The Cutler Formation or Cutler Group is a
rock unit
A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features (facies) that characterize it ...
that is exposed across the
U.S. states
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 ...
of
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 ...
, northwest
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, Ker ...
, southeast
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 ...
and southwest
Colorado
Colorado (, other variants) is a state in the 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 western edge of t ...
. It was laid down in the
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), 01'' (Richard Müller album), 2001
* 01 (Son of Dave album), ''01'' (Son of Dave album), 2000
* 01 (Urban ...
during the
Wolfcampian
The Cisuralian is the first Series (stratigraphy), series/Epoch (geology), epoch of the Permian. The Cisuralian was preceded by the Pennsylvanian (geology), Pennsylvanian and followed by the Guadalupian. The Cisuralian Epoch is named after the w ...
epoch
In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured.
The moment of epoch is usually decided by ...
.
Description
At its type area north of
Ouray, Colorado
Ouray () is a home rule municipality that is the county seat of Ouray County, Colorado, United States. The city population was 1,000 as of the 2010 census. The Ouray Post Office has the ZIP Code 81427. Located at an elevation of , Ouray's clim ...
, the Cutler Formation consists of over of bright red
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) ...
,
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, p ...
, and
conglomerate beds alternating with reddish
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 (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...
or
clay
Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4).
Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...
-rich
limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
.
[ Further west, the unit shows great lithological diversity, and can be divided into easily recognizable mappable subunits. Here the Cutler is raised from ]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 ...
to group
A group is a number of persons or things that are located, gathered, or classed together.
Groups of people
* Cultural group, a group whose members share the same cultural identity
* Ethnic group, a group whose members share the same ethnic iden ...
rank and its subunits are themselves designated as formations. The unit in its type area remains at formation rank and is often described as the "undifferentiated Cutler".
The formation overlies the Hermosa Group
The Hermosa Group is a group of geologic formations in Utah and Colorado. It preserves fossils dating back to the Carboniferous period.
See also
* List of fossiliferous stratigraphic units in Utah
* Paleontology in Utah
The location of the st ...
and is in turn overlain by either the Dolores Formation (near its type area) or the Moenkopi Formation
The Moenkopi Formation is a geological formation that is spread across the U.S. states of New Mexico, northern Arizona, Nevada, southeastern California, eastern Utah and western Colorado. This unit is considered to be a group in Arizona. Part ...
(further west). It is laterally equivalent 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 channel ...
of central New Mexico, to which it seamlessly transitions in the Jemez Mountains
The Jemez Mountains are a group of mountains in Rio Arriba, Sandoval, and Los Alamos counties, New Mexico, United States.
Numerous Puebloan Indian tribes have lived in the Jemez Mountains region since before the Spanish arrived in New Mexico. T ...
.
The formation has been dated to Wolfcampian
The Cisuralian is the first Series (stratigraphy), series/Epoch (geology), epoch of the Permian. The Cisuralian was preceded by the Pennsylvanian (geology), Pennsylvanian and followed by the Guadalupian. The Cisuralian Epoch is named after the w ...
near its type area.[ At this point in geologic time, the Uncompahgre Uplift of the ]Ancestral Rocky Mountains
The geology of the Rocky Mountains is that of a discontinuous series of mountain ranges with distinct geological origins. Collectively these make up the Rocky Mountains, a mountain system that stretches from Northern British Columbia through cen ...
was still rising along an arc from eastern Utah through southwestern Colorado and into northern New Mexico. Tremendous quantities of sediment were eroded off the uplift and accumulated at its southwest margin to form the undifferentiated Cutler, which in some places reached a thickness of . Further west, eolian (wind), fluvial
In geography and geology, fluvial processes are associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or fluviog ...
(river) and marine influences became important and produced the lithological variety of the Cutler Group.
The undifferentiated Cutler consists of alluvial fan
An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to semiarid climates, but a ...
deposits in a narrow belt very close to the Uncompahgre Uplift, and fluvial deposits further out. The coarsest exposures are near Gateway, Colorado
Gateway is an unincorporated community and a U.S. Post Office located in Mesa County, Colorado, United States.
Description
The Gateway Post Office has the ZIP Code 81522. A post office called Gateway has been in operation since 1903. The comm ...
, within a mile of the thrust fault
A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks.
Thrust geometry and nomenclature
Reverse faults
A thrust fault is a type of reverse fault that has a dip of 45 degrees or less.
If ...
defining the southwest margin of the ancient Uncompahgre Uplift. Some granite boulders in these deposits are up to in diameter. However, thrusting along the uplift margin had ceased by the time the youngest beds were deposited. Further west, the formation transitions to thin (less than ) sandstone and comglomerate beds, in which the grains become finer towards the top of the bed (a fining upward
In geology, a graded bed is one characterized by a systematic change in grain or clast size from one side of the bed to the other. Most commonly this takes the form of normal grading, with coarser sediments at the base, which grade upward into pro ...
sequence). These are interpreted as recording individual sheet flood Sheet erosion or sheet wash is the even erosion of substrate along a wide area. It occurs in a wide range of settings such as coastal plains, hillslopes, floodplains, beaches, savanna plains and semi-arid plains. Water moving fairly uniformly with ...
events.
