The Glen Canyon Group is a geologic group of

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondar ...

s that is spread across the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sove ...

s of

Nevada Nevada ( ; ) is a state in the Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the 7th-most extensive, ...

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...

, northern

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

, north west

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ke ...

and western

Colorado Colorado (, other variants) is a state in the Mountain states, Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the wes ...

. It is called the Glen Canyon Sandstone in the

Green River Basin Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a combina ...

of Colorado and Utah. There are four formations within the group. From oldest to youngest, these are the

Wingate Sandstone The Wingate Sandstone is a geologic formation in the Glen Canyon Group of the Colorado Plateau province of the United States which crops out in northern Arizona, northwest Colorado, Nevada, and Utah. Geology Wingate Sandstone is particularly ...

Moenave Formation The Moenave Formation is a Mesozoic geologic formation, in the Glen Canyon Group. It is found in Utah and Arizona. The Moenave was deposited on an erosion surface on the Chinle Formation following an early Jurassic uplift and unconformity that re ...

Kayenta Formation The Kayenta Formation is a geological formation in the Glen Canyon Group that is spread across the Colorado Plateau province of the United States, including northern Arizona, northwest Colorado, Nevada, and Utah. Traditionally has been suggested ...

, and

Navajo Sandstone The Navajo Sandstone is a geological formation in the Glen Canyon Group that is spread across the U.S. states of southern Nevada, northern Arizona, northwest Colorado, and Utah as part of the Colorado Plateau province of the United States.Anonymo ...

. Part of the Colorado Plateau and the

Basin and Range Basin and range topography is characterized by alternating parallel mountain ranges and valleys. It is a result of crustal extension due to mantle upwelling, gravitational collapse, crustal thickening, or relaxation of confining stresses. The e ...

, this group of formations was laid down during the

Late Triassic The Late Triassic is the third and final epoch of the Triassic Period in the geologic time scale, spanning the time between Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch and followed by the Early Jurassic Epoch. ...

and

Early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-J ...

, with the Triassic-Jurassic boundary within the Wingate Sandstone. The top of the Glen Canyon Group is thought to date to the

Toarcian The Toarcian is, in the ICS' geologic timescale, an age and stage in the Early or Lower Jurassic. It spans the time between 182.7 Ma (million years ago) and 174.1 Ma. It follows the Pliensbachian and is followed by the Aalenian. The Toarcian ...

stage of the Early Jurassic. Asterisks (*) below indicate usage by the

U.S. Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and ...

Description

The Glen Canyon Group consists of extensive eolian deposits of latest

Triassic The Triassic ( ) is a geologic period and system (stratigraphy), system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Year#Abbreviations yr and ya, Mya), to the beginning of the Jurassic Period 201.36 ...

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 Glen Canyon is a natural canyon carved by a length of the Colorado River, mostly in southeastern and south-central Utah, in the United States. Glen Canyon starts where Narrow Canyon ends, at the confluence of the Colorado River and the Dirty D ...

. Deposition of the Glen Canyon Group ceased in the Middle Jurassic with the transgression of the

Sundance Sea The Sundance Sea was an epeiric sea that existed in North America during the mid-to-late Jurassic Period of the Mesozoic Era. It was an arm of what is now the Arctic Ocean, and extended through what is now western Canada into the central west ...

, which separated deposition of the Glen Canyon Group from deposition of the overlying San Rafael Group. 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. 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. The Kayenta Formation pinches out and disappears to the north, in the

Uintah Basin The Uinta Basin (also known as the Uintah Basin) is a physiographic section of the larger Colorado Plateaus province, which in turn is part of the larger Intermontane Plateaus physiographic division. It is also a geologic structural basin in e ...

, 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 In statistics, correlation or dependence is any statistical relationship, whether causal or not, between two random variables or bivariate data. Although in the broadest sense, "correlation" may indicate any type of association, in statistic ...

with the

Nugget Sandstone The Nugget Sandstone is a Late Triassic to Early Jurassic geologic Formation (geology), formation that outcrops in Colorado, Idaho and Utah, western United States. Fossil theropod tracks have been reported from the formation.Weishampel, et al. ( ...

further north, and it has been recommended that they be assigned to the Nugget Sandstone.

Subunits

Group rank (stratigraphic order): *

(AZ*, CO*, NM*, UT*), *

(AZ, CO*, UT*), *

(AZ*, NV*, UT*), *

(AZ*, CO*, NM*, UT*)

History of investigation

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

of the

Colorado River The Colorado River ( es, Río Colorado) is one of the principal rivers (along with the Rio Grande) in the Southwestern United States and northern Mexico. The river drains an expansive, arid watershed that encompasses parts of seven U.S. s ...

