224 
FLORIDA STAFF GEOLOGICAL SURVEY. 
At Marco the limestone may run out and be represented by un¬ 
consolidated material. No wells have been drilled inland through 
rocks that can as yet be correlated with the Lostmans River limestone. 
The nearest deep wells to the east of Cape Romano are those on cattle 
ranges in Tps. 47 and 48, Rs. 31 and 33. According to the driller, 
H. Seniff, of Fort Myers, no hard rock was found in these wells near 
the surface. 
Areal Distribution:—Marine limestones have been found to under¬ 
lie the shore of the mainland wherever samples have been collected, 
from Jewfish Creek westward and northwestward to near Marco. 
They outcrop in the southernmost patch of the west coast pineland 
three miles northeast of the head of Rock Creek and at the heads of 
Turners and Allens Rivers and Hendersons Creek. 
At Everglade the writer was told that limestones are found in the 
hammock land about Deep Lake, twelve miles to the east, and at Hen¬ 
dersons Creek he was informed that outcrops makihg bare ridges 
occur in the pineland. Limestone is also reported along the road from 
Fort Myers to Fort Shackelford, but the marine origin of exposure 
more than 20 miles from the coast of southern Florida has not been 
established. 
Origin:—Willis 1 has suggested that the rock at Lostmans River was 
perhaps formed by the deposition of crystallizing calcium carbonate 
from the presumably limy waters of the Everglades. While there can 
be no doubt that deposits of marl are now accumulating along the coast, 
the present hardening of marl to crystalline limestone or the direct de¬ 
position of such limestone is not established. As the writer has stated, 
the bed rock of the western coast, wherever soundings have been made, 
whether in the Everglades, on swamp islands, along the coast, or in 
the numerous creek channels, seems to have a gentle slope toward the 
Gulf. The rock is no farther below water level in the swamp than in 
adjacent channels; moreover, the rock surface in channels where the 
current runs strongly, is full of crevices, is extremely rough, and is 
evidently being eroded. Loose fragments that have been detached • 
by solution are found, not only near the mouths of rivers, but at their 
heads, on the bare rock, under marl, and under vegetable muck. 
Another fact that impairs the deposition and crystallization theory is 
the character of the Everglades water. Most of the marl in the Ten 
Thousand Islands has come from the ever-dirty shallows of the Gulf. 
The dark limestones below water in the creeks are the same as those 
that outcrop above water a short distance away, and a recent crystal¬ 
lization from -solution of those is hard to understand. 
1 Willis, Bailey. Journal of Geology, I, 1893, pp. 512-514. 
