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Disconformity. A disconformity is an unconformity between parallel layers of sedimentary rocks which represents a period of erosion or non-deposition. [3] Disconformities are marked by features of subaerial erosion. This type of erosion can leave channels and paleosols in the rock record. [4]
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 and by different ...
Disconformity: the contact between younger and older beds is marked by visible, irregular erosional surfaces. Paleosol might develop right above the disconformity surface because of the non-deposition setting. Paraconformity: the bedding planes below and above the unconformity are parallel. A time gap is present, as shown by a faunal break, but ...
Within the Unkar Group, the contact between the Hakatai Shale and overlying Shinumo Sandstone is a distinct disconformity. This contact is the only significant unconformity that occurs within the Unkar Group. This disconformity is sharp and locally truncates cross-bedding and channels exhibited by sandstones in the underlying Hakatai Shale.
It also contains thin beds of shale and siltstone, and conglomerate. The Muav Limestone weathers to a dark gray or rusty-orange color and forms cliffs or small ledges. This formation varies between 45 and 254 m (148 and 833 ft) in thickness. Its upper contact is a disconformity with the overlying Frenchman Mountain Dolostone.
The unconformity and disconformity are inferred to represent most of Permian time (including the Leonardian) and part of Early Triassic time. [ 1 ] [ 6 ] [ 8 ] Although the Moenkopi Formation overlies the Kaibab Limestone, its redbeds have been removed almost entirely by erosion because they are less resistant to erosion than the strata of the ...
Identifying and understanding the relationship between contacts is important in determining relative ages of rocks and formations. [6] Contacts are a key feature used to create geological maps. Cross-cutting relationships of these contacts can be used to determine the relative geological history of an area or of an outcrop.
The Knox lies beneath a unconformity known as the Knox Unconformity. There is well-developed karst topography at the top of the Knox Supergroup. This demonstrates a prolonged period of erosion. This has modern economic impact because of forming reservoirs for hydrocarbons as well as some mineral deposits. [2]