SECOND ANNUAL REPORT^STRATIGRAPHIC GEOLOGY. 103 
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mains, whereas the marl is densely charged with them. Among the recognizable 
forms occurring here, I .determined. a number of well-known and distinctive 
Miocene species of mollusks, such as Pecten Jeffersonms, P« Madisonius , Perna 
maxillata, Venus alveata, Area incongrua, etc., which left no doubt as to the 
age of the deposits 1 in which they were imbedded. 
The exposures'in the vicinity of Ellenton are of xonsiderable inter¬ 
est because they-contain valuable deposits of-fullers earth. 
Three-fourths of a mile southeast ol Ellenton,: a section was meas¬ 
ured, which showed: 
1. Dark gray to black sandy loam............ V.. 4 to 6 feet. 
2. Dark colored clayey sand,' containing chert pebbles, worn and 
rounded fragments- of bones,'and sharks’ teeth. “Clam” 
shells are said.to occur; in this bed, but none could be found 0 to 2 feet. 
3; Unconformity. . 
4. Dense thinly laminated light gray fullers earth, weathering- 
pale yellow .... 5 to 8 feet. 
Total .0 to 16 feet. 
About one-fourth of a .mile farther east is another exposure which 
shows both the fullers earth and the underlying limestone, ktere the 
sandy loam and fullers earth are both thinner than at the other lo¬ 
cality. 
1. Light and- dark gray, sandy loam, about../. <. . .... ................. . 1 . foot- 
2. Black clayey loam with bone fragments. .. . 1. foot. 
3. Unconformity. 
4. Light gray fullers earth.. ....... 2-3 feet. 
5. Dense light gray to pale’ yellow impure foss'iliferous limestone 
(above water) ........... .•.........".. ...... . 4 feet. 
■ • (below - water) ...v^. ...■ 9--}-:feet. 
Total ... ... ... 17.4- feet. 
This is the locality which is known as Rocky Bluff. The material 
which' Heilprin 1 called sandstone appears to be a coarse-grained sandy 
limestone. Shells and fragments of bone are numerous in certain 
horizons; but the rock is so brittle’ that it is difficult to get good col¬ 
lections. The presence of Turritella alcida Dali, and Pec'teii madi- 
soiiins var, saydnus Dali have led to this limestone being referred to 
the Alum Bluff formation, but larger collections may show that it be¬ 
longs to some other subdivision of the Apalachicola group. The exact 
relation of the fullers earth bed to the limestone was difficult to de¬ 
termine, though it is apparently conformable; and if so, it belongs to 
the Oligocene. HeilpriiTs reference of the exposures at Rocky Bluff 
to the Miocene appears to have been an error,' unless he intended to 
1 Loc. cit 
