7O FLORIDA GEOLOGICAL SURVEY-TWELFTH ANNUAL REPORT 
with Joseph Willcox, visited this locality in 1886, refers to this 
formation as follows.* “This is without question the most re¬ 
markable fossiliferous deposit that has as yet been discovered in 
the State, and from a purely paleontological standpoint, perhaps, 
the most significant in the entire United States east of the Missis¬ 
sippi River. The fossils, which are about equally distributed be¬ 
tween both banks, crop out in almost countless numbers, and attract 
attention, apart from their prodigious development, by their great 
variety, large size, and beautiful state of preservation. The whole 
bank much resembles a fossil shell-beach, and recalled to my mind 
the wall of shells extending from Little Sarasota Inlet to Casey’s 
Pass.” At Fort Thompson this marl passes beneath later forma¬ 
tions from which it is separated by a well marked unconformity 
which is best seen in the exposures along the river between Labelle 
and Fort Thompson. The following section is seen at a cut-off 
between two bends in the river about one-half mile below Fort 
Thompson. The section as given here was made by the writer in 
1908. 
SECTION ONE-HALF MILE BELOW FORT THOMPSON. 
8. Sand and soil at top of bank about 2 feet. 
7. Shell marl in which Chione cancellata predominates 2 feet. 
6. Shell marl in which fresh water gastropods predominate 2 feet. 
5. Shell marl, marine shells y 2 foot. 
4. Unconformity. 
3. Calcareous stratum weathering rough on exposure containing Pliocene 
fossils 3 feet. 
2. Shell marl with Pliocene fossils 1 foot. 
1. Blue sandy clay marl with few fossils to the waters edge 3 feet. 
An examination of the banks above and below this locality 
shows that while the details of the section vary, the unconformity 
is persistent and is well marked. As illustrating local variation 
it may be noted that a few rods down stream from the point from 
which this section was made, the marine shell (No. 5) is lacking, 
the fresh water marl being the first member above the uncon¬ 
formity, while about one-fourth mile down stream clay lenses as 
*Trans. Wagner Free Inst. Sci., Vol. 1 , p. 28, 1887. 
