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Duricrust
Duricrust is a hard layer on or near the surface of soil. Duricrusts can range in thickness from a few millimeters or centimeters to several meters. It is a general term (not to be confused with duripan) for a zone of chemical precipitation and hardening formed at or near the surface of sedimentary bodies through pedogenic or non-pedogenic processes. It is typically formed by the accumulation of soluble minerals deposited by mineral-bearing waters that move upward, downward, or laterally by capillary action. It is commonly assisted in arid settings by evaporation.Dixon, J.C. and McLaren, S.J., 2009. ''Duricrusts''. In A.J. Parsons and A.D. Abrahams, ed., pp. 123-151. ''Geomorphology of desert environments.'' Springer, Dordrecht. Woolnough, W.G., 1930. ''The influence of climate and topography in the formation and distribution of products of weathering.'' ''Geological Magazine'', 67(3), pp.123-132. There are different types of duricrusts, each distinguished by a dominant mineralo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gypcrust
Gypcrete or gypcrust is a hardened layer of soil, consisting of around 95% gypsum (calcium sulfate). Gypcrust is an arid zone duricrust. It can also occur in a semiarid climate in a basin with internal drainage, and is initially developed in a playa as an evaporate. Gypcrete is the arid climate's equivalent to calcrete, which is a duricrust that is unable to generate in very arid climates. Composition Gypcrust horizons can be up to thick with a 75–97% gypsum (CaSO4∙2H2O) content. The majority of gypsum-rich layers occur where the average annual rainfall is less than 250 mm because gypsum is moderately soluble (c. 2.6 g−1 at 25 °C) and is normally leached out under higher rainfall conditions. Gypsum cements are rarely, if ever, as strong as calcretes or silcretes. Formation Gypcrust forms in a manner similar to that of caliche, which is composed of calcium carbonate Calcium carbonate is a chemical compound with the chemical formula . It is a common ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silcrete
Silcrete is an indurated (resists crumbling or powdering) soil duricrust formed when surface soil, sand, and gravel are cemented by dissolved silica. The formation of silcrete is similar to that of calcrete, formed by calcium carbonate, and ferricrete, formed by iron oxide. It is a hard and resistant material, and though different in origin and nature, appears similar to quartzite. As a duricrust, there is potential for preservation of root structures as trace fossils. Silcrete is common in the arid regions of Australia and Africa often forming the resistant cap rock on features such as the ''breakaways'' of the Stuart Range of South Australia. Silcrete can be found at a lesser extent throughout the world especially England (e.g. '' Hertfordshire puddingstone and sarsen stone''), and France. In the Great Plains of the United States, polished silcrete cobbles are locally common on the surface and in river gravels east of the outcrops of the Ogallala Formation. Human use In Au ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferricrete
Ferricrete is a hard, erosion-resistant layer of sedimentary rock, usually conglomerate or breccia, that has been cemented into a duricrust by iron oxides. The iron oxide cements are derived from the oxidation of percolating solutions of iron salts.Dictionary of Mining, Mineral, and Related Terms, 2nd Edition. American Geological Institute in cooperation with the Society for Mining, Metallurgy, and Exploration, Inc., 646 p., . Ferricretes form at or near the land surface and may contain non-local sediments that have been transported from outside the immediate area of the deposit. The name is a combination of ''ferruginous'' and ''concrete''. Synonyms include ferruginous duricrust, hardpan and ironpan. Ferricrete deposits along the Animas River watershed in Colorado have been classified as: * alluvial iron oxyhydroxide-cemented conglomerates along old stream channels; * colluvial iron oxyhydroxide-cemented, poorly sorted breccias with massive to minor layering subparallel to h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inselberg
An inselberg or monadnock ( ) is an isolated rock hill, knob, ridge, or small mountain that rises abruptly from a gently sloping or virtually level surrounding plain. In Southern Africa, a similar formation of granite is known as a koppie, an Afrikaans word ("little head") from the Dutch diminutive word ''kopje''. If the inselberg is dome-shaped and formed from granite or gneiss, it can also be called a bornhardt, though not all bornhardts are inselbergs. An inselberg results when a body of rock resistant to erosion, such as granite, occurring within a body of softer rocks, is exposed by differential erosion and lowering of the surrounding landscape. Etymology Inselberg The word ''inselberg'' is a loan word from German, and means "island mountain". The term was coined in 1900 by geologist Wilhelm Bornhardt (1864–1946) to describe the abundance of such features found in eastern Africa. At that time, the term applied only to arid landscape features. However, it has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caliche
Caliche () is a soil accumulation of soluble calcium carbonate at depth, where it precipitates and binds other materials—such as gravel, sand, clay, and silt. It occurs worldwide, in aridisol and mollisol soil orders—generally in arid or semiarid regions, including in central and western Australia, in the Kalahari Desert, in the High Plains (United States), High Plains of the western United States, in the Sonoran Desert, Chihuahuan Desert and Mojave Desert of North America, and in eastern Saudi Arabia at Al-Ahsa Oasis, Al-Hasa. Caliche is also known as calcrete or kankar (in India). It belongs to the duricrusts. The term is borrowed from Spanish and is originally from the Latin word , meaning Lime (mineral), lime. Caliche is generally light-colored but can range from white to light pink to reddish-brown, depending on the minerals present. Caliche is a mark of older landscapes. It generally occurs on or very near the surface. Where caliche layers originate at some depth from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laterite
