Active patterned ground at sea level, Fourchu, Nova Scotia, Canada

A field of nonsorted circles was discovered along the southeast coast of Cape Breton Island, Nova Scotia, that appear to be actively forming. The circles vary in their degree of development from prominent well-developed forms with flat bare centers and vegetated raised rims to incipient circles nearly covered with vegetation. Current activity of the forms is indicated by recently displaced ploughing blocks, sediment displacement along frost cracks, and oriented stones lying within the loosely packed rims. The formation of patterned ground in this relatively mild maritime environment is attributed to a saturated soil layer, similar to the active layer of permafrost, that is maintained by impermeable bedrock and high annual precipitation. The saturated sediment and frequent freeze-thaw cycles during winter provide a mechanism for the formation and maintenance of patterned ground. -from Authors