1.
Desert pavement
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A desert pavement, also called reg, serir, gibber, or saï is a desert surface covered with closely packed, interlocking angular or rounded rock fragments of pebble and cobble size. Desert varnish collects on the surface rocks over time. Geologists debate the mechanics of pavement formation and their age, several theories have been proposed for the formation of desert pavements. A common theory suggests they form through the removal of sand, dust and other fine-grained material by the wind and intermittent rain. The removal of particles by wind does not continue indefinitely, because once the pavement forms. The small particles collect underneath the pavement surface, forming a vesicular A soil horizon, a newer theory of pavement formation comes from studies of places such as Cima Dome, in the Mojave Desert of California, by Stephen Wells and his coworkers. At Cima Dome, geologically recent lava flows are covered by younger layers, with desert pavement on top of them. The soil has built up, not blown away, yet the stones remain on top. There are no stones in the soil, not even gravel, researchers can determine how many years a stone has been exposed on the ground. Wells used a method based on cosmogenic helium-3, which forms by cosmic ray bombardment at the ground surface, helium-3 is retained inside grains of olivine and pyroxene in the lava flows, building up with exposure time. The helium-3 dates show that the stones in the desert pavement at Cima Dome have all been at the surface the same amount of time as the solid lava flows right next to them. He wrote in a July 1995 article in Geology, that he concluded, while the stones remain on the surface due to heave, deposition of windblown dust must build up the soil beneath that pavement. For the geologist, this means that some desert pavements preserve a long history of dust deposition beneath them. The dust is a record of ancient climate, just as it is on the sea floor. Desert pavement surfaces are coated with desert varnish, a dark brown. In the USA a famous example can be found on Newspaper Rock in southeastern Utah, Desert varnish is a thin coating of manganese, iron and clays on the surface of sun-baked boulders. It is formed by colonies of bacteria living on the surface for thousands of years. Desert varnish is also prevalent in the Mojave desert and Great Basin geomorphic province, stony deserts may be known by different names according to the region
2.
Rock (geology)
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Rock or stone is a natural substance, a solid aggregate of one or more minerals or mineraloids. For example, granite, a rock, is a combination of the minerals quartz, feldspar. The Earths outer solid layer, the lithosphere, is made of rock, rock has been used by mankind throughout history. The minerals and metals found in rocks have been essential to human civilization, three major groups of rocks are defined, igneous, sedimentary, and metamorphic. The scientific study of rocks is called petrology, which is a component of geology. At a granular level, rocks are composed of grains of minerals, the aggregate minerals forming the rock are held together by chemical bonds. The types and abundance of minerals in a rock are determined by the manner in which the rock was formed, many rocks contain silica, a compound of silicon and oxygen that forms 74. 3% of the Earths crust. This material forms crystals with other compounds in the rock, the proportion of silica in rocks and minerals is a major factor in determining their name and properties. Rocks are geologically classified according to such as mineral and chemical composition, permeability, the texture of the constituent particles. These physical properties are the end result of the processes that formed the rocks, over the course of time, rocks can transform from one type into another, as described by the geological model called the rock cycle. These events produce three general classes of rock, igneous, sedimentary, and metamorphic, the three classes of rocks are subdivided into many groups. However, there are no hard and fast boundaries between allied rocks, hence the definitions adopted in establishing rock nomenclature merely correspond to more or less arbitrary selected points in a continuously graduated series. Igneous rock forms through the cooling and solidification of magma or lava and this magma can be derived from partial melts of pre-existing rocks in either a planets mantle or crust. Typically, the melting of rocks is caused by one or more of three processes, an increase in temperature, a decrease in pressure, or a change in composition, igneous rocks are divided into two main categories, plutonic rock and volcanic. Plutonic or intrusive rocks result when magma cools and crystallizes slowly within the Earths crust, a common example of this type is granite. Volcanic or extrusive rocks result from magma reaching the surface either as lava or fragmental ejecta, the chemical abundance and the rate of cooling of magma typically forms a sequence known as Bowens reaction series. Most major igneous rocks are found along this scale, about 64. 7% of the Earths crust by volume consists of igneous rocks, making it the most plentiful category. Of these, 66% are basalts and gabbros, 16% are granite, only 0. 6% are syenites and 0. 3% peridotites and dunites
3.
Arid
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A region is arid when it is characterized by a severe lack of available water, to the extent of hindering or preventing the growth and development of plant and animal life. Environments subject to arid climates tend to lack vegetation and are called xeric or desertic, most arid climates surround the equator, these places include most of Africa and parts of South America, Central America and Australia. The distribution of aridity observed at any one point in time is largely the result of the circulation of the atmosphere. The latter does change significantly over time through climate change, for example, temperature increase across the Nile Basin over the next 30–40 years could change the region from semi-arid to arid, resulting in a significant reduction in agricultural land. In addition, changes in use can result in greater demands on soil water. Durrenberger, R. W. Arid Climates, article in The Encyclopedia of Climatology, p. 92-101, Edited by J. E. Oliver and R. W. Fairbridge, Van Nostrand Reinhold Company, New York, ISBN 0-87933-009-0. J Aridity Indexes, article in The Encyclopedia of Climatology, p. 102-107, Edited by J. E. Oliver and R. W. Fairbridge, Van Nostrand Reinhold Company, New York, blue Peace for the Nile Report,2009, Strategic Foresight Group
4.
Precipitation
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In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation include drizzle, rain, sleet, snow, graupel, Precipitation occurs when a portion of the atmosphere becomes saturated with water vapor, so that the water condenses and precipitates. Thus, fog and mist are not precipitation but suspensions, because the vapor does not condense sufficiently to precipitate. Two processes, possibly acting together, can lead to air becoming saturated, Precipitation forms as smaller droplets coalesce via collision with other rain drops or ice crystals within a cloud. Short, intense periods of rain in scattered locations are called showers, moisture that is lifted or otherwise forced to rise over a layer of sub-freezing air at the surface may be condensed into clouds and rain. This process is active when freezing rain is occurring. A stationary front is often present near the area of freezing rain, provided necessary and sufficient atmospheric moisture content, the moisture within the rising air will condense into clouds, namely stratus and cumulonimbus. Eventually, the droplets will grow large enough to form raindrops. Lake-effect snowfall can be locally heavy, thundersnow is possible within a cyclones comma head and within lake effect precipitation bands. In mountainous areas, heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at elevation, on the leeward side of mountains, desert climates can exist due to the dry air caused by compressional heating. The movement of the trough, or intertropical convergence zone. Precipitation is a component of the water cycle, and is responsible for depositing the fresh water on the planet. Approximately 505,000 cubic kilometres of water falls as precipitation each year,398,000 cubic kilometres of it over the oceans and 107,000 cubic kilometres over land. Given the Earths surface area, that means the globally averaged annual precipitation is 990 millimetres, Climate classification systems such as the Köppen climate classification system use average annual rainfall to help differentiate between differing climate regimes. Precipitation may occur on celestial bodies, e. g. when it gets cold, Mars has precipitation which most likely takes the form of frost. Precipitation is a component of the water cycle, and is responsible for depositing most of the fresh water on the planet. Approximately 505,000 km3 of water falls as precipitation each year,398,000 km3 of it over the oceans, given the Earths surface area, that means the globally averaged annual precipitation is 990 millimetres. Mechanisms of producing precipitation include convective, stratiform, and orographic rainfall, Precipitation can be divided into three categories, based on whether it falls as liquid water, liquid water that freezes on contact with the surface, or ice
5.
