128 FLORIDA GEOLOGICAL SURVEY SIXTH ANNUAL REPORT. 



LAKE JACKSON, 



Lake Jackson lies 

 near the western border 

 of Leon County within 

 one and a half oi"^ 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 

 Fig. 28.-Lake Jackson. -^ ^^^^^ ^^^^^ 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 

 southeast 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. 



