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nunatak

{{short description|Landform within an ice field or glacier}}

{{otheruses}}

File:Einzelne, bis zu 3000 Meter hohe Bergspitzen ragen aus dem südpolaren Eispanzer hervor (24327852733).jpg

File:Estrela Março 2010-16b.jpg, Portugal, formed as a nunatak during the last ice age and now exposed

{{cite book

|last1=Vieira

|first1=G.T.

|last2=Ferreira

|first2=A.B.

|editor=G.T. Vieira

|title=Glacial and Periglacial Geomorphology of the Serra da Estrela. Guidebook for the field-trip IGU Commission on Climate Change and Periglacial Environments, 26–28 August 1998

|chapter-url=http://www.fl.ul.pt/pessoais/gtvieira/ficheiros_download/Glacial%20Geomorphology%20of%20the%20Serra%20da%20Estrela.pdf

|year=1998

|pages=37–48

|chapter=General characteristics of the glacial geomorphology of the Serra da Estrela

|access-date=October 16, 2011

}}]]

A nunatak (from Inuit {{Lang|kl|nunataq}}) is the summit or ridge of a mountain that protrudes from an ice field or glacier that otherwise covers most of the mountain or ridge. They often form natural pyramidal peaks. Isolated nunataks are also called glacial islands,Physical Geography: Hydrosphere, 2006, {{ISBN|8183561675}}, [https://books.google.com/books?id=T1Y_Ytx9wp4C&pg=PA114 p. 114] and smaller nunataks rounded by glacial action may be referred to as rognons.{{Cite book|url=https://books.google.com/books?id=yD79FqfECCYC&pg=PA560|title=Glossary of Geology|last1=Neuendorf|first1=Klaus K. E.|last2=Institute|first2=American Geological|date=2005|publisher=Springer Science & Business Media|isbn=9780922152766|language=en}}{{Cite web|url=https://www.collinsdictionary.com/dictionary/english/rognon|title=Rognon definition and meaning {{!}} Collins English Dictionary|website=www.collinsdictionary.com|language=en|access-date=2019-02-06}}

The word is of Greenlandic origin

{{Cite web

|title=Merriam-Webster: nunatak

|url=http://www.m-w.com/cgi-bin/dictionary?va=nunatak

|access-date=October 16, 2011

}} and has been used in English since the 1870s.

Description

The term nunatak is typically used in areas where a permanent ice sheet is present and the ridge protrudes above the sheet.J. J. Zeeberg, Climate and Glacial History of the Novaya Zemlya Archipelago, Russian Arctic. pp. 82–84 Nunataks present readily identifiable landmark reference points in glaciers or ice caps and are often named. While some are isolated, they can also form dense clusters, such as Queen Louise Land in Greenland.{{cite web|url=http://mapcarta.com/19193676|title=Dronning Louise Land|work=Mapcarta|access-date=2 July 2016}}

Nunataks are generally angular and jagged, hampering the formation of glacial ice on their tops, although snow can accumulate on them. This can contrast strongly with the softer contours of the glacially eroded land after a glacier retreats. They are not greatly affected by frost weathering, given the low frequency of freeze-thaw cycles in areas of ice caps and ice sheets.{{Cite book |title=Introduction à la Géomorphologie Climatique |last1=Tricart |first1=Jean |year=1968 |language=French |last2=Cailleux |first2=André |chapter= |author-link1=Jean Tricart |author-link2=André Cailleux}}{{page needed|date=November 2022}}

Typically nunataks are the only places where plant life can survive on ice sheets or ice caps. Lifeforms on nunataks are often isolated by the surrounding ice or glacier, providing unique habitats.[http://nationalgeographic.org/encyclopedia/ice-cap/ ice cap – National Geographic Society]

List

{{main|List of nunataks}}

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See also

  • {{annotated link|Fell}}
  • {{annotated link|Glacial landform}}

References

{{Reflist|2}}

External links

  • {{commonscat inline}}
  • [http://onlinelibrary.wiley.com/doi/10.1046/j.1365-294X.2002.01595.x/abstract Nunatak survival of the high Alpine plant Eritrichium nanum]

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Category:Glaciology

Nunatak