HISTORY

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 Geological History of the Clark Creek Area

The geological units encountered in the Clark Creek are assigned to three named stratigraphic intervals; the Peoria loess, the Upland Complex (also known as the Citronelle formation), and the Fleming Formation. They can be seen in order of increasing age as one descends from the parking area to the creek bottom. 

The top most formation consists of the Peoria loess formation. Radiocarbon dates from the Peoria Loess established that these materials were deposited in the Holocene Epoch, about 22,000 to 20,000 years before the present.. The lack of fossils and no straitification of layers suggests that the deposit was placed by wind instead of water. A high amount of carbonate exists in this formation.

Underlying the loess is the Citronelle Formation. The sediments of the Citronelle Formation are probably older than 100,000 years, but the scarcity of fossils makes their age difficult to assess reliably. They are generally considered to be Pleistocene or Late Pliocene in age and thus may be as much as 2,000,000 years old. It consists basically of sands and fine gravel deposited by streams crossing a gently sloping coastal plain (similar to that of present day southern Louisiana). 

Below the Citronelle Formation lies the Fleming Formation. The Fleming Formation is assigned to the Pliocene and Miocene Epochs of the Tertiary Period, 5 to 10 million years ago. This formation contains iron oxide nodules that were formed when the sand was being converted to soil. These iron oxide nodules account for the deep red spots that can be seen throughout the formation. Upon exposure to the environment the formation dries out and becomes hard and ledgy. This along with a cementing action forms a siltstone ledge that forms the waterfalls in the area. Pascagoula clay of the Miocene Era underlies the Fleming Formation. This clay has been exposed in a few places along the creeks bottom. 

 


 


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