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Dreikanter
A Dreikanter is a type of ventifact that typically forms in desert or periglacial environments due to the abrasive action of blowing sand. Dreikanters exhibit a characteristic pyramidal shape with three wind-abraded facets. The word ''Dreikanter'' is German for "three-edged." Similarly, a zweikanter ("two-edged") has two wind facets, an einkanter ("one-edged"), has only one wind facet. Greeley, R., N. T. Bridges, R. O. Kuzmin, and J. E. Laity, Terrestrial analogs to wind-related features at the Viking and Pathfinder landing sites on Mars, J. Geophys. Res., 107(E1), doi:10.1029/2000JE001481, 2002. Most places on the planet have several weathering processes acting at the same time, so finding good examples of Dreikanters is often difficult. Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dreikanter From The Wind River Basin, Wyoming, USA
A Dreikanter is a type of ventifact that typically forms in desert or periglacial environments due to the abrasive action of blowing sand. Dreikanters exhibit a characteristic pyramidal shape with three wind-abraded facets. The word ''Dreikanter'' is German for "three-edged." Similarly, a zweikanter ("two-edged") has two wind facets, an einkanter ("one-edged"), has only one wind facet. Greeley, R., N. T. Bridges, R. O. Kuzmin, and J. E. Laity, Terrestrial analogs to wind-related features at the Viking and Pathfinder landing sites on Mars, J. Geophys. Res., 107(E1), doi:10.1029/2000JE001481, 2002. Most places on the planet have several weathering processes acting at the same time, so finding good examples of Dreikanters is often difficult. Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ventifact
A ventifact (also wind-faceted stone, windkanter) is a rock that has been abraded, pitted, etched, grooved, or polished by wind-driven sand or ice crystals. These geomorphic features are most typically found in arid environments where there is little vegetation to interfere with aeolian particle transport, where there are frequently strong winds, and where there is a steady but not overwhelming supply of sand. Ventifacts can be abraded to eye-catching natural sculptures such as the main features of the White Desert National Park 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. This occurs because, even in strong winds, sand grains can't be continuously held in the air. Instead, the particles bounce along the ground, rarely reaching higher than a few feet above the Earth. Over time, the bouncing sand grains can erode the lower portions of a ventifact, while leavin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Desert
A desert is a barren area of landscape 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 denudation. About one-third of the land surface of the Earth is arid or semi-arid. This includes much of the polar regions, where little precipitation occurs, and which are sometimes called polar deserts or "cold deserts". Deserts can be classified by the amount of precipitation that falls, by the temperature that prevails, by the causes of desertification or by their geographical location. 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 rubble strewn over t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Periglacial
Periglaciation (adjective: "periglacial", also referring to places at the edges of glacial areas) describes geomorphic processes that result from seasonal thawing of snow in areas of permafrost, the runoff from which refreezes in ice wedges and other structures. "Periglacial" suggests an environment located on the margin of past glaciers. However, freeze and thaw cycles influence landscapes outside areas of past glaciation. Therefore, periglacial environments are anywhere that freezing and thawing modify the landscape in a significant manner. Tundra is a common ecological community in periglacial areas. History Periglaciation became a distinct subject within the study of geology after Walery Łoziński, a Polish geologist, introduced the term in 1909. Łoziński drew upon the early work of Johan Gunnar Andersson. According to Alfred Jahn, his introduction of his work at the 1910 International Geological Congress held in Stockholm caused significant discussion. In the field t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saltation (geology)
In geology, saltation () is a specific type of particle transport by fluids such as wind or water. It occurs when loose materials are removed from a bed and carried by the fluid, before being transported back to the surface. Examples include pebble transport by rivers, sand drift over desert surfaces, soil blowing over fields, and snow drift over smooth surfaces such as those in the Arctic or Canadian Prairies. Process At low fluid velocities, loose material rolls downstream, staying in contact with the surface. This is called ''creep'' or ''reptation''. Here the forces exerted by the fluid on the particle are only enough to roll the particle around the point of contact with the surface. Once the wind speed reaches a certain critical value, termed the ''impact'' or ''fluid threshold'', the drag and lift forces exerted by the fluid are sufficient to lift some particles from the surface. These particles are accelerated by the fluid, and pulled downward by gravity, causing them t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyramid
