Chinle Formation

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Chinle Formation
Stratigraphic range:
Late Triassic
Chinle Badlands.jpg
TypeGeological formation
Sub-unitsShinarump Conglomerate,
Mesa Redondo Member,
Bluewater Creek Member,
Blue Mesa Member,
Sonsela Member,
Moss Back Member,
Petrified Forest Member,
Owl Rock Member,
Rock Point Member,
Church Rock Member
UnderliesWingate Sandstone,
Moenave Formation,
Nugget Sandstone
OverliesMoenkopi Formation or Cutler Group
Primaryfluvial mudstone, siltstone, and sandstone
RegionColorado Plateau
New Mexico
Type section
Named forChinle, AZ
Named byHerbert E. Gregory

The Chinle Formation is an Upper Triassic continental geological formation of fluvial, lacustrine, and palustrine to eolian deposits spread across the U.S. states of Nevada, Utah, northern Arizona, western New Mexico, and western Colorado. The Chinle is controversially considered to be synonymous to the Dockum Group of eastern Colorado and New Mexico, western Texas, the Oklahoma panhandle, and southwestern Kansas. The Chinle is sometimes colloquially named as a formation within the Dockum Group in New Mexico and in Texas. The Chinle Formation is part of the Colorado Plateau, Basin and Range, and the southern section of the Interior Plains.[1]

A probable separate depositional basin within the Chinle is found in northwestern Colorado and northeastern Utah. The southern portion of the Chinle reaches a maximum thickness of a little over 520 m. Typically, the Chinle rests unconformably on the Moenkopi Formation.

History of investigation[edit]

There is no designated type locality for this formation. It was named for Chinle Valley in Apache County, Arizona by Herbert E. Gregory in 1917 without officially designating it as the formation's name until two years later and without a specified type locality.[2]

United States Geological Survey economic geologist Raymond C. Robeck in 1956 revised the unnamed members of Gregory by identifying and naming the Temple Mountain member as the basal-most unit in the area of the San Rafael Swell of Utah. In 1957 John H. Stewart revised the Shinarump Conglomerate of G. K. Gilbert, 1875, and Edwin E. Howell, 1875, and Gregory, 1917, and renamed it the Shinarump member of the Chinle formation. An overview of the geology of the area was created by USGS geologist Forrest G. Poole and Stewart in 1964. Steve W. Sikich revised the unit and assigned more members assigned in 1965.[3] The areal extent of the unit was mapped by R.F. Wilson and Stewart in 1967.[4] In 1972 the areal limits were modified and an overview created by Stewart and others (they published a revision the same year). V.C. Kelley assigned more members and revised the unit in 1972.[5] Spencer G. Lucas and S.N. Hayden did the same thing in 1989.[6] The Rock Point Member was assigned by R.F. Dubiel in 1989.[7]

The Chinle was raised to group rank by Lucas in 1993,[8] thus also raising many of the members to formation status. He also included the formations of the Dockum Group of eastern New Mexico and west Texas within the "Chinle Group". This modified nomenclature is controversial; many still retain the Chinle as a formation and separate out the Dockum Group.[9][10] The Dockum was named in 1890, before the Chinle. Lucas also advocated abandoning the name Dolores Formation as a parochial synonym for the Chinle Group.

Overviews of the Chinle were created by Dubiel and others (1992) and Hintze and Axen (1995).[11]


The formation members and their thicknesses are highly variable across the Chinle. The stratigraphically lowest formation is the Temple Mountain Member. However, in most areas, the basal member is the Shinarump Member.[12] The Shinarump is a braided-river system channel-deposit facies.[7] The Monitor Butte Member overlies the Shinarump in most areas. The Monitor Butte is an overbank (distal floodplain) facies with lacustrine deposits. This is overlain in western areas by the channel-deposit facies Moss Back Member. More commonly, the Monitor Butte grades into the Petrified Forest Member. The Petrified Forest is predominately overbank deposits with thin lenses of channel-deposit facies and lacustrine deposits.

The Petrified Forest Member can be divided into the Lower Petrified Forest Member and Upper Petrified Forest Member in Arizona and New Mexico, separated by the Sonsela Sandstone. The Sonsela Sandstone is a braided-stream channel facies. The Petrified Forest grades into the Owl Rock Member. The Owl Rock is a marginal lacustrine to lacustrine facies possibly representing a large lake system. The upper Petrified Forest Member includes the thin but extensive Correo Sandstone Bed.[6] Finally, either the Rock Point or Church Rock Members overlie the Owl Rock. Some researchers feel the two Members may be synonymous.[citation needed] The two Members are complex heterolithic units, representing variously braided-river facies, lacustrine, and overbank deposits.

