148 FLORIDA GEOLOGICAL SURVEY SIXTH ANNUAL REPORT. 



a surface stream to the Apalachicola River, At a distance of three 

 or four miles from the river, this stream, after cutting its channel 

 some depth, reached the Chattahoochee Limestone. When this 

 formation was reached the water passed into the earth, the drain- 

 age becoming subterranean. Subsequent erosion carried the basin 

 to its present level. 



METHODS OF DRAINAGE. 



Two methods of draining basins of this type may be considered, 

 (i) drainage by surface ditching to some stream or other outlet 

 lying at a lower level; or (2) drainage into the underlying water 

 bearing formation. 



DRAINAGE BY SURFACE DITCHING. 



Surface ditching usually suggests itself as the more natural 

 method of drainage, and it is often inferred in the absence of de- 

 finite information that the lakes lie at a higher level than near-by 

 streams. This frequently is not the case, and such an assumption 

 miay lead to a very costly error. A lake or prairie of this type a few 

 miles southeast of Citra was connected many years ago by canal 

 at considerable expense with a tributary of the Ocklawaha River. 

 Upon completion of the canal it was found that the lake basin was 

 at a lower level than the stream bed, the water from the stream ac- 

 tually flowing into the lake. The peculiar method of formation of 

 these lake basins by solution, as previously explained, carries them 

 frequently to a lower level than the stream which served in earlier 

 stages as an outlet. . Lake lamonia as previously stated lies prac- 

 tically on a level with the Ocklocknee River, and receives the over- 

 flow of that river during high water stages. Alachua Lake basin 

 lies, as shown by the topographic map, at practically the same level 

 as Orange Lake and the headwaters of Orange Creek which served 

 formerly as the outlet. 



DRAINAGE INTO THE UNDERLYING FORMATIONS BY WELLS. 



Drainage into the underlying formations takes place naturally 

 through the sinks already existing. Artificial drainage either by 

 enlarging the sinks, or wells dug or drilled through to the water 

 bearing formation is frequently resorted to. In either case the 

 principle is the same. The underlying limestone is porous and 

 cavernous, and is filled with water to a definite although slightly 

 variable line or level known as the permanent underground water 

 level. 



