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, Portugal, formed as a nunatak during the last ice age and now exposed ]] A nunatak (from Inuit language 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 . Isolated nunataks are also called glacial islands, Physical Geography: Hydrosphere, 2006, , p. 114 and smaller nunataks rounded by glacial action may be referred to as rognons.
The word is of Greenlandic origin and has been used in English since the 1870s.
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.
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.
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