximate.'^ an average of ten inches jier month during the 
months of June, July, and August, is not sufficient. From what 
we know as to the subterranean relations between the lakes in 
the lake region, from the well-known conditions of Silver, Blue, 
and De Leon springs, as well as from data acquired by drilling 
for artesian water, it is reasonable to infer that the volume of 
water due to ))recipitation is materially increased b}’ an under- 
ground supi)ly. As some justification of this assumption, I may 
mention a spring which has its issue from the rocky rim just 
l)elow the falls of the Miami river. Over the rocky ledge the 
dark brown water of the glade pours itself in a turbulent flood 
into the rapids of the Miami. But onl 3 '^ a little distance below 
the falls, and e.\i)Osed to view during the period of low water in 
the glade, the clear and uncolored volume of a huge spring gives 
itself up to the sunshine. The quality of the water is entirely 
different from that of the glades, and, as far as I have been able 
to observe, is unsurpassed in purity. 
Approaching the glades from either east or west, the water 
gradually dee])ens, the rock forming the floor of the basin re- 
ceding toward the middle at the rate of about 8.6 inches to the 
mile. In the valley thus formed, running north and south, the 
rock is about 15 feet below the surface. It is traceable directly 
across the glade, leaving no manner of doubt as to its persistence. 
Immediately over the rock is deposited the result of ages of de- 
cayed vegetation, forming a soft peat or muck, the depth of 
Avhich varies from a few inches to five feet. It is everywhere 
present over the floor of the great basins, and if ever drained 
will afford a soil of incalculable richne.ss and fertility. 
For miles east and west from the valle}" of the basin and north 
