Also known as Cryosols in the UN Food and Agriculture Organization. From the latin word 'gelare' meaning "to freeze".
Although some Gelisols may occur on very old land surfaces, they show relatively little morphological development. Low soil temperatures cause soil-forming processes such as decomposition of organic materials to proceed very slowly. As a result, Gelisols store large quantities of organic carbon - only soils of wetland ecosystems contain more organic matter.
Gelisols are soils of very cold climates that contain permafrost within 2 meters of the surface. These soils are limited geographically to the high-latitude polar regions and localized areas at high mountain elevations. Because of the extreme environment in which they are found, Gelisols support only ~0.4% of the world's population - the lowest percentage of any of the soil orders.
The frozen condition of Gelisol landscapes makes them sensitive to human activities.
Histels - Gelisols that have large quantities of organic matter (80% or more within 50 cm of the surface) that commonly accumulate under anaerobic conditions, or organic matter partially fills voids in other soil materials.
Turbels - Gelisols that have evidence of extensive mixing by frost action (cryoturbation). Soils must have adaquate moisture to allow cryoturbation. Turbels account for around 1/2 of Gelisols on a global basis. Most common in High and Middle Arctic vegetation at latitudes of 65 degrees N. or more.
Orthels - soils that show little or no cryoturbation (less than one-third of the depth of the active layer). Patterned ground (except for polygons) generally is lacking. Orthels occur primarily within the zone of widespread permafrost, and in alpine areas.