The Redwall Limestone is a resistant cliff-forming unit of

Mississippian age The Mississippian ( , also known as Lower Carboniferous or Early Carboniferous) is a subperiod in the geologic timescale or a subsystem of the geologic record. It is the earlier of two subperiods of the Carboniferous period lasting from roughly ...

that forms prominent, red-stained cliffs in the

Grand Canyon The Grand Canyon (, yuf-x-yav, Wi:kaʼi:la, , Southern Paiute language: Paxa’uipi, ) is a steep-sided canyon carved by the Colorado River in Arizona, United States. The Grand Canyon is long, up to wide and attains a depth of over a m ...

, ranging in height from to .

Lithology

Redwall Limestone consists predominantly of light-olive-gray to light-gray, fine- to coarse-grained, thin- to thick-bedded, often cherty,

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

. Its lower part consists of brownish-gray, interbedded finely crystalline

dolomite Dolomite may refer to: *Dolomite (mineral), a carbonate mineral *Dolomite (rock), also known as dolostone, a sedimentary carbonate rock *Dolomite, Alabama, United States, an unincorporated community *Dolomite, California, United States, an unincor ...

and fine- to coarse-grained limestone with layers of white

chert Chert () is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a prec ...

lenses and yellowish-gray and brownish-gray, cliff-forming, thick-bedded, fine-grained dolomite. It is divided into Horseshoe Mesa Member, Mooney Falls Member, Thunder Springs Member, and Whitmore Wash Member.Chronic, H (1983) ''Roadside Geology of Arizona.'' The Mountaineers Books, Seattle, Washington. (softcover, ) Its origins date to the Mississippian age.

Contacts

The upper and lower contacts of the Redwall Limestone are both unconformities. Locally, the Redwall Limestone directly overlies the unconformity that forms its lower contact consisting of a basal conglomerate. This basal conglomerate is typically composed of

gravel Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes; it is also produced in large quantities commercially as crushed stone. Gravel is classifi ...

that is locally derived from either the underlying Temple Butte Formation or Muav Limestone. The Temple Butte Formation consists of a thin layer of

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...

strata In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as ei ...

that fills paleovalleys cut into the underlying

Cambrian The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...

Muav Limestone. Outside of the paleovalleys, the Redwall Limestone overlies the Muav Limestone. The upper contact of the Redwall Limestone consists of a deeply eroded disconformity characterized by deeply incised paleovalleys and deep paleo

karst Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathering-resistant ro ...

depressions that are often filled by sediments of the

Surprise Canyon Formation The Surprise Canyon Formation is a geologic formation that consists of clastic and calcareous sedimentary rocks that fill paleovalleys and paleokarst of Late Mississippian ( Serpukhovian) age in Grand Canyon. These strata outcrop as isolated, le ...

.Kenny, R (2010
''Continental paleoclimate estimates from the late Mississippian Redwall karst event: northern and north-central Arizona (USA).''
Carbonates Evaporites. 25(4):297–302

References

External links

* Abbot, W, (2001
''Revisiting the Grand Canyon – Through the Eyes of Seismic Sequence Stratigraphy.''Search and Discovery Article # 40018
America Association of Petroleum Geologists, Tulsa, Oklahoma. * Anonymous (nda
''The Redwall Limestone Formation.''
* Mathis, A., and C. Bowman (2007
''The Grand Age of Rocks: The Numeric Ages for Rocks Exposed within Grand Canyon''Grand Canyon National Park, Arizona
National Park Service, Grand Canyon National Park, Arizona. * Shur, C., and D. Shur (2008

Limestone formations of the United States Natural history of the Grand Canyon Geologic formations of Arizona Geologic formations of Utah Carboniferous Arizona Carboniferous geology of Utah Carboniferous System of North America Carboniferous southern paleotropical deposits {{US-geology-stub

Lithology

Contacts

See also

References

Further reading

External links