Pingo

[3] It is estimated that there are more than 11,000 pingos on Earth,[4] with the Tuktoyaktuk peninsula area having the greatest concentