The Garita Creek Formation is a geologic formation in

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

that contains vertebrate

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

s characteristic of the

Carnian The Carnian (less commonly, Karnian) is the lowermost stage (stratigraphy), stage of the Upper Triassic series (stratigraphy), Series (or earliest age (geology), age of the Late Triassic Epoch (reference date), Epoch). It lasted from 237 to 227.3 ...

Age Age or AGE may refer to: Time and its effects * Age, the amount of time someone has been alive or something has existed ** East Asian age reckoning, an Asian system of marking age starting at 1 * Ageing or aging, the process of becoming older ...

of the

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

.Lucas and Hunt 1989 The formation may be synonymous with the

Tecovas Formation The Tecovas Formation is a geological Formation (geology), formation in the Texas panhandle and eastern New Mexico. It is one of several formations encompassed by the Late Triassic Dockum Group.Weishampel, David B; et al. (2004). "Dinosaur distri ...

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

.Lehman 1994

Description

The formation consists mostly of gray red to red or mottled gray green

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from ''shale'' by its lack of fissility.Blatt, H., and R.J. Tracy, 1996, ''Petrology.'' New York, New York, ...

containing

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

nodules. About 25% of the formation is massive fine-grained laminar gray red

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

. It rests

conformably Lithostratigraphy is a sub-discipline of stratigraphy, the geological science associated with the study of strata or rock layers. Major focuses include geochronology, comparative geology, and petrology. In general, strata are primarily igneous ...

on the Santa Rosa Formation, and is overlain disconformably by the Trujillo Formation. The total thickness of the formation is . It is exposed throughout the drainage of the Conchas River and its tributaries west to the

Sangre de Cristo Mountains The Sangre de Cristo Mountains (Spanish language, Spanish for "Blood of Christ") are the southernmost mountain range, subrange of the Rocky Mountains. They are located in southern Colorado and northern New Mexico in the United States. The mountai ...

.Lucas ''et al.'' 1990

Fossils

The formation contains vertebrate fossils of ''

Desmatosuchus ''Desmatosuchus'' (, from Greek language, Greek δεσμός ''desmos'' 'link' + σοῦχος ''soûkhos'' 'crocodile') is an extinct genus of archosaur belonging to the Order Aetosauria. It lived during the Late Triassic. Description ''Desma ...

'', '' Typothorax'', '' Paratypothorax'', '' Postosuchus'',

rauisuchia "Rauisuchia" is a paraphyletic group of mostly large and carnivorous Triassic archosaurs. Rauisuchians are a category of archosaurs within a larger group called Pseudosuchia, which encompasses all archosaurs more closely related to crocodilians ...

ns, metoposaurids, '' Ceratodus'', and indeterminate phytosaurs. Drepanosaurids, including '' Unguinychus'' and at least one other unnamed species, have been described from the formation's Homestead Site.

History of investigation

The formation was first named by

Lucas Lucas or LUCAS may refer to: People * Lucas (surname) * Lucas (given name) Arts and entertainment * Luca Family Singers, or the Lucas, a 19th-century African-American singing group * Lucas, a 1960s Swedish pop group formed by Janne Lucas Perss ...

and Hunt in 1989 for beds formerly assigned to the informal lower shale member of the

Chinle Formation 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. In ...

in the Tucumcari Basin. The formation definition has been criticized as a junior synonym for the

across the border in

Footnotes

References

* * * {{cite journal , last1=Lucas , first1=S.G. , author1-link=Spencer G. Lucas , last2=Hunt , first2=A.P. , last3=Huber , first3=P. , year=1990 , title=Triassic stratigraphy in the Sangre de Cristo Mountains, New Mexico , journal=New Mexico Geological Society Field Conference Guidebook , volume=41 , pages=305–318 , url=https://nmgs.nmt.edu/publications/guidebooks/downloads/41/41_p0305_p0318.pdf , accessdate=17 September 2020 Triassic formations of New Mexico Shale formations of the United States

Description

Fossils

History of investigation

See also

Footnotes

References