Vertisolic Soils map
These soils occupy less than 1% of the land area of Canada.
Vertisolic soils are found throughout the Prairie Ecozone on parent materials high in clay (i.e., greater than 60 % clay). Typically they occupy level landsurfaces such as the Eston and Regina Plains that were glacial lakes during the retreat of the last (Wisconsinan) glaciers. The heavy clay swells when wet and shrinks when the soil dries out, which causes cracking at the soil surface and mixing of the soil layers underneath the surface. Because of the mixing, soil horizons of the Vertisols are relatively weakly developed compared to comparable Chernozemic soils.
The physical disruption associated with shrinking and swelling produces shiny shear planes (slickensides) in the subsoil and either prevents the formation of subsurface horizons or severely disrupts and mixes them