68 
FLORIDA GEOLOGICAL SURVEY—THIRD 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 OP 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 is not always the case, and such an assumption may 
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 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 Iamonia as previously 
stated lies practically on a level with the Ocklocknee River, and 
receives the overflow of that river during high water stages. 
Alachua Lake basin lies, as shown by the topographic map, at practi¬ 
cally 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 consists 
either in enlarging the sinks, or in making artificial openings in 
the form of dug or drilled wells through to the water bearing for¬ 
mation. 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 per¬ 
manent underground water level. 
