96 
FLORIDA STAFF GEOLOGICAL SURVEY. 
mine belonging to Mr. Hymeson, Vaughan reports the following sec¬ 
tion. 1 
4. Surface sands, beneath which are reddish sands containing some 
quartz gravel ... 60 feet. 
3. Stiff blue clay, the top of the fullers earth deposit. 4 feet. 
2. Fullers earth. A considerable amount of the overburden had been 
thrown off, but due to weathering and wash there is really no 
good exposure. Judging from what can now be seen, accord¬ 
ing to a roughly leveled section, it seems that the deposit is at 
least 8 feet thick, and it may be thicker. There is no means 
of determining its horizontal extent. A box of the earth was 
collected from the best exposure. 
1. Immediately beneath the fullers earth, there appears to be a deposit 
of sandy, very stiff blue day. Thickness unknown. 
The following is the generalized section, according to aneroid readings made 
in the vicinity of River Junction : 
Generalised, section near River Junction. 
Surface sands ... 60 feet. 
Clay and fullers earth.. .... . 10 feet. 
Not exposed, but probably argillaceous sands... 17 feet. 
Chalk or limestone with some layers of marl (Chattahoochee), about.. 88 feet. 
The rocks beneath the Chattahoochee formation are not exposed near River 
Junction. 
The inference from this section apparently would be that the Chattahoochee 
formation is 88-f- feet in thickness, separated by 17 feet of unexposed strata from 
the deposit of fullers, earth, which would come above. This would strati- 
graphically correlate the deposit of fullers earth with the Alum Bluff formation. 
The following is the detailed description and section of Rock bluff on the 
Apalachicola River published by Dali and Stanley-Brown. 2 The writer is of the 
opinion that the fullers earth horizon corresponds to No. 3 of their section. 
The lower part of the bluff formed by the Chattahoochee limestone is vertical, 
rising 12 feet above the water, and presumably nearly as much below it, at low 
stages of the river. Above this is a mass of marl varying from bluish green to 
gray in color, weathering white, more arenaceous below and more marly above, 
replete with oyster shells, a fine, large Anomia, a pecten, like young madisonius 
(but, as observed by Foerste, only four-sevenths the size of that species; it is 
really a Chipola species), Turritella, and many Balani. This assemblage of 
species indicates a shallow water oyster-reef fauna unquestionably belonging to 
the “old Miocene” (Apalachicola group) and forming the shoal-water equivalent 
of the Chipola and Alum Bluff beds, especially the latter. Above this marl lie 
the red Lafayette clays and gravels—in this case worked-over materials—variable 
in thickness, owing to denudation, but apparently averaging about fifteen feet, 
and covered with a thin layer of superficial soil and sand. This section was 
carefully measured with a steel tapeline, due allowance being made for the in¬ 
clination of the tape from the vertical. It shows the finest and thickest section 
of the greenish marl exposed anywhere on the river. The contact of the marl 
1 Ibid. pp. 926-927. 
2 Bull. Geol. Soc. Amer., vol. v, 1894, pp. 155-156. 
