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Nivation

 
(nī′vā·shən)

(geology) Rock or soil erosion beneath a snowbank or snow patch, due mainly to frost action but also involving chemical weathering, solifluction, and meltwater transport of weathering products. Also known as snow patch erosion.


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Geography Dictionary: nivation
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The effects of snow on a landscape. These include abrasion and freeze-thaw. Furthermore, melted snow triggers mass movements such as solifluction and slope wash. These processes may produce the shallow pits known as nivation hollows. In time, these hollows may trap more snow and may deepen further with more nivation so that cirques or thermocirques are formed. Nivation is 2-3 times as active on shaded, pole-facing slopes. See aspect. Snow has the greatest effect on a landscape where it is thin and melting.

Wikipedia: Nivation
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Nivation is a collective name for the different processes that occur under a snow patch. One of them are the alternative freeze and thaw by which fallen snow gets converted into mass of ice or Névé, hence the term, nivation. The term glacier is applied only when the ice has accumulated enough for the mass to reach the moving stage. [1]

Nivation has nowadays come to include various subprocesses related to snow patches which may be immobile or semi-permanent. These sub-processes include erosion (if any) or initiation of erosion, weathering, meltwater flow from beneath the snowpatch etc.

Freeze-thaw action and possibly chemical weathering, operating under the snow, the weathered particles are moved downslope by the meltwater and also by solifluction. Over some time, this leads to the formation of nivation hollows which, when enlarged, can be the beginnings of a corrie (cirque).

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Sci-Tech Dictionary. McGraw-Hill Dictionary of Scientific and Technical Terms. Copyright © 2003, 1994, 1989, 1984, 1978, 1976, 1974 by McGraw-Hill Companies, Inc. All rights reserved.  Read more
Geography Dictionary. A Dictionary of Geography. Copyright © Susan Mayhew 1992, 1997, 2004. All rights reserved.  Read more
Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Nivation" Read more