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{{Short description|Geologic formation in Arizona, USA}}
{{Infobox rockunit
{{Infobox rockunit
| image = Grand Canyon view.jpg
| image = Grand Canyon view.jpg
| imagesize = 250px
| imagesize = 250px
| caption = Redwall Limestone cliff, and upper platform of cliff extension from Tower of Set, central [[Grand Canyon]], adjacent Granite Gorge. <br>The bottom of Redwall cliffs typically rest on sections of [[Temple Butte Formation]]-(locally), or attached sections of [[Muav Limestone]] cliffs (regionally exposed in Grand Canyon, elsewhere in Arizona, not always with surface exposure).
| caption = Redwall Limestone cliff, and upper platform of cliff extension (resting on very short [[Muav Limestone]] cliff), from [[Tower of Set]], central [[Grand Canyon]], adjacent Granite Gorge. <br>The bottom of Redwall cliffs typically rest on sections of [[Temple Butte Formation]]-(locally), or attached sections of [[Muav Limestone]] cliffs (regionally exposed in Grand Canyon, elsewhere in Arizona, not always with surface exposure).
| period = Mississippian
| period = Mississippian
| age = Early and early Late Mississippian<ref name="Beuss2003a">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.</ref><ref name="Anonymous2006e">Anonymous (2006) [http://3dparks.wr.usgs.gov/coloradoplateau/index.html Stratigraphy of the Parks of the Colorado Plateau]. U.S. Geological Survey, Reston, Virginia.{{Dead link|date=May 2019}}</ref>
| age = Early and early Late Mississippian<ref name="Beuss2003a">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.</ref><ref name="McKeeOthers1969a"/>
| type = [[Geological formation]]
| type = [[Geological formation]]
| prilithology = fossiliferous [[limestone]]
| prilithology = [[fossiliferous limestone]]
| otherlithology = [[Dolomite (rock)|dolomite]] and [[chert]]
| otherlithology = [[Dolomite (rock)|dolomite]] and [[chert]]
| namedfor = Named for red appearance of its escarpment on either side of the Grand Canyon.<ref name="Gilbert1875a">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.</ref>
| namedfor = the red appearance of its escarpment on either side of the Grand Canyon<ref name="Gilbert1875a"/>
| namedby = Gilbert (1875)<ref name="Gilbert1875a"/>
| namedby = Gilbert (1875)<ref name="Gilbert1875a"/>
| region = Northern Arizona, southeast California, New Mexico, and southern Utah, Nevada
| region = Northern Arizona, southeast California, New Mexico, and southern Utah, Nevada
|country = [[Southwest United States|United States of America]]
|country = [[Southwest United States|United States of America]]
| coordinates =
| coordinates =
| unitof =
| unitof =
| subunits =
| subunits =
| overlies = [[Muav Limestone]] and [[Temple Butte Formation]]
| overlies = [[Muav Limestone]] and [[Temple Butte Formation]]
| underlies = [[Surprise Canyon Formation]] (Surprise Canyon Formation locally fills paleovalleys, caves, and collapse structures cut into the underlying Redwall Limestone.)
| underlies = [[Supai Group]] and locally [[Surprise Canyon Formation]]. The Surprise Canyon Formation fills local paleovalleys, caves, and collapse structures cut into the underlying Redwall Limestone.
| thickness = {{convert|800|ft|m|sp=us}}, at maximum
| thickness = {{convert|244|m|ft|abbr=on}}, at maximum
| extent =
| extent =
| area =
| area =
| map =
| map =
| map_caption =
| map_caption =
}}
}}


The '''Redwall Limestone''' is a resistant [[cliff-former|cliff-forming]] unit of [[Mississippian age]] that forms prominent, red-stained cliffs ranging in height from {{convert|500|ft|m|sp=us}} to {{convert|800|ft|m|sp=us}}.
The '''Redwall Limestone''' is an erosion-resistant, [[Mississippian age]], [[cliff-former|cliff-forming]] [[geological formation]] that forms prominent, red-stained cliffs in the [[Grand Canyon]]. these cliffs range in height from {{convert|150|m|ft|abbr=on}} to {{convert|244|m|ft|abbr=on}}. It is one of the most [[fossiliferous]] formations exposed in the Grand Canyon region.<ref name="Beuss2003a"/><ref name="McKeeOthers1969a"/>


