126 FLORIDA GEOLOGICAL SURVEY-NINTH ANNUAL REPORT. 
from the stream the water in the sink was being gradually lowered. 
Heavy rains occurred in this vicinity on September 21, 1909, and 
this stream when seen two days later was carrying approximately 
7,000 gallons of water per minute. At this time the sink was being 
rapidly filled, having filled several feet during the two preceding 
days. From these observations it appears that the opening at the 
bottom of this sink permits the escape of water at a rate in excess 
of 200 gallons per minute, but much less than 7,000 gallons per 
minute. From the behavior of the sink it is probable that not more 
than 1,000 gallons of water are escaping per minute, and the rate of 
escape may be much less. 
The principal escape of water from Lake Miccosukee when the 
lake is full is through a drain which leads out from the south end of 
the lake and enters a sink about two and one.-fourth miles from the 
south end of the lake. This sink is formed in a light-colored lime¬ 
stone of Upper Oligocene age, probably representing the Chattahoo¬ 
chee formation. The drain from the lake as it approaches the sink 
passes through a narrow gorge cut in this limestone. About one- 
half mile farther south (Sec. 14) another sink is found. This 
third sink receives the flow from Mill Creek, a small stream draining 
considerable territory lying south of the. Seaboard Air Line Railway 
and east of Lloyd. 
During a season of excessive rains these sinks are unable to 
carry away the water. Under these conditions the overflow from 
Lake Miccosukee. as well as from Mill Creek ultimately finds its 
escape by flowing to the southwest past Lloyd to the St. Marks 
River. 
The surface, in Miccosukee Basin is covered with muck to a 
varying depth. Borings put down near the north end of the basin, 
out from the margin of the drain, indicated the presence of muck 
for a depth of six inches to one foot. Beneath the muck in this part 
of the basin was found a gray sand. This sand is underlaid, at a 
variable depth, by the usual red sandy clay. At the south end of the 
lake the sand is largely absent, the muck which is from one. to three 
or more feet deep, resting, so far as observed, directly upon the red 
clay. 
Lake Miccosukee probably represents a basin developed by solu¬ 
tion near the headwaters of streams originally tributary to the St. 
Marks River. Previous to the formation of Miccosukee Basin, the 
drainage of this part of the country doubtless passed through small 
