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San Pedro Arroyo Formation
The San Pedro Arroyo Formation is a geologic formation in south-central New Mexico. It preserves fossils dating back to the late Triassic period. Description The formation consists of variegated bentonitic mudstone, sandstone, conglomerate, siltstone, and minor limestone, with a total thickness of . The sandstones are purple to red in color and are crossbedded, laminar, ripple laminated and micaceous. They are interbedded with conglomerates composed of mudstone and calcrete clasts. The formation rests on the Santa Rosa Formation and underlies either the Morrison Formation or, where that is not present, the Mesa Rica Formation or Dakota Group. A set of limestone beds near the base of the formation have been designated the Ojo Huelos Member. This consists of brown-weathering limestone beds a few meters thick, interbedded with meter-thick yellowish to greenish mudstone. History of investigation The formation was defined by Lucas ''et al.'' in 1991 to resolve an inconsistency i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formation (stratigraphy)
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 exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by Abraham Gottlob W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Period (geology)
The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronology (scientific branch of geology that aims to determine the age of rocks). It is used primarily by Earth scientists (including geologists, paleontologists, geophysicists, geochemists, and paleoclimatologists) to describe the timing and relationships of events in geologic history. The time scale has been developed through the study of rock layers and the observation of their relationships and identifying features such as lithologies, paleomagnetic properties, and fossils. The definition of standardized international units of geologic time is the responsibility of the International Commission on Stratigraphy (ICS), a constituent body of the International Union of Geological Sciences (IUGS), whose primary objective is to precisely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Fossiliferous Stratigraphic Units In New Mexico
This article contains a list of fossil-bearing stratigraphic units in the state of New Mexico, U.S. Sites See also * Paleontology in New Mexico References * {{DEFAULTSORT:Fossiliferous stratigraphic units in New Mexico 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 ... Stratigraphic units Stratigraphy of New Mexico New Mexico geography-related lists United States geology-related lists ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phytosaur
Phytosaurs (Φυτόσαυροι in greek) are an extinct group of large, mostly semiaquatic Late Triassic archosauriform reptiles. Phytosaurs belong to the order Phytosauria. Phytosauria and Phytosauridae are often considered to be equivalent groupings containing the same species, but some studies have identified non-phytosaurid phytosaurians. Phytosaurs were long-snouted and heavily armoured, bearing a remarkable resemblance to modern crocodilians in size, appearance, and lifestyle, as an example of convergence or parallel evolution. The name "phytosaur" means "plant reptile", as the first fossils of phytosaurs were mistakenly thought to belong to plant eaters. The name is misleading because the sharp teeth in phytosaur jaws clearly show that they were predators. For many years, phytosaurs were considered to be the most basal group of Pseudosuchia (crocodile-line archosaurs), meaning that they were thought to be more closely related to the crocodilians than to birds (the other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cooper Canyon Formation
The Cooper Canyon Formation is a geological formation of Norian age in Texas and New Mexico.Weishampel, David B; et al. (2004).Dinosaur distribution (Late Triassic, North America)" In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 518–521. . Type area of the formation is situated in Garza County, Texas. An equivalent formation in eastern New Mexico is named Bull Canyon Formation. Some researchers argue that the latter name should be abandoned. The formation consist of reddish siltstone and mudstone with lenses of sandstone and conglomerate. Thickness of the formation in the type area is 161.5 meters. It increases to the south, and in some places exceeds 200 m. The formation contains diverse fossils, including vertebrate remains. Vertebrate fauna Temnospondyls Allokotosaurs Archosaurs and related Procolophonomorphs Misc. See also * List of dinosaur-bearing rock formatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Group (geology)
In geology, a group is a lithostratigraphic unit consisting of a series of related formations that have been classified together to form a group. Formations are the fundamental unit of stratigraphy. Groups may sometimes be combined into supergroups. Groups are useful for showing relationships between formations, and they are also useful for small-scale mapping or for studying the stratigraphy of large regions. Geologists exploring a new area have sometimes defined groups when they believe the strata within the groups can be divided into formations during subsequent investigations of the area. It is possible for only some of the strata making up a group to be divided into formations. An example of a group is the Glen Canyon Group, which includes (in ascending order) the Wingate Sandstone, the Moenave Formation, the Kayenta Formation, and the Navajo Sandstone. Each of the formations