==Lithology==
== Nomenclature ==
In 1875, Gilbert<ref name="Gilbert1875a">Gilbert, G.K., 1875. ''Report upon the geology of portions of Nevada, Utah, California, and Arizona, Chapter 6.'' In Wheeler, G.M., ed., pp. 17-187, ''Report on the Geographical and Geological Explorations and Surveys West of the One Hundredth Meridian'', vol. 3. U.S. Geological and Geographical Survey, Publication of the Wheeler Survey, Washington, D.C., 681 pp.</ref> recognized and named the Redwall Limestone for the red coloration of its [[escarpment]] on either side of Grand Canyon. As originally defined by him, it included some [[strata]] younger and older than as it is currently defined. Later in 1910, Darton<ref name="Darton1910a">Darton, N. H., 1910. ''A reconnaissance of parts of northwestern New Mexico and northern Arizona''. ''U.S. Geological Survey Bulletin''. 435, 88p.</ref> selected a canyon that he named the ''Redwall Canyon'' in the Shinumo drainage basin, on north side of the Grand Canyon, as the [[stratotype|type section]] of the Redwall Limestone. At this location, it consists ''mostly'' of the ''usual heavily bedded massive [[limestone]]'' and is circa {{convert|244|m|ft|abbr=on}} thick. Noble<ref name="Noble1914a">Noble, LF (1914) ''The Shinumo quadrangle, Grand Canyon district, Arizona.'' Bulletin no. 549, US Geological Survey, Reston, Virginia. 42 pp.</ref> subsequently redefined the Redwall Limestone in its present definition, which includes all strata of Mississippian age. As a result of studies in [[Yavapai County, Arizona]], Gutschick<ref name="Gutschlck1943a">Gutschlck, R. C., 1943. ''The Redwall Limestone (Mississippian) of Yavapai County, Arizona''. ''Plateau'', 16(1), pp. 1-11.</ref> recognized four informal members within the Redwall Limestone and McKee<ref name="McKee1963a">McKee, E. D., 1963. ''Nomenclature for lithologic subdivisions of the Redwall Limestone, Arizona''. ''U.S. Geological Survey Professional Paper''. 475-C, pp. C21-C23.</ref> later formally named them. The most comprehensive study of the Redwall Limestone is the ''History of the Redwall Limestone of northern Arizona'' by McKee and Gutschick.<ref name="McKeeOthers1969a">McKee, E.D., and Gutschick, R.C., eds., 1969. ''History of the Redwall Limestone of northern Arizona, [with] chapters on paleontology of the Redwall Limestone by B. Skipp, W.J. Sando, H. Duncan, E.L. Yochelson, W.M. Furnish, D.B. Macurda, Jr., and J.C. Brower''. ''Geological Society of America Memoir''. 114. Boulder, Colorado, Geological Society of America. 612 pp {{ISBN|978-08-137-1114-0}}</ref>
⚫
Redwall Limestone consists predominately of light-olive-gray to light-gray, fine- to coarse-grained, thin- to thick-bedded, often cherty, [[limestone]]. Its lower part consists of brownish-gray, interbedded finely crystalline [[Dolomite (rock)|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.<ref name="Beuss2003a"/><ref name="Chronic1983a">Chronic, H (1983) ''Roadside Geology of Arizona.'' The Mountaineers Books, Seattle, Washington. (softcover, {{ISBN|978-0-87842-147-3}})</ref> Its origins date to the Mississippian age.


==Contacts==
== Description ==
⚫
Redwall Limestone consists predominantly of light-olive-gray to light-gray, fine- to coarse-grained, thin- to thick-bedded, often cherty, limestone. Its lower part consists of brownish-gray, interbedded with finely crystalline [[Dolomite (rock)|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.<ref name="Beuss2003a"/><ref name="McKeeOthers1969a"/>
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 (geology)|conglomerate]]. This basal conglomerate is typically composed of [[gravel]] 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]] [[strata]] that fills paleovalleys cut into the underlying [[Cambrian]] Muav Limestone. Outside of the paleovalleys, the Redwall Limestone overlies the Muav Limestone.<ref name="Beuss2003a"/>


In ascending order, the Redwall Limestone is divided into the ''Whitmore Wash'', ''Thunder Springs'', ''Mooney Falls'', and ''Horseshoe Mesa'' members. All four [[Stratigraphic unit|member]] have their type locality in the Grand Canyon or its tributaries. They are recognized throughout the Grand Canyon area, northern Arizona, and southern Utah. They are all Mississippian in age.<ref name="Beuss2003a"/><ref name="McKeeOthers1969a"/>
The upper contact of the Redwall Limestone consists of a deeply eroded disconformity characterized by deeply incised paleovalleys and deep paleo[[karst]] depressions that are often filled by sediments of the [[Surprise Canyon Formation]].<ref name="Beuss2003a"/><ref name="Kenny2010a">Kenny, R (2010) [http://faculty.fortlewis.edu/KENNY_R/publications/carb%20and%20evap%202010.pdf ''Continental paleoclimate estimates from the late Mississippian Redwall karst event: northern and north-central Arizona (USA).''] Carbonates Evaporites. 25(4):297-302</ref>

The '''Whitmore Wash Member''' is the basal, oldest, member of the Redwall Limestone. It typically forms a high, resistant cliff standing on a narrow bench or series of ledges typical of underlying [[strata]]. This member consists of nearly pure limestone and dolomite, which contains less than 2 percent insoluble [[gypsum]] and [[iron oxide]]s. This member is predominately composed of thick-bedded, ranging from {{convert|0.6 to 1.22|m|ft|abbr=on}} and locally thicker, limestone in western Grand Canyon and changes to mostly very thick-bedded {{convert|1.2 to 4.5|m|ft|abbr=on}}, fine-grained dolomite in central and eastern Grand Canyon. The limestones are composed mostly of pelletal, skeletal or [[oolite|oolitic]] [[wackestone]]s and [[packstone]]s. In a few places, this member exhibits conspicuous medium-scale [[crossbed]]ding. In the Grand Canyon, the Whitmore Wash Member varies in thickness from about {{convert|9|m|ft|abbr=on}} in the eastern Grand Canyon to nearly {{convert|30|m|ft|abbr=on}} at Iceberg Ridge, {{convert|8|km|mi|abbr=on}} beyond the western end of Grand Canyon. The overlying Thunder Springs Member lies comfortably on Whitmore Wash Member and its base is easily recognized by the lowest appearance of thin, dark, [[chert]] beds alternating with thin beds of lighter gray limestone or dolomite.<ref name="Beuss2003a"/><ref name="McKee1963a"/>

