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The Great Unconformity of Powell in the Grand Canyon is a regional unconformity that separates the Tonto Group from the underlying, faulted and tilted sedimentary rocks of the Grand Canyon Supergroup and vertically foliated metamorphic and igneous rocks of the Vishnu Basement Rocks. The unconformity between the Tonto Group and the Vishnu ...
Hutton's Unconformity. Hutton's Unconformity is a name given to various notable geological sites in Scotland identified by the 18th-century Scottish geologist James Hutton as places where the junction between two types of rock formations can be seen. This geological phenomenon marks the location where rock formations created at different times ...
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 ...
Figure 1. A geologic cross section of the Grand Canyon. [12] Throughout the majority of its extent, the Tapeats Sandstone lies unconformably on the surface of underlying Precambrian rocks forming the Great Unconformity. Where the Sixtymile Formation underlies the Tapeats Sandstone, the Great Unconformity lies at the base of the Sixtymile Formation.
James Hutton FRSE ( / ˈhʌtən /; 3 June O.S. [1] 1726 – 26 March 1797) was a Scottish geologist, agriculturalist, chemical manufacturer, naturalist and physician. [2] Often referred to as the "Father of Modern Geology," [3][4] he played a key role in establishing geology as a modern science. Hutton advanced the idea that the physical world ...
[10] [11] The contact between the overlying Tapeats Sandstone and the folded and faulted Nankoweap Formation is a prominent angular unconformity that is part of the Great Unconformity. [7] Uranium-lead dating of detrital zircons from the Nankoweap Formation indicate the presence of zircon grains in approximately the 800–770 Ma age range. This ...
Los Angeles Basin. The Los Angeles Basin is a sedimentary basin located in Southern California, in a region known as the Peninsular Ranges. The basin is also connected to an anomalous group of east-west trending chains of mountains collectively known as the Transverse Ranges. The present basin is a coastal lowland area, whose floor is marked by ...
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 ...