Description: Bentonite usually forms from the weathering of volcanic ash. Geologically, volcanic ash layers are extremely important in that they provide a contemporaneous time horizon allowing correlation from area to area,

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Figure 1 - Layers of white Bentonite found near the Denjeck River, Yukon. (Photo 1973)

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Figure 2 - Close-up of Bentonite viewed in Figure 1. (Photo 1973)

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Figure 3 - The T-3 Bentonite near Davis Crossroads, Georgia, USA.  Bentonites are commonly difficult to locate due to their soft, crumbly nature that leads to the formation of a soil.  The T-3 Bentonite in the southern Appalachians, however, can be readily located since it is underlain by a resistant Chert formed from the leaching of silica from the Volcanic Ash. 

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Figure 4 - A close-up view of the contact between the Bentonite (greenish-brown) above and the T-3 Chert (black) below found at Davis Crossroads, Georgia, USA.