The '''Thunder Springs Member''' is the most distinctive member of the Redwall Limestone, because it forms cliffs that exhibit prominent black and light-brown banding. Its light and dark banded appearance is imparted by thin beds of either light gray limestone or light gray dolomite alternating with thin beds of dark reddish brown or dark gray beds or lenses of chert. Most of the limestone is fine to very coarse, thin-bedded, [[crinoid]]al [[grainstone]] or packstone. The carbonate beds vary from being predominately limestone in the western Grand Canyon and to predominately dolomite in the eastern Grand Canyon. The thin chert beds in this member consist of silicified [[bryozoan]] wackestones and lime [[mudstones]]. The Thunder Springs Member gradually increases in thickness from {{convert|30|m|ft|abbr=on}} in eastern Grand Canyon to about {{convert|46|m|ft|abbr=on}} in the western Grand Canyon. The contact of the overlying Mooney Falls Member with the underlying Thunder Springs Member is disconformable except in the extreme western end of Grand Canyon. Locally, this contact is a low-angle unconformity. This is indicative of a period of emergence, minor tectonic activity, and [[erosion]] between the deposition of the Thunder Springs and Mooney Falls members.<ref name="Beuss2003a"/><ref name="McKee1963a"/>

[[File:McKee(1963)_Redwall_Limestone_Stratigarphic_Column.png|thumb|upright=1.25|Stratigraphic column showing stratigraphic relations, lithology, and thickness of the members of the Redwall Limestone along the [[Bright Angel Trail]], Grand Canyon.<ref name="McKee1963a"/>]]
The '''Mooney Falls Member''' forms a major part of the high, sheer escarpment for which the Redwall Limestone is named. It consists predominantly of pure limestone, except locally where it is dolomitized. It contains less than 0.5 percent insoluble residue. These limestones consist of oolites, pellets, and a variety of skeletal fragments dominated by crinoid plates. In its upper part near its contact with the overlying Horseshoe Mesa Member, one or two zones containing thin beds or lenses of chert occur. The Mooney Falls Member is normally thick-bedded and looks massive in outcrop. The upper third of this member at several localities in central and eastern Grand Canyon reportedly exhibits large-scale, tabular-planar cross-bedding. The Mooney Falls Member is the thickest member of the Redwall, ranging from about {{convert|61|m|ft|abbr=on}} in eastern Grand Canyon to nearly {{convert|120|m|ft|abbr=on}} at the western end. The overlying Horseshoe Mesa Member lies conformably on the Mooney Falls Member and its contact can be difficult to define in outcrops. Typically, the boundary is located at the change from vertical, cliff-forming, medium- and coarse-grained, and thick- or massive-bedded limestone to a receding-ledge-forming, fine-grained, and relatively thin-bedded, limestone.<ref name="Beuss2003a"/><ref name="McKee1963a"/>

The '''Horseshoe Mesa Member''' is the youngest, thinnest, and of the least areal extensive member of the Redwall Limestone. This member is normally composed of thin-bedded, light gray, fine-grained, limestone, typically a mudstone to wackestone that commonly contains encrusting and sediment-binding [[algal]] structures. It contains some chert lenses in its lower part. Also, crossbedding, ripple marks, and oolite beds occur locally. The Horseshoe Mesa Member typically forms weak receding ledges in contrast to the massive cliff that characterizes the Mooney Falls below. Within the Grand Canyon it varies from {{convert|14 to 38|m|ft|abbr=on}}. It normally thinnest in the eastern Grand Canyon. Because of erosion, this member wedges out {{convert|48 to 64|km|mi|abbr=on}} south of the Grand Canyon. The Horseshoe Mesa Member is also absent from the Redwall Limestone in most of central Arizona.<ref name="Beuss2003a"/><ref name="McKee1963a"/>

== Contacts ==
The upper and lower contacts of the Redwall Limestone are both unconformities. The lower contact of the Redwall Limestone is a disconformity that rests either on upon the Devonian Temple Butte Formation or, where it is missing in the eastern Grand Canyon, strata of Cambrian [[Tonto Group]]. Often, the Redwall Limestone immediately overlying this disconformity contains a basal [[Conglomerate (geology)|conglomerate]]. Normally, this basal conglomerate is composed of [[gravel]] that is locally derived from either the underlying [[Temple Butte Formation]] or [[Muav Limestone]]. In the eastern Grand Canyon, the Temple Butte Formation consists of a thin, discontinuous layer of [[Devonian]] strata that fills paleovalleys cut into the underlying [[Cambrian]] Muav Limestone. Westward, the Temple Butte Formation thickens until it becomes a continuous, westward thickening, layer underlying the Redwall Limestone. In western Grand Canyon, this contact consist of an irregular erosional surface having up to {{convert|3|m|ft|abbr=on}} of relief in a lateral distance of {{convert|30 to 61|m|ft|abbr=on}}. The duration of geologic time represented by this unconformity increases eastward across the Grand Canyon and the rest of northern Arizona.<ref name="Beuss2003a"/><ref name="McKeeOthers1969a"/>