can be distinguished from its neighbor by its lithology, but all were deposited in the same ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 336,700 km2 (130,000 mi2) within western Colorado, northwestern New Mexico, southern and eastern Utah, northern Arizona, and a tiny fraction in the extreme southeast of Nevada. About 90% of the area is drained by the Colorado River and its main tributaries: the Green, San Juan, and Little Colorado. Most of the remainder of the plateau is drained by the Rio Grande and its tributaries. The Colorado Plateau is largely made up of high desert, with scattered areas of forests. In the south-west corner of the Colorado Plateau lies the Grand Canyon of the Colorado River. Much of the Plateau's landscape is related to the Grand Canyon in both appearance and geologic history. The nickname "Red Rock Country" suggests the brightly colo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 New Mexico, it is often raised to the status of a geological group, the Chinle Group. Some authors have controversially considered the Chinle to be synonymous to the Dockum Group of eastern Colorado and New Mexico, western Texas, the Oklahoma panhandle, and southwestern Kansas. The Chinle Formation is part of the Colorado Plateau, Basin and Range, and the southern section of the Interior Plains.GEOLEX database entry for Chinle USGS (viewed 19 March 2006) A probable separate depositional basin within the Chinle is found in northwestern Colorado and northeas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shinarump Formation
The Shinarump Conglomerate is a geologic formation found in the Four Corners region of the United States. It was deposited in the early part of the Late Triassic period. Description The Shinarump Conglomerate is a highly resistant coarse-grained sandstone and pebble conglomerate, (minor or major conglomerates are a typical base layer after unconformities or disconformities; the Shinarump is a major conglomerate) with rare lenses of mudstone, sometimes forming a caprock because of its hardness, cementation, and erosion resistance. The Shinarump is found throughout the Colorado Plateau with significant exposures as the canyon rimrock in the vicinity of Canyon De Chelly National Monument, at the north-northeast of the Defiance Plateau/Defiance Uplift. At Canyon De Chelly the Shinarump Conglomerate was laid down upon De Chelly Sandstone-(280 Ma, an erosion unconformity of 50 my), in a region at the west foothill region of the mostly north-south trending Chuska Mountains of northea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Member (stratigraphy)
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. Units must be ''mappable'' and ''distinct'' from one another, but the contact need not be particularly distinct. For instance, a unit may be defined by terms such as "when the sandstone component exceeds 75%". Lithostratigraphic units Sequences of sedimentary and volcanic rocks are subdivided the basis of their shared or associated lithology. Formally identified lithostratigraphic units are structured in a hierarchy of lithostratigraphic rank, higher rank units generally comprising two or more units of lower rank. Going from smaller to larger in rank, the main lithostratigraphic ranks are Bed, Member, Formation, Group and Supergroup. Formal names of lithostratigraphic units are assigned by geological surveys. Units of formation or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dakota Group
The Dakota is a sedimentary geologic unit name of formation and group rank in Midwestern North America. The Dakota units are generally composed of sandstones, mudstones, clays, and shales deposited in the Mid-Cretaceous opening of the Western Interior Seaway.Monroe, James S. and Wicander, Reed (1997) ''The Changing Earth: Exploring Geology and Evolution'' (2nd edition) Wadsworth Publishing Company, Belmont, California, page 610, The usage of the name Dakota for this particular Albian- Cenomanian strata is exceptionally widespread; from British Columbia and Alberta to Montana and Wisconsin to Colorado and Kansas to Utah and Arizona. It is famous for producing massive colorful rock formations in the Rocky Mountains and the Great Plains of the United States, and for preserving both dinosaur footprints and early deciduous tree leaves. Owing to extensive weathering of older rocks during the Jurassic and Triassic, the Dakota strata lie unconformably atop many different formations ran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesa Rica Formation
The Mesa Rica Sandstone is a geologic formation in Oklahoma and New Mexico. It preserves fossils dating back to the Cretaceous period. Description The Mesa Rica Sandstone consists of crossbedded white to buff sandstone. The sandstone is massive and medium- to coarse-grained. It is a very mature sandstone, consisting of almost pure quartz and kaolin, which may reflect its provenance as reworked sediments of the Morrison Formation, or may be due to a slow rate of deposition that permitted meteoric water (water originating as rain or snow) to circulate through the sediments for an unusually long time. In some locations, there is minor quartz-pebble conglomerate at the base of the formation, which lies on the Tucumcari Shale or Glencairn Formation. It is overlain by the Pajarito Formation and has a thickness of up to . The formation was laid down in a low- accommodation deltaic environment. Fossils Dinosaur remains diagnostic to the genus level are among the fossils that have been ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