Ventifact
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A ventifact is a rock that has been abraded, pitted, etched, grooved, or polished by wind-driven sand or ice crystals. Ventifacts can be abraded to eye-catching natural sculptures such as the features of the White Desert near Farafra oasis in Egypt. In moderately tall, isolated rock outcrops, mushroom shaped pillars of rock may form as the outcrop is eroded by saltating sand grains and this occurs because, even in strong winds, sand grains cant be continuously held in the air. Instead, the bounce along the ground, rarely reaching higher than a few feet above the earth. Over time, the sand grains can erode the lower portions of a ventifact. The results can be fantastic stone mushrooms, individual stones, such as those forming desert pavement, are often found with grooved, etched, or polished surfaces where these same wind-driven processes have slowly worn away the rock. Stones with a number of wind facets have names reflecting this number. When ancient ventifacts are preserved without being moved or disturbed, they may serve as a paleo-wind indicators, the wind direction at the time the ventifact formed will be parallel to grooves or striations cut in the rock. An example of a Martian ventifact was named Jake Matijevic, by analyzing its shape, it was possible to reconstruct the main wind direction which sculpted the rock. Arkenu structures Blowout Dune Yardang The Bibliography of Aeolian Research
6.
Clay
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Clay is a fine-grained natural rock or soil material that combines one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure. Clays are plastic due to water content and become hard, brittle. Depending on the content in which it is found, clay can appear in various colours from white to dull grey or brown to deep orange-red. Although many naturally occurring deposits include both silts and clay, clays are distinguished from other fine-grained soils by differences in size, silts, which are fine-grained soils that do not include clay minerals, tend to have larger particle sizes than clays. There is, however, some overlap in size and other physical properties. The distinction between silt and clay varies by discipline, geologists and soil scientists usually consider the separation to occur at a particle size of 2 µm, sedimentologists often use 4–5 μm, and colloid chemists use 1 μm. Geotechnical engineers distinguish between silts and clays based on the plasticity properties of the soil, as measured by the soils Atterberg limits, ISO14688 grades clay particles as being smaller than 2 μm and silt particles as being larger. These solvents, usually acidic, migrate through the rock after leaching through upper weathered layers. In addition to the process, some clay minerals are formed through hydrothermal activity. There are two types of deposits, primary and secondary. Primary clays form as residual deposits in soil and remain at the site of formation, secondary clays are clays that have been transported from their original location by water erosion and deposited in a new sedimentary deposit. Clay deposits are associated with very low energy depositional environments such as large lakes. Depending on the source, there are three or four main groups of clays, kaolinite, montmorillonite-smectite, illite, and chlorite. Chlorites are not always considered to be a clay, sometimes being classified as a group within the phyllosilicates. There are approximately 30 different types of clays in these categories. Varve is clay with visible annual layers, which are formed by deposition of those layers and are marked by differences in erosion. This type of deposit is common in glacial lakes
7.
Iron
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Iron is a chemical element with symbol Fe and atomic number 26. It is a metal in the first transition series and it is by mass the most common element on Earth, forming much of Earths outer and inner core. It is the fourth most common element in the Earths crust, like the other group 8 elements, ruthenium and osmium, iron exists in a wide range of oxidation states, −2 to +6, although +2 and +3 are the most common. Elemental iron occurs in meteoroids and other low oxygen environments, but is reactive to oxygen, fresh iron surfaces appear lustrous silvery-gray, but oxidize in normal air to give hydrated iron oxides, commonly known as rust. Unlike the metals that form passivating oxide layers, iron oxides occupy more volume than the metal and thus flake off, Iron metal has been used since ancient times, although copper alloys, which have lower melting temperatures, were used even earlier in human history. Pure iron is soft, but is unobtainable by smelting because it is significantly hardened and strengthened by impurities, in particular carbon. A certain proportion of carbon steel, which may be up to 1000 times harder than pure iron. Crude iron metal is produced in blast furnaces, where ore is reduced by coke to pig iron, further refinement with oxygen reduces the carbon content to the correct proportion to make steel. Steels and iron alloys formed with metals are by far the most common industrial metals because they have a great range of desirable properties. Iron chemical compounds have many uses, Iron oxide mixed with aluminium powder can be ignited to create a thermite reaction, used in welding and purifying ores. Iron forms binary compounds with the halogens and the chalcogens, among its organometallic compounds is ferrocene, the first sandwich compound discovered. Iron plays an important role in biology, forming complexes with oxygen in hemoglobin and myoglobin. Iron is also the metal at the site of many important redox enzymes dealing with cellular respiration and oxidation and reduction in plants. A human male of average height has about 4 grams of iron in his body and this iron is distributed throughout the body in hemoglobin, tissues, muscles, bone marrow, blood proteins, enzymes, ferritin, hemosiderin, and transport in plasma. The mechanical properties of iron and its alloys can be evaluated using a variety of tests, including the Brinell test, Rockwell test, the data on iron is so consistent that it is often used to calibrate measurements or to compare tests. An increase in the content will cause a significant increase in the hardness. Maximum hardness of 65 Rc is achieved with a 0. 6% carbon content, because of the softness of iron, it is much easier to work with than its heavier congeners ruthenium and osmium. Because of its significance for planetary cores, the properties of iron at high pressures and temperatures have also been studied extensively
8.
