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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 ...
[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 ...
The Vishnu Basement Rocks were deposited as mafic and felsic volcanic rocks and sediments but were later metamorphosed and intruded by igneous rock. The Vishnu Basement Rocks is the name recommended for all Early Proterozoic crystalline rocks (metamorphic and igneous) exposed in the Grand Canyon region. They form the crystalline basement rocks ...
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 ...
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.. The Tonto Group is a name for an assemblage of related sedimentary strata, collectively known by geologists as a Group, that comprises the basal sequence Paleozoic strata exposed in the sides of the Grand Canyon.
Eparchaean Unconformity. / 13.6833; 79.35. Tirupati Eparchaean Unconformity, a notified National Geo-heritage Monument [ 1][ 2][ 3] is a major discontinuity of stratigraphic significance that represents a period of remarkable serenity in the geological history of the Earth i.e. sudden changes and discontinuity in the rock layers in Earth's crust.
Sep. 5—A new study led by University of Colorado Boulder researchers sheds light on one of the world's great geological mysteries: a missing chapter of the earth's rock record known as the Great ...