SOME FLORIDA LAKES AND LAKE BASINS. I27 



This lake only occasionally goes entirely dry and as a result a 

 covering of muck or peat occurs over the greater part of the bottom 

 of the lake. This deposit of muck reaches a considerable thickness 

 in such natural depressions as occur over the lake bottom. Be- 

 neath the muck is usually found a deposit of light colored sand and 

 beneath this is the red sandy clay. 



The fact that the Ocklocknee River at flood stage flows into 

 this lake makes any attempt at drainage doubtful of success. An 

 effort which proved unsuccessful was made at one time to prevent 

 the river water from entering the lake by means of a dam. It 

 seemed to be the views of the party constructing the dam that if 

 the water of the Ocklocknee River could be kept out the sink 

 would carry ofif the water from the lake. This, however, is not 

 probable, since in the several other lakes to be described the sinks 

 have not proved sufficient to carry ofif the water except in times of 

 greatly reduced rainfall. Lake lamonia basin represents apparently 

 a stream valley lowered by solution and enlarged laterally by Sub- 

 sidence through the formation of sinks. Originally a small stream 

 tributary to the Ocklocknee River flowed through this section. In 

 this part of the country soluble limestones occur at no great distance 

 from the surface, and in the course of the natural processes of ero- 

 sion the stream approached sufficiently near this limestone to permit 

 of the formation of sinks and the escape of the water of the 

 stream through the sinks. The enlargement of the valley to its pre- 

 sent size has proceeded through the formation and partial filling of 

 successive sinks. As each sink forms, it carries down to or below 

 the lake level, a certain small area of land. Moreover the water 

 passing through the bottom of the sink carries with it more or less 

 detrital material so that the surrounding area is somewhat lower- 

 ed by wash through the sink. In the course of time other sinks 

 form, while the older sinks become clogged and usually partly fill 

 up. The direction of active enlargement of each lake can be de- 

 termined from the location of the recent sinks. As previously re- 

 marked this rapid enlargement is usually around the sink which is 

 at present actively receiving the drainage. 