Manganese
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Manganese is a chemical element with symbol Mn and atomic number 25. It is not found as an element in nature, it is often found in minerals in combination with iron. Manganese is a metal with important industrial metal alloy uses, particularly in stainless steels, by the mid-18th century, Swedish chemist Carl Wilhelm Scheele had used pyrolusite to produce chlorine. Scheele and others were aware that pyrolusite contained a new element, johan Gottlieb Gahn was the first to isolate an impure sample of manganese metal in 1774, which he did by reducing the dioxide with carbon. Manganese phosphating is used for rust and corrosion prevention on steel, ionized manganese is used industrially as pigments of various colors, which depend on the oxidation state of the ions. The permanganates of alkali and alkaline earth metals are powerful oxidizers, Manganese dioxide is used as the cathode material in zinc-carbon and alkaline batteries. In biology, manganese ions function as cofactors for a variety of enzymes with many functions. Manganese enzymes are essential in detoxification of superoxide free radicals in organisms that must deal with elemental oxygen. Manganese also functions in the complex of photosynthetic plants. The element is a trace mineral for all known living organisms but is a neurotoxin. In larger amounts, and apparently with far greater effectiveness through inhalation, Manganese is a silvery-gray metal that resembles iron. It is hard and very brittle, difficult to fuse, Manganese metal and its common ions are paramagnetic. Manganese tarnishes slowly in air and oxidizes like iron in water containing dissolved oxygen, naturally occurring manganese is composed of one stable isotope, 55Mn. Eighteen radioisotopes have been isolated and described, the most stable being 53Mn with a half-life of 3.7 million years, 54Mn with a half-life of 312.3 days, and 52Mn with a half-life of 5.591 days. All of the radioactive isotopes have half-lives of less than three hours, and the majority of less than one minute. Manganese also has three meta states, Manganese is part of the iron group of elements, which are thought to be synthesized in large stars shortly before the supernova explosion. 53Mn decays to 53Cr with a half-life of 3.7 million years, because of its relatively short half-life, 53Mn is relatively rare, produced by cosmic rays impact on iron. Manganese isotopic contents are combined with chromium isotopic contents and have found application in isotope geology
9.
Redox
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Redox is a chemical reaction in which the oxidation states of atoms are changed. Any such reaction involves both a process and a complementary oxidation process, two key concepts involved with electron transfer processes. Redox reactions include all chemical reactions in which atoms have their oxidation state changed, in general, the chemical species from which the electron is stripped is said to have been oxidized, while the chemical species to which the electron is added is said to have been reduced. It can be explained in terms, Oxidation is the loss of electrons or an increase in oxidation state by a molecule, atom. Reduction is the gain of electrons or a decrease in state by a molecule, atom. As an example, during the combustion of wood, oxygen from the air is reduced, the reaction can occur relatively slowly, as in the case of rust, or more quickly, as in the case of fire. Redox is a portmanteau of reduction and oxidation, the word oxidation originally implied reaction with oxygen to form an oxide, since dioxygen was historically the first recognized oxidizing agent. Later, the term was expanded to encompass oxygen-like substances that accomplished parallel chemical reactions, ultimately, the meaning was generalized to include all processes involving loss of electrons. The word reduction originally referred to the loss in weight upon heating a metallic ore such as an oxide to extract the metal. In other words, ore was reduced to metal, antoine Lavoisier showed that this loss of weight was due to the loss of oxygen as a gas. Later, scientists realized that the atom gains electrons in this process. The meaning of reduction then became generalized to all processes involving gain of electrons. Even though reduction seems counter-intuitive when speaking of the gain of electrons, it help to think of reduction as the loss of oxygen. Since electrons are charged, it is also helpful to think of this as reduction in electrical charge. The electrochemist John Bockris has used the words electronation and deelectronation to describe reduction and oxidation processes respectively when they occur at electrodes and these words are analogous to protonation and deprotonation, but they have not been widely adopted by chemists. The term hydrogenation could be used instead of reduction, since hydrogen is the agent in a large number of reactions. But, unlike oxidation, which has been generalized beyond its root element, the word redox was first used in 1928. The processes of oxidation and reduction occur simultaneously and cannot happen independently of one another, the oxidation alone and the reduction alone are each called a half-reaction, because two half-reactions always occur together to form a whole reaction
10.
Bishop Tuff
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The Bishop Tuff is a welded tuff that formed 767,100 ±900 years ago as a rhyolitic pyroclastic flow during the eruption that created the Long Valley Caldera. Large outcrops of the tuff are located in Inyo and Mono Counties, California, the Bishop Tuff caps a volcanic plateau in the northern Owens Valley. The tableland formation is located east of U. S. Route 395 and west of the Nevada stateline, sitting northwest of Bishop and southeast of Crowley Lake, another part of the flow is south of Mono Lake, and surrounding the Mono-Inyo Craters. Deposits of Bishop Tuff in this area cover nearly 2, 200-square-kilometer, the Owens River cut through the volcanic plateau, creating the Owens River Gorge. One of the monsters from the 1990 film Tremors exits from the Bishop Tuff close to Bishop Glass Mountain Long Valley Observatory - Bishop Tuff BLM Bishop Field Office web page
11.
Desert
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A desert is a barren area of land where little precipitation occurs and consequently living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to the processes of denudation, about one third of the land surface of the world is arid or semi-arid. This includes much of the regions where little precipitation occurs. Deserts can be classified by the amount of precipitation falls, by the temperature that prevails. Deserts are formed by weathering processes as large variations in temperature between day and night put strains on the rocks which consequently break in pieces, although rain seldom occurs in deserts, there are occasional downpours that can result in flash floods. Rain falling on hot rocks can cause them to shatter and the resulting fragments and this picks up particles of sand and dust and wafts them aloft in sand or dust storms. Wind-blown sand grains striking any solid object in their path can abrade the surface, rocks are smoothed down, and the wind sorts sand into uniform deposits. The grains end up as level sheets of sand or are piled high in billowing sand dunes, other deserts are flat, stony plains where all the fine material has been blown away and the surface consists of a mosaic of smooth stones. These areas are known as desert pavements and little further erosion takes place, other desert features include rock outcrops, exposed bedrock and clays once deposited by flowing water. Temporary lakes may form and salt pans may be left when waters evaporate, there may be underground sources of water in the form of springs and seepages from aquifers. Where these are found, oases can occur, plants and animals living in the desert need special adaptations to survive in the harsh environment. Plants tend to be tough and wiry with small or no leaves, water-resistant cuticles, some annual plants germinate, bloom and die in the course of a few weeks after rainfall while other long-lived plants survive for years and have deep root systems able to tap underground moisture. Animals need to cool and find enough food and water to survive. Many are nocturnal and stay in the shade or underground during the heat of the day and they tend to be efficient at conserving water, extracting most of their needs from their food and concentrating their urine. Some animals remain in a state of dormancy for long periods and they then reproduce rapidly while conditions are favorable before returning to dormancy. People have struggled to live in deserts and the surrounding lands for millennia. Nomads have moved their flocks and herds to wherever grazing is available, the cultivation of semi-arid regions encourages erosion of soil and is one of the causes of increased desertification. Many trade routes have been forged across deserts, especially across the Sahara Desert, large numbers of slaves were also taken northwards across the Sahara
12.