Subunits
The Cutler has been placed at either 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 ...
or group
A group is a number of persons or things that are located, gathered, or classed together.
Groups of people
* Cultural group, a group whose members share the same cultural identity
* Ethnic group, a group whose members share the same ethnic iden ...
stratigraphic rank, depending on the publication. Its subunits, therefore, are variously called formations or members.
Subunits on the Colorado Plateau are:
* De Chelly Sandstone
The Yeso Group is a group of geologic formations in New Mexico. It contains fossils characteristic of the Kungurian Age of the early Permian Period.
Description
The Yeso Group is lithologically complex, ranging from marine shelf carbonate ...
(Arizona, Colorado, New Mexico, Utah) — youngest
* White Rim Sandstone
The White Rim Sandstone is a sandstone geologic formation located in southeastern Utah. It is the last member of the Permian Cutler Group, and overlies the major Organ Rock Formation and Cedar Mesa Sandstone; and again overlies thinner units of ...
(Utah)
* Organ Rock Shale
The Organ Rock Formation or Organ Rock Shale is a formation within the late Pennsylvanian to early Permian Cutler Group and is deposited across southeastern Utah, northwestern New Mexico, and northeastern Arizona. This formation notably outcrops ar ...
(Arizona, Colorado, New Mexico, Utah)
* Cedar Mesa Sandstone
Cedar Mesa Sandstone (also known as the Cedar Mesa Formation) is a sandstone memberThe Cutler Formation is sometimes classified as the Cutler Group, in which case Cedar Mesa Sandstone is classified as a formation rather than a member. of the Cutle ...
(Arizona, Utah)
* lower Cutler beds (Arizona, Colorado, New Mexico, Utah) — oldest
Beds formerly assigned to the Elephant Canyon Formation
The Elephant Canyon Formation is the basal Permian geologic formation of the Cutler Group overlying an unconformity on the Pennsylvanian Honaker Trail Formation in the Paradox Basin of southern Utah.
Description
It consists of pink dolomite, li ...
, the Halgaito Shale
The Halgaito Formation is the basal Permian geologic member of the Cutler Group in southern Utah. The member consists of silty sandstone, siltstone and limestone. The Elephant Canyon may grade into the Halgaito and grades northward into the Cedar ...
, or the Rico Formation are included in the lower Cutler beds.
The stratigraphy of the lower Cutler beds has long been controversial. Charles Whitman Cross
Charles Whitman Cross (September 1, 1854 – April 20, 1949) was an American geologist. He was educated at Amherst College, the University of Göttingen, and Leipzig University. A petrologist, much of his field work concerned rocks in Colorado. H ...
and A.C. Spencer applied the name ''Rico Formation'' to beds in the Rico Mountains of southwestern Colorado that were transitional from the marine Hermosa Formation and the overlying continental Cutler Formation. These contained marine fossils suggesting the beds covered the Pennsylvanian to Permian
The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...
time interval. The name came into wide use for transitional beds further west as petroleum geologists mapped the Colorado Plateau. However, the definition of the Rico was vague and it was mapped inconsistently in the region. This led Don Baars to recommend abandoning the Rico in favor of placing the upper, Permian beds in his new Elephant Canyon Formation and reassigning the lower, Pennsylvanian, beds to the underlying Honaker Trail Formation
The Honaker Trail Formation is a geologic formation in Utah. It preserves fossils dating back to the Carboniferous period.
It is a member of the 3-member Hermosa Group and is located above the Paradox Formation in the dramatic site of Goose ...
. However, other geologists objected to this because the contact was defined by the 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 di ...
s present in the beds, which made this a chronostratigraphic
Chronostratigraphy is the branch of stratigraphy that studies the ages of rock strata in relation to time.
The ultimate aim of chronostratigraphy is to arrange the sequence of deposition and the time of deposition of all rocks within a geological ...
rather than a lithostratigraphic
Lithostratigraphy is a sub-discipline of stratigraphy, the geology, geological science associated with the study of stratum, strata or rock layers. Major focuses include geochronology, comparative geology, and petrology.
In general, strata are ...
distinction, and by a subtle angular unconformity that was not easily recognized in the field. This led to abandonment of the Elephant Canyon Formation and designation of all beds between the Honaker Trail Formation and the Cedar Mesa Sandstone as simply the lower Cutler beds. These also include beds previously assigned to the Halgaito Formation.
In the Chama Basin
The Chama Basin is a geologic structural basin located in northern New Mexico. The basin closely corresponds to the drainage basin of the Rio Chama and is located between the eastern margin of the San Juan Basin and the western margin of the R ...
of New Mexico, the Cutler Group has been divided into two formations:
* Arroyo del Agua Formation
The Arroyo del Agua Formation is a geologic formation in New Mexico. It preserves fossils dating back to the early Permian period.
