84 
FLORIDA STATE GEOLOGICAL SURVEY. 
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7. 
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5. 
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1 . 
Cement Quarry one-half mile south of River Junction. Thickness. 
Feet. Inches. 
Superficial coating of black humus and some gray sand 
Friable chalky limestone forming slope of hill. 13+ 
Harder chalky layer . 
Softer chalky layer . 1 
Harder, somewhat saccharoidal limestone. 
Softer fossiliferous chalk . 1 
Harder limestone with numerous fossils, the commonest the 
Hemicardium and an orbitoid foraminifer. This material 
when weathered turns reddish and forms a residual red 
clay. No original molluscan tests were observed, but they 
are sometimes replaced by crystalline calcite. 1 
Soft white chalk, indurating upon exposure, used in making 
cement brick .. 4 
5 
5 
9 
7 
3 
According to the barometer, the base of No. 1 is 50 feet above the railroad 
at River Junction. 
Some twelve to fifteen feet of limestone belonging to the Chatta¬ 
hoochee formation is exposed at Rock Bluff, and it doubtless under¬ 
lies the Chipola marl member at Alum Bluff. On the Chipola River 
the same limestone is exposed at intervals from near the mouth of 
Ten-mile Creek northward to beyond the Peacock Bridge. These ex¬ 
posures seldom exceed four or five feet in thickness and the rock is a 
chalky limestone similar to that exposed on Apalachicola River. The 
outcrops at Peacock and Willis bridges on the Chipola River were 
visited, but they proved to be nearly destitute of organic remains. 
This limestone, doubtless, forms the natural bridges over Ten-mile 
and Sinking Creeks, tributaries of the Chipola River, but high water 
prevented a close examination of these localities. Similar limestone 
occurs in the form of loose bowlders in the vicinity of Knoxhill, Wal¬ 
ton County, and outcrops of it are reported on the Choctawhatchee 
River, south of the Touisville and Nashville Railroad bridge. At 
Caryville, the well of the Wood Lumber Company penetrated eight 
feet of pinkish limestone, which doubtless belongs to the Chattahoochee 
formation. The limestone at St. Marks and at some localities farther 
north and east is also tentatively referred to this formation. 
TAMPA FORMATION. 
The Tampa formation consists of greenish clays, light gray to 
yellow limestones, and a very fossiliferous bed of “silex.” Hitherto, 
the “silex” and a portion of the limestone have been all that was known 
of the formation. The “silex beds” and limestone of the Tampa forma¬ 
tion were first examined by Conrad 1 over sixty years ago. In the 
1 Conrad, T. A., Observations on Eocene formations and descriptions of 
105 new fossils of that period from the vicinity of Vicksburg, Miss.; Phila. Acad. 
Science Proc., vol. iii, p. 28. 
