Coosawhatchie Formation
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| Coosawhatchie Formation | |
|---|---|
| Stratigraphic range: Miocene | |
| Type | Geological formation |
| Unit of | Hawthorn Group |
| Sub-units | Charlton Member |
| Lithology | |
| Primary | Sand, clay, limestone, dolomite, phosphate clay |
| Location | |
| Region | North Florida |
| Country | United States |
| Type section | |
| Named for | Coosawhatchie River |
| Named by | Dall and Stanley-Brown (1894) |
The Coosawhatchie Formation is a Miocene geologic formation with an outcrop in North Florida. It is within the Hawthorn Group.
Period: Neogene
Epoch: Miocene ~23.03 to 5.33 mya, calculates to a period of 17.7 million years
Faunal stage: Arikareean through Hemphillian
Location
The Coosawhatchie Formation is located on the eastern flank of the Ocala Platform near southern Columbia County and southern Marion County, Florida. It extends south-southeast and is present in Alachua, Marion, Sumter, and Lake County. It is exposed or lies beneath a thin overburden.
Lithography
The Coosawhatchie Formation varies in color from a light gray to olive gray. It is poorly consolidated, variably clayey and phosphate containing sand which occasionally contain a dolomitic component but rarely is it dominated with dolomite or limestone.
Silicified nodules are often present in the sediments and may contain 20% or more phosphate. The permeability factor of the Coosawhatchie sediments is generally low, forming part of the intermediate confining aquifer system.