Mesaverde Formation
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The Mesaverde Group is a
Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
stratigraphic
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 ide ...
found in areas of
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 ...
,
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
Wyoming Wyoming () is a U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the south ...
, in the
Western United States The Western United States (also called the American West, the Far West, and the West) is the region comprising the westernmost states of the United States. As American settlement in the U.S. expanded westward, the meaning of the term ''the Wes ...
.


History

The Mesaverde Formation was first described by W.H.Holmes in 1877 during the
Hayden Survey Ferdinand Vandeveer Hayden (September 7, 1829 – December 22, 1887) was an American geologist noted for his pioneering surveying expeditions of the Rocky Mountains in the late 19th century. He was also a physician who served with the Union Ar ...
. Holmes described the formation in the northern
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 ...
as consisting of three units, which were a "Lower Escarpment" consisting of 40 m of ledge- and cliff-forming massive
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) ...
; a "Middle Coal Group" consisting of up to 300 m of thick slope-forming sandstone,
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, especial ...
,
marl Marl is an earthy material rich in carbonate minerals, clays, and silt. When hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae. Marl makes up the lower part o ...
, and
lignite Lignite, often referred to as brown coal, is a soft, brown, combustible, sedimentary rock formed from naturally compressed peat. It has a carbon content around 25–35%, and is considered the lowest rank of coal due to its relatively low heat ...
; and an "Upper Escarpment" consisting of 60 m of ledge- and cliff-forming sandstone. A.J. Collier redesignated these units in 1919 as the
Point Lookout Sandstone The Point Lookout Sandstone is a Cretaceous bedrock formation occurring in New Mexico and Colorado. Description The formation consists of two informal members. The lower is a sequence of thinly bedded sandstone and shale, while the upper is a ...
, the
Menefee Formation The Menefee Formation is a lower Campanian geologic formation found in Colorado and New Mexico, United States. Description The Menefee Formation consists of fluvial sandstone, shale, and coal. Based on ammonite biostratigraphy, the age of the Me ...
, and the Cliff House Sandstone, and raised the Mesaverde Formation to group rank. The group was later traced to the greater
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 ...
, the Uintah and
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 ...
s, the
Bighorn Basin The Bighorn Basin is a plateau region and intermontane basin, approximately 100 miles (160 km) wide, in north-central Wyoming in the United States. It is bounded by the Absaroka Range on the west, the Pryor Mountains on the north, the Bighor ...
, the
Front Range The Front Range is a mountain range of the Southern Rocky Mountains of North America located in the central portion of the U.S. State of Colorado, and southeastern portion of the U.S. State of Wyoming. It is the first mountain range encountere ...
, the Zuni Basin, the
Wasatch Plateau The Wasatch Plateau is a plateau located southeast of the southernmost part of the Wasatch Range in central Utah. It is a part of the Colorado Plateau. Geography The plateau has an elevation of and includes an area of . Its highest point in the ...
,
Wind River Basin The Wind River Basin or Shoshone Basin is a semi-arid intermontane foreland basin in central Wyoming, United States. It is bounded by Laramide uplifts on all sides. On the west is the Wind River Range and on the North are the Absaroka Range and t ...
, Washakie Basin, and the
Powder River Basin The Powder River Basin is a geologic structural basin in southeast Montana and northeast Wyoming, about east to west and north to south, known for its extensive coal reserves. The former hunting grounds of the Oglala Lakota, the area is very s ...
. It is spectacularly exposed along the
Book Cliffs The Book Cliffs are a series of desert mountains and cliffs in western Colorado and eastern Utah in the western United States. They are so named because the cliffs of Cretaceous sandstone that cap many of the south-facing buttes appear similar ...
of eastern Utah and western Colorado. With the recognition of the vast extent of the group, the group has been divided into formations by region, with the original Point Lookout Sandstone, Menefee Formation, and Cliff House Sandstone being restricted largely to the San Juan Basin and the
Madrid, New Mexico Madrid (/ˈmædrɪd/, Spanish: aˈðɾið is a census-designated place (CDP) in Santa Fe County, New Mexico, United States. It is part of the Santa Fe, New Mexico Metropolitan Statistical Area. The population was 149 at the 2000 census and 204 i ...
area.