In 2020, Lucas proposed the names Blue Mesa Member and Painted Desert Member for the lower and upper Petrified Forest members in west-central New Mexico, where he also raises the Chinle Formation to group rank.[13] He also assigns beds between the Shinarump Formation and the Petrified Forest Formation to the Bluewater Creek Formation.[6]

Ages of Chinle Members[edit]

Fossil wood from the Chinle Formation

The Chinle Formation is aged from early Late Triassic. Age correlation is based on Lucas's Land Vertebrate Faunachrons. The faunachrons are based on first and last appearances of phytosaurs. Simplified stratigraphy based on Litwin.[14]

Shinarump Conglomerate (Member) as erosion resistant cap rock in Monument Valley
Sub-stage Faunachron Chinle Member(s)
Late Norian-Rhaetian Apachean Rock Point/Church Rock
Early to Middle Norian Revueltian Owl Rock

Upper Petrified Forest

upper Late Carnian Adamanian Sonsela Sandstone

Lower Petrified Forest

Moss Back

Monitor Butte

lower Late Carnian Otischalkian Shinarump

Temple Mountain


Hayden Quarry fossil locality (Ghost Ranch). Stratigraphic column including members of the Chinle Formation
Stratigraphy of Canyonlands N.P. with members of the Chinle Formation

Asterisks (*) indicate usage by the U.S. Geological Survey. Other usages by state geological surveys.

Group rank (alphabetical – rank and formations not recognized by the USGS)[1]

Formation rank (alphabetical – several members not recognized by the USGS):[1]

Places found[edit]

The Permian through Jurassic stratigraphy of the Colorado Plateau area of southeastern Utah that makes up much of the famous prominent rock formations in protected areas such as Capitol Reef National Park and Canyonlands National Park.
From top to bottom: (youngest to oldest)
5 – Rounded tan domes of the Navajo Sandstone,
4 – layered red Kayenta Formation,
3 – cliff-forming, vertically-jointed, red Wingate Sandstone,
2 – slope-forming, purplish Chinle Formation, layered, lighter-red Moenkopi Formation, and
1 – white, layered Cutler Formation sandstone.
Picture from Glen Canyon National Recreation Area, Utah

Geologic Province:[1]



See also[edit]


  1. ^ a b c d GEOLEX database entry for Chinle, USGS (viewed 19 March 2006)
  2. ^ Gregory, Herbert E. (1917). 1917; #164, with Raymond C. Moore, The Kaiparowits: A Geographic Reconnaissance of Parts of Utah and Arizona, 1931; #188, The San Juan. United States Geological Survey Professional Papers #93.
  3. ^ Sikitch, Steve W. (1965). "Upper Triassic stratigraphy in the eastern Uinta Mountains". The Mountain Geologist. 2 (3): 167–172. Retrieved 30 October 2020.
  4. ^ Wilson, Richard F.; Stewart, John H. (1967). "Correlation of Upper Triassic and Triassic Formations between southwestern Utah and southern Nevada". U.S. Geological Survey Bulletin. 1244-D: D1–D20. doi:10.3133/b1244D.
  5. ^ Kelley, V.C. (1972). "Geology of the Fort Sumner sheet, New Mexico" (PDF). New Mexico Bureau of Mines and Mineral Resources Bulletin. 98. Retrieved 30 October 2020.
  6. ^ a b c Lucas, S.G.; Hayden, S.N. (1989). "Triassic stratigraphy of west-central New Mexico" (PDF). New Mexico Geological Society Field Conference Guidebook. 40: 191–211. Retrieved 30 October 2020.
  7. ^ a b Dubiel, R.F., 1989. Depositional and climatic setting of the Upper Triassic Chinle Formation, Colorado Plateau. In Lucas, S.G., and Hunt, A.P. (eds.): Dawn of the Age of Dinosaurs: New Mexico Museum of Natural History, pp. 171–187.
  8. ^ Lucas, S.G., 1993. The Chinle Group: revised stratigraphy and biochronology of Upper Triassic Nonmarine strata in the western United States. Museum of Northern Arizona Bulletin, v. 59, pp. 27–50.
  9. ^ Lehman, T.M. (1994). "The saga of the Dockum Group and the case of the Texas/New Mexico boundary fault" (PDF). New Mexico Bureau of Mines & Mineral Resources Bulletin. 150: 37–51. Retrieved 1 September 2020.
  10. ^ Cather, S.M.; Zeiger, Kate E.; Mack, Greg H.; Kelley, Shari A. (2013). "Toward standardization of Phanerozoic stratigraphic nomenclature in New Mexico". New Mexico Geological Society Spring Meeting: 12. CiteSeerX Retrieved 26 August 2020.
  11. ^ GEOLEX database bibliographic references for Chinle (viewed 19 March 2006)
  12. ^ "Shinarump Member of Chinle Formation". Colorado River Basin Stratigraphy. USGS. 6 May 2006. Retrieved 10 January 2011.
  13. ^ Lucas, Spencer G. (2020). "Triassic stratigraphy of the southeastern Colorado Plateau, west-central New Mexico" (PDF). New Mexico Geological Society Special Publication. 14: 123–133. Retrieved 30 October 2020.
  14. ^ Litwin, R.J., Traverse, A., and Ash, S.R., 1991. Preliminary palynological zonation of the Chinle Formation, southwestern U.S.A., and its correlation to the Newark Supergroup (eastern U.S.A.). Review of Paleobotany and Palynology, v. 77, pp. 269–287.
  15. ^
  • Lehman, T.M. (1994). "The saga of the Dockum Group and the case of the Texas/New Mexico boundary fault". New Mexico Bureau of Mines & Mineral Resources Bulletin, v. 150, pp. 37–51.[ISBN missing]
  • Lucas, S.G. (1998). "Global Triassic tetrapod biostratigraphy and biochronology". Palaeogeography, Palaeoclimatology, and Palaeoecology, v. 143, pp. 347–384.

External links[edit]