Chipola Formation

Chipola Formation Stratigraphic range: Late Oligocene-Early Miocene
Type	Geological formation
Unit of	Alum Bluff Group
Lithology
Primary	Dolostone, phosphate, clay, sand
Location
Named for	Chipola River
Region	Florida Panhandle
Country	United States

The Chipola Formation is a Late Oligocene to Early Miocene geologic formation in the Florida Panhandle and member of the Alum Bluff Group.

Age

Period: Neogene
Epoch: Early Miocene to Middle Miocene
Faunal stage: Aqitanian ~18.9 to 18.3 mya, calculates to a period of 0.6 million years

Location

The Chipola Formation is found along the Chipola River.

Lithography

The Chipola Formation is composed of clays, sands and shell beds. These vary from fossil bearing sandy clays to sands, clays, and carbonate beds absent of fossil content with glauconite and phosphate mica which is common. The coloration is from cream to olive gray with mottled reddish brown in the weathered sections. The sands are soft and very fine to coarse with sporadic gravel while carbonate lenses are quite hard. Permeability of the sediments are generally low and are part of the intermediate confining unit/aquifer system.^[1]

Dolabella Auricularia found at Chipola.

Fossils

The Chipola Formation of the Early Miocene contains one of the most diverse, high-abundance ecosystems of mollusks ever described. It contained herbivorous and carnivorous mollusks at 30–50% as well as filter feeders at 7%. The formation was clearly an algae or detritus-based ecosystem not heavily dependent on phytoplankton.^[2] Small land-mammal fauna from an overlying unit supports the older age for the Chipola Formation at 18.9 – 18.3 Ma. (H. Kline et al).

See also

The Choctaw Sea which gave rise to the Chipola Subsea.

References

1. ^ United States Geologic Survey, Open File Report No. 80
2. ^ Kline, H., Herbert, G., Harries, P., Oches, E., Ches, E., and Portell, R., Trophic Structure of Shell Beds from the Early Miocene Chipola Formations of Florida