SOME FLORJDA' LAKES AND LAKE BASINS.

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. Beneath 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 flow 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 subsidence 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 erosion 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 present 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 lowered 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 determined from the location of the recent sinks. As previously remarked this rapid enlargement is usually around the sink Which is at present actively receiving ,the drainage.

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