Description
The Arroyo del Agua Formation consists of siliclastic red beds with a total thickness of roughly . The ...
— younger
* El Cobre Canyon Formation
The El Cobre Canyon Formation is a geologic formation in New Mexico. It preserves fossils dating back to the late Pennsylvanian to early Permian periods.
Description
The El Cobre Canyon Formation consists of siliciclastic red beds with a total t ...
— older
A sandstone unit resembling the De Chelly Sandstone is present above the Arroyo del Agua Formation in the southernmost part of the basin, but in this region it is assigned to the Yeso Group
The Yeso Group is a group of geologic formations in New Mexico. It contains fossils characteristic of the Kungurian Age of the early Permian Period.
Description
The Yeso Group is lithologically complex, ranging from marine shelf carbonate ...
.[
]
Extent
Cutler outcrops are found in these geologic locations in 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 ...
, Colorado
Colorado (, other variants) is a state in the 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 western edge of t ...
, 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, Ker ...
and 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 ...
.
* Black Mesa Basin
Black Mesa (also called Big Mountain) is an upland mountainous mesa of Arizona, north-trending in Navajo County, west and southeast-trending in Apache County. In Navajo it is called ('Black Mountain') and during Mexican rule of Arizona it was c ...
* 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 ...
* San Juan Mountains
The San Juan Mountains is a high and rugged mountain range in the Rocky Mountains in southwestern Colorado and northwestern New Mexico. The area is highly mineralized (the Colorado Mineral Belt) and figured in the gold and silver mining industry ...
province[
* ]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 a ...
[
* ]Uinta 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 ...
History of investigation
There is no designated type locality for the Cutler. It was named by Charles Whitman Cross
Charles Whitman Cross (September 1, 1854 – April 20, 1949) was an American geologist. He was educated at Amherst College, the University of Göttingen, and Leipzig University. A petrologist, much of his field work concerned rocks in Colorado. H ...
and Ernest Howe in 1905 after Cutler Creek, which enters Uncompahgre River
The Uncompahgre River is a tributary of the Gunnison River, approximately 75 mi (121 km) long, in southwestern Colorado in the United States. Lake Como at 12,215 ft (3723m) in northern San Juan County, in the Uncompahgre National ...
about 4 miles north of Ouray, Colorado.[Keroher, Grace C., ] They found that nonfossiliferous red beds
Red beds (or redbeds) are sedimentary rocks, typically consisting of sandstone, siltstone, and shale, that are predominantly red in color due to the presence of ferric oxides. Frequently, these red-colored sedimentary strata locally contain ...
provisionally assigned to the Dolores Formation were separated from overlying fossiliferous Triassic
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...
beds by a significant angular unconformity. The lower beds were tentatively identified as Permian beds, and were removed from the Dolores Formation to the newly designated Cutler Formation.
Baker and Reeside revised Cross and Howe's work in 1929, tracing the Cutler across the Colorado Plateau
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 of ...
and dividing the formation into the Halgaito Tongue, Cedar Mesa Sandstone
Cedar Mesa Sandstone (also known as the Cedar Mesa Formation) is a sandstone memberThe Cutler Formation is sometimes classified as the Cutler Group, in which case Cedar Mesa Sandstone is classified as a formation rather than a member. of the Cutle ...
Member, Organ Rock Tongue, and White Rim Sandstone
The White Rim Sandstone is a sandstone geologic formation located in southeastern Utah. It is the last member of the Permian Cutler Group, and overlies the major Organ Rock Formation and Cedar Mesa Sandstone; and again overlies thinner units of ...
Member. They also confirmed Cross and Howe's dating of the formation to the Permian. The Cutler was traced through the Jemez Mountains and found to be laterally equivalent to the Abo Formation by Wood and Northrop in 1946.[
In 1958, Wengerd and Matheny raised the formation to ]group
A group is a number of persons or things that are located, gathered, or classed together.
Groups of people
* Cultural group, a group whose members share the same cultural identity
* Ethnic group, a group whose members share the same ethnic iden ...
rank.
File:Lisbon Valley Cutler Fm.jpg, Cutler and Chinle formations in Lisbon Valley, San Juan County, Utah
San Juan County ( ) is a County (United States), 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, Utah, Monticello, while its most popul ...
Image:Cedar Mesa Sandstone on top of Organ Rock Shale in Needles District of Canyonlands.jpeg, Cedar Mesa Sandstone overlaying Organ Rock Shale, Canyonlands, Utah
References
External links
{{Chronostratigraphy of Nevada
Geologic formations of Arizona
Geologic formations of Colorado
Geologic formations of Utah
Permian Arizona
Permian Colorado
Permian formations of New Mexico
Permian geology of Utah
Cisuralian Series of North America
Sandstone formations of the United States
Fluvial deposits
Lacustrine deposits
Permian northern paleotropical deposits
Paleontology in Colorado
Paleontology in New Mexico
Paleontology in Utah