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dune
dune mound or ridge of wind-blown sand formed in arid regions and along coasts. Dunes are common in most of the great deserts of the world. Often a dune begins to form because material is deposited by the wind as it encounters a bush, a rock, or other obstacle to impede its flow. Dunes that are not stabilized by vegetation have a tendency to migrate, driven by the prevailing wind. These free-moving dunes are of two main kinds, transverse and longitudinal, and the characteristic form is maintained in migration. Transverse dunes usually form where wind blows quite constantly from one direction across expanses of loose sand; the windward slope is typically gentle, and the lee side, where the sand blown over the crest seeks its natural angle of repose, is steep. Such dune ridges have a tendency, especially with increasing distance from the source of sand, to break up into individual small hills. One of the commonest forms of these hills is the symmetrical, crescent-shaped, transverse dune called a barkhan; examples can be found at Pismo Beach, Calif., and near Arequipa, Peru. Longitudinal dunes are ridges, with about the same slope on both sides, elongated in the direction of the prevailing wind. They are especially well developed in the African deserts and are also seen in Arizona and in the Imperial Valley, Calif. Coastal blowout dunes, which are approximately U-shaped with their open ends upwind, form along shores where vegetation cover is locally broken. Examples are the dunes along the southern and eastern shores of Lake Michigan. Dunes reaching a height of more than 500 ft (150 m) exist in the Great Sand Dunes National Monument and Preserve, Colo.; gleaming white dunes of gypsum sand are formed in White Sands National Monument, N.Mex. Sand dunes may cause destruction as they migrate; in France on the coast of the Bay of Biscay they destroyed villages and farmland. In some areas of Europe and the United States this danger has been checked by planting vegetation and by erecting barriers. One value of dunes is their absorption of rain, which helps to raise the level of the water table and thus produces oases in some areas and provides accessible sources of water through rather shallow wells. |
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"dune." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. 26 May. 2012 <http://www.encyclopedia.com>. "dune." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. (May 26, 2012). http://www.encyclopedia.com/doc/1E1-dune.html "dune." The Columbia Encyclopedia, 6th ed.. 2011. Retrieved May 26, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-dune.html |
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dune
dune A land-form produced by the action of wind on unconsolidated sediment, normally sand. Aeolian dune forms range from small ripples less than 1 cm in height, to the draa forms of the Sahara which rise to more than 300 m. Such dunes may be divided into three basic categories: barchans; longitudinal or ‘seif’ dunes, which parallel the wind direction; and transverse dunes which are aligned normally to the dominant wind. Transverse dunes are initial forms on sandy coastlines in temperate regions. They migrate inland and may be eroded locally by the wind to form a damp hollow or ‘dune slack’. The enclosing crescentic dune is a ‘parabolic’ dune whose form reverses that of the barchan. See also AKLÉ DUNE; COPPICE DUNE; DUNE BEDFORM; and STAR DUNE.
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AILSA ALLABY and MICHAEL ALLABY. "dune." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 26 May. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "dune." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 26, 2012). http://www.encyclopedia.com/doc/1O13-dune.html AILSA ALLABY and MICHAEL ALLABY. "dune." A Dictionary of Earth Sciences. 1999. Retrieved May 26, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-dune.html |
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dune
dune A land-form produced by the action of wind on unconsolidated sediment, normally sand. Aeolian dune forms range from small ripples less than 1 cm in height to the draa forms of the Sahara, which rise to more than 300 m. Such dunes may be divided into three basic categories: barchans; longitudinal or ‘seif’ dunes, which parallel the wind direction; and transverse dunes, which are aligned normally to the dominant wind. Transverse dunes are initial forms on sandy coastlines in temperate regions. They migrate inland and may be eroded locally by the wind to form a damp hollow or ‘dune slack’. The enclosing crescentic dune is a ‘parabolic’ dune whose form reverses that of the barchan. See also aklé dune; dune bedform; and star dune.
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Cite this article
MICHAEL ALLABY. "dune." A Dictionary of Ecology. 2004. Encyclopedia.com. 26 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "dune." A Dictionary of Ecology. 2004. Encyclopedia.com. (May 26, 2012). http://www.encyclopedia.com/doc/1O14-dune.html MICHAEL ALLABY. "dune." A Dictionary of Ecology. 2004. Retrieved May 26, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O14-dune.html |
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dune
dune Ridge of wind-blown particles, most often sand. They occur in deserts in many shapes: barchans (crescent-shaped) are formed by a constant wind; seifs are narrow ridges.
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"dune." World Encyclopedia. 2005. Encyclopedia.com. 26 May. 2012 <http://www.encyclopedia.com>. "dune." World Encyclopedia. 2005. Encyclopedia.com. (May 26, 2012). http://www.encyclopedia.com/doc/1O142-dune.html "dune." World Encyclopedia. 2005. Retrieved May 26, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O142-dune.html |
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dune
dune / d(y)oōn/ • n. a mound or ridge of sand or other loose sediment formed by the wind, esp. on the sea coast or in a desert: a sand dune. |
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"dune." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. 26 May. 2012 <http://www.encyclopedia.com>. "dune." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (May 26, 2012). http://www.encyclopedia.com/doc/1O999-dune.html "dune." The Oxford Pocket Dictionary of Current English. 2009. Retrieved May 26, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-dune.html |
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dune
dune sandhill on the sea-coast. XVIII. — (O)F. — MDu. dūne (Du. duin) = OE. dūn DOWN 1.
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T. F. HOAD. "dune." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. 26 May. 2012 <http://www.encyclopedia.com>. T. F. HOAD. "dune." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. (May 26, 2012). http://www.encyclopedia.com/doc/1O27-dune.html T. F. HOAD. "dune." The Concise Oxford Dictionary of English Etymology. 1996. Retrieved May 26, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O27-dune.html |
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dune
dune
•afternoon, attune, autoimmune, baboon, balloon, bassoon, bestrewn, boon, Boone, bridoon, buffoon, Cameroon, Cancún, cardoon, cartoon, Changchun, cocoon, commune, croon, doubloon, dragoon, dune, festoon, galloon, goon, harpoon, hoon, immune, importune, impugn, Irgun, jejune, June, Kowloon, lagoon, lampoon, loon, macaroon, maroon, monsoon, moon, Muldoon, noon, oppugn, picayune, platoon, poltroon, pontoon, poon, prune, puccoon, raccoon, Rangoon, ratoon, rigadoon, rune, saloon, Saskatoon, Sassoon, Scone, soon, spittoon, spoon, swoon, Troon, tune, tycoon, typhoon, Walloon
•fortune, misfortune
•vodun • veldskoen • honeymoon
•forenoon • tablespoon • teaspoon
•soupspoon • dessertspoon • Neptune
•tribune • triune • opportune
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"dune." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. 26 May. 2012 <http://www.encyclopedia.com>. "dune." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. (May 26, 2012). http://www.encyclopedia.com/doc/1O233-dune.html "dune." Oxford Dictionary of Rhymes. 2007. Retrieved May 26, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O233-dune.html |
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