A pyramid (from el, πυραμίς ') is a structure whose outer surfaces are triangular and converge to a single step at the top, making the shape roughly a pyramid in the geometric sense. The base of a pyramid can be trilateral, quadrilateral, or of any polygon shape. As such, a pyramid has at least three outer triangular surfaces (at least four faces including the base). The square pyramid, with a square base and four triangular outer surfaces, is a common version. A pyramid's design, with the majority of the weight closer to the ground and with the pyramidion at the apex, means that less material higher up on the pyramid will be pushing down from above. This distribution of weight allowed early civilizations to create stable monumental structures. Civilizations in many parts of the world have built pyramids. The largest pyramid by volume is the Great Pyramid of Cholula, in the Mexican state of Puebla. For thousands of years, the largest structures on Earth were py ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
German Language
German ( ) is a West Germanic language mainly spoken in Central Europe. It is the most widely spoken and official or co-official language in Germany, Austria, Switzerland, Liechtenstein, and the Italian province of South Tyrol. It is also a co-official language of Luxembourg and Belgium, as well as a national language in Namibia. Outside Germany, it is also spoken by German communities in France ( Bas-Rhin), Czech Republic ( North Bohemia), Poland (Upper Silesia), Slovakia ( Bratislava Region), and Hungary (Sopron). German is most similar to other languages within the West Germanic language branch, including Afrikaans, Dutch, English, the Frisian languages, Low German, Luxembourgish, Scots, and Yiddish. It also contains close similarities in vocabulary to some languages in the North Germanic group, such as Danish, Norwegian, and Swedish. German is the second most widely spoken Germanic language after English, which is also a West Germanic language. Germ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antarctica
Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest continent, being about 40% larger than Europe, and has an area of . Most of Antarctica is covered by the Antarctic ice sheet, with an average thickness of . Antarctica is, on average, the coldest, driest, and windiest of the continents, and it has the highest average elevation. It is mainly a polar desert, with annual precipitation of over along the coast and far less inland. About 70% of the world's freshwater reserves are frozen in Antarctica, which, if melted, would raise global sea levels by almost . Antarctica holds the record for the lowest measured temperature on Earth, . The coastal regions can reach temperatures over in summer. Native species of animals include mites, nematodes, penguins, seals and tardigrades. Where ve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluting (geology)
In the earth sciences, the terms fluting and flute have very different meanings in its subdisciplines of geomorphology, glaciology, sedimentology, and speleology.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds. (2005) ''Glossary of Geology'' (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. Geomorphology In geomorphology, a flute is a narrow, shallow channel that runs nearly vertically down the face of a rock surface. It is formed by the weathering and erosion of the rock surface. Correspondingly, fluting is the erosional process by which a well-jointed coarse-grained rock, such as granite or gneiss, surface develops a set of flutes. The includes the formation of small-scale ridges and depressions by wave action. Glaciology ''For the main article about glacial flutes, please see Flute (glacial).'' In glaciology, flutes are narrow, elongated, straight, parallel ridges generally consisting of till, but sometimes composed of sand or silt/clay. Flutes ty ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bradley 1930 Dreikanter
Bradley is an English surname derived from a place name meaning "broad wood" or "broad meadow" in Old English. Like many English surnames Bradley can also be used as a given name and as such has become popular. It is also an Anglicisation of the Irish name Ó Brolacháin (also O’Brallaghan) from County Tyrone in Northern Ireland. The family moved and spread to counties Londonderry, Donegal and Cork, and England. Surname Bradley is the surname of the following notable people: * A. C. Bradley (Andrew Cecil Bradley, 1851–1935), English Shakespearean scholar * A. C. Bradley (screenwriter), an American screenwriter * Abraham Bradley Jr. (1767–1838), first Assistant Postmaster-General of the U.S. * Amy Lynn Bradley (born 1974), an American woman who disappeared during a Caribbean cruise * Andrew M. Bradley (1906–1983), American accountant and public official * Archie Bradley (baseball) (born 1992), American baseball player * Arthur Granville Bradley (1850–1943), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geomorphology
Geomorphology (from Ancient Greek: , ', "earth"; , ', "form"; and , ', "study") is the scientific study of the origin and evolution of topographic and bathymetric features created by physical, chemical or biological processes operating at or near Earth's surface. Geomorphologists seek to understand why landscapes look the way they do, to understand landform and terrain history and dynamics and to predict changes through a combination of field observations, physical experiments and numerical modeling. Geomorphologists work within disciplines such as physical geography, geology, geodesy, engineering geology, archaeology, climatology, and geotechnical engineering. This broad base of interests contributes to many research styles and interests within the field. Overview Earth's surface is modified by a combination of surface processes that shape landscapes, and geologic processes that cause tectonic uplift and subsidence, and shape the coastal geography. Surface processe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
