Solution Lakes 



69 



SinK 



the best development of lakes about them is in the 

 upland region of northern Florida. These lakes are 

 shallow basins having much of their borders ill-defined 

 and swampy. Perhaps the 

 most remarkable of them is 

 Lake Alachua near Gaines- 

 ville. At high water this 

 lake has an area of some 

 twenty-five square miles and 

 a depth (outside the sink) of 

 from two to fourteen feet. 

 At its lowest known stage it 

 is reduced to pools filling 

 the sinks. During its re- 

 corded history it has several 

 times alternated between 

 these conditions. It has 

 been for years a vast ex- 

 panse of water carrying 

 steamboat traffic, and it has 

 been for other years a broad 

 grassy plain, with no water 

 in sight. The widening or 

 the stoppage of the sinks 

 combined with excessive or 

 scanty rainfall have been 

 the causes of these remark- 

 able changes of level. 



The sinks are more or 

 less funnel-shaped openings 

 leading down through the soil into the limestone. 

 Ditchlike channels often lead into them across the lake's 

 bottom. The accompanying diagram shows that they 

 are sometimes situated outside the lake's border, and 

 suggest that such lakes may originate through the 

 formation of sinks in the bed of a slow stream. 



fmt. 



FIG. 1 8. Lake Miccosukee, (after 

 Sellards), showing sinks; one in 

 lake bottom at north end, two in 

 outflowing stream, 2> miles dis- 

 tant. Arrows indicate normal 

 direction of stream flow, (reversed 

 south of sinks in flood time when 

 run-off is into St. Mark's River). 