Coconino County, Arizona Coconino County is a county in the north-central part of the U.S. state of Arizona. Its population was 145,101 at the 2020 census. The county seat is Flagstaff. The county takes its name from ''Cohonino'', a name applied to the Havasupai p ...

and

San Juan County, Utah San Juan County ( ) is a county in the southeastern portion of the U.S. state of Utah. As of the 2010 United States Census, the population was 14,746. Its county seat is Monticello, while its most populous city is Blanding. The Utah State Legi ...

, though their report was not published until 1931. The name had by then been published by Gilluly and Reeside, who gave an overview of the group. In 1936, A.A. Baker reexamined the group and named the

. 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

, and Cedar City Tongue (new) and Tenney Canyon Tongue (new) to the Kayenta Formation. In 1957 Harshbarger and others created an overview and revision that assigned the

and divided the

into the newly named Rock Point and Lukachukai members. 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. Poole and Stewart mapped the group into the Green River Basin in 1964, treating it here as a single formation. Areal extent limits were revised by Wilson and Stewart in 1967 and again by Green in 1974, who added the Iyanbito Member. Peterson and Pipiringos revised the upper contact and created an overview in 1979. In 1989 the age of the group was reexamined by Padian and separately by Dubiel (who also revised the lower contact).

Places found

Geologic Province: * Black Mesa Basin * Great Basin province *

Paradox Basin The Paradox Basin is an asymmetric foreland basin located mostly in southeast Utah and southwest Colorado, but extending into northeast Arizona and northwest New Mexico. The basin is a large elongate northwest to southeast oriented depression for ...

Piceance Basin The Piceance Basin is a geologic structural basin in northwestern Colorado, in the United States. It includes geologic formations from Cambrian to Holocene in age, but the thickest section is made up of rocks from the Cretaceous Period. The basi ...

Plateau Sedimentary Province The Colorado Plateau, also known as the Colorado Plateau Province, is a physiographic and desert region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. This province covers an area ...

San Juan Basin The San Juan Basin is a geologic structural basin located near the Four Corners region of the Southwestern United States. The basin covers 7,500 square miles and resides in northwestern New Mexico, southwestern Colorado, and parts of Utah ...

* Uinta Uplift

Paleontology

Prehistoric animals from the various formations of the Glen Canyon Group include several types of

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

s, 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

theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...

s "Syntarsus" ''kayentakatae'' and ''

Dilophosaurus ''Dilophosaurus'' ( ) is a genus of theropod dinosaurs that lived in what is now North America during the Early Jurassic, about 193 million years ago. Three skeletons were discovered in northern Arizona in 1940, and the two best preserve ...

'', the

prosauropod Sauropodomorpha ( ; from Greek, meaning "lizard-footed forms") is an extinct clade of long-necked, herbivorous, saurischian dinosaurs that includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had l ...

Sarahsaurus ''Sarahsaurus'' is a genus of basal sauropodomorph dinosaur which lived during the Early Jurassic period in what is now northeastern Arizona, United States. Discovery and naming All specimens of ''Sarahsaurus'' were collected from the Lower J ...

'', an unnamed heterodontosaurid, and the armored dinosaurs ''

Scelidosaurus ''Scelidosaurus'' (; with the intended meaning of "limb lizard", from Greek / meaning 'rib of beef' and ''sauros''/ meaning 'lizard')Liddell & Scott (1980). Greek-English Lexicon, Abridged Edition. Oxford University Press, Oxford, UK. is a gen ...

'' and ''

Scutellosaurus ''Scutellosaurus'' ( ) is a genus of thyreophoran ornithischian dinosaur that lived approximately 196 million years ago during the early part of the Jurassic Period in what is now Arizona, USA. It is classified in Thyreophora, the armoured di ...

