284 FLORIDA GEOLOGICAL SURVEY-THIRD ANNUAL REPORT.
SOUTHERN PART OF THE EVERGLADES.
(FIGS. 27, 28)
There are several streams and other bodies of water in Florida (besides Helena Run, just described) which in dry weather, when they are fed chiefly by springs, are clear and bluish, but become coffee-colored in wet weather when the swamps and marshes are full of water.*
Most of these are of no particular interest as sources of peat, but there is one which deserves to be described on account of its uniqueness, namely, the south end of the Everglades. In the middle of the Everglades, as already pointed out, the bottom is said to be mostly sand, and the water is probably blackish all or nearly all the time, as in most of our swamps. But at the south end, in the Miami limestone region, there is no sand, and the water which stands in pools and pot-holes or circulates in subterranean channels is decidedly calcareous in the dry season, as shown by its clearness, and by the whitish incrustation that it leaves all over the ground and the bases of plant stems as it dries up.t
"An interesting case of this in Taylor County deserves to be mentioned here. In January, 19o9, I saw in the southern edge of the town of Perry what appeared'to be a limestone spring with a small bluish creek issuing from it, and as far as I followed the creek there were lime-loving plants growing in -t and in the swamps bordering it. In March, I9IO, I revisited the place and was surprised to find the water coming out of the same hole in the ground dark brown, like typical swamp water. On inquiry I was told that this hole in the ground was not a true spring, ut the outlet of the subterranean portion of one of several streams wHich have their source in San Pedro Bay, a few miles to the northeastward; and that the bay was then overflowing as a result of unusually heavy rains the month before, which accounted for the color of the water. This creek must be calcareous most of the time, though, otherwise the vegetation in it (Ceratophylhtm, etc.), would not be so distinctly calciphile.
Ichetucknee Spring, in the southwestern part of Columbia County, seems to be another case of the same kind. B. M. Hall (in U. S. Geol. Surv. Water Supply & Irrigation Paper No. 102, p. 275, 1904), says of this spring:-"The water of the spring has a decided amber color, probably due to surface swamp drainage coming into it." He does not mention the date of his visit, but it must have been shortly after a rainy spell. Every time I have crossed the creek which flows from this spring (Feb. 4 and April 27, 19o9, April 17, 1910) it has appeared to be a typical blue limestone stream.
tThis incrustation is not brittle as it would be if it was wholly inorganic, but is a soft, slightly coherent fiaterial somewhat resembling damp wood-ashes. It probably contains' a considerable proprotion of vegetable matter (such as algae), which gives it a somewhat fibrous consistency.