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Rincon Valley Formation
The Rincon Valley Formation is a geologic formation found in the Rincon Valley of New Mexico. It preserves fossils dating back to the Miocene epoch and records a time when the valley was a closed basin, just before being integrated into the ancestral Rio Grande River. Description The formation consists of pink to reddish-brown gypsiferous claystone and siltstone; conglomerate; and conglomeratic sandstone. The thickness is . The formation is exposed in the badlands bordering the Rio Grande valley north of Las Cruces, New Mexico. It grades below into the Hayner Ranch Formation and unconformably underlies the Camp Rice Formation. It is interbedded with flows of the Selden Basalt Member with a radiometric age of 9.6 million years. The formation consists of two facies representing different depositional environments. The first is a fine-grained gypsiferous slope-forming facies interpreted as playa deposits in a closed basin. This contains gypsum beds up to thick. The second faci ... [...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] |
Rio Grande River
The Rio Grande ( and ), known in Mexico as the Río Bravo del Norte or simply the Río Bravo, is one of the principal rivers (along with the Colorado River) in the southwestern United States and in northern Mexico. The length of the Rio Grande is . It originates in south-central Colorado, in the United States, and flows to the Gulf of Mexico. The Rio Grande drainage basin (watershed) has an area of ; however, the endorheic basins that are adjacent to and within the greater drainage basin of the Rio Grande increase the total drainage-basin area to . The Rio Grande with its fertile valley, along with its tributaries, is a vital watersource for seven US and Mexican states, and flows primarily through arid and semi-arid lands. After traversing the length of New Mexico, the Rio Grande becomes the Mexico–United States border, between the U.S. state of Texas and the northern Mexican states of Chihuahua and Coahuila, Nuevo León and Tamaulipas; a short segment of the Rio Grande ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sink (geography)
An endorheic basin (; also spelled endoreic basin or endorreic basin) is a drainage basin that normally retains water and allows no outflow to other external bodies of water, such as rivers or oceans, but drainage converges instead into lakes or swamps, permanent or seasonal, that equilibrate through evaporation. They are also called closed or terminal basins, internal drainage systems, or simply basins. Endorheic regions contrast with exorheic regions. Endorheic water bodies include some of the largest lakes in the world, such as the Caspian Sea, the world's largest inland body of water. Basins with subsurface outflows which eventually lead to the ocean are generally not considered endorheic; they are cryptorheic. Endorheic basins constitute local base levels, defining a limit of erosion and deposition processes of nearby areas. Etymology The term was borrowed from French ''endor(rh)éisme'', coined from the combining form ''endo-'' (from grc, ἔνδον ''éndon'' 'wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Facies (geology)
In geology, a facies ( , ; same pronunciation and spelling in the plural) is a body of rock with specified characteristics, which can be any observable attribute of rocks (such as their overall appearance, composition, or condition of formation), and the changes that may occur in those attributes over a geographic area. A facies encompasses all of the characteristics of a rock including its chemical, physical, and biological features that distinguish it from adjacent rock. The term facies was introduced by the Swiss geologist Amanz Gressly in 1838 and was part of his significant contribution to the foundations of modern stratigraphy, which replaced the earlier notions of Neptunism. Types of facies Sedimentary facies Ideally, a sedimentary facies is a distinctive rock unit that forms under certain conditions of sedimentation, reflecting a particular process or environment. Sedimentary facies are either descriptive or interpretative. Sedimentary facies are bodies of sediment t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiometric Dating
Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares the abundance of a naturally occurring radioactive isotope within the material to the abundance of its decay products, which form at a known constant rate of decay. The use of radiometric dating was first published in 1907 by Bertram Boltwood and is now the principal source of information about the absolute age of rocks and other geological features, including the age of fossilized life forms or the age of Earth itself, and can also be used to date a wide range of natural and man-made materials. Together with stratigraphic principles, radiometric dating methods are used in geochronology to establish the geologic time scale. Among the best-known techniques are radiocarbon dating, potassium–argon dating and uranium–lead dating. ... [...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] |
Basalt
Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90% of all volcanic rock on Earth is basalt. Rapid-cooling, fine-grained basalt is chemically equivalent to slow-cooling, coarse-grained gabbro. The eruption of basalt lava is observed by geologists at about 20 volcanoes per year. Basalt is also an important rock type on other planetary bodies in the Solar System. For example, the bulk of the plains of Venus, which cover ~80% of the surface, are basaltic; the lunar maria are plains of flood-basaltic lava flows; and basalt is a common rock on the surface of Mars. Molten basalt lava has a low viscosity due to its relatively low silica content (between 45% and 52%), resulting in rapidly moving lava flows that can spread over great areas before cooling and solidifying. Flood basalts are thick sequence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unconformity (geology)
An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger layer, but the term is used to describe any break in the sedimentary geologic record. The significance of angular unconformity (see below) was shown by James Hutton, who found examples of Hutton's Unconformity at Jedburgh in 1787 and at Siccar Point in 1788. The rocks above an unconformity are younger than the rocks beneath (unless the sequence has been overturned). An unconformity represents time during which no sediments were preserved in a region or were subsequently eroded before the next deposition. The local record for that time interval is missing and geologists must use other clues to discover that part of the geologic history of that area. The interval of geologic time not represented i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Las Cruces, New Mexico
Las Cruces (; "the crosses") is the second-largest city in the U.S. state of New Mexico and the seat of Doña Ana County. As of the 2020 census the population was 111,385. Las Cruces is the largest city in both Doña Ana County and southern New Mexico. The Las Cruces metropolitan area had an estimated population of 213,849 in 2017. It is the principal city of a metropolitan statistical area which encompasses all of Doña Ana County and is part of the larger El Paso–Las Cruces combined statistical area. Las Cruces is the economic and geographic center of the Mesilla Valley, the agricultural region on the floodplain of the Rio Grande which extends from Hatch to the west side of El Paso, Texas. Las Cruces is the home of New Mexico State University (NMSU), New Mexico's only land-grant university. The city's major employer is the federal government on nearby White Sands Test Facility and White Sands Missile Range. The Organ Mountains, to the east, are dominant in the city's l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rio Grande
The Rio Grande ( and ), known in Mexico as the Río Bravo del Norte or simply the Río Bravo, is one of the principal rivers (along with the Colorado River) in the southwestern United States and in northern Mexico. The length of the Rio Grande is . It originates in south-central Colorado, in the United States, and flows to the Gulf of Mexico. The Rio Grande drainage basin (watershed) has an area of ; however, the endorheic basins that are adjacent to and within the greater drainage basin of the Rio Grande increase the total drainage-basin area to . The Rio Grande with its fertile valley, along with its tributaries, is a vital watersource for seven US and Mexican states, and flows primarily through arid and semi-arid lands. After traversing the length of New Mexico, the Rio Grande becomes the Mexico–United States border, between the U.S. state of Texas and the northern Mexican states of Chihuahua and Coahuila, Nuevo León and Tamaulipas; a short segment of the Rio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Badlands
Badlands are a type of dry terrain where softer sedimentary rocks and clay-rich soils have been extensively eroded."Badlands" in '' Chambers's Encyclopædia''. London: George Newnes, 1961, Vol. 2, p. 47. They are characterized by steep slopes, minimal vegetation, lack of a substantial regolith, and high drainage density.A.J. Parsons and A.D. Abrahams, Editors (2009) ''Geomorphology of Desert Environments'' (2nd ed.) Springer Science & Business Media Ravines, gullies, buttes, hoodoos and other such geologic forms are common in badlands. Badlands are found on every continent except Antarctica, being most common where there are unconsolidated sediments. They are often difficult to navigate by foot, and are unsuitable for agriculture. Most are a result of natural processes, but destruction of vegetation by overgrazing or pollution can produce anthropogenic badlands. Badlands topography Badlands are characterized by a distinctive badlands topography. This is terrain i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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) because they are the most resistant minerals to weathering processes at the Earth's surface. Like uncemented sand, sandstone may be any color due to impurities within the minerals, but the most common colors are tan, brown, yellow, red, grey, pink, white, and black. Since sandstone beds often form highly visible cliffs and other topographic features, certain colors of sandstone have been strongly identified with certain regions. Rock formations that are primarily composed of sandstone usually allow the percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs. Quartz-bearing sandstone can be changed into quartzite through metamorphism, usually r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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