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Cântaro Magro, Serra da Estrela, Portugal, formed as a nunatak during the last ice age and now exposed[1]

A nunatak (from Inuit nunataq) is an exposed, often rocky element of a ridge, mountain, or peak not covered with ice or snow within (or at the edge of) an ice field or glacier. They are also called glacial islands.[2] Examples are natural pyramidal peaks. When rounded by glacial action, smaller rock promontories may be referred to as rognons.[3][4]

The word is of Greenlandic origin[5] and has been used in English since the 1870s.

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DescriptionEdit

The term is typically used in areas where a permanent ice sheet is present and the nunataks protrude above the sheet.[6] Nunataks present readily identifiable landmark reference points in glaciers or ice caps and are often named. While some nunataks are isolated, sometimes they form dense clusters, such as Queen Louise Land in Greenland.[7]

Nunataks are generally angular and jagged, which hampers the formation of glacial ice on their tops, although snow can accumulate on them. They usually contrast strongly with the softer contours of the glacially eroded land after a glacier retreats.

Typically nunataks are the only places where plant life can survive on ice sheets or ice caps. Lifeforms on nunataks are frequently isolated by the surrounding ice or glacier, providing unique habitats.[8]

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See alsoEdit

  • Fell – High and barren landscape feature
  • Glacial landform – Landform created by the action of glaciers

ReferencesEdit

  1. ^ Vieira, G.T.; Ferreira, A.B. (1998). "General characteristics of the glacial geomorphology of the Serra da Estrela" (PDF). In G.T. Vieira (ed.). Glacial and Periglacial Geomorphology of the Serra da Estrela. Guidebook for the field-trip IGU Commission on Climate Change and Periglacial Environments, 26-28 August1998. pp. 37–48. Retrieved October 16, 2011.
  2. ^ Physical Geography: Hydrosphere, 2006, ISBN 8183561675, p. 114
  3. ^ Neuendorf, Klaus K. E.; Institute, American Geological (2005). Glossary of Geology. Springer Science & Business Media. ISBN 9780922152766.
  4. ^ "Rognon definition and meaning | Collins English Dictionary". www.collinsdictionary.com. Retrieved 2019-02-06.
  5. ^ "Merriam-Webster: nunatak". Retrieved October 16, 2011.
  6. ^ J. J. Zeeberg, Climate and Glacial History of the Novaya Zemlya Archipelago, Russian Arctic. pp. 82-84
  7. ^ "Dronning Louise Land". Mapcarta. Retrieved 2 July 2016.
  8. ^ ice cap - National Geographic Society

External linksEdit