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Aïr Mountains
The Aïr Mountains or Aïr Massif (Air Tamajeq language, Tamajăq: ''Ayǝr''; Hausa language, Hausa: Eastern ''Azbin'', Western ''Abzin'') is a triangular massif, located in northern Niger, within the Sahara. Part of the West Saharan montane xeric woodlands ecoregion, they rise to more than and extend over . Lying in the midst of desert north of the 17th parallel north, 17th parallel, the Aïr plateau, with an average altitude between , forms an island of Sahel climate which supports a wide variety of life, many pastoral and farming communities, and dramatic geological and archaeological sites. There are notable archaeological excavations in the region that illustrate the prehistoric past of this region. The endangered African wild dog (''Lycaon pictus'') once existed in this region, but may now be Local extinction, extirpated due to habitat fragmentation, human population pressures in this region. Geology The Precambrian to Cenozoic Aïr Mountains consist of p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agadez Region
Agadez Region is one of the seven regions of Niger. At , it covers more than half of Niger's land area, and is the largest region in the country, as well as the list of the largest country subdivisions by area, largest African state subdivision. The capital of the department is Agadez. History The region is a centre for palaeontology, with numerous dinosaur skeletons being found here, including the ''Ouranosaurus nigeriensis''. Cave painting and the remains of ancient human settlements are also located here. Tuareg peoples began migrating to the region from the mid-8th century. From the mid-15th century to the early 20th, much of the region was under the control of the Sultanate of Agadez, except for a period when the area came under the rule of the Songhai Empire in the 1500s. The region suffered with the advent of French colonialism as power shifted away to the southwest; Tuareg disaffection with French rule resulted in the Kaocen revolt in 1916–17. This process continued fol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Habitat Fragmentation
Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological processes that slowly alter the layout of the physical environment (suspected of being one of the major causes of speciation), and human activity such as land conversion, which can alter the environment much faster and causes the extinction of many species. More specifically, habitat fragmentation is a process by which large and contiguous habitats get divided into smaller, isolated patches of habitats. Definition The term habitat fragmentation includes five discrete phenomena: * Reduction in the total area of the habitat * Decrease of the interior: edge ratio * Isolation of one habitat fragment from other areas of habitat * Breaking up of one patch of habitat into several smaller patches * Decrease in the average size of each patch of habit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mont Greboun
Mont may refer to: Places * Mont., an abbreviation for Montana, a U.S. state * Mont, Belgium (other), several places in Belgium * Mont, Hautes-Pyrénées, a commune in France * Mont, Pyrénées-Atlantiques, a commune in France * Mont, Saône-et-Loire, a commune in France Other uses * Mont (food), a category of Burmese snacks and desserts * Mont (surname) * Mont., botanical author abbreviation of Camille Montagne (1784-1866), French military physician and botanist * ''Seawise Giant'', the largest ship in the world, later renamed MV ''Mont'' for her final journey * Menthu or Mont, a deity in Egyptian mythology * M.O.N.T, South Korean boy group * Metal-organic nanotubes, a class of polymers See also * Le Mont (other) * Monts (other) * Monte (other) Monte may refer to: Places Argentina * Argentine Monte, an ecoregion * Monte Desert * Monte Partido, a ''partido'' in Buenos Aires Province Italy * Monte Bregagno * Monte Cassino * Montecorvino ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metamorphic Rock
Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock ( protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causing profound physical or chemical changes. During this process, the rock remains mostly in the solid state, but gradually recrystallizes to a new texture or mineral composition. The protolith may be an igneous, sedimentary, or existing metamorphic rock. Metamorphic rocks make up a large part of the Earth's crust and form 12% of the Earth's land surface. They are classified by their protolith, their chemical and mineral makeup, and their texture. They may be formed simply by being deeply buried beneath the Earth's surface, where they are subject to high temperatures and the great pressure of the rock layers above. They can also form from tectonic processes such as continental collisions, which cause horizontal pressure, friction, and dist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erosion Surface
In geology and geomorphology, an erosion surface is a surface of rock (geology), rock or regolith that was formed by erosion and not by construction (e.g. lava flows, sediment deposition) nor fault (geology), fault displacement. Erosional surfaces within the Lithostratigraphy#Stratigraphic relationship, stratigraphic record are known as unconformity, unconformities, but not all unconformities are buried erosion surfaces. Erosion surfaces vary in scale and can be formed on a mountain range or a rock. Particularly large and flat erosion surfaces receive the names of peneplain, wikt:paleoplain, paleoplain, planation surface or pediplain. An example of erosion surface is road surface erosion which is caused by natural and anthropogenic factors. Erosion surface can be measured through direct, contact measurement methods and indirect, non-contact measurement methods. Road surface erosion Just like mountains and rocks, erosion can also occur on unsealed roads due to natural and Human im ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian
