56 
FLORIDA GEOLOGICAL SURVEY—THIRD ANNUAL REPORT. 
LAKE JACKSON. 
Lake Jackson lies 
near the western border 
of Leon County within 
one and a half or two 
miles of the Ocklocknee 
River. This lake is ir¬ 
regular in shape, and has 
a total area of about 4,- 
500 acres. The bound¬ 
aries of the basin are 
sharply marked by the 
surrounding highlands 
which rise 75 to 100 feet 
above the level of the 
lake. Several sinks oc¬ 
cur in the southern half 
of the lake. The largest 
of these, known locally as 
the “lime sink,” is located 
well out in the basin and 
in the angle between the 
north and east arms. 
(See map). An opening 
in the bottom of this sink 
in May, 1907, permitted 
the water to run out, leaving the sink dry, and also draining 
the lake or such part of it as was connected with the sinks. An 
indefinitely defined broad depression or slough extends to the 
south-east from the lime sink. Several water holes representing 
old sinks occur along the line of this depression. A new sink oc¬ 
curred along the bottom of the depression about one mile south¬ 
east of the lime sink in June, 1907. A compact limestone showed 
in the bottom of this sink at a depth of about 25 feet from the sur¬ 
face. At the time this sink formed the lake was low, a part of 
the water having been carried off through the opening which had 
formed in the lime sink a month earlier. All the water that could 
reach the new sink was carried off in the course of two or three 
days, leaving the lake dry except /for occasional water holes. When 
examined in September, 1909, a small open sink was found in the 
slough which carried away all of the water that reached it from 
the surrounding parts of the lake. 