Dew
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Dew is water in the form of droplets that appears on thin, exposed objects in the morning or evening due to condensation. As the exposed surface cools by radiating its heat, atmospheric moisture condenses at a greater than that at which it can evaporate. When temperatures are low enough, dew takes the form of ice, Dew should not be confused with guttation, which is the process by which plants release excess water from the tips of their leaves. Water vapor will condense into droplets depending on the temperature, the temperature at which droplets form is called the dew point. When surface temperature drops, eventually reaching the dew point, atmospheric water vapor condenses to form small droplets on the surface and this process distinguishes dew from those hydrometeors, which form directly in air that has cooled to its dew point, such as fog or clouds. The thermodynamic principles of formation, however, are the same, Dew is usually formed at night. Adequate cooling of the surface typically takes place when it more energy by infrared radiation than it receives as solar radiation from the sun. Poor thermal conductivity restricts the replacement of such losses from deeper ground layers, preferred objects of dew formation are thus poor conducting or well isolated from the ground, and non-metallic, while shiny metal coated surfaces are poor infrared radiators. Preferred weather conditions include the absence of clouds and little water vapor in the atmosphere to minimize greenhouse effects. Typical dew nights are considered calm, because the wind transports warmer air from higher levels to the cold surface. However, if the atmosphere is the source of moisture. The highest optimum wind speeds could be found on arid islands, if the wet soil beneath is the major source of vapor, however, wind always seems adverse. The processes of dew formation do not restrict its occurrence to the night and they are also working when eyeglasses get steamy in a warm, wet room or in industrial processes. However, the term condensation is preferred in these cases, a classical device for dew measurement is the drosometer. A small, artificial condenser surface is suspended from an arm attached to a pointer or a pen that records the changes of the condenser on a drum. Besides being very sensitive, however, this, like all artificial surface devices. The actual amount of dew in a place is strongly dependent on surface properties. Further methods include estimation by means of comparing the droplets to standardized photographs, some of these methods include guttation, while others only measure dewfall and/or distillation
13.
Microorganism
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A microorganism or microbe is a microscopic organism, which may be single-celled or multicellular. The study of microorganisms is called microbiology, a subject that began with the discovery of microorganisms in 1674 by Antonie van Leeuwenhoek, microorganisms are very diverse and include all bacteria, archaea and most protozoa. This group also contains some fungi, algae, and some such as rotifers. Many macroscopic animals and plants have microscopic juvenile stages, some microbiologists classify viruses and viroids as microorganisms, but others consider these as nonliving. In July 2016, scientists identified a set of 355 genes from the last universal ancestor of all life, including microorganisms. Microorganisms, under certain test conditions, have observed to thrive in the vacuum of outer space. Microorganisms likely far outweigh all other living things combined, the mass of prokaryote microorganisms including the bacteria and archaea may be as much as 0.8 trillion tons of carbon, out of the total biomass of between 1 and 4 trillion tons. Microorganisms appear to thrive in the Mariana Trench, the deepest spot in the Earths oceans, in August 2014, scientists confirmed the existence of microorganisms living 800 m below the ice of Antarctica. According to one researcher, You can find microbes everywhere — theyre extremely adaptable to conditions, microorganisms are crucial to nutrient recycling in ecosystems as they act as decomposers. As some microorganisms can fix nitrogen, they are a part of the nitrogen cycle. Microorganisms are also exploited in biotechnology, both in food and beverage preparation, and in modern technologies based on genetic engineering. A small proportion of microorganisms are pathogenic, causing disease and even death in plants, Robert Hooke coined the term cell after viewing plant cells under his microscope. Antonie Van Leeuwenhoek was one of the first people to observe microorganisms in 1673, later, in the 19th century, Louis Pasteur found that microorganisms caused food spoilage, debunking the theory of spontaneous generation. In 1876 Robert Koch discovered that microorganisms cause diseases, single-celled microorganisms were the first forms of life to develop on Earth, approximately 3–4 billion years ago. Further evolution was slow, and for about 3 billion years in the Precambrian eon, so, for most of the history of life on Earth, the only forms of life were microorganisms. Bacteria, algae and fungi have been identified in amber that is 220 million years old, microorganisms tend to have a relatively fast rate of evolution. Most microorganisms can reproduce rapidly, and bacteria are able to freely exchange genes through conjugation, transformation and transduction. This rapid evolution is important in medicine, as it has led to the development of multidrug resistant pathogenic bacteria, superbugs, the possible existence of microorganisms was discussed for many centuries before their discovery in the 17th century
14.
Mixotroph
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Possible combinations are photo- and chemotrophy, litho- and organotrophy, auto- and heterotrophy or other combinations of these. Mixotrophs can be either eukaryotic or prokaryotic and they can take advantage of different environmental conditions. If a trophic mode is obligate, then it is necessary for sustaining growth and maintenance, if facultative. Some organisms have incomplete Calvin cycles, so they are incapable of fixing carbon dioxide, organisms may employ mixotrophy obligately or facultatively. Obligate mixotrophy, in order to support growth and maintenance, an organism must utilize both heterotrophic and autotrophic means. Facultative autotrophy with obligate heterotrophy, Heterotrophy is sufficient for growth and maintenance, but autotrophy may be used to supplement, for example, facultative mixotrophy, Maintenance and growth may be obtained by heterotrophic or autotrophic means alone, and mixotrophy is used only when necessary. In order to characterize the sub-domains within mixotrophy, several very similar categorization schemes have been suggested, a, Heterotrophy is the norm, and phototrophy is only used when prey concentrations are limiting. B, Phototrophy is the dominant strategy, and phagotrophy is employed as a supplement when light is limiting, C, Phototrophy results in substances for both growth and ingestion, phagotrophy is employed when light is limiting. D, Phototrophy is most common type, phagotrophy only used during prolonged dark periods. This scheme characterizes mixotrophs by their efficiency, paracoccus pantotrophus is a bacterium that can live chemoorganoheterotrophically, whereby a large variety of organic compounds can be metabolized. The sulfur compounds serve as electron donors and are consumed to produce ATP, the carbon source for these organisms can be carbon dioxide or organic carbon. Organoheterotrophy can occur under aerobic or under conditions, lithoautotrophy takes place aerobically. Zooxanthellate soft corals Many examples of the genus Euglena, oriental hornet Vespa orientalis Venus Flytrap Dionaea muscipula Amongst plants, mixotrophy classically applies to carnivorous, hemi-parasitic and partially hetero-mycotrophic species. Primary nutritional groups Photosynthesis Troost TA, Kooi BW, Kooijman SA, adaptive dynamics theory applied to a dynamic energy budget model. Sanders, Robert W. Mixotrophic Nutrition of Phytoplankton, Venus Fly Traps of the microbial world
15.