[[File:BillingsleyOthers1985 Redwall SurpiseCanyon Stratigraphic Column.png|thumb|Schematic cross-section of uncomformity at the top of the Redwall Limestone showing paleochannels and karstified paleosurface that form it and stratigraphic relationships of Redwall Limestone, it members, Surpise Canyon Formation, and Watahomigi Formation (Supai Group).<ref name="BillingsleyOthers1985a">Billingsley, G.H., and Beus, S.S., 1985, ''The Surprise Canyon Formation—an upper Mississippian and Lower Pennsylvanian (?) rock unit in the Grand Canyon, Arizona.'' ''Stratigraphic Notes'', 1984. U. S. Geological Survey Bulletin, no. 1605-A, pp. 27–33.</ref>]]
The upper contact of the Redwall Limestone is a disconformity that represents a buried, irregular and karstified paleosurface that contains many contemporaeous caves and collapse structures. Eroded into this palesurafce are the remnants of a westward-draining network of coastal paleovalleys and paleochannels. Filling these buried paleovalleys, paleochannels, caves, and collapse structures are sedimentary strata of the Surprised Canyon Formation. Overlying the Surprised Canyon Formation and adjacent protruding paleosurface of the Redwall Limestone are marine, [[fluvial]], and aeolian deposits of the Supai Group. The paleovalleys are incised as much as {{convert|122|m|ft|abbr=on}} through the underlying Horseshoe Mesa and Mooney Falls members and into the Thunder Springs Member.<ref name="McKeeOthers1969a"/><ref name="Kenny2010a">Kenny, R (2010) [https://web.archive.org/web/20160304041003/http://faculty.fortlewis.edu/KENNY_R/publications/carb%20and%20evap%202010.pdf ''Continental paleoclimate estimates from the late Mississippian Redwall karst event: northern and north-central Arizona (USA).''] Carbonates Evaporites. 25(4):297–302</ref><ref name="MvNab+2022a">McNab, F. and White, N., 2022. ''Geodynamic significance of a buried transient Carboniferous landscape''. ''Geological Society of America Bulletin'', 134(5-6), pp.1180-1201.</ref>

== Fossils ==
[[File:11064 Grand Canyon Fossil Brachiopod in Redwall Limestone (4748974977).jpg|thumb|upright=1.25|Fossil Brachiopod from Redwall Limestone. Image courtesy of Grand Canyon National Park]]
Overall, the strata of the Redwall Limestone commonly contain the [[fossil]]s of shallow marine animals. The analysis of data collected by McKee and Gutschick found that the most abundant [[macrofossil]]s are [[brachiopod]]s and [[coral]]s. they are followed in abundance by [[bryozoan]]s, [[crinoid]]s, [[Bivalvia|bivalve]]s, invertebrate burrows and trails, and [[cephalopod]]s. Less common are the fossils of [[blastoid]]s, [[trilobite]]s, [[ostracod]]s, [[fish]] teeth, and algal remains. [[Microfossil]]s of [[foraminifer]]s and [[conodont]]s have also been found.<ref name="Beuss2003a"/><ref name="LassiterOthers2020a">Lassiter, S.L., Tweet, J.S., Sundberg, F.A., Foster, J.R., and Bergman, P.J., 2020. ''Chapter 5. Paleozoic Invertebrate Paleontology of Grand Canyon National Park.'' In: Santucci, V.L., Tweet, J.S., ed., pp. 109-236, ''Grand Canyon National Park: Centennial Paleontological Resource Inventory (Non-sensitive Version) ''. Natural Resource Report NPS/GRCA/NRR—2020/2103. National Park Service, Fort Collins, Colorado, 603 pp.</ref>

The members of the Redwall Limestone vary greatly in the abundance and presevation of fossils that they contain. As the result of the extensive alteration of the original sediments and bioclasts by [[dolomitization]], fossils are rare in the Whitmore Wash Member. However, [[nautiloid]] fossils are found in abundance at in the Whitmore Wash Member at Nautiloid Canyon. The chert beds of the Thunder Springs Member contain an abundance [[invertebrate]] marine fossils. The fossils found in these cherts are corals (particularly the colonial coral, ''Syringapara''), bryozoans, brachiopods, crinoids, and a few [[gastropod]]s, blastoids, and cephalopods. Similar fossils and conodonts occur in the carbonate beds of the Thunder Springs Member. They are less abundant and not at well preserved, likely as the result of alteration of the original sediments by dolomitization. Invertebrate marine fossils are abundant throughout the Mooney Falls Member. They include solitary and colonial corals, [[Spiriferida|spiriferid brachiopod]]s, crinoids, foraminifers, and conodonts. Finally, although rare, well-preserved, invertebrate, marine fossils are present throughout the Horseshoe Mesa Member. Among the most abundant fossils found in it are spiriferid brachiopods, bivalves, and corals. In addition, at least 16 species of foraminifers occur in it.<ref name="Beuss2003a"/><ref name="LassiterOthers2020a"/>

== Age ==
The Redwall Limestone has yielded index fossils that constrain time of accumulation of most of the it. The initial accumulation of the basal Whitmore Wash Member in western Grand Canyon occurred during early Early Mississippian time. The basal strata of the Redwall Limestone become progressively younger as the sea transgressed eastward across northern Arizona and submerged it under a shallow epiric sea. Thus, they are no older than late Early Mississippian age in eastern Grand Canyon. Subsequently, the shallow marine sediments comprising the Thunder Springs Member accumulated as the sea regressed back towards the west leaving northern as dry land. Terrestrial weathering, erosion, and lack of sediment accumulation formed an unconfortmity separating the Thunder Springs and Mooney Falls members. A second marine transgression submerged northern Arizona and permitted the accumulation of shallow marine sediments that comprise the Mooney Falls Member. The Horseshoe Mesa Member accumulated during early Late Mississippian time as the shoreline retreated westward and back into Nevada.<ref name="McKeeOthers1969a"/><ref name="LassiterOthers2020a"/>

