Hydrolaccolith:
A pingo, also called a hydrolaccolith,[1] is a mound of earth-covered ice found in the Arctic and subarctic that can reach up to 70 metres (230 ft) in height and up to 600 m (2,000 ft) in diameter. The term originated as the Inuvialuktun word for a small hill. The plural form is “pingos”. [Wikipedia]
