Earth Hummocks in the Sunshine Area of the Rocky Mountains, Alberta and British Columbia

Earth hummocks were found on the Continental Divide of the Rocky Mountains in a non-permafrost environment. Many hummocks show involutions of organic layers within 25 cm of the surface, suggesting that the hummocks are still active. The soil material is a non-plastic, silt-textured volcanic ash. During brief periods in the spring the upper soil horizons can become super-saturated with water; the soil then becomes liquid, resulting in involutions in the surface layers. This mechanism is generally erosional and it is unlikely that it contributed to the formation of earth hummocks. The hummocks are believed to be relict features that were formed under colder conditions, when permafrost was likely present in the ground. Key words: Rocky Mountains, hummocks, permafrost, soil horizons