SOME FLORIDA LAKES AND LAKE BASINS. 1 55 



Approximate measurements of the water level in Alligator 

 Lake near Lake City have also been made. This is one of the 

 smaller basins and the measurements indicate that the level of the 

 water in the lake stands appreciably above the underground water 

 level. In this instance the measurements of the water level and the 

 lake level were made at different seasons of the year and the results 

 can be only approximately compared. The data on this lake are as 

 follows : Levels made by Professor N. H. Cox, on June 19, 1903, 

 showed that the water in Alligator Lake stood 94.22 feet below the 

 Union Depot at Lake City. 



The lake at the time the levels were made was at medium full 

 stage. The water of the Lake City public well, located near, and 

 en about the same level as the depot was found at the time the 

 well was completed in 1907 to stand 134 feet from the surface. 

 Allowing for any correction that it might be necessary to make 

 owing- to the fact that the measurements of lake level and ground 



't3 



water level were not made at the same time it would still seem that 

 the lake basin in this instance stands somewhat above the water 

 level. 



RELATION OF THE GROUND WATER LEVEL TO THE FORMA- 

 TION OF SINKS. 



It is of interest in this connection to note the influence of the 

 ground water level on the formation of sinks. Sinks do not form in 

 Florida in that part of the State in which the water first encountered 

 as permanent water in the limestone is under sufficient pressure to 

 flow at the surface. The reason for this seems obvious. In areas 

 of artesian flow, such cavities as exist in the limestone are filled with 

 water under pressure, which, together with the resistance of the 

 strata to breakage, is sufficient to prevent the overlying materials 

 from subsiding and thus forming sinks. Along the border line be- 

 tween the flowing and non-flowing area the artesian water fre- 

 quently breaks out forming springs. On the other hand the areas 

 of most rapid formation of sinks are those in which (i), the lime- 

 stone is rather near the surface; (2), the underground water level 

 is below, although comparatively near the surface, and (3), the ma- 

 terials lying above the water bearing limestones are so far disin- 

 tegrated that they permit the surface water, rainfall, to pass readily 

 through them into the limestones beneath. Under these conditions 

 the fluctuation of the water level has a pronounced effect. When 

 the water level is high, as following the rainy season, the materials 

 are water soaked almost to the surface. When the water level is 



