SOME FLORIDA’ LAKES AND LAKE BASINS. 
55 
ment by solution and subsidence, may have been most active in some 
other locality or direction or part of the lake basin. 
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 off 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 off the water except in times of 
greatly reduced rainfall. Lake Iamonia 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 county 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 Tiling 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. 