Geology

The group is a single regression- transgression sequence in its type location in the
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 ...
, dividing the older marine
Mancos Shale The Mancos Shale or Mancos Group is a Late Cretaceous (Upper Cretaceous) geologic formation of the Western United States. The Mancos Shale was first described by Cross and Purington in 1899 and was named for exposures near the town of Mancos, ...
and younger
Lewis Shale The Lewis Shale is a geologic formation in the Western United States. It preserves fossils dating back to the Campanian to Maastrichtian stages of the late Cretaceous period. Description The Lewis Shale is an olive-gray marine shale with som ...
deposited in the
Western Interior Seaway The Western Interior Seaway (also called the Cretaceous Seaway, the Niobraran Sea, the North American Inland Sea, and the Western Interior Sea) was a large inland sea that split the continent of North America into two landmasses. The ancient sea, ...
. The
Point Lookout Sandstone The Point Lookout Sandstone is a Cretaceous bedrock formation occurring in New Mexico and Colorado. Description The formation consists of two informal members. The lower is a sequence of thinly bedded sandstone and shale, while the upper is a ...
represents the regression, the
Menefee Formation The Menefee Formation is a lower Campanian geologic formation found in Colorado and New Mexico, United States. Description The Menefee Formation consists of fluvial sandstone, shale, and coal. Based on ammonite biostratigraphy, the age of the Me ...
the subsequent fluvial delta deposits, and the Cliff House Sandstone the return of the sea. In other locations, such as along the Book Cliffs, the picture is more complicated, with multiple regression-transgression sequences from tectonic activity along the Sevier mountain front. In the Cody area, the group is a simple regression sequence and remains at formation rank. Here the group is described as interbedded light gray sandstone and gray shale in the upper part; massive, light-buff, ledge-forming sandstone containing thin lenticular coal beds in the lower part.


Formations

northern Piceance Basin: *
Williams Fork Formation The Williams Fork Formation is a Campanian (Edmontonian) geologic formation of the Mesaverde Group in Colorado. Dinosaur remains are among the fossils that have been recovered from the formation, most notably ''Pentaceratops sternbergii'',. Other ...
* Iles Formation southwestern Piceance Basin: * Hunter Canyon Formation * Mount Garfield Formation Powder River Basin: * Teapot Sandstone * Parkman Sandstone Northern San Juan Basin: * Point Lookout Sandstone * Menefee Formation * Cliff House Sandstone Southern San Juan Basin and southern New Mexico: * Point Lookout Sandstone * Crevasse Canyon Formation * Gallup Sandstone Uintah Basin: * Tuscher Formation * Farrer Formation * Neslen Formation * Sego Sandstone * Price River Formation * Castlegate Sandstone * Blackhawk Formation * Star Point Sandstone Washakie Basin: * Almond Formation * Ericson Sandstone * Rock Springs Formation * Blair Formation


Fossils

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 ...
remains are among the fossils that have been recovered from the group, although none have yet been referred to a specific
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
. ''
Deinosuchus ''Deinosuchus'' () is an extinct genus of alligatoroid crocodilian, related to modern alligators and caimans, that lived 82 to 73 million years ago (Ma), during the late Cretaceous period. The name translates as "terrible crocodile" and i ...
'' has also been reported from Mesaverde outcrops in Wyoming.


See also

*
List of dinosaur-bearing rock formations This list of dinosaur-bearing rock formations is a list of geologic formations in which dinosaur fossils have been documented. Containing body fossils * List of stratigraphic units with dinosaur body fossils ** List of stratigraphic units with ...
**
List of stratigraphic units with indeterminate dinosaur fossils This list of stratigraphic units with indeterminate dinosaur fossils includes stratigraphic units of formation rank or higher that have produced dinosaur body fossils, although none of these remains have been referred to a specific genus in the sci ...


Footnotes


References

* * * * * * * * * * * * * * * * * * * * {{cite book , editor-last1=Weishampel , editor-first1=David B. , editor-last2=Dodson , editor-first2=Peter , editor-last3=Osmólska , editor-first3=Halszka , year=2004 , title=The Dinosauria , edition=2nd , location=Berkeley , publisher=University of California Press , isbn=0-520-24209-2 Cretaceous formations of New Mexico Cretaceous geology of Utah Cretaceous geology of Wyoming Geologic groups of New Mexico Upper Cretaceous Series of North America