Gelisol

Gelisols are an order in USDA soil taxonomy. They are soils of very cold climates which are defined as containing permafrost within two meters 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 characteristic of Gelisols.

In the World Reference Base for Soil Resources[1] (WRB), Gelisols are known as Cryosols. In soil taxonomy, Gelisols key out before the Histosols. In the WRB, the Histosols key out before the Cryosols. Organic permafrost soils are therefore Gelisols (Histels) in the soil taxonomy and Histosols (Cryic Histosols) in the WRB.

Structurally, Gelisols may have a B horizon and more commonly have an A horizon and/or O horizon resting on the permafrost. Because soil organic matter accumulates in the upper layer, most Gelisols are black or dark brown in soil color, followed by a shallow mineral layer. Despite the influence of glaciation in most areas where Gelisols occur, chemically they are not highly fertile because nutrients, especially calcium and potassium, are very easily leached above the permafrost. The permafrost greatly restricts the engineering use of Gelisols, as large structures (e.g. buildings) subside as the frozen earth thaws when they are put in place.

Gelisols are found chiefly in Siberia, Alaska and Canada. Smaller areas are found in the Andes (mainly near the intersection between Chile, Bolivia and Argentina), Tibet, northern Scandinavia and the ice-free parts of Greenland and Antarctica. Fossil Gelisols are known from as far back as Precambrian ice ages 900 million years ago.

Gelisol
Gelisol profile
a Gelisol profile
Used inUSDA soil taxonomy
ProfileOAC
Key processcryoturbation
Parent materialpeat, other
Climatesubarctic, tundra

Suborders

In USDA soil taxonomy, Gelisols are subdivided into:

  • Histels: organic soils similar to histosols except that they have permafrost within two meters below ground surface. They have 80% or more organic materials from the soil surface to a depth of 50 cm or to a glacic layer or densic, lithic, or paralithic contact, whichever is shallowest. These soils occur predominantly in subarctic and low arctic regions of continuous or widespread permafrost. Less than one-third of the active layer (the soil between the ground surface and a permafrost table) or an ice layer which is at least 30-cm thick has been cryoturbated.
  • Turbels: soils that show marked influence of cryoturbation (more than one-third of the depth of the active layer) such as irregular, broken, or distorted horizon boundaries and involutions and areas with patterned ground. They commonly contain tongues of mineral and organic horizons, organic and mineral intrusions and oriented rock fragments. Organic matter is accumulated on top of the permafrost and ice or sand wedges are a common features. Turbels occur primarily in the zone of continuous permafrost.
  • 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 discontinuous permafrost, and in alpine areas.

See also

Weblinks

References

  • Soil Survey Staff: Keys to Soil Taxonomy. 12th edition. Natural Resources Conservation Service. U.S. Department of Agriculture. Washington D.C., USA, 2014.
  • "Gelisols". USDA-NRCS. Archived from the original on 2006-05-09. Retrieved 2006-05-14.
  • "Gelisols". University of Florida. Archived from the original on September 18, 2004. Retrieved 2006-05-14.
  • "Gelisols". University of Idaho. Retrieved 2006-05-14.
  • "Permafrost Soils and Biogeochemistry" (PDF). University of Wisconsin. Archived from the original (pdf) on 2004-03-20. Retrieved 2006-05-14.
  1. ^ IUSS Working Group WRB (2015). "World Reference Base for Soil Resources 2014, Update 2015" (PDF). World Soil Resources Reports 106, FAO, Rome.
Lithalsa

Lithalsa is a frost-induced raised land form in permafrost areas with mineral-rich soils, where a perennial ice lens has developed within the soil. The term sometimes also refers to palsas and pingos.

Paleopedological record

The paleopedological record is, essentially, the fossil record of soils. The paleopedological record consists chiefly of paleosols buried by flood sediments, or preserved at geological unconformities, especially plateau escarpments or sides of river valleys. Other fossil soils occur in areas where volcanic activity has covered the ancient soils.

Siberia

Siberia (; Russian: Сиби́рь, tr. Sibír';, IPA: [sʲɪˈbʲirʲ] (listen)) is an extensive geographical region spanning much of Eurasia and North Asia. Siberia has historically been a part of modern Russia since the 17th century.

The territory of Siberia extends eastwards from the Ural Mountains to the watershed between the Pacific and Arctic drainage basins. The Yenisei River conditionally divides Siberia into two parts, Western and Eastern. Siberia stretches southwards from the Arctic Ocean to the hills of north-central Kazakhstan and to the national borders of Mongolia and China.With an area of 13.1 million square kilometres (5,100,000 sq mi), Siberia accounts for 77% of Russia's land area, but it is home to approximately 36 million people—27% of the country's population. This is equivalent to an average population density of about 3 inhabitants per square kilometre (7.8/sq mi) (approximately equal to that of Australia), making Siberia one of the most sparsely populated regions on Earth. If it were a country by itself, it would still be the largest country in area, but in population it would be the world's 35th-largest and Asia's 14th-largest.

Worldwide, Siberia is well known primarily for its long, harsh winters, with a January average of −25 °C (−13 °F), as well as its extensive history of use by Russian and Soviet administrations as a place for prisons, labor camps, and exile.

USDA soil taxonomy

USDA soil taxonomy (ST) developed by 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. The classification was originally developed by Guy Donald Smith, former director of the U.S. Department of Agriculture's soil survey investigations.

USDA soil taxonomy
World Reference Base
for Soil Resources
(1998–)
Other systems
Non-systematic soil types

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