PH
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In chemistry, pH is a numeric scale used to specify the acidity or basicity of an aqueous solution. It is approximately the negative of the base 10 logarithm of the concentration, measured in units of moles per liter. More precisely it is the negative of the logarithm to base 10 of the activity of the hydrogen ion, solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic. Pure water is neutral, at pH7, being neither an acid nor a base, contrary to popular belief, the pH value can be less than 0 or greater than 14 for very strong acids and bases respectively. The pH scale is traceable to a set of standard solutions whose pH is established by international agreement, the pH of aqueous solutions can be measured with a glass electrode and a pH meter, or an indicator. In the first papers, the notation had the H as a subscript to the p, as so. The exact meaning of the p in pH is disputed, but according to the Carlsberg Foundation and it has also been suggested that the p stands for the German Potenz, others refer to French puissance. Another suggestion is that the p stands for the Latin terms pondus hydrogenii, potentia hydrogenii and it is also suggested that Sørensen used the letters p and q simply to label the test solution and the reference solution. Currently in chemistry, the p stands for decimal cologarithm of, PH is defined as the decimal logarithm of the reciprocal of the hydrogen ion activity, aH+, in a solution. P H = − log 10 = log 10 For example and this definition was adopted because ion-selective electrodes, which are used to measure pH, respond to activity. For H+ number of electrons transferred is one and it follows that electrode potential is proportional to pH when pH is defined in terms of activity. The reference electrode may be a silver chloride electrode or a calomel electrode, the hydrogen-ion selective electrode is a standard hydrogen electrode. Reference electrode | concentrated solution of KCl || test solution | H2 | Pt Firstly, the cell is filled with a solution of hydrogen ion activity. Then the emf, EX, of the cell containing the solution of unknown pH is measured. PH = pH + E S − E X z The difference between the two measured emf values is proportional to pH and this method of calibration avoids the need to know the standard electrode potential. The proportionality constant, 1/z is ideally equal to 12.303 R T / F the Nernstian slope, to apply this process in practice, a glass electrode is used rather than the cumbersome hydrogen electrode. A combined glass electrode has a reference electrode. It is calibrated against buffer solutions of hydrogen ion activity
16.
Arid climate
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An area that features this climate usually experiences from 25 to 200 mm per year of precipitation and in some years may experience no precipitation at all. Averages may be even less such as in Arica, Chile, there are usually two or three variations of a desert climate, a hot desert climate, a cold desert climate and, sometimes, a mild desert climate. To determine whether a location has a climate, the precipitation threshold is determined. If the areas precipitation is less than half the threshold. Hot desert climates are found under the subtropical ridge where there is largely unbroken sunshine for the whole year due to the stable descending air. These areas are located between 30 degrees south and 30 degrees north latitude, under the subtropical latitudes called the horse latitudes, hot desert climates are generally hot, sunny and dry year-round. Hot desert climates also reach similar latitudes in the Middle East, North Africa, hot desert climates usually feature hot, sometimes exceptionally hot, periods of the year. In many locations featuring a hot climate, maximum temperatures of over 40 °C are not uncommon in summer. The world absolute heat records, over 50 °C, are generally in the hot deserts, some desert locations consistently experience very high temperatures all year long, even during wintertime. These locations feature some of the highest annual average temperatures recorded on Earth and this last feature is seen in some parts of deserts of Africa and Arabia. During colder periods of the year, night-time temperatures can drop to freezing or below due to the radiation loss under the clear skies. However, very rarely do temperatures drop far below freezing, only one region in Europe has a hot desert climate, Province of Almeria, Province of Alicante and Province of Murcia in South Eastern Spain. Cold desert climates usually feature warm and dry summers, though summers typically are not quite as hot as summers in hot desert climates, unlike hot desert climates, cold desert climates tend to feature cold winters with rare snow. Cold desert climates are found at higher altitudes than hot desert climates. A cold desert climate is found in temperate zones, usually in the rain shadow of high mountains. A classic example of this is the Patagonian Desert in Argentina bounded by the Andes to its west, in the case of Central Asia, mountains restrict precipitation from the monsoon. The Gobi desert in Mongolia is an example of this. Though hot in summer, it shares the cold winters of the rest of Central Asia
17.
Valley of Fire State Park
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Valley of Fire State Park is a public recreation and nature preservation area covering nearly 46,000 acres located 16 miles south of Overton, Nevada. The state park derives its name from red sandstone formations, the Aztec Sandstone and these features, which are the centerpiece of the parks attractions, often appear to be on fire when reflecting the suns rays. It is Nevadas oldest state park, as commemorated with Nevada Historical Marker #150 and it was designated as a National Natural Landmark in 1968. Valley of Fire is located 50 miles northeast of Las Vegas and it abuts the Lake Mead National Recreation Area on the east at the Virgin River confluence. It lies in a 4 by 6 mi basin, complex uplifting and faulting of the region, followed by extensive erosion, have created the present landscape. The rough floor and jagged walls of the park contain brilliant formations of eroded sandstone, other important rock formations include limestones, shales, and conglomerates. Prehistoric users of the Valley of Fire included the Ancient Pueblo Peoples, also known as the Anasazi and their approximate span of occupation has been dated from 300 BC to 1150 AD. Their visits probably involved hunting, food gathering, and religious ceremonies, fine examples of rock art left by these ancient peoples can be found at several sites within the park. The creation of Valley of Fire State Park began with transfer of 8,760 acres of land to the state at Nevada in 1931. Work on the park was initiated by the Civilian Conservation Corps in 1933, the park opened in 1934, it achieved official designation by the state legislature in 1935. The Valley of Fire State Park has a dry and warm climate typical of the Mojave Desert in which it lies, winters are mild with daytime temperatures ranging from 54 °F to 75 °F. and over night lows in the mid 30°Fs to mid 40°Fs. Storms moving east from the Pacific Ocean occasionally bring rain during winter months, daily summer highs usually range from 100 °F to 115 °F and on occasion may reach near 120 °F. Thunderstorms from the Southwestern Monsoon can produce heavy showers during summer. The average annual precipitation is 6.50, Valley of Fire Road is the main road through the park. The 10.5 mi road connects the east and west entrances of the park and it was designated as a Nevada Scenic Byway on June 30,1995. Although petroglyphs are present throughout the park, Mouses Tank. The park also contains three cabins built by the Civilian Conservation Corps, there are facilities for picnicking, camping, and hiking. Valley of Fire is a location for shooting automobile commercials. The Professionals with Burt Lancaster, Lee Marvin, and Claudia Cardinale was filmed in 1966, Valley of Fire was one of three locations used in the film
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Las Vegas
