OCKLOCKNEE AND AUCILLA RIVERS. 
137 
them. One such view of the stream making its way underground 
is to be had at what is known as the. River Sinks in Wakulla County. 
These underground streams make their way, as we may believe, in 
a general southeast direction and re-emerge, in part at least, to form 
the great Wakulla Spring, and from that place continue as an open 
surface stream to the Gulf. The subsequent history of Wakulla 
River may be readily inferred. If the natural development of the 
stream is not interfered with, the open channel through the lime¬ 
stone will be extended to the northwest and ultimately, as in the 
case of the St. Marks River, the stream will lie throughout its whole 
course in the limestone. 
PHYSIOGRAPHIC FEATURES. 
It has been stated in the earlier pages of this report that the 
large lake basins of this area, of which Miccosukee, Iamonia, Jack- 
son and Lafayette are examples, have been formed by the gradual 
processes of solution of limestone and disintegration of the over- 
lying sands and clays, attended by subsidence and to some extent 
by surface wash. The sinkholes which form in and around the 
lake-basins vary in depth, some, of them extending when first formed 
much below the level of the. floor of the basin. The sink which 
receives water from Lafayette basin at the present time is 75 feet 
deep, while that of Lake Iamonia extends as much as 50 feet below 
the. lake level. It is probable that in the history of development of 
the basins many such sinks have formed and subsequently refilled. 
The land surface is lowered chiefly by subsidence to a given level, 
while all sink-holes that extend below this level are subsequently 
refilled. The controlling agency in determining the level at which 
the plane of the bottom of the basin is formed is with little doubt 
the ground water level of the formation in which the basin lies.* 
So nearly is the plane of the lake basin at ground water level that 
while the basin usually is a shallow water lake in normal or rainy 
years, it is dry or nearly so in periods of unusual drought. The 
drainage sinks retain water continuously, and usually maintain their 
*In reports previously published by the Survey, the writer has described the 
lake basins of the State, including a discussion of the relation of the lake basins, 
to the ground water table, and the description of Iamonia, Jackson, Miccosukee 
and Lafayette basins in the present report is taken largely from the earlier 
report, which is no longer available for distribution, the supply being exhausted. 