''. The Navajo Sandstone has body fossils of the theropod '' Segisaurus'' and an '' Ammosaurus''-like prosauropod, and tracks. The following summarizes vertebrate fossils and tracks reported in the Glen Canyon Group: Navajo Sandstone: :Body fossils ::

Tritylodontidae Tritylodontidae ("three-knob teeth", named after the shape of their cheek teeth) is an extinct family of small to medium-sized, highly specialized mammal-like cynodonts, bearing several mammalian traits like erect limbs, endothermy and detail ...

indet. ::

Protosuchidae Protosuchidae was a family of crocodylomorph reptiles from the Late Triassic, Jurassic, and Cretaceous time periods. They were closely related to the Gobiosuchidae. Distribution Triassic protosuchids are known from Lesotho, Argentina, and Arizon ...

indet. ::'' Segisaurus hallii'' Camp ::'' Ammosaurus'' :Trace fossils :: Actinopterygii ::'' Anchisauripus'' ::''

Anomoepus ''Anomoepus'' is the name assigned to several fossil footprints first reported from Early Jurassic beds of the Connecticut River Valley, Massachusetts, USA in 1802. All four feet have left impressions. The smaller forefeet have five toes, wher ...

?'' ::''

Brasilichnium ''Brasilichnium'' is the name of fossilised mammaliamorph footprints dating from the Jurassic and Cretaceous. They have been identified from Brazil and western North America. ''Brasilichnium'' is the name of the footprints, identified by their sh ...

'' ::''

Eubrontes ''Eubrontes'' is the name of fossilised dinosaur footprints dating from the Late Triassic and Early Jurassic. They have been identified from France, Poland, Slovakia, Czech Republic, Italy, Spain, Sweden, Australia (Queensland), USA, India and C ...

'' ::''

Grallator ''Grallator'' GRA-luh-tor"is an ichnogenus (form taxon based on footprints) which covers a common type of small, three-toed print made by a variety of bipedal theropod dinosaurs. ''Grallator''-type footprints have been found in formations dati ...

'' ::'' Tetrasauropus'' ::''

Otozoum ''Otozoum'' ("giant animal") is an extinct ichnospecies of fossilized sauropodomorph dinosaur footprints and other markings in sandstones. They were made by heavy, bipedal animals (probably dinosaurs) with a short stride that walked on four toes ...

'' ::''

'' Kayenta Formation: :Body fossils ::

Hybodontidae Hybodontidae is an extinct family of sharks that first appeared in the Mississippian subperiod of the Carboniferous and disappeared at the end of the Late Cretaceous.

incert. ::'' Osteichthyes incert.'' ::'' Prosalirus bitis'' Shubin and Jenkins ::''

Eocaecilia ''Eocaecilia'' is an extinct genus of gymnophionan amphibian from the early Jurassic Kayenta Formation of Arizona, United States. One species is described, ''Eocaecilia micropodia''. ''Eocaecilia'' shared some characteristics with salamanders a ...

micropodia'' Jenkins and Wash ::'' Kayentachelys aprix'' Gaffney ''et al.'' :Trace fossils ::''Brasilichnium?'' ::''Eubrontes'' ::''Grallator'' ::''Otozoum'' Moenave Formation: :Body fossils :: Semionotidae incert. ::

Reptilia Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...

indet. ::'' Protosuchus'' ::''

Lepidosauria The Lepidosauria (, from Greek meaning ''scaled lizards'') is a subclass or superorder of reptiles, containing the orders Squamata and Rhynchocephalia. Squamata includes snakes, lizards, and amphisbaenians. Squamata contains over 9,000 species ...

indet.'' ::''

Megapnosaurus ''Megapnosaurus'' (meaning "big dead lizard", from Greek μεγα = "big", 'απνοος = "not breathing", "dead", σαυρος = "lizard") is an extinct genus of coelophysid theropod dinosaur that lived approximately 188 million years ago dur ...

'' :Trace fossils ::''Brasilichnium'' ::''Grallator'' ::''Tetrasauropus'' ::''Eubrontes'' Wingate Sandstone: :Trace fossils: ::''Brasilichnium'' ::''Tetrasauropus'' ::''Grallator''

References

Notes

External links

GEOLEX database entry for Glen Canyon
USGS (viewed 19 March 2006)

USGS (viewed 19 March 2006) {{Jurassic Footer Lower Jurassic Series Upper Triassic Series Sandstone formations of the United States Colorado Plateau Geologic groups of Arizona Geologic groups of Colorado Geologic groups of New Mexico Geologic groups of Utah Geologic groups of Wyoming Jurassic Arizona Triassic Arizona Jurassic Colorado Triassic Colorado Jurassic geology of Nevada Triassic geology of Nevada Jurassic formations of New Mexico Triassic formations of New Mexico Jurassic geology of Utah Triassic geology of Utah Mesozoic Erathem of North America

Description

Subunits

History of investigation

Places found

Paleontology

See also

References

Notes

External links