A nunatak (from Inuit 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, and smaller nunataks rounded by glacial action may be referred to as rognons .
4-435: The Snow Nunataks (or Ashley Snow Nunataks ) are a line of four widely separated nunataks on the coast of Palmer Land , Antarctica , trending east–west for 20 mi (32 km) southward of Case Island . They consist of volcanic outcrops that probably represent several small subglacial volcanoes . Most of the nunataks are mounds of pillow lava overlain by lapilli tuffs . However, two of them may be tuyas due to
8-571: Is of Greenlandic origin and has been used in English since the 1870s. The term nunatak is typically used in areas where a permanent ice sheet is present and the ridge protrudes above the sheet. 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. Nunataks are generally angular and jagged, hampering
12-648: The existence of subaerially-chilled caprocks. The Snow Nunataks are uncertain in age but they probably formed in the Late Miocene or later. The nunataks were discovered by the United States Antarctic Service (USAS) (1939–41) and named for Ashley C. Snow , aviation pilot on the expedition. This Palmer Land location article is a stub . You can help Misplaced Pages by expanding it . 73°35′S 77°15′W / 73.583°S 77.250°W / -73.583; -77.250 Nunatak The word
16-467: 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
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