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Geology Of The 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 central New Mexico and which is part of the great mountain system known as the North American Cordillera. The rocky cores of the mountain ranges are, in most places, formed of pieces of continental crust that are over one billion years old. In the south, an older mountain range was formed 300 million years ago, then eroded away. The rocks of that older range were reformed into the Rocky Mountains. The Rocky Mountains took shape during an intense period of plate tectonic activity that resulted in much of the rugged landscape of western North America. The Laramide orogeny, about 80–55 million years ago, was the last of the three episodes and was responsible for raising the Rocky Mountains. Subsequent erosion by glaciers has produced the cu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gneiss
Gneiss (pronounced ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. This rock is formed under pressures ranging from 2 to 15 kbar, sometimes even more, and temperatures over 300 °C (572 °F). Gneiss nearly always shows a banded texture characterized by alternating darker and lighter colored bands and without a distinct Cleavage (geology), cleavage. Gneisses are common in the ancient crust of Continental Shield, continental shields. Some of the oldest rocks on Earth are gneisses, such as the Acasta Gneiss. Description image:Orthogneiss Geopark.jpg, Orthogneiss from the Czech Republic In traditional English and North American usage, a gneiss is a coarse-grained metamorphic rock showing compositional banding (gneissic banding) but poorly developed schistosity and indistinct Cleavage (geology), cleavage. In other words, it i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medicine Bow Mountains
The Medicine Bow Mountains are a mountain range in the Rocky Mountains that extend from northern Colorado into southern Wyoming. The northern extent of this range is the sub-range the Snowy Range. From the northern end of Colorado's Never Summer Mountains, the Medicine Bow mountains extend north from Cameron Pass along the border between Larimer and Jackson counties in Colorado and northward into south central Wyoming. In Wyoming, the range sits west of Laramie, in Albany and Carbon counties to the route of the Union Pacific Railroad and U.S. Interstate 80. The mountains often serve as a symbol for the city of Laramie. The range is home to Snowy Range Ski Area. The highest peak in the range is Clark Peak (), located in the Rawah Wilderness along the southern end of the range in Northern Colorado.The elevation of Clark Peak includes an adjustment of +1.628 m (+5.34 ft) from NGVD 29 to NAVD 88. Much of the range is located within the Medicine Bow N ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syenite
Syenite is a coarse-grained intrusive igneous rock with a general composition similar to that of granite, but deficient in quartz, which, if present at all, occurs in relatively small concentrations (< 5%). It is considered a granitoid. Some syenites contain larger proportions of components and smaller amounts of material than most granites; those are classed as being of . The |
Anorthosite
Anorthosite () is a phaneritic, intrusive rock, intrusive igneous rock characterized by its composition: mostly plagioclase feldspar (90–100%), with a minimal mafic component (0–10%). Pyroxene, ilmenite, magnetite, and olivine are the mafic minerals most commonly present. Anorthosites are of enormous geologic interest, because it is still not fully understood how they form. Most models involve fractional crystallization (geology), separating plagioclase crystals based on their density. Plagioclase crystals are usually less dense than magma; so, as plagioclase crystallizes in a magma chamber, the plagioclase crystals float to the top, concentrating there. Anorthosite on Earth can be divided into five types: # Archean anorthosites # Proterozoic anorthosite (also known as massif or massif-type anorthosite) – the most abundant type of anorthosite on Earth # Layers within Layered intrusion, Layered Intrusions (e.g., Bushveld Igneous Complex, Bushveld and Stillwater igneous com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selway Terrane
Selway may refer to: * Selway (surname) * Selway National Forest, established in Idaho in 1911 from parts of Clearwater National Forest and Nez Perce National Forest *Selway River The Selway River is a large tributary of the Middle Fork of the Clearwater River in the U.S. state of Idaho. It flows within the Selway-Bitterroot Wilderness, the Bitterroot National Forest, and the Nez Perce National Forest of North Central ..., in North Central Idaho in the north-western United States within the Selway-Bitterroot Wilderness See also * Selway-Bitterroot Wilderness, protected wilderness area in the states of Idaho and Montana, in the United States {{disambiguation, geo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Columbia (supercontinent)
Columbia, also known as Nuna or Hudsonland, is a hypothetical ancient supercontinent. It was first proposed by John J.W. Rogers and M. Santosh in 2002 and is thought to have existed approximately (Ma), in the Paleoproterozoic era. The assembly of the supercontinent was likely completed during global-scale collisional events from 2,100 to 1,800 Ma. Columbia consisted of proto-cratons that made up the cores of the continents of Laurentia, Baltica, Ukrainian Shield, Amazonian craton, Amazonian Craton, Australia (continent), Australia, and possibly Siberia (continent), Siberia, North China craton, North China, and Kalahari craton, Kalaharia as well. The evidence of Columbia's existence is provided by geology, geological and paleomagnetism, paleomagnetic data.; Size and location Columbia is estimated to have been approximately from north to south at its broadest part. The eastern coast of India was attached to western North America, with southern Australia (continent), Australia a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supercontinent
