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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.
[2] [3] Gleysoils may be sticky and hard to work, especially where the gleying is caused by surface water held up on a slowly permeable layer. However, some ground-water gley soils have permeable lower horizons , including, for example, some sands in hollows within sand dune systems (known as slacks), and in some alluvial situations.
In the US, Gelisols occur only in parts of Alaska; they are characterized by having permafrost within 100 cm of the surface. Histosols are organic soils lacking permafrost within 100 cm of the surface; they are characteristically formed on wet sites, e.g. bogs, some fens and some muskeg areas. Some Histosols have been drained, especially to ...
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 .
However, Histosols formed on very recent glacial lands can often be very productive when drained and produce high-grade pasture for dairying or beef cattle. They can sometimes be used for fruit if carefully managed, but there is a great risk of the organic matter becoming dry powder and eroding under the influence of drying winds.
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.
Unweatherable parent materials – sand, iron oxide, aluminium oxide, kaolinite clay. Erosion – common on shoulder slopes; other kinds also important.; Deposition – continuous, repeated deposition of new parent materials by flood as diluvium, aeolian processes which means by wind, slope processes as colluvium, mudflows, other means.