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The city anchors the Las Vegas Valley metropolitan area and is the largest city within the greater Mojave Desert. Las Vegas is an internationally renowned major resort city known primarily for its gambling, shopping, fine dining, entertainment and it is the leading financial, commercial, and cultural center for Nevada. The city bills itself as The Entertainment Capital of the World and it is a top three destination in the United States for business conventions and a global leader in the hospitality industry, claiming more AAA Five Diamond hotels than any city in the world. Today, Las Vegas annually ranks as one of the worlds most visited tourist destinations. The citys tolerance for numerous forms of adult entertainment earned it the title of Sin City, and has made Las Vegas a popular setting for literature, films, television programs, Las Vegas was settled in 1905 and officially incorporated in 1911. At the close of the 20th century, it was the most populated American city founded within that century, population growth has accelerated since the 1960s, and between 1990 and 2000 the population nearly doubled, increasing by 85. 2%. Rapid growth has continued into the 21st century, and according to a 2013 estimate, perhaps the earliest visitors to the Las Vegas area were nomadic Paleo-Indians, who traveled there 10,000 years ago, leaving behind petroglyphs. Anasazi and Paiute tribes followed at least 2,000 years ago, a young Mexican scout named Rafael Rivera is credited as the first non-Native American to encounter the valley, in 1829. Trader Antonio Armijo led a 60-man party along the Spanish Trail to Los Angeles, the area was named Las Vegas, which is Spanish for the meadows, as it featured abundant wild grasses, as well as desert spring waters for westward travelers. The year 1844 marked the arrival of John C, frémont, whose writings helped lure pioneers to the area. Downtown Las Vegas Fremont Street is named after him, eleven years later members of the LDS Church chose Las Vegas as the site to build a fort halfway between Salt Lake City and Los Angeles, where they would travel to gather supplies. The fort was abandoned several years afterward, the remainder of this Old Mormon Fort can still be seen at the intersection of Las Vegas Boulevard and Washington Avenue. Las Vegas was founded as a city in 1905, when 110 acres of adjacent to the Union Pacific Railroad tracks were auctioned in what would become the downtown area. In 1911, Las Vegas was incorporated as a city,1931 was a pivotal year for Las Vegas. At that time, Nevada legalized casino gambling and reduced residency requirements for divorce to six weeks and this year also witnessed the beginning of construction on nearby Hoover Dam. The influx of workers and their families helped Las Vegas avoid economic calamity during the Great Depression. The construction work was completed in 1935, in 1941, the Las Vegas Army Air Corps Gunnery School was established. Currently known as Nellis Air Force Base, it is home to the team called the Thunderbirds
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Native Americans in the United States
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In the United States, Native Americans are people descended from the Pre-Columbian indigenous population of the land within the countrys modern boundaries. These peoples were composed of distinct tribes, bands, and ethnic groups. Most Native American groups had historically preserved their histories by oral traditions and artwork, at the time of first contact, the indigenous cultures were quite different from those of the proto-industrial and mostly Christian immigrants. Some of the Northeastern and Southwestern cultures in particular were matrilineal, the majority of Indigenous American tribes maintained their hunting grounds and agricultural lands for use of the entire tribe. Europeans at that time had patriarchal cultures and had developed concepts of property rights with respect to land that were extremely different. Assimilation became a consistent policy through American administrations, during the 19th century, the ideology of manifest destiny became integral to the American nationalist movement. Expansion of European-American populations to the west after the American Revolution resulted in increasing pressure on Native American lands and this resulted in the ethnic cleansing of many tribes, with the brutal, forced marches coming to be known as The Trail of Tears. As American expansion reached into the West, settler and miner migrants came into increasing conflict with the Great Basin, Great Plains and these were complex nomadic cultures based on horse culture and seasonal bison hunting. Over time, the United States forced a series of treaties and land cessions by the tribes, in 1924, Native Americans who were not already U. S. citizens were granted citizenship by Congress. Contemporary Native Americans have a relationship with the United States because they may be members of nations, tribes. The terms used to refer to Native Americans have at times been controversial, by comparison, the indigenous peoples of Canada are generally known as First Nations. It is not definitively known how or when the Native Americans first settled the Americas and these early inhabitants, called Paleoamericans, soon diversified into many hundreds of culturally distinct nations and tribes. The archaeological periods used are the classifications of archaeological periods and cultures established in Gordon Willey and Philip Phillips 1958 book Method and they divided the archaeological record in the Americas into five phases, see Archaeology of the Americas. The Clovis culture, a hunting culture, is primarily identified by use of fluted spear points. Artifacts from this culture were first excavated in 1932 near Clovis, the Clovis culture ranged over much of North America and also appeared in South America. The culture is identified by the distinctive Clovis point, a flaked flint spear-point with a notched flute, dating of Clovis materials has been by association with animal bones and by the use of carbon dating methods. Recent reexaminations of Clovis materials using improved carbon-dating methods produced results of 11,050 and 10,800 radiocarbon years B. P, other tribes have stories that recount migrations across long tracts of land and a great river, believed to be the Mississippi River. Genetic and linguistic data connect the people of this continent with ancient northeast Asians
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Petroglyph
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Petroglyphs are images created by removing part of a rock surface by incising, picking, carving, or abrading, as a form of rock art. Outside North America, scholars often use such as carving, engraving. Petroglyphs are found world-wide, and are associated with prehistoric peoples. The word comes from the Greek word petro-, theme of the word meaning stone, and glyphein meaning to carve. The term petroglyph should not be confused with petrograph, which is an image drawn or painted on a rock face, both types of image belong to the wider and more general category of rock art or parietal art. Petroforms, or patterns and shapes made by large rocks. Inukshuks are also unique, and found only in the Arctic and they are a category of rock art, and sometimes found in conjunction with rock-cut architecture. However, they tend to be omitted in most works on rock art, a few such works exploit the natural contours of the rock and use them to define an image, but they do not amount to man-made reliefs. Rock reliefs have been made in many cultures, and were important in the art of the Ancient Near East. Rock reliefs are generally large, as they need to be to make an impact in the open air. Most have figures that are over life-size, and in many the figures are multiples of life-size, the vertical relief is most common, but reliefs on essentially horizontal surfaces are also found. The term typically excludes relief carvings inside caves, whether natural or themselves man-made, natural rock formations made into statues or other sculpture in the round, most famously at the Great Sphinx of Giza, are also usually excluded. Reliefs on large boulders left in their location, like the Hittite İmamkullu relief, are likely to be included. Some petroglyphs are dated to approximately the Neolithic and late Upper Paleolithic boundary, about 10,000 to 12,000 years ago, if not earlier. Sites in Australia have petroglyphs that are estimated to be as much as 27,000 years old, around 7,000 to 9,000 years ago, other precursors of writing systems, such as pictographs and ideograms, began to appear. Petroglyphs were still common though, and some cultures continued using them much longer, petroglyphs have been found in all parts of the globe except Antarctica with highest concentrations in parts of Africa, Scandinavia, Siberia, southwestern North America and Australia. There are many theories to explain their purpose, depending on their location, age, some petroglyphs are thought to be astronomical markers, maps, and other forms of symbolic communication, including a form of pre-writing. Petroglyph maps may show trails, symbols communicating time and distances traveled, as well as the terrain in the form of rivers, landforms
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Limestone
