Search results
Results from the WOW.Com Content Network
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]
At the base of this sequence, the Great Unconformity, with the Tapeats Sandstone of the Tonto Group overlying the Vishnu Basement Rocks, is well exposed in a manner that is atypical and scientifically significant in its combination of extent and accessibility. This exposure is frequently illustrated in popular and educational publications, and ...
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.
Also called Indianite. A mineral from the lime-rich end of the plagioclase group of minerals. Anorthites are usually silicates of calcium and aluminium occurring in some basic igneous rocks, typically those produced by the contact metamorphism of impure calcareous sediments. anticline An arched fold in which the layers usually dip away from the fold axis. Contrast syncline. aphanic Having the ...
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 ...
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.
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.
The upper contact of the Sixtymile Formation is a disconformity that laterally becomes an angular unconformity. Within the center of the Chuar Syncline, this upper contact is a disconformity. Away from the center, the strata of the Sixtymile Formation, an angular discordance between the formations of 6° to 10° can be seen.