The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordovician Period 486.85 Ma. Most of the continents lay in the southern hemisphere surrounded by the vast Panthalassa Ocean. The assembly of Gondwana during the Ediacaran and early Cambrian led to the development of new convergent plate boundaries and continental-margin arc magmatism along its margins that helped drive up global temperatures. Laurentia lay across the equator, separated from Gondwana by the opening Iapetus Ocean. The Cambrian marked a profound change in life on Earth; prior to the Period, the majority of living organisms were small, unicellular and poorly preserved. Complex, multicellular organisms gradually became more common during the Ediacaran, but it was not until the Cambrian that fossil diversity seems to rapidly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plateau
In geology and physical geography, a plateau (; ; : plateaus or plateaux), also called a high plain or a tableland, is an area of a highland consisting of flat terrain that is raised sharply above the surrounding area on at least one side. Often one or more sides have deep hills or escarpments. Plateaus can be formed by a number of processes, including upwelling of volcanic magma, extrusion of lava, and erosion by water and glaciers. Plateaus are classified according to their surrounding environment as intermontane, piedmont, or continental. A few plateaus may have a small flat top while others have wider ones. Formation Plateaus can be formed by a number of processes, including upwelling of volcanic magma, extrusion of lava, plate tectonics movements, and erosion by water and glaciers. Volcanic Volcanic plateaus are produced by volcanic activity. They may be formed by upwelling of volcanic magma or extrusion of lava. The underlining mechanism in forming p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
G06 S65 63158
G, or g, is the seventh letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages, and others worldwide. Its name in English is ''gee'' (pronounced ), plural ''gees''. The lowercase version can be written in two forms: the single-storey (sometimes "opentail") and the double-storey (sometimes "looptail") . The former is commonly used in handwriting and fonts based on it, especially fonts intended to be read by children. History The evolution of the Latin alphabet's G can be traced back to the Latin alphabet's predecessor, the Greek alphabet. The voiced velar stop was represented by the third letter of the Greek alphabet, gamma (Γ), which was later adopted by the Etruscan language. Latin then borrowed this "rounded form" of gamma, C, to represent the same sound in words such as ''recei'', which was likely an early dative form of '' rex'', meaning "king", as found in an "early Latin inscription." Over time, how ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States's civil list of government space agencies, space program, aeronautics research and outer space, space research. National Aeronautics and Space Act, Established in 1958, it succeeded the National Advisory Committee for Aeronautics (NACA) to give the American space development effort a distinct civilian orientation, emphasizing peaceful applications in space science. It has since led most of America's space exploration programs, including Project Mercury, Project Gemini, the 1968–1972 Apollo program missions, the Skylab space station, and the Space Shuttle. Currently, NASA supports the International Space Station (ISS) along with the Commercial Crew Program and oversees the development of the Orion (spacecraft), Orion spacecraft and the Sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Granite
Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies underground. It is common in the continental crust of Earth, where it is found in igneous intrusions. These range in size from dike (geology), dikes only a few centimeters across to batholiths exposed over hundreds of square kilometers. Granite is typical of a larger family of ''granitic rocks'', or ''granitoids'', that are composed mostly of coarse-grained quartz and feldspars in varying proportions. These rocks are classified by the relative percentages of quartz, alkali feldspar, and plagioclase (the QAPF diagram, QAPF classification), with true granite representing granitic rocks rich in quartz and alkali feldspar. Most granitic rocks also contain mica or amphibole minerals, though a few (known as leucogranites) conta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peralkaline
Peralkaline rocks include those igneous rocks which have a deficiency of aluminium such that sodium and potassium are in excess of that needed for feldspar. The presence of aegerine (sodium pyroxene) and riebeckite (sodium amphibole) are indicative of peralkaline conditions. Examples are the peralkaline rhyolites, comendite and pantellerite, with comendite being the more felsic (silica-rich) rock. Another example is the peralkaline granite that forms the islet of Rockall in the North Atlantic Ocean. Peralkaline rocks are indicative of continental rift-related volcanicity (e.g. the peralkaline rhyolites of the East African Rift in central Kenya) as well as continental and oceanic hotspot volcanicity (e.g. the peralkaline rhyolites of the Glass House Mountains in eastern Australia and the Canary Islands in the Atlantic Ocean). Peralkaline rocks related to subduction zone volcanicity have also been reported (e.g. Sardinia in Italy). Peralkaline magmas likely form when fractiona ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