Laterite is a soil type rich in iron and aluminium and is commonly considered to have formed in hot and wet tropical areas. Nearly all laterites are of rusty-red coloration, because of high iron oxide content. They develop by intensive and prolonged weathering of the underlying parent rock, usually when there are conditions of high temperatures and heavy rainfall with alternate wet and dry periods. The process of formation is called laterization. Tropical weathering is a prolonged process of chemical weathering which produces a wide variety in the thickness, grade, chemistry and ore mineralogy of the resulting soils. The majority of the land area containing laterites is between the tropics of Cancer and Capricorn. Laterite has commonly been referred to as a soil type as well as being a rock type. This, and further variation in the modes of conceptualizing about laterite (e.g. also as a complete weathering profile or theory about weathering), has led to calls for the term to be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dori, Burkina Faso
Dori (also known as Winde or Wendu) is a town in northeastern Burkina Faso, near the border of Niger. It is located at around . It is the capital of Sahel Region and has a population of 46,512 (2019). The main ethnic group is the Fula people, Fula (Fulani) but Tuaregs and Songhai people, Songhai are often present. It is a town known for its herders and popular livestock markets. Dori recorded a temperature of in 1984, which is the highest temperature to have ever been recorded in Burkina Faso. In 2020, it was reported that the Emir of Liptako lived in Dori. Climate Dori has a semi-arid climate (Köppen climate classification ''BSh''). Mines In 2004, a proposal surfaced to link the manganese mines by rail with the seaports of Transport in Ghana, Ghana. Notable people * Roukiatou Maiga, humanitarian * Albert Ouédraogo, former interim Burkinabé Prime Minister * Ousmane Amirou Dicko, Emir of Liptako See also * Railway stations in Burkina Faso Gallery File:ASC Leiden - ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aluminum
Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has a great affinity towards oxygen, passivation (chemistry), forming a protective layer of aluminium oxide, oxide on the surface when exposed to air. It visually resembles silver, both in its color and in its great ability to reflect light. It is soft, magnetism, nonmagnetic, and ductility, ductile. It has one stable isotope, 27Al, which is highly abundant, making aluminium the abundance of the chemical elements, 12th-most abundant element in the universe. The radioactive decay, radioactivity of aluminium-26, 26Al leads to it being used in radiometric dating. Chemically, aluminium is a post-transition metal in the boron group; as is common for the group, aluminium forms compounds primarily in the +3 oxidation state. The aluminium cation Al3+ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phoenix (spacecraft)
''Phoenix'' was an uncrewed space probe that landed on the surface of Mars on May 25, 2008, and operated until November 2, 2008. ''Phoenix'' was operational on Mars for sols ( days). Its instruments were used to assess the local habitability and to research the history of water on Mars. The mission was part of the Mars Scout Program; its total cost was $420 million, including the cost of launch. The multi-agency program was led by the Lunar and Planetary Laboratory at the University of Arizona, with project management by NASA's Jet Propulsion Laboratory. Academic and industrial partners included universities in the United States, Canada, Switzerland, Denmark, Germany, the United Kingdom, NASA, the Canadian Space Agency, the Finnish Meteorological Institute, Lockheed Martin Space Systems, MacDonald Dettwiler & Associates (MDA) in partnership with Optech Incorporated ( Optech) and other aerospace companies. It was the first NASA mission to Mars led by a public university. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viking 2
The ''Viking 2'' mission was part of the American Viking program to Mars, and consisted of an orbiter and a lander essentially identical to that of the '' Viking 1'' mission. ''Viking 2'' was operational on Mars for sols ( days; '). The ''Viking 2'' lander operated on the surface for days, or sols, and was turned off on April 12, 1980, when its batteries eventually failed. The orbiter worked until July 25, 1978, returning almost 16,000 images in 706 orbits around Mars. Mission profile The craft was launched on September 9, 1975. Following launch using a Titan/Centaur launch vehicle and a 333-day cruise to Mars, the ''Viking 2'' Orbiter began returning global images of Mars prior to orbit insertion. The orbiter was inserted into a 1,500 x 33,000 km, 24.6 h Mars orbit on August 7, 1976, and trimmed to a 27.3 h site certification orbit with a periapsis of 1,499 km and an inclination of 55.2 degrees on August 9. The orbiter then began taking photographs of candidate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mars
Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmospheric pressure is a few thousandths of Earth's, atmospheric temperature ranges from and cosmic radiation is high. Mars retains some water, in the ground as well as thinly in the atmosphere, forming cirrus clouds, frost, larger polar regions of permafrost and ice caps (with seasonal snow), but no liquid surface water. Its surface gravity is roughly a third of Earth's or double that of the Moon. It is half as wide as Earth or twice the Moon, with a diameter of , and has a surface area the size of all the dry land of Earth. Fine dust is prevalent across the surface and the atmosphere, being picked up and spread at the low Martian gravity even by the weak wind of the tenuous atmosphere. The terrain of Mars roughly follows a north-south ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
