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The frost line—also known as frost depth or freezing depth—is most commonly the depth to which the groundwater in soil is expected to freeze. The frost depth depends on the climatic conditions of an area, the heat transfer properties of the soil and adjacent materials, and on nearby heat sources.
The active layer thickness is the maximum thaw depth over a period of two years. The layer of soil over the thaw depth is called the active layer, while the soil below is called permafrost. The term frost front refers to the varying position of the thaw line during the periods of freezing/thawing.
The red dotted-to-solid line depicts the average temperature profile with depth of soil in a permafrost region. The trumpet-shaped lines at the top show seasonal maximum and minimum temperatures in the "active layer", which commences at the depth where the maximum annual temperature intersects 0 °C. The active layer is seasonally frozen.
Photograph taken 21 March 2010 in Norwich, Vermont. Frost heaving (or a frost heave) is an upwards swelling of soil during freezing conditions caused by an increasing presence of ice as it grows towards the surface, upwards from the depth in the soil where freezing temperatures have penetrated into the soil (the freezing front or freezing boundary).
In soil science, the sporadic permafrost zone is abbreviated SPZ and the extensive discontinuous permafrost zone DPZ. [33] Exceptions occur in un-glaciated Siberia and Alaska where the present depth of permafrost is a relic of climatic conditions during glacial ages where winters were up to 11 °C (20 °F) colder than those of today.
A soil map is a geographical representation showing diversity of soil types or soil properties (soil pH, textures, organic matter, depths of horizons etc.) in the area of interest. [1] It is typically the result of a soil survey inventory, i.e. soil survey .
Cut-away section of soil, showing movement of soil layers due to cryoturbation. In gelisols (permafrost soils), cryoturbation (frost churning) refers to the mixing of materials from various horizons of the soil down to the bedrock due to freezing and thawing. Cryoturbation occurs to varying degrees in most gelisols.
The three types of taliks. A talik is a layer of year-round unfrozen ground that lies in permafrost areas. In regions of continuous permafrost, taliks often occur underneath shallow thermokarst lakes and rivers, where the deep water does not freeze in winter and thus the soil underneath does not freeze either.