 Cryosolic soils, occupying about 3 672 000 km2 (about 40%) of Canada's land area, are dominant in much of the Yukon, Northwest Territories and Nunavut and occur in northern areas of all but the Atlantic provinces (excluding Labrador).The order and its 3 great groups were defined in 1973, after soil and terrain surveys in the Mackenzie Valley yielded new knowledge about the properties, genesis and significance of these soils.Turbic Cryosols have a patterned surface (hummocks, stone nets, etc.)