Permafrost facts for kids

Two men dig in Alaska to study soil. A jackhammer is used to break the hard permafrost

In geology, permafrost is soil that stays at or below 0 °C (32 °F) for two or more years. It is also called cryotic soil. Most permafrost is on land close to the North and South poles.

Landforms

Permafrost processes manifest themselves in large-scale land forms, such as palsas and pingos and smaller-scale phenomena, such as patterned ground found in arctic, periglacial and alpine areas.

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  A group of palsas, as seen from above, formed by the growth of ice lenses.

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  Pingos near Tuktoyaktuk, Northwest Territories, Canada

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  Ground polygons

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  Stone rings on Spitsbergen

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  Ice wedges seen from top

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  Solifluction on Svalbard

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  Contraction crack (ice wedge) polygons on Arctic sediment.

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  Cracks forming at the edges of the Storflaket permafrost bog in Sweden.

Images for kids

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  Slope failure of permafrost soil, revealing the top of an ice wedge.

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  Southern limit of permafrost in Eurasia according to Karl Ernst von Baer (1843), and other authors.

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  Red lines: Seasonal temperature extremes (dotted=average).

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  Massive blue ground ice exposure on the north shore of Herschel Island, Yukon, Canada.

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  Several types of massive ground ice, including ice wedges and intrasedimental ice within the cliff wall of a retrogressive thaw slump located on the southern coast of Herschel Island within an approximately 22-metre (72 ft) by 1,300-metre (4,300 ft) headwall.

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  Recently thawed Arctic permafrost and coastal erosion on the Beaufort Sea, Arctic Ocean, near Point Lonely, Alaska in 2013.

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  A peat plateau complex south of Fort Simpson, Northwest Territories

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  Thawing permafrost in Herschel Island, Canada, 2013

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  Permafrost and ice in Herschel Island, Canada, 2012

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  Permafrost thaw ponds on peatland in Hudson Bay, Canada in 2008.

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  Permafrost polygons on Mars imaged by the Phoenix lander.

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  False-color Mars Reconnaissance Orbiter image of polygonal surface pattern.

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  Patterned ground on earth.

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  Modern buildings in permafrost zones may be built on piles to avoid permafrost-thaw foundation failure from the heat of the building.

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  Heat pipes in vertical supports maintain a frozen bulb around portions of the Trans-Alaska Pipeline that are at risk of thawing.

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  Pile foundations in Yakutsk, a city underlain with continuous permafrost.

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  District heating pipes run above ground in Yakutsk to avoid thawing permafrost.

See also

In Spanish: Permafrost para niños