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Limestone is a sedimentary rock, composed mainly of skeletal fragments of marine organisms such as coral, forams and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate, about 10% of sedimentary rocks are limestones. The solubility of limestone in water and weak acid solutions leads to karst landscapes, most cave systems are through limestone bedrock. The first geologist to distinguish limestone from dolomite was Belsazar Hacquet in 1778, like most other sedimentary rocks, most limestone is composed of grains. Most grains in limestone are skeletal fragments of organisms such as coral or foraminifera. Other carbonate grains comprising limestones are ooids, peloids, intraclasts and these organisms secrete shells made of aragonite or calcite, and leave these shells behind when they die. Limestone often contains variable amounts of silica in the form of chert or siliceous skeletal fragment, some limestones do not consist of grains at all, and are formed completely by the chemical precipitation of calcite or aragonite, i. e. travertine. Secondary calcite may be deposited by supersaturated meteoric waters and this produces speleothems, such as stalagmites and stalactites. Another form taken by calcite is oolitic limestone, which can be recognized by its granular appearance, the primary source of the calcite in limestone is most commonly marine organisms. Some of these organisms can construct mounds of rock known as reefs, below about 3,000 meters, water pressure and temperature conditions cause the dissolution of calcite to increase nonlinearly, so limestone typically does not form in deeper waters. Limestones may also form in lacustrine and evaporite depositional environments, calcite can be dissolved or precipitated by groundwater, depending on several factors, including the water temperature, pH, and dissolved ion concentrations. Calcite exhibits a characteristic called retrograde solubility, in which it becomes less soluble in water as the temperature increases. Impurities will cause limestones to exhibit different colors, especially with weathered surfaces, Limestone may be crystalline, clastic, granular, or massive, depending on the method of formation. Crystals of calcite, quartz, dolomite or barite may line small cavities in the rock, when conditions are right for precipitation, calcite forms mineral coatings that cement the existing rock grains together, or it can fill fractures. Travertine is a banded, compact variety of limestone formed along streams, particularly there are waterfalls. Calcium carbonate is deposited where evaporation of the leaves a solution supersaturated with the chemical constituents of calcite. Tufa, a porous or cellular variety of travertine, is found near waterfalls, coquina is a poorly consolidated limestone composed of pieces of coral or shells. During regional metamorphism that occurs during the building process, limestone recrystallizes into marble
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Basalt
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Basalt is a common extrusive igneous rock formed from the rapid cooling of basaltic lava exposed at or very near the surface of a planet or moon. Flood basalt describes the formation in a series of basalt flows. By definition, basalt is an igneous rock with generally 45-55% silica and less than 10% feldspathoid by volume. Basalt commonly features a very fine-grained or glassy matrix interspersed with visible mineral grains, the average density is 3.0 gm/cm3. Basalt is defined by its content and texture, and physical descriptions without mineralogical context may be unreliable in some circumstances. Basalt is usually grey to black in colour, but rapidly weathers to brown or rust-red due to oxidation of its mafic minerals into hematite, although usually characterized as dark, basaltic rocks exhibit a wide range of shading due to regional geochemical processes. Due to weathering or high concentrations of plagioclase, some basalts can be quite light-coloured and these phenocrysts usually are of olivine or a calcium-rich plagioclase, which have the highest melting temperatures of the typical minerals that can crystallize from the melt. Basalt with a texture is called vesicular basalt, when the bulk of the rock is mostly solid. Gabbro is often marketed commercially as black granite and these ultramafic volcanic rocks, with silica contents below 45% are usually classified as komatiites. Agricola applied basalt to the black rock of the Schloßberg at Stolpen. Tholeiitic basalt is relatively rich in silica and poor in sodium, included in this category are most basalts of the ocean floor, most large oceanic islands, and continental flood basalts such as the Columbia River Plateau. Basalt rocks are in some cases classified after their content in High-Ti and Low-Ti varieties. High-Ti and Low-Ti basalts have been distinguished in the Paraná and Etendeka traps and it has greater than 17% alumina and is intermediate in composition between tholeiite and alkali basalt, the relatively alumina-rich composition is based on rocks without phenocrysts of plagioclase. Alkali basalt is relatively poor in silica and rich in sodium and it is silica-undersaturated and may contain feldspathoids, alkali feldspar and phlogopite. Boninite is a form of basalt that is erupted generally in back-arc basins. Ocean island basalt Lunar basalt On Earth, most basalt magmas have formed by melting of the mantle. Basalt commonly erupts on Io, the third largest moon of Jupiter, and has formed on the Moon, Mars, Venus. The crustal portions of oceanic tectonic plates are composed predominantly of basalt, produced from upwelling mantle below, the mineralogy of basalt is characterized by a preponderance of calcic plagioclase feldspar and pyroxene
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Quartzite
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Quartzite is a hard, non-foliated metamorphic rock which was originally pure quartz sandstone. Sandstone is converted into quartzite through heating and pressure related to tectonic compression within orogenic belts. Pure quartzite is usually white to grey, though quartzites often occur in shades of pink. Other colors, such as yellow, green, blue and orange, are due to other minerals, when sandstone is cemented to quartzite, the individual quartz grains recrystallize along with the former cementing material to form an interlocking mosaic of quartz crystals. Most or all of the texture and sedimentary structures of the sandstone are erased by the metamorphism. The grainy, sandpaper-like surface becomes glassy in appearance, minor amounts of former cementing materials, iron oxide, silica, carbonate and clay, often migrate during recrystallization and metamorphosis. This causes streaks and lenses to form within the quartzite, orthoquartzite is a very pure quartz sandstone composed of usually well-rounded quartz grains cemented by silica. Orthoquartzite is often 99% SiO2 with only minor amounts of iron oxide and trace resistant minerals such as zircon, rutile. Although few fossils are present, the original texture and sedimentary structures are preserved. The term is traditionally used for quartz-cemented quartz arenites. Quartzite is very resistant to weathering and often forms ridges. The nearly pure silica content of the rock provides little for soil, therefore, because of its hardness and angular shape, crushed quartzite is often used as railway ballast. Quartzite is a stone and may be used to cover walls, as roofing tiles, as flooring. Its use for countertops in kitchens is expanding rapidly and it is harder and more resistant to stains than granite. Crushed quartzite is used in road construction. High purity quartzite is used to produce ferrosilicon, industrial silica sand, during the Paleolithic quartzite was used, in addition to flint, quartz, and other lithic raw materials, for making stone tools. Quartzite is also found in the Morenci Copper Mine in Arizona, the town of Quartzsite in western Arizona derives its name from the quartzites in the nearby mountains in both Arizona and Southeastern California. A glassy vitreous quartzite has been described from the Belt Supergroup in the Coeur d’Alene district of northern Idaho, in the United Kingdom, a craggy ridge of quartzite called the Stiperstones runs parallel with the Pontesford-Linley fault,6 km north-west of the Long Mynd in south Shropshire
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Metamorphic rock
