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Geologic stratigraphic column of strata exposed in and near the Grand Canyon. Of the many unconformities (gaps) observed in geological strata, the term Great Unconformity is frequently applied to either the unconformity observed by James Hutton in 1787 at Siccar Point in Scotland, [1] [failed verification] or that observed by John Wesley Powell in the Grand Canyon in 1869. [2]
The geology of the Grand Canyon area includes one of the most complete and studied sequences of rock on Earth. The nearly 40 major sedimentary rock layers exposed in the Grand Canyon and in the Grand Canyon National Park area range in age from about 200 million to nearly 2 billion years old. Most were deposited in warm, shallow seas and near ...
(3.5 mi by 2.0 mi block) At Apollo Temple landform, the Cambrian Tapeats Sandstone lies above the angular Great Unconformity with strata of the Chuar Group, Nankoweap Formation (the striped), Cardenas Basalt (the dark), and Dox Formation (red) below. (The lower strata are dipping to the right (east), as well as a total regional-dip to the ...
Throughout the majority of it extent, the Tonto Group lies unconformably on underlying Precambrian rocks forming the Great Unconformity. This contact is either an angular unconformity truncating tilted strata of the Grand Canyon Supergroup or a nonconformity cut into the crystalline Vishnu Basement Rocks. The base of the Tonto Group consists of ...
Where the Sixtymile Formation underlies the Tapeats Sandstone, the Great Unconformity lies at the base of the Sixtymile Formation. This unconformity is either an angular unconformity truncating tilted strata of the Grand Canyon Supergroup or a nonconformity with the Vishnu Basement Rocks and other Precambrian metamorphic or plutonic rocks ...
The Unkar Group is a sequence of strata of Proterozoic age that are subdivided into five geologic formations and exposed within the Grand Canyon, Arizona, Southwestern United States. The Unkar Group is the basal formation of the Grand Canyon Supergroup. The Unkar is about 1,600 to 2,200 m (5,200 to 7,200 ft) thick and composed, in ascending ...
An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger layer, but the term is used to describe any break in the ...
The Los Angeles Basin contains what is known as the "Great Unconformity" which has been interpreted as a large scale erosional event in the basement rock unit. This unconformity is used to correlate strata throughout the basin. The record of the Cenozoic activity begins above this unconformity. [1]