Redwall Limestone

Redwall Limestone
Stratigraphic range: Early and early Late Mississippian[1][2]

Redwall Limestone cliff, and upper platform of cliff extension from Tower of Set, central Grand Canyon, adjacent Granite Gorge.
The bottom of Redwall cliffs typically rest on sections of Temple Butte Limestone-(locally), or attached sections of Muav Limestone cliffs (regionally exposed in Grand Canyon, elsewhere in Arizona, not always with surface exposure).
Type Geological formation
Underlies Surprise Canyon Formation (Surprise Canyon Formation locally fills paleovalleys, caves, and collapse structures cut into the underlying Redwall Limestone.)
Overlies Muav Limestone and Temple Butte Limestone
Thickness 800 feet (240 m), at maximum
Lithology
Primary fossiliferous limestone
Other dolomite and chert
Location
Region Northern Arizona, southeast California, New Mexico, and southern Utah
Country United States of America
Type section
Named for Named for red appearance of its escarpment on either side of the Grand Canyon.[3]
Named by Gilbert (1875)[3]

Redwall Limestone is a resistant cliff-forming unit that forms prominent, red-stained cliffs that range in height from 500 feet (150 m) to 800 feet (240 m). Dating to the Mississippian age, it consists predominately of light-olive-gray to light-gray, thin-bedded, fine- to coarse-grained, thin- to thick-bedded, often cherty, limestone. Its lower part consists of brownish-gray, interbedded finely crystalline dolomite and fine- to coarse-grained limestone with layers of white chert 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.[1][4]

The upper and lower contacts of the Redwall Limestone are both unconformities. Its upper contact is a disconformity that characteristically is a nearly horizontal surface with little or no relief. (In the Grand Canyon, the upper disconformity forms a horizontal platform at the top of the Redwall Limestone.) Locally, the bottom unconformity of the Redwall Limestone contains a basal conglomerate that directly rests upon this bottom unconformity. This basal conglomerate is typically composed of gravel that is locally derived from either the underlying Temple Butte Limestone or Muav Limestone.

The upper contact of the Redwall Limestone consists of a deeply eroded disconformity characterized by deeply incised paleovalleys and deep paleokarst depressions that are often filled by sediments of the Surprise Canyon Formation.[1][5]

See also

References

  1. 1 2 3 Beus, SS (2003) Redwall Limestone and Surprise Canyon Formation. in: Beus, S.S., Morales, M., eds., pp. 115-134, Grand Canyon Geology, 2nd. Oxford University Press, New York.
  2. ↑ Anonymous (2006e) Redwall Limestone. Stratigraphy of the Parks of the Colorado Plateau. U.S. Geological Survey, Reston, Virginia.
  3. 1 2 Gilbert, GK (1875) Chapter 6 Report upon the geology of portions of Nevada, Utah, California, and Arizona. in GM Wheeler, ed., pp. 17-187, Report on the geographical and geological explorations and surveys west of the One hundredth meridian. Publication of the Wheeler Survey, U.S. Geological and Geographical Survey, Washington, DC.
  4. ↑ Chronic, H (1983) Roadside Geology of Arizona. The Mountaineers Books, Seattle, Washington. (softcover, ISBN 978-0-87842-147-3)
  5. ↑ 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
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.