The Glen Canyon Group consists of extensive
eolian deposits of latest
Triassic to
Early Jurassic age on the Colorado Plateau. These form the spectacular orange canyon walls of
Canyonlands National Park and
Paria Canyon as well as the unflooded portions of
Glen Canyon. Deposition of the Glen Canyon Group ceased in the
Middle Jurassic with the
transgression of the
Sundance Sea, which separated deposition of the Glen Canyon Group from deposition of the overlying
San Rafael Group.[6] The Glen Canyon Group is separated from the underlying
Chinle Formation by the regional J-0 unconformity, which represents a time of widespread erosion across western North America. The group is likewise separated from the overlying San Rafael Group by the regional J-2 conformity, representing a renewal of widespread erosion.[7]
The Glen Canyon Group was deposited in a
foreland basin created by the uplift of the
Sevier Mountains in what is now Nevada and eastern Utah. As a result, the formations of the group thicken to the west.[8]
The Kayenta Formation pinches out and disappears to the north, in the
Uintah Basin, and the Wingate Sandstone and Navajo Sandstone become indistinguishable. These remaining eolian beds have sometimes been mapped as simply Glen Canyon Formation, but they
correlate with the
Nugget Sandstone further north, and it has been recommended that they be assigned to the Nugget Sandstone.[9]
There is no designated
type locality for this group. It was named by Gregory and Moore prior to 1928 for exposures in walls that form the
Glen Canyon of the
Colorado River in
Coconino County, Arizona and
San Juan County, Utah, though their report was not published until 1931.[18] The name had by then been published by Gilluly and Reeside, who gave an overview of the group.[19]
In 1936, A.A. Baker reexamined the group and named the
Kayenta Formation.[20] The work was revised again in 1955 by Averitt and others. They assigned the Shurtz Sandstone Tongue (new) and Lamb Point Tongue (new) to the
Navajo Sandstone, and Cedar City Tongue (new) and Tenney Canyon Tongue (new) to the Kayenta Formation.[17] In 1957 Harshbarger and others created an overview and revision that assigned the
Moenave Formation and divided the
Wingate Sandstone into the newly named Rock Point and Lukachukai members.[2] In 1963, the upper contact was revised by Phoenix, who moved the uppermost silstone beds of the Navajo Sandstone into the Judd Hollow Tongue of the Carmel Formation.[21] Poole and Stewart mapped the group into the Green River Basin in 1964, treating it here as a single formation.[22] Areal extent limits were revised by Wilson and Stewart in 1967[23] and again by Green in 1974, who added the Iyanbito Member.[24] Peterson and Pipiringos revised the upper contact and created an overview in 1979.[13] In 1989 the age of the group was reexamined by Padian[10] and separately by Dubiel (who also revised the lower contact).[25]
Prehistoric animals from the various formations of the Glen Canyon Group include several types of
dinosaurs, known from both skeletal remains and tracks. Dinosaur finds in the Wingate and Moenave formations are presently almost entirely tracks. The Kayenta Formation has a diverse skeletal fauna including the
theropods"Syntarsus" kayentakatae and Dilophosaurus, the
prosauropodSarahsaurus, an unnamed
heterodontosaurid, and the armored dinosaurs Scelidosaurus and Scutellosaurus. The Navajo Sandstone has body fossils of the theropod Segisaurus and an Ammosaurus-like prosauropod, and tracks.[5]
The following summarizes vertebrate fossils and tracks reported in the Glen Canyon Group:
^
abWeishampel, David B.; Barrett, Paul M.; Coria, Rodolfo A.; Le Loueff, Jean; Xu, Xing Zhao Xijin; Sahni, Ashok; Gomani, Elizabeth M.P.; Noto, Christopher N. (2004). "Dinosaur distribution". In Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 517–606.
ISBN0-520-24209-2.
^Fillmore, Robert (2010). Geological evolution of the Colorado Plateau of eastern Utah and western Colorado, including the San Juan River, Natural Bridges, Canyonlands, Arches, and the Book Cliffs. Salt Lake City: University of Utah Press. p. 177.
ISBN978-1-60781-004-9.
^Stephens, Mark (May 1994). "Architectural element analysis within the Kayenta Formation (Lower Jurassic) using ground-probing radar and sedimentological profiling, southwestern Colorado". Sedimentary Geology. 90 (3–4): 179–211.
Bibcode:
1994SedG...90..179S.
doi:
10.1016/0037-0738(94)90038-8.
^
abcdefghijSmith, J.A.; Santucci, V.L.; Reynolds, R.E. (April 2001). "Vertebrate ichnostratigraphy of the Glen Canyon Group (Jurassic) in Zion National Park, Utah". In Reynolds, R.E. (ed.).
The changing face of the east Mojave Desert. 2001 Desert Symposium(PDF). Fullerton: California State University Desert Studies Consortium. pp. 15–19. Archived from
the original(PDF) on 2 November 2023. Retrieved 30 October 2021.