The age of the Redwall Limestone indicates that it accumulated during the same period of time as the Escabrosa Limestone of southeastern Arizona, the Leadville Limestone of southwestern Colorado, and the Monte Cristo Group of southeastern Nevada. Four of the five formations in the Monte Cristo share nearly identical lithologic characteristics and stratigraphic position with the four members of the Redwall Limestone in northern Arizona. It is likely that the Redwall Limestone deposits were laterally continuous with all the above unit.<ref name="McKeeOthers1969a"/><ref name="LassiterOthers2020a"/>


==See also==
==See also==
*[[Geology of the Grand Canyon area]]
* [[Geology of the Grand Canyon area]]


==References==
==References==
{{reflist}}
{{reflist}}


==Popular Publications==
==Further reading==
*Blakey, Ron and Wayne Ranney, ''Ancient Landscapes of the Colorado Plateau,'' Grand Canyon Association (publisher), 2008, 176 pages, {{ISBN|978-1934656037}}
* Blakey, Ron and Wayne Ranney, ''Ancient Landscapes of the Colorado Plateau,'' Grand Canyon Association (publisher), 2008, 176 pages, {{ISBN|978-1934656037}}
*Chronic, Halka. ''Roadside Geology of Arizona,'' Mountain Press Publishing Co., 1983, 23rd printing, pp.&nbsp;229–232, {{ISBN|978-0-87842-147-3}}
* Chronic, Halka. ''Roadside Geology of Arizona,'' Mountain Press Publishing Co., 1983, 23rd printing, pp.&nbsp;229–232, {{ISBN|978-0-87842-147-3}}
*Lucchitta, Ivo, ''Hiking Arizona's Geology,'' 2001, Mountaineers's Books, {{ISBN|0-89886-730-4}}
* Lucchitta, Ivo, ''Hiking Arizona's Geology,'' 2001, Mountaineers's Books, {{ISBN|0-89886-730-4}}


== External links ==
== External links ==
{{commons category|Redwall Limestone|position=left}}
{{commons category|Redwall Limestone|position=left}}
* Abbot, W, (2001) [http://www.searchanddiscovery.com/documents/geophysical/Abbott/ ''Revisiting the Grand Canyon – Through the Eyes of Seismic Sequence Stratigraphy.''] [http://www.searchanddiscovery.com/ Search and Discovery Article # 40018], America Association of Petroleum Geologists, Tulsa, Oklahoma.
* Abbot, W, (2001) [http://www.searchanddiscovery.com/documents/geophysical/Abbott/ ''Revisiting the Grand Canyon – Through the Eyes of Seismic Sequence Stratigraphy.''] [http://www.searchanddiscovery.com/ Search and Discovery Article # 40018], America Association of Petroleum Geologists, Tulsa, Oklahoma.
* Anonymous (nda) [http://www.utahgeology.com/fm_redwall.php ''The Redwall Limestone Formation.''] [http://www.utahgeology.com/index.html Utah Geology.]
* Anonymous (nda) [https://web.archive.org/web/20150416143107/http://www.utahgeology.com/fm_redwall.php ''The Redwall Limestone Formation.''] [http://www.utahgeology.com/index.html Utah Geology.]
* Mathis, A., and C. Bowman (2007) [https://web.archive.org/web/20121220094947/http://www.nature.nps.gov/geology/parks/grca/age/index.cfm ''The Grand Age of Rocks: The Numeric Ages for Rocks Exposed within Grand Canyon''], [https://web.archive.org/web/20121220094947/http://www.nature.nps.gov/geology/parks/grca/age/index.cfm Grand Canyon National Park, Arizona], National Park Service, Grand Canyon National Park, Arizona.
* Mathis, A., and C. Bowman (2007) [https://web.archive.org/web/20121220094947/http://www.nature.nps.gov/geology/parks/grca/age/index.cfm ''The Grand Age of Rocks: The Numeric Ages for Rocks Exposed within Grand Canyon''], [https://web.archive.org/web/20121220094947/http://www.nature.nps.gov/geology/parks/grca/age/index.cfm Grand Canyon National Park, Arizona], National Park Service, Grand Canyon National Park, Arizona.
* Shur, C., and D. Shur (2008) [http://www.schursastrophotography.com/paleo/formations/redwall.html ''The Mississippi Redwall Limestone In Northern Arizona.''] [http://www.schursastrophotography.com/fossiladventures.html Arizona Fossil Adventures.]
* Shur, C., and D. Shur (2008) [http://www.schursastrophotography.com/paleo/formations/redwall.html ''The Mississippi Redwall Limestone In Northern Arizona.''] [http://www.schursastrophotography.com/fossiladventures.html Arizona Fossil Adventures.]
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[[Category:Geologic formations of Utah]]
[[Category:Geologic formations of Utah]]
[[Category:Carboniferous Arizona]]
[[Category:Carboniferous Arizona]]
[[Category:Carboniferous geology of New Mexico]]
[[Category:Carboniferous geology of Utah]]
[[Category:Carboniferous geology of Utah]]
[[Category:Carboniferous System of North America]]
[[Category:Carboniferous System of North America]]
[[Category:Carboniferous southern paleotropical deposits]]
[[Category:Carboniferous southern paleotropical deposits]]


