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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 ...
Entisols: Least soil profile development; ochric epipedon is common; no B horizons; most common order by surface area (16.3% of global and 12.2% of U.S. ice-free land). Gelisols: Soils with permafrost within 100 cm or cryoturbation (frost churning) within 100 cm plus permafrost within 200 cm; commonly at high latitudes and elevations; 8.6% of ...
Wetness is the main limitation on agriculture of virgin gleysols; [2] these are covered with natural swamp vegetation and lie idle or are used for extensive grazing. Farmers use artificially-drained gleysols for arable cropping, dairy farming and horticulture. Gleysols in the tropics and subtropics are widely planted with rice.
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.
Andosols cover an estimated 1–2% of Earth's ice-free land surface. Andosols are a Reference Soil Group of the World Reference Base for Soil Resources (WRB). [ 2 ] They are closely related to other types of soils such as Vitrosols, Vitrandosols, Vitrons and Pumice Soils that are used in different soil classification systems.
Ten general strands or standards of mathematics content and processes were defined that cut across the school mathematics curriculum. Specific expectations for student learning, derived from the philosophy of outcome-based education, are described for ranges of grades (preschool to 2, 3 to 5, 6 to 8, and 9 to 12).
Mathematics Teacher: Learning and Teaching PK-12. According the the NCTM, this journal "reflects the current practices of mathematics education, as well as maintaining a knowledge base of practice and policy in looking at the future of the field. Content is aimed at preschool to 12th grade with peer-reviewed and invited articles."
The main processes of soil formation of oxisols are weathering, humification and pedoturbation due to animals. These processes produce the characteristic soil profile.They are defined as soils containing at all depths no more than ten percent weatherable minerals, and low cation exchange capacity.