Age and History of Investigation
The age of the Navajo Sandstone is somewhat controversial. It may originate from the Late Triassic but is at least as old as the Early Jurassic stages Pliensbachian and Toarcian. There is no type locality of the name. It was simply named for the 'Navajo Country' of the southwestern United States. The two major subunits of the Navajo are the Lamb Point Tongue (Cedar City area) and the Shurtz Sandstone Tongue (Kanab area).
The Navajo Sandstone was originally named as the uppermost formation of the La Plata Group by Gregory and Stone in 1917. Baker reassigned it as the upper formation of Glen Canyon Group in 1936. Its age was modified by Lewis and others in 1961. The name was originally not used in northwest Colorado and northeast Utah, where the name 'Glen Canyon Sandstone' was preferred. Its age was modified again by Padian in 1989.
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