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Bentonite layers from an ancient deposit of weathered volcanic ash tuff in Wyoming Gray shale and bentonites (Benton Shale; Colorado Springs, Colorado). Bentonite (/ ˈ b ɛ n t ə n aɪ t / BEN-tə-nyte) [1] [2] is an absorbent swelling clay consisting mostly of montmorillonite (a type of smectite) which can either be Na-montmorillonite or Ca-montmorillonite.
Bentonite usually forms from weathering of volcanic ash, most often in the presence of water. However, the term bentonite, as well as a similar clay called tonstein, have been used for clay beds of uncertain origin. For industrial purposes, two main classes of bentonite exist: sodium bentonite and calcium bentonite.
Several different types of bentonite can be found; however, potassium bentonite is the main one associated with the Deicke and Millbrig eruptions. The Deicke and Millbrig K-bentonite layers can be found from Alabama to New York to Minnesota. These K-bentonite layers are up to a meter thick in some locations. [8] Such thickness is unique.
One cluster called the Tioga Middle Coarse Zone (MCZ) is located in the Onondaga Group deposited 391.4 million years ago. Finally Tioga A-G K-bentonites are located in the Onodaga Group and the Union Springs Member of the Marcellus Formation deposited 390.0 million years ago. [2] The volcanic ash was deposited in sea water. [1]
Thunderbird Archaeological District and Jasper quarry, near Limeton, Virginia, is an archaeological district described as consisting of "three sites—Thunderbird Site, the Fifty Site, and the Fifty Bog. It is located in Warren County Virginia, near modern-day Front Royal, in the Shenandoah River Valley.
The Great White Throne in Zion National Park is an example of white Navajo Sandstone Stevens Arch, near the mouth of Coyote Gulch in the Canyons of the Escalante, is formed from a layer of Navajo Sandstone.
Mowry Shale exposed in a road cut, Uintah Basin, Utah. The Mowry Shale or Fish-scale Beds because of the abundance of fish scales, is a dark-gray, siliceous shale that weathers silver gray; it is 10-70 m thick. 40Ar/39Ar of sanidine from a bentonite yielded an age of 97.17 +/-0.69 Ma, [3] thus is Cenomanian in age.
Petrified Forest National Park is a national park of the United States in Navajo and Apache counties in northeastern Arizona.Named for its large deposits of petrified wood, the park covers about 346 square miles (900 square kilometers), encompassing semi-desert shrub steppe as well as highly eroded and colorful badlands.