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Gila Conglomerate
The Gila Group is a group of geologic formations found along the upper tributaries of the Gila River in Arizona and New Mexico. Radiometric dating of lava flows within the group yields an age of Miocene to Quaternary. Description The group is primarily conglomerate composed of clasts (rock fragments) weathered from nearby outcrops. There are also occasional thin sandstone and tuff beds and basalt flows. Total thickness is . Radiometric ages of basalt flows within the group range from 12.1 million years ( Ma) to 1 Ma. The group is similar in age and character to the Santa Fe Group. Both are sedimentary fill of extensional basins. The two groups are separated by the Continental Divide, and the Gila Group is separated from formations of similar age to the north by the Rim Divide, which separates the San Francisco and Salt River drainage basins to the south from the Little Colorado River drainage basin to the north. Fossils The Gila Group has yielded a diversity of fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Group (stratigraphy)
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 vast ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clasts
Clastic rocks are composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus,Essentials of Geology, 3rd Ed, Stephen Marshak, p. G-3 chunks, and smaller grains of rock broken off other rocks by physical weathering.Essentials of Geology, 3rd Ed, Stephen Marshak, p. G-5 Geologists use the term clastic to refer to sedimentary rocks and particles in sediment transport, whether in suspension or as bed load, and in sediment deposits. Sedimentary clastic rocks Clastic sedimentary rocks are rocks composed predominantly of broken pieces or ''clasts'' of older weathered and eroded rocks. Clastic sediments or sedimentary rocks are classified based on grain size, clast and cementing material (matrix) composition, and texture. The classification factors are often useful in determining a sample's environment of deposition. An example of clastic environment would be a river system in which the full range of grains being transported by th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wheeler Survey
The Wheeler Survey, carried out in 1872-1879, was one of the "Four Great Surveys" conducted by the US government after the Civil War primarily to document the geology and natural resources of the American West. Supervised by First Lieutenant (later Captain) George Montague Wheeler, the Wheeler Survey documented and mapped the United States west of the 100th meridian. The survey team included Lieutenant (later Brigadier General) Montgomery M. Macomb. Wheeler led early expeditions from 1869 to 1871 in the West, and in 1872 the US Congress authorized an ambitious plan to map the portion of the United States west of the 100th meridian at a scale of eight miles to the inch. This plan necessitated what became known as the Wheeler Survey. The survey's main goal was to make topographic maps of the southwestern United States. In addition he was to ascertain everything related to the physical features of the region; discover the numbers, habits, and disposition of Indians in the section; ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Irvingtonian
The Irvingtonian North American Land Mammal Age on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), spanning from 1.9 million – 250,000 years BP.The _Blancan, Irvingtonian and Rancholabrean Mammal Ages by Christopher J. Bell and Ernest L. Lundelius Jr., Anthony D. Barnosky, Russell W. Graham, Everett H. Lindsay, Dennis R. Ruez Jr., Holmes A. Semken Jr., S. David Webb, and Richard J. Zakrzewski. January 2004 in the book: Late Cretaceous and Cenozoic Mammals of North America: Biostratigraphy and Geochronology. Chapter: 7. Publisher: Columbia University Press; Editors: Michael O. Woodburne. pp274-276 Named after an assemblage of fossils from the [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glyptotherium
''Glyptotherium'' (from Greek for 'grooved or carved beast') is a genus of glyptodont (an extinct group of large, herbivorous armadillos) that lived from the Early Pliocene, about 4.9 million years ago, to the Early Holocene, around 7,000 years ago, in the United States, Mexico, Guatemala, Costa Rica, Honduras, El Salvador, Panama, Venezuela, and Brazil. The genus was first described in 1903 by American paleontologist Henry Fairfield Osborn with the type species being, ''G. texanum,'' based on fossils that had been found in the Pliocene Blancan Beds in Llano Estacado, Texas, USA. The genus has since been discovered in many more fossil sites. Another species, ''G. cylindricum'', was named in 1912 by fossil hunter Barnum Brown on the basis of a partial carapace, teeth, and several additional fossils that had been unearthed from the Pleistocene deposits in Jalisco, Mexico. Glyptodonts were typically large, graviportal, herbivorous armadillos with armored carapaces that were made ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Armadillo
Armadillos (meaning "little armored ones" in Spanish) are New World placental mammals in the order Cingulata. The Chlamyphoridae and Dasypodidae are the only surviving families in the order, which is part of the superorder Xenarthra, along with the anteaters and sloths. Nine extinct genera and 21 extant species of armadillo have been described, some of which are distinguished by the number of bands on their armor. All species are native to the Americas, where they inhabit a variety of different environments. Armadillos are characterized by a leathery armor shell and long, sharp claws for digging. They have short legs, but can move quite quickly. The average length of an armadillo is about , including its tail. The giant armadillo grows up to and weighs up to , while the pink fairy armadillo has a length of only . When threatened by a predator, ''Tolypeutes'' species frequently roll up into a ball; they are the only species of armadillo capable of this. Etymology The wor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Little Colorado River
The Little Colorado River () is a tributary of the Colorado River in the U.S. state of Arizona, providing the principal drainage from the Painted Desert region. Together with its major tributary, the Puerco River, it drains an area of about in eastern Arizona and western New Mexico. Although it stretches almost , only the headwaters and the lowermost reaches flow year-round. Between St. Johns and Cameron, most of the river is a wide, braided wash, only containing water after heavy snowmelt or flash flooding. The lower is known as the Little Colorado River Gorge and forms one of the largest arms of the Grand Canyon, at over deep where it joins the Colorado near Desert View in Grand Canyon National Park. An overlook of the gorge is a Navajo Nation Tribal Park. Course The river rises as two forks in the White Mountains of mid-eastern Arizona, in Apache County. The West Fork starts in a valley on the north flank of Mount Baldy at an elevation of nearly , while the East For ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drainage Basin
A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, the '' drainage divide'', made up of a succession of elevated features, such as ridges and hills. A basin may consist of smaller basins that merge at river confluences, forming a hierarchical pattern. Other terms for a drainage basin are catchment area, catchment basin, drainage area, river basin, water basin, and impluvium. In North America, they are commonly called a watershed, though in other English-speaking places, "watershed" is used only in its original sense, that of a drainage divide. In a closed drainage basin, or endorheic basin, the water converges to a single point inside the basin, known as a sink, which may be a permanent lake, a dry lake, or a point where surface water is lost underground. Drainage basins are similar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salt River (Arizona)
The Salt River (Spanish: , O'odham ima , Yavapai: or , Maricopa language: Va Shly’ay) is a river in Gila and Maricopa counties in Arizona, United States, that is the largest tributary of the Gila River. The river is about 200 miles (320 km) long.Calculated with Google Maps and Google Earth Its drainage basin is about 13,700 square miles (35,000 km2) large. The longest of the Salt River's many tributaries is the 195-mile (314 km) Verde River. The Salt's headwaters tributaries, the Black River and East Fork, increase the river's total length to about 300 miles (480 km). The name Salt River comes from the fact that the river flows over large salt deposits shortly after the merging of the White and Black Rivers. Variant names According to the Geographic Names Information System, the Salt River has also been known as: * Assumption * Black River * Blau Fluss * Blue River * Rio Asuncion * Rio Azulrio de Lasrio * Rio de la Asuncion ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
San Francisco River (Gila River Tributary)
The San Francisco River is a river in the southwest United States, the largest tributary of the Upper Gila River. It originates near Alpine, Arizona and flows into New Mexico before reentering Arizona and joining the Gila downstream from Clifton. See also * List of Arizona rivers * List of New Mexico rivers * List of tributaries of the Colorado River The principal tributaries of the Colorado River of North America are the Gila River, the San Juan River, the Green River, and the Gunnison River. Tributary tree The following is a tree demonstrating the points at which the major and minor trib ... References External links San Francisco River {{Coord, 32.9761743, -109.3720169, display=title, format=dms Rivers of Arizona Rivers of New Mexico Rivers of Greenlee County, Arizona Rivers of Apache County, Arizona Tributaries of the Gila River Rivers of Catron County, New Mexico ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Continental Divide
A continental divide is a drainage divide on a continent such that the drainage basin on one side of the divide feeds into one ocean or sea, and the basin on the other side either feeds into a different ocean or sea, or else is endorheic, not connected to the open sea. Every continent on earth except Antarctica (which has no known significant, definable free-flowing surface rivers) has at least one continental drainage divide; islands, even small ones like Killiniq Island on the Labrador Sea in Canada, may also host part of a continental divide or have their own island-spanning divide. The endpoints of a continental divide may be coastlines of gulfs, seas or oceans, the boundary of an endorheic basin, or another continental divide. One case, the Great Basin Divide, is a closed loop around an endoreic basin. The endpoints where a continental divide meets the coast are not always definite since the exact border between adjacent bodies of water is usually not clearly defined. The I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Santa Fe Group (geology)
The Santa Fe Group is a group of geologic formations in New Mexico and Colorado. It contains fossils characteristic of the Oligocene through Pleistocene epochs. The group consists of basin-filling sedimentary and volcanic rocks of the Rio Grande rift, and contains important regional aquifers. Description The Santa Fe Group is widely defined as basin-filling sedimentary and volcanic rocks of the Rio Grande rift. These range in age from late Oligocene to Pleistocene. The oldest formations in the group correspond to the earliest structural deformation associated with rifting. Geologic uplift of the region around the rift has ended deposition, and erosion in the Rio Grande river system has exposed many of the beds deposited earlier, often spectacularly, as in the badlands north of Santa Fe. The formations in the group are divided into lower and upper sections. The lower Santa Fe Group was deposited in bolsons (closed arid basins) where streams drained into intermittent play ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
