2, WEST FLORIDA LIME-SINK REGION. 203 



water level is usually lower, and force-pumps and artesian wells are 

 used. 



In the river strip above mentioned the ground-water level ex- 

 hibits some curious irregularities. A few miles south of Sneads, if 

 not elsewhere, can be found places where the water is perpeiually 

 seeping out on gentle slopes, characterized by sandy bog vegetation, 

 and then at the bottom of the same slope, perhaps fifty yards away, 

 may often be found a lime-sink with no water in it; showing that 

 the ground-water surface is more irregular than the surface of the 

 ground in such places. (See Fig. 43.) 



Vegetation Types — The prevailing type of vegetation is open 

 forests of long-leaf pine, so open that wagons can be driven through 

 them almost anywhere (and consequently the minor roads are ill- 

 defined and changeable). The scarcity of underbrush seems to be 

 due primarily to the fires, set originally by lightning, and now 

 mostly by man, either purposely or accidentally. The fires burn ovei 

 every part of the pine woods nearly every year, usually in the 

 latter part of the dry season (early spring), with little injury to the 

 pines, as explained on page 184, The pine forests can be divided ac- 

 cording to topography and moisture into three types, namely, high 

 or dry, low or wet, and intermediate. These all intergrade, and 

 have much the same general appearance, but in the low pine land 

 the trees are mostly slash pine instead of long-leaf. 



Most of the ponds are so full of trees that it would be impossible 

 to use row-boats on them. In those where the water fluctuates 

 three or four feet during the year the pond cypress is almost the 

 only tree; where the annual fluctuation averages about two feet 

 tliere is usually some slash pine mixed with the cypress ; and where 

 it is a foot or less there is a dense undergrowth of evergreen shrubs 

 ar d vines, making a type of vegetation known as bays.* Some of 

 the smaller ponds in the more clayey soils contain black gum or May 

 haw instead of cypress and pine. 



The streams are bordered by swamps and bottoms, varying in 

 character with the size and fluctuation of the stream and the 

 amount of lime or mud in the water. Strips of hammock vegeta- 



*Where the fluctuation is greatest the proportion of 'evergreens is 

 least, and vice versa; which seems to indicate that a constant water-level 

 limits the availability of the potassium compounds and other mineral plant 

 food, perhaps simply by preventing aeration. (See Wiley, U. S. Dept. 

 Agric. Yearbook 1896:127; Harper, Torreya 11:225-234, 1911-) 



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