Redwall Limestone

Redwall Limestone Stratigraphic range: Early and early Late Mississippian
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.
Named by	Gilbert (1875)

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.

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.