In geology, a supercontinent is the assembly of most or all of Earth's continent, continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", which leaves room for interpretation and is easier to apply to Precambrian times. To separate supercontinents from other groupings, a limit has been proposed in which a continent must include at least about 75% of the continental crust then in existence in order to qualify as a supercontinent. Moving under the forces of plate tectonics, supercontinents have assembled and dispersed multiple times in the geologic past. According to modern definitions, a supercontinent does not exist today; the closest is the current Afro-Eurasian landmass, which covers approximately 57% of Earth's total land area. The last period in which the continental landmasses were near to one another was 336 to 175 million years ago, forming the supercontinent Pangaea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yavapai Orogeny
The Yavapai orogeny was an orogenic (mountain-building) event in what is now the Southwestern United States that occurred between 1710 and 1680 million years ago ( Mya), in the Statherian Period of the Paleoproterozoic. Recorded in the rocks of New Mexico and Arizona, it is interpreted as the collision of the 1800-1700 Mya age Yavapai island arc terrane with the proto-North American continent. This was the first in a series of orogenies within a long-lived convergent boundary along southern Laurentia that ended with the ca. 1200–1000 Mya Grenville orogeny during the final assembly of the supercontinent Rodinia, which ended an 800-million-year episode of convergent boundary tectonism. Description Age and isotope data show that southern North America is composed of a series of northeast-trending provinces representing island arc terranes accreted onto the 1800 Mya core of Laurentia. These are the Yavapai province (1800–1700 Mya), the Mazatzal province (1700–1650 Mya), the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laramie Mountains
The Laramie Mountains are a range of moderately high peaks on the eastern edge of the Rocky Mountains in the U.S states of Wyoming and Colorado. The range is the northernmost extension of the line of the ranges along the eastern side of the Rockies, and in particular of the higher peaks of the Front Range directly to the south. North of the range, the gap between the Laramie range and the Bighorn Mountains provided the route for historical trails, such as the Oregon Trail, the Mormon Trail, and the Pony Express. The Laramie Mountains begin in northern Colorado and extend discontinuously into southeastern Wyoming between Cheyenne and Laramie and northward to Casper. (By some definitions the Laramies are only in Wyoming.) They are named after the Laramie River, which cuts through the range from southwest to northeast and joins the North Platte River east of the range in eastern Wyoming. The mountains in turn give their name to the Laramide orogeny, the uplift of the North Ameri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cheyenne, Wyoming
Cheyenne ( or ) is the List of capitals in the United States, capital and List of municipalities in Wyoming, most populous city of the U.S. state of Wyoming. It is the county seat of Laramie County, Wyoming, Laramie County, with 65,132 residents per the 2020 United States census, 2020 census. It is the principal city of the Cheyenne metropolitan area, which encompasses all of Laramie County and had 100,512 residents as of the 2020 census. Local residents named the town for the Cheyenne Native Americans in the United States, Native American people in 1867 when it was founded in the Dakota Territory. Along with Honolulu, Hawaii, Oklahoma City, Oklahoma, and Topeka, Kansas, Cheyenne is one of four state capitals with an indigenous name in a state with an indigenous name. Cheyenne is the northern terminus of the extensive Southern Rocky Mountain Front, which extends southward to Albuquerque, New Mexico, and includes the fast-growing Front Range Urban Corridor. Cheyenne is situated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cheyenne Belt
The Cheyenne Belt is the tectonic suture zone between the Archean-age Wyoming craton to the north and the Paleoproterozoic-age Yavapai province to the south. It runs through the southeastern quadrant of the state of Wyoming, United States. It was formed during the Paleoproterozoic Medicine Bow orogeny between 1.78 and 1.74 billion years ago when island arcs collided with the Wyoming craton. This is an example of a convergent boundary in tectonics. Description The exposed geology consists of a series of northeast- striking, steeply-dipping shear zones. These separate Archean crust to the north from 1800-1600 million year old ( Ma) to the south. The Wyoming craton north of the belt is an Archean basement with a cover of younger miogeoclinal strata (sedimentary rock deposited on the passive margin of a continent.) The craton is intruded by dikes and sills of tholeiitic basalt with a minimum age of 2000 Ma, and this is taken as the time at which the Wyoming craton was rifted from a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
