Gelisol
Figure 3-3. A soil (a Glacistel in Alaska) with a permanently frozen ice layer (designated “Wf”) between depths of 60 and 130 cm.
(Soil Survey Manual, USDA Handbook No. 18; issued March 2017).
Glacistels are the Histels that are saturated with water for 30 or more cumulative days during normal years and that have both a glacic layer within 100 cm of the soil surface; and less than three-fourths (by volume) Sphagnum fibers in the organic soil material to a depth of 50 cm or to a densic, lithic, or paralithic contact, whichever is shallower.
Histels have organic soil materials that meet one or more of the following:
1. Overlie cindery, fragmental, or pumiceous materials and/or fill their interstices and directly below these materials have either a densic, lithic, or paralithic contact; or
2. When added with the underlying cindery, fragmental, or pumiceous materials, total 40 cm or more between the soil surface and a depth of 50 cm; or
3. Comprise 80 percent or more, by volume, from the soil surface to a depth of 50 cm or to a glacic layer or a densic, lithic, or paralithic contact, whichever is shallower.
Soil Profile: These somewhat poorly drained soils have very high runoff. The saturated hydraulic conductivity is moderately high in the alluvium mantle and impermeable in the permafrost.
Landscape: The soils are used for recreation and wildlife habitat. The native vegetation includes black spruce and rose. In the US, they occur mostly in the Interior Alaska Highlands. The series is of small extent.
The central concept of Gelisols is that of soils with gelic materials underlain by permafrost. Freezing and thawing are important processes in Gelisols. Gelic materials are mineral or organic soil materials that show evidence of cryoturbation (frost churning) and/or ice segregation in the active layer (seasonal thaw layer) and/or the upper part of the permafrost.
Permafrost is defined as a thermal condition in which a material (including soil material) remains below 0 degrees C for 2 or more years in succession. Those gelic materials having permafrost contain the unfrozen soil solution that drives cryopedogenic processes. Permafrost may be impregnated by ice or, in the case of insufficient interstitial water, may be dry. The frozen layer has a variety of ice lenses, vein ice, segregated ice crystals, and ice wedges. The permafrost table is in dynamic equilibrium with the environment.
A glacic layer is massive ice or ground ice in the form of ice lenses or wedges. The layer is 30 cm or more thick and contains 75 percent or more visible ice.
For more information about describing, sampling, classifying, and/or mapping soils, please refer to the following references: "Field Book for Describing and Sampling Soils", "Keys to Soil Taxonomy", and the "Soil Survey Manual".
Gelisol
Figure 3-3. A soil (a Glacistel in Alaska) with a permanently frozen ice layer (designated “Wf”) between depths of 60 and 130 cm.
(Soil Survey Manual, USDA Handbook No. 18; issued March 2017).
Glacistels are the Histels that are saturated with water for 30 or more cumulative days during normal years and that have both a glacic layer within 100 cm of the soil surface; and less than three-fourths (by volume) Sphagnum fibers in the organic soil material to a depth of 50 cm or to a densic, lithic, or paralithic contact, whichever is shallower.
Histels have organic soil materials that meet one or more of the following:
1. Overlie cindery, fragmental, or pumiceous materials and/or fill their interstices and directly below these materials have either a densic, lithic, or paralithic contact; or
2. When added with the underlying cindery, fragmental, or pumiceous materials, total 40 cm or more between the soil surface and a depth of 50 cm; or
3. Comprise 80 percent or more, by volume, from the soil surface to a depth of 50 cm or to a glacic layer or a densic, lithic, or paralithic contact, whichever is shallower.
Soil Profile: These somewhat poorly drained soils have very high runoff. The saturated hydraulic conductivity is moderately high in the alluvium mantle and impermeable in the permafrost.
Landscape: The soils are used for recreation and wildlife habitat. The native vegetation includes black spruce and rose. In the US, they occur mostly in the Interior Alaska Highlands. The series is of small extent.
The central concept of Gelisols is that of soils with gelic materials underlain by permafrost. Freezing and thawing are important processes in Gelisols. Gelic materials are mineral or organic soil materials that show evidence of cryoturbation (frost churning) and/or ice segregation in the active layer (seasonal thaw layer) and/or the upper part of the permafrost.
Permafrost is defined as a thermal condition in which a material (including soil material) remains below 0 degrees C for 2 or more years in succession. Those gelic materials having permafrost contain the unfrozen soil solution that drives cryopedogenic processes. Permafrost may be impregnated by ice or, in the case of insufficient interstitial water, may be dry. The frozen layer has a variety of ice lenses, vein ice, segregated ice crystals, and ice wedges. The permafrost table is in dynamic equilibrium with the environment.
A glacic layer is massive ice or ground ice in the form of ice lenses or wedges. The layer is 30 cm or more thick and contains 75 percent or more visible ice.
For more information about describing, sampling, classifying, and/or mapping soils, please refer to the following references: "Field Book for Describing and Sampling Soils", "Keys to Soil Taxonomy", and the "Soil Survey Manual".