Arctic soils have a wide range of textures, including clay, silty clay, loam, sandy loam and coarse gravelly sand (Table 1.3), with the texture depending mainly on the mode of deposition of the parent material.
The structure of the soil, as has already been mentioned in the macromorphology section (see Sect. 1.5.1), is the result of cryogenic processes. The granular structure (Table 1.3) is the result of freeze-thaw processes, which induce desiccation and rolling by frost action. The common platy structure (Table 1.3) is the result of vein ice formation, as is shown in Fig. 1.6. The massive structure is the result of cryo-desiccation during freeze-back.
One of the unique features of Arctic soils is that not all of the water in the permafrost layer is in the form of ice throughout the year. The ice in the subsoil is very dynamic, and increases in thickness and volume over time because of the migration of this liquid water along the thermal gradient from warm to cold.
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