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Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means change in form. The original rock is subjected to heat and pressure, causing profound physical and/or chemical change, the protolith may be a sedimentary, an igneous, or even an existing type of metamorphic rock. Metamorphic rocks make up a part of the Earths crust. They are classified by texture and by chemical and mineral assemblage and they may be formed simply by being deep beneath the Earths surface, subjected to high temperatures and the great pressure of the rock layers above it. They can form from tectonic processes such as continental collisions, which cause horizontal pressure and they are also formed when rock is heated up by the intrusion of hot molten rock called magma from the Earths interior. The study of rocks provides information about the temperatures and pressures that occur at great depths within the Earths crust. Some examples of rocks are gneiss, slate, marble, schist. Metamorphic minerals are those that only at the high temperatures and pressures associated with the process of metamorphism. These minerals, known as index minerals, include sillimanite, kyanite, staurolite, andalusite, and some garnet. Other minerals, such as olivines, pyroxenes, amphiboles, micas, feldspars, and quartz, may be found in metamorphic rocks and these minerals formed during the crystallization of igneous rocks. They are stable at temperatures and pressures and may remain chemically unchanged during the metamorphic process. However, all minerals are only within certain limits. The change in the size of the rock during the process of metamorphism is called recrystallization. Both high temperatures and pressures contribute to recrystallization, high temperatures allow the atoms and ions in solid crystals to migrate, thus reorganizing the crystals, while high pressures cause solution of the crystals within the rock at their point of contact. The layering within metamorphic rocks is called foliation, and it occurs when a rock is being shortened along one axis during recrystallization. This causes the platy or elongated crystals of minerals, such as mica and chlorite and this results in a banded, or foliated rock, with the bands showing the colors of the minerals that formed them. Textures are separated into foliated and non-foliated categories, foliated rock is a product of differential stress that deforms the rock in one plane, sometimes creating a plane of cleavage. For example, slate is a metamorphic rock, originating from shale
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Shale
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Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable, shale is characterized by breaks along thin laminae or parallel layering or bedding less than one centimeter in thickness, called fissility. Mudstones, on the hand, are similar in composition. Before the mid 19th century, the slate, shale. In the context of underground mining, shale was frequently referred to as slate well into the 20th century. Non-fissile rocks of similar composition but made of smaller than 0.06 mm are described as mudstones or claystone. Rocks with similar sizes but with less clay and therefore grittier are siltstones. Shale is the most common sedimentary rock, shales are typically composed of variable amounts of clay minerals and quartz grains and the typical color is gray. Addition of variable amounts of minor constituents alters the color of the rock, black shale results from the presence of greater than one percent carbonaceous material and indicates a reducing environment. Black shale can also be referred to as black metal, red, brown and green colors are indicative of ferric oxide, iron hydroxide, or micaceous minerals. Clays are the constituent of shales and other mudrocks. The clay minerals represented are largely kaolinite, montmorillonite and illite, clay minerals of Late Tertiary mudstones are expandable smectites whereas in older rocks especially in mid- to early Paleozoic shales illites predominate. The transformation of smectite to illite produces silica, sodium, calcium, magnesium, iron and these released elements form authigenic quartz, chert, calcite, dolomite, ankerite, hematite and albite, all trace to minor minerals found in shales and other mudrocks. Shales and mudrocks contain roughly 95 percent of the matter in all sedimentary rocks. However, this amounts to less than one percent by mass in an average shale, black shales, which form in anoxic conditions, contain reduced free carbon along with ferrous iron and sulfur. Pyrite and amorphous iron sulfide along with carbon produce the black coloration, the process in the rock cycle which forms shale is called compaction. The fine particles that compose shale can remain suspended in long after the larger particles of sand have deposited. Shales are typically deposited in very slow moving water and are found in lakes and lagoonal deposits, in river deltas, on floodplains
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Aeolian processes
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Aeolian processes, also spelled eolian or æolian, pertain to wind activity in the study of geology and weather and specifically to the winds ability to shape the surface of the Earth. Winds may erode, transport, and deposit materials and are effective agents in regions with sparse vegetation, a lack of soil moisture, although water is a much more powerful eroding force than wind, aeolian processes are important in arid environments such as deserts. The term is derived from the name of the Greek god Aeolus, wind erodes the Earths surface by deflation and by abrasion. Regions which experience intense and sustained erosion are called deflation zones, most aeolian deflation zones are composed of desert pavement, a sheet-like surface of rock fragments that remains after wind and water have removed the fine particles. Almost half of Earths desert surfaces are stony deflation zones, the rock mantle in desert pavements protects the underlying material from deflation. A dark, shiny stain, called desert varnish or rock varnish, is found on the surfaces of some desert rocks that have been exposed at the surface for a long period of time. Manganese, iron oxides, hydroxides, and clay minerals form most varnishes, deflation basins, called blowouts, are hollows formed by the removal of particles by wind. Blowouts are generally small, but may be up to kilometers in diameter. In parts of Antarctica wind-blown snowflakes that are technically sediments have also caused abrasion of exposed rocks, grinding by particles carried in the wind creates grooves or small depressions. Ventifacts are rocks which have cut, and sometimes polished. Sculpted landforms, called yardangs, are up to tens of meters high, the famous Great Sphinx of Giza in Egypt may be a modified yardang. Particles are transported by winds through suspension, saltation and creeping along the ground, small particles may be held in the atmosphere in suspension. Upward currents of air support the weight of suspended particles and hold them indefinitely in the surrounding air, typical winds near Earths surface suspend particles less than 0.2 millimeters in diameter and scatter them aloft as dust or haze. Saltation is downwind movement of particles in a series of jumps or skips, saltation normally lifts sand-size particles no more than one centimeter above the ground and proceeds at one-half to one-third the speed of the wind. A saltating grain may hit other grains that jump up to continue the saltation, the grain may also hit larger grains that are too heavy to hop, but that slowly creep forward as they are pushed by saltating grains. Surface creep accounts for as much as 25 percent of grain movement in a desert, aeolian turbidity currents are better known as dust storms. Air over deserts is cooled significantly when rain passes through it and this cooler and denser air sinks toward the desert surface. When it reaches the ground, the air is deflected forward, crops, people, villages, and possibly even climates are affected by dust storms
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Manganite
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Manganite is a mineral composed of manganese oxide-hydroxide, MnO, crystallizing in the monoclinic system. Crystals of manganite are prismatic and deeply striated parallel to their length, the color is dark steel-grey to iron-black, and the luster brilliant and submetallic. The streak is dark reddish brown, the hardness is 4, and the specific gravity is 4.3. There is a cleavage parallel to the brachypinacoid, and less-perfect cleavage parallel to the prism faces. The mineral contains 89. 7% manganese sesquioxide, it dissolves in acid with evolution of chlorine. Manganite occurs with other manganese oxides in deposits formed by circulating meteoric water in the environment in clay deposits. It forms by low temperature hydrothermal action in veins in association with calcite, barite, often associated with pyrolusite, braunite, hausmannite and goethite. Manganite occurs in specimens exhibiting good crystal form at Ilfeld in the Harz Mountains of Germany, good crystals have also been found at Atikokan, Ontario and Nova Scotia, Canada. As an ore of manganese it is less abundant than pyrolusite or psilomelane. Although described with various names as early as 1772, the name manganite was first applied in a publication by W. Haidinger in 1827. The mineral was used in times as a pigment, by humans. Manganite is believed to have used in prehistoric times to start a wood fire. Manganite lowers the temperature of wood from 350 degrees Celsius to 250 degrees Celsius. Manganite powder has been a common find in Neanderthal archaeological sites, in this article Manganese oxide This article incorporates text from a publication now in the public domain, Chisholm, Hugh, ed. article name needed