{{US-geology-stub}}

Latest revision as of 01:57, 20 June 2024

Redwall Limestone
Stratigraphic range: Early and early Late Mississippian[1][2]
Redwall Limestone cliff, and upper platform of cliff extension (resting on very short Muav Limestone cliff), from Tower of Set, central Grand Canyon, adjacent Granite Gorge.
The bottom of Redwall cliffs typically rest on sections of Temple Butte Formation-(locally), or attached sections of Muav Limestone cliffs (regionally exposed in Grand Canyon, elsewhere in Arizona, not always with surface exposure).
TypeGeological formation
UnderliesSupai Group and locally Surprise Canyon Formation. The Surprise Canyon Formation fills local paleovalleys, caves, and collapse structures cut into the underlying Redwall Limestone.
OverliesMuav Limestone and Temple Butte Formation
Thickness244 m (801 ft), at maximum
Lithology
Primaryfossiliferous limestone
Otherdolomite and chert
Location
RegionNorthern Arizona, southeast California, New Mexico, and southern Utah, Nevada
CountryUnited States of America
Type section
Named forthe red appearance of its escarpment on either side of the Grand Canyon[3]
Named byGilbert (1875)[3]

The Redwall Limestone is an erosion-resistant, Mississippian age, cliff-forming geological formation that forms prominent, red-stained cliffs in the Grand Canyon. these cliffs range in height from 150 m (490 ft) to 244 m (801 ft). It is one of the most fossiliferous formations exposed in the Grand Canyon region.[1][2]

Nomenclature[edit]

In 1875, Gilbert[3] recognized and named the Redwall Limestone for the red coloration of its escarpment on either side of Grand Canyon. As originally defined by him, it included some strata younger and older than as it is currently defined. Later in 1910, Darton[4] selected a canyon that he named the Redwall Canyon in the Shinumo drainage basin, on north side of the Grand Canyon, as the type section of the Redwall Limestone. At this location, it consists mostly of the usual heavily bedded massive limestone and is circa 244 m (801 ft) thick. Noble[5] subsequently redefined the Redwall Limestone in its present definition, which includes all strata of Mississippian age. As a result of studies in Yavapai County, Arizona, Gutschick[6] recognized four informal members within the Redwall Limestone and McKee[7] later formally named them. The most comprehensive study of the Redwall Limestone is the History of the Redwall Limestone of northern Arizona by McKee and Gutschick.[2]

Description[edit]

Redwall Limestone consists predominantly of light-olive-gray to light-gray, fine- to coarse-grained, thin- to thick-bedded, often cherty, limestone. Its lower part consists of brownish-gray, interbedded with 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.[1][2]

In ascending order, the Redwall Limestone is divided into the Whitmore Wash, Thunder Springs, Mooney Falls, and Horseshoe Mesa members. All four member have their type locality in the Grand Canyon or its tributaries. They are recognized throughout the Grand Canyon area, northern Arizona, and southern Utah. They are all Mississippian in age.[1][2]

The Whitmore Wash Member is the basal, oldest, member of the Redwall Limestone. It typically forms a high, resistant cliff standing on a narrow bench or series of ledges typical of underlying strata. This member consists of nearly pure limestone and dolomite, which contains less than 2 percent insoluble gypsum and iron oxides. This member is predominately composed of thick-bedded, ranging from 0.6 to 1.22 m (2.0 to 4.0 ft) and locally thicker, limestone in western Grand Canyon and changes to mostly very thick-bedded 1.2 to 4.5 m (3.9 to 14.8 ft), fine-grained dolomite in central and eastern Grand Canyon. The limestones are composed mostly of pelletal, skeletal or oolitic wackestones and packstones. In a few places, this member exhibits conspicuous medium-scale crossbedding. In the Grand Canyon, the Whitmore Wash Member varies in thickness from about 9 m (30 ft) in the eastern Grand Canyon to nearly 30 m (98 ft) at Iceberg Ridge, 8 km (5.0 mi) beyond the western end of Grand Canyon. The overlying Thunder Springs Member lies comfortably on Whitmore Wash Member and its base is easily recognized by the lowest appearance of thin, dark, chert beds alternating with thin beds of lighter gray limestone or dolomite.[1][7]

The Thunder Springs Member is the most distinctive member of the Redwall Limestone, because it forms cliffs that exhibit prominent black and light-brown banding. Its light and dark banded appearance is imparted by thin beds of either light gray limestone or light gray dolomite alternating with thin beds of dark reddish brown or dark gray beds or lenses of chert. Most of the limestone is fine to very coarse, thin-bedded, crinoidal grainstone or packstone. The carbonate beds vary from being predominately limestone in the western Grand Canyon and to predominately dolomite in the eastern Grand Canyon. The thin chert beds in this member consist of silicified bryozoan wackestones and lime mudstones. The Thunder Springs Member gradually increases in thickness from 30 m (98 ft) in eastern Grand Canyon to about 46 m (151 ft) in the western Grand Canyon. The contact of the overlying Mooney Falls Member with the underlying Thunder Springs Member is disconformable except in the extreme western end of Grand Canyon. Locally, this contact is a low-angle unconformity. This is indicative of a period of emergence, minor tectonic activity, and erosion between the deposition of the Thunder Springs and Mooney Falls members.[1][7]

