Search results
Results from the WOW.Com Content Network
Angular unconformity. An angular unconformity is an unconformity where horizontally parallel strata of sedimentary rock are deposited on tilted and eroded layers, producing an angular discordance with the overlying horizontal layers. [6] The whole sequence may later be deformed and tilted by further orogenic activity. A typical case history is ...
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 ...
[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 ...
Cross-cutting relationships can be used to determine the relative ages of rock strata and other structures. Explanations: A – folded rock strata cut by a thrust fault; B – large intrusion (cutting through A); C – erosional angular unconformity (cutting off A & B) on which rock strata were deposited; D – volcanic dike (cutting through A, B & C); E – even younger rock strata (overlying ...
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 ...
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 ...
Hutton's angular unconformity at Siccar Point where 370-million-year-old Devonian Old Red Sandstone overlies 435-million-year-old Silurian greywacke. [2]Old Red Sandstone, abbreviated ORS, is an assemblage of rocks in the North Atlantic region largely of Devonian age.
The unconformity between the Tonto Group and the Vishnu Basement Rocks is a nonconformity. The break between the Tonto Group and the Grand Canyon Supergroup is an angular unconformity. [2] [3] [4] Powell's Great Unconformity is part of a continent-wide unconformity that extends across Laurentia, the ancient core of