The Sangre de Cristo Formation is a

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

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 ...

and

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...

. It preserves

fossils 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 preserved ...

dating back to the late Pennsylvanian to

early Permian 01 or '01 may refer to: * The year 2001, or any year ending with 01 * The month of January * 1 (number) Music * 01'' (Richard Müller album), 2001 * ''01'' (Son of Dave album), 2000 * ''01'' (Urban Zakapa album), 2011 * ''O1'' (Hiroyuki Sawano ...

Description

The formation is divided into an informal lower member and an upper Crestone Conglomerate Member. The lower informal member consists of about of red arkosic

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

, conglomeratic sandstone,

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, ...

, and

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especia ...

. These are arranged into fining upwards cycles. The Crestone Conglomerate Member consists of about of red conglomerate, conglomeratic sandstone, sandstone, and minor siltstone and shale.Lindsey ''et al.'' 1985 The formation is exposed in the

Sangre de Cristo Mountains The Sangre de Cristo Mountains ( Spanish for "Blood of Christ") are the southernmost subrange of the Rocky Mountains. They are located in southern Colorado and northern New Mexico in the United States. The mountains run from Poncha Pass in South ...

in both southern Colorado and northern New Mexico. However, the exposures in the southeastern Sangre de Cristo Mountains were deposited in a distinct basin (the Rowe-Mora basin) rather than the central Colorado basin, lack the marine beds found in Colorado, and should probably be assigned instead to the

Abo Formation The Abo Formation is a geologic formation in New Mexico. It contains fossils characteristic of the Cisuralian epoch of the Permian period. Description The Abo Formation consists of fluvial redbed mudstones and sandstones, including river chann ...

.Lucas ''et al.'' 2015

Fossils

The informal lower members contains sparse fossiliferous limestone beds containing

crinoid Crinoids are marine animals that make up the Class (biology), class Crinoidea. Crinoids that are attached to the sea bottom by a stalk in their adult form are commonly called sea lilies, while the unstalked forms are called feather stars or coma ...

brachiopod Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, ...

stromatolite Stromatolites () or stromatoliths () are layered sedimentary formations ( microbialite) that are created mainly by photosynthetic microorganisms such as cyanobacteria, sulfate-reducing bacteria, and Pseudomonadota (formerly proteobacteria). ...

fusulinid The Fusulinida is an extinct order within the Foraminifera in which the tests are traditionally considered to have been composed of microgranular calcite. Like all forams, they were single-celled organisms. In advanced forms the test wall was dif ...

s, and

conodont Conodonts ( Greek ''kōnos'', " cone", + ''odont'', " tooth") are an extinct group of agnathan (jawless) vertebrates resembling eels, classified in the class Conodonta. For many years, they were known only from their tooth-like oral elements, w ...

s. Outcrops near the headwaters of the

Pecos River The Pecos River ( es, Río Pecos) originates in north-central New Mexico and flows into Texas, emptying into the Rio Grande. Its headwaters are on the eastern slope of the Sangre de Cristo mountain range in Mora County north of Pecos, New Mexico ...

include tetrapod footprints, identified as ''Batrachichnus'', '' Limnopus'', '' Ichniotherium'', ''Tambachichnium'', ''Dimetropus'', and '' Dromopus''. Less identifiable specimens may be ''Matthewichnus'', ''Notalacerta'', and ''Hyloidichnus''. The assemblage is consistent with a late

Artinskian In the geologic timescale, the Artinskian is an age or stage of the Permian. It is a subdivision of the Cisuralian Epoch or Series. The Artinskian likely lasted between and million years ago (Ma) according to the most recent revision of th ...

age. Voigt and Lucas 2015

History of investigation

The formation was first described by Hills in 1899.Hills 1899 F.A.Melton described the unit in 1925 as the Sangre de Cristo Conglomerate and defined a Crestone Conglomerate Phase (later Crestone Conglomerate Member).Melton 1925

Footnotes

References

* * * * * {{Chronostratigraphy of Colorado, Paleozoic state=expanded Carboniferous Colorado Permian formations of New Mexico

Description

Fossils

History of investigation

Footnotes

See also

References