Stratigraphic column showing stratigraphic relations, lithology, and thickness of the members of the Redwall Limestone along the Bright Angel Trail, Grand Canyon.[7]

The Mooney Falls Member forms a major part of the high, sheer escarpment for which the Redwall Limestone is named. It consists predominantly of pure limestone, except locally where it is dolomitized. It contains less than 0.5 percent insoluble residue. These limestones consist of oolites, pellets, and a variety of skeletal fragments dominated by crinoid plates. In its upper part near its contact with the overlying Horseshoe Mesa Member, one or two zones containing thin beds or lenses of chert occur. The Mooney Falls Member is normally thick-bedded and looks massive in outcrop. The upper third of this member at several localities in central and eastern Grand Canyon reportedly exhibits large-scale, tabular-planar cross-bedding. The Mooney Falls Member is the thickest member of the Redwall, ranging from about 61 m (200 ft) in eastern Grand Canyon to nearly 120 m (390 ft) at the western end. The overlying Horseshoe Mesa Member lies conformably on the Mooney Falls Member and its contact can be difficult to define in outcrops. Typically, the boundary is located at the change from vertical, cliff-forming, medium- and coarse-grained, and thick- or massive-bedded limestone to a receding-ledge-forming, fine-grained, and relatively thin-bedded, limestone.[1][7]

The Horseshoe Mesa Member is the youngest, thinnest, and of the least areal extensive member of the Redwall Limestone. This member is normally composed of thin-bedded, light gray, fine-grained, limestone, typically a mudstone to wackestone that commonly contains encrusting and sediment-binding algal structures. It contains some chert lenses in its lower part. Also, crossbedding, ripple marks, and oolite beds occur locally. The Horseshoe Mesa Member typically forms weak receding ledges in contrast to the massive cliff that characterizes the Mooney Falls below. Within the Grand Canyon it varies from 14 to 38 m (46 to 125 ft). It normally thinnest in the eastern Grand Canyon. Because of erosion, this member wedges out 48 to 64 km (30 to 40 mi) south of the Grand Canyon. The Horseshoe Mesa Member is also absent from the Redwall Limestone in most of central Arizona.[1][7]

Contacts[edit]

The upper and lower contacts of the Redwall Limestone are both unconformities. The lower contact of the Redwall Limestone is a disconformity that rests either on upon the Devonian Temple Butte Formation or, where it is missing in the eastern Grand Canyon, strata of Cambrian Tonto Group. Often, the Redwall Limestone immediately overlying this disconformity contains a basal conglomerate. Normally, this basal conglomerate is composed of gravel that is locally derived from either the underlying Temple Butte Formation or Muav Limestone. In the eastern Grand Canyon, the Temple Butte Formation consists of a thin, discontinuous layer of Devonian strata that fills paleovalleys cut into the underlying Cambrian Muav Limestone. Westward, the Temple Butte Formation thickens until it becomes a continuous, westward thickening, layer underlying the Redwall Limestone. In western Grand Canyon, this contact consist of an irregular erosional surface having up to 3 m (9.8 ft) of relief in a lateral distance of 30 to 61 m (98 to 200 ft). The duration of geologic time represented by this unconformity increases eastward across the Grand Canyon and the rest of northern Arizona.[1][2]

Schematic cross-section of uncomformity at the top of the Redwall Limestone showing paleochannels and karstified paleosurface that form it and stratigraphic relationships of Redwall Limestone, it members, Surpise Canyon Formation, and Watahomigi Formation (Supai Group).[8]

The upper contact of the Redwall Limestone is a disconformity that represents a buried, irregular and karstified paleosurface that contains many contemporaeous caves and collapse structures. Eroded into this palesurafce are the remnants of a westward-draining network of coastal paleovalleys and paleochannels. Filling these buried paleovalleys, paleochannels, caves, and collapse structures are sedimentary strata of the Surprised Canyon Formation. Overlying the Surprised Canyon Formation and adjacent protruding paleosurface of the Redwall Limestone are marine, fluvial, and aeolian deposits of the Supai Group. The paleovalleys are incised as much as 122 m (400 ft) through the underlying Horseshoe Mesa and Mooney Falls members and into the Thunder Springs Member.[2][9][10]

Fossils[edit]

Fossil Brachiopod from Redwall Limestone. Image courtesy of Grand Canyon National Park

Overall, the strata of the Redwall Limestone commonly contain the fossils of shallow marine animals. The analysis of data collected by McKee and Gutschick found that the most abundant macrofossils are brachiopods and corals. they are followed in abundance by bryozoans, crinoids, bivalves, invertebrate burrows and trails, and cephalopods. Less common are the fossils of blastoids, trilobites, ostracods, fish teeth, and algal remains. Microfossils of foraminifers and conodonts have also been found.[1][11]

The members of the Redwall Limestone vary greatly in the abundance and presevation of fossils that they contain. As the result of the extensive alteration of the original sediments and bioclasts by dolomitization, fossils are rare in the Whitmore Wash Member. However, nautiloid fossils are found in abundance at in the Whitmore Wash Member at Nautiloid Canyon. The chert beds of the Thunder Springs Member contain an abundance invertebrate marine fossils. The fossils found in these cherts are corals (particularly the colonial coral, Syringapara), bryozoans, brachiopods, crinoids, and a few gastropods, blastoids, and cephalopods. Similar fossils and conodonts occur in the carbonate beds of the Thunder Springs Member. They are less abundant and not at well preserved, likely as the result of alteration of the original sediments by dolomitization. Invertebrate marine fossils are abundant throughout the Mooney Falls Member. They include solitary and colonial corals, spiriferid brachiopods, crinoids, foraminifers, and conodonts. Finally, although rare, well-preserved, invertebrate, marine fossils are present throughout the Horseshoe Mesa Member. Among the most abundant fossils found in it are spiriferid brachiopods, bivalves, and corals. In addition, at least 16 species of foraminifers occur in it.[1][11]

Age[edit]

The Redwall Limestone has yielded index fossils that constrain time of accumulation of most of the it. The initial accumulation of the basal Whitmore Wash Member in western Grand Canyon occurred during early Early Mississippian time. The basal strata of the Redwall Limestone become progressively younger as the sea transgressed eastward across northern Arizona and submerged it under a shallow epiric sea. Thus, they are no older than late Early Mississippian age in eastern Grand Canyon. Subsequently, the shallow marine sediments comprising the Thunder Springs Member accumulated as the sea regressed back towards the west leaving northern as dry land. Terrestrial weathering, erosion, and lack of sediment accumulation formed an unconfortmity separating the Thunder Springs and Mooney Falls members. A second marine transgression submerged northern Arizona and permitted the accumulation of shallow marine sediments that comprise the Mooney Falls Member. The Horseshoe Mesa Member accumulated during early Late Mississippian time as the shoreline retreated westward and back into Nevada.[2][11]

The age of the Redwall Limestone indicates that it accumulated during the same period of time as the Escabrosa Limestone of southeastern Arizona, the Leadville Limestone of southwestern Colorado, and the Monte Cristo Group of southeastern Nevada. Four of the five formations in the Monte Cristo share nearly identical lithologic characteristics and stratigraphic position with the four members of the Redwall Limestone in northern Arizona. It is likely that the Redwall Limestone deposits were laterally continuous with all the above unit.[2][11]

See also[edit]

References[edit]

  1. ^ a b c d e f g h i j k 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. ^ a b c d e f g h i McKee, E.D., and Gutschick, R.C., eds., 1969. History of the Redwall Limestone of northern Arizona, [with] chapters on paleontology of the Redwall Limestone by B. Skipp, W.J. Sando, H. Duncan, E.L. Yochelson, W.M. Furnish, D.B. Macurda, Jr., and J.C. Brower. Geological Society of America Memoir. 114. Boulder, Colorado, Geological Society of America. 612 pp ISBN 978-08-137-1114-0
  3. ^ a b c Gilbert, G.K., 1875. Report upon the geology of portions of Nevada, Utah, California, and Arizona, Chapter 6. In Wheeler, G.M., ed., pp. 17-187, Report on the Geographical and Geological Explorations and Surveys West of the One Hundredth Meridian, vol. 3. U.S. Geological and Geographical Survey, Publication of the Wheeler Survey, Washington, D.C., 681 pp.
  4. ^ Darton, N. H., 1910. A reconnaissance of parts of northwestern New Mexico and northern Arizona. U.S. Geological Survey Bulletin. 435, 88p.
  5. ^ Noble, LF (1914) The Shinumo quadrangle, Grand Canyon district, Arizona. Bulletin no. 549, US Geological Survey, Reston, Virginia. 42 pp.
  6. ^ Gutschlck, R. C., 1943. The Redwall Limestone (Mississippian) of Yavapai County, Arizona. Plateau, 16(1), pp. 1-11.
  7. ^ a b c d e f McKee, E. D., 1963. Nomenclature for lithologic subdivisions of the Redwall Limestone, Arizona. U.S. Geological Survey Professional Paper. 475-C, pp. C21-C23.
  8. ^ Billingsley, G.H., and Beus, S.S., 1985, The Surprise Canyon Formation—an upper Mississippian and Lower Pennsylvanian (?) rock unit in the Grand Canyon, Arizona. Stratigraphic Notes, 1984. U. S. Geological Survey Bulletin, no. 1605-A, pp. 27–33.
  9. ^ 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
  10. ^ McNab, F. and White, N., 2022. Geodynamic significance of a buried transient Carboniferous landscape. Geological Society of America Bulletin, 134(5-6), pp.1180-1201.
  11. ^ a b c d Lassiter, S.L., Tweet, J.S., Sundberg, F.A., Foster, J.R., and Bergman, P.J., 2020. Chapter 5. Paleozoic Invertebrate Paleontology of Grand Canyon National Park. In: Santucci, V.L., Tweet, J.S., ed., pp. 109-236, Grand Canyon National Park: Centennial Paleontological Resource Inventory (Non-sensitive Version) . Natural Resource Report NPS/GRCA/NRR—2020/2103. National Park Service, Fort Collins, Colorado, 603 pp.

Further reading[edit]

  • Blakey, Ron and Wayne Ranney, Ancient Landscapes of the Colorado Plateau, Grand Canyon Association (publisher), 2008, 176 pages, ISBN 978-1934656037
  • Chronic, Halka. Roadside Geology of Arizona, Mountain Press Publishing Co., 1983, 23rd printing, pp. 229–232, ISBN 978-0-87842-147-3
  • Lucchitta, Ivo, Hiking Arizona's Geology, 2001, Mountaineers's Books, ISBN 0-89886-730-4

External links[edit]

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