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Gelisols are an order in USDA soil taxonomy. They are soils of very cold climates which are defined as containing permafrost within two meters (6 ft 7 in) of the soil surface. The word "Gelisol" comes from the Latin gelare meaning "to freeze", a reference to the process of cryoturbation that occurs from the alternating thawing and freezing ...
USDA soil taxonomy (ST) developed by the United States Department of Agriculture and the National Cooperative Soil Survey provides an elaborate classification of soil types according to several parameters (most commonly their properties) and in several levels: Order, Suborder, Great Group, Subgroup, Family, and Series.
[1] The clay on the right is exposed to air and is oxidized a reddish hue. The clay on the left is identical, but sealed in a glass jar for two weeks in an anaerobic setting, causing redox and color change to gley.
In both the World Reference Base for Soil Resources (WRB) [1] and the USDA soil taxonomy, [2] a Histosol is a soil consisting primarily of organic materials. They are defined as having 40 centimetres (16 in) or more of organic soil material starting within 40 cm from the soil surface.
Cryoturbation occurs to varying degrees in most gelisols. The cause of cryoturbation lies in the way in which the repeated freezing of the soil during autumn causes the formation of ice wedges at the most easily erodible parts of the parent rock .
They form quickly through alteration of parent material. They are more developed than Entisols. [1] They have no accumulation of clays, iron oxide, aluminium oxide or organic matter. They have an ochric or umbric horizon and a cambic subsurface horizon. In the World Reference Base for Soil Resources (WRB), most Inceptisols are Cambisols or ...
The most distinctive landforms created by gelifluction include gelifluction lobes and gelifluction benches. The former refer to tongue-shaped deposits of geliflucted material orientated downslope that tend to form on slopes of between 10° and 20°, whereas the latter refer to terrace-like deposits forming on gentler slopes with a long axis running parallel to the slope contour.
Expansive clay, also called expansive soil, is a clay soil prone to large volume changes (swelling and shrinking) directly related to changes in water content. [1] Soils with a high content of expansive minerals can form deep cracks in drier seasons or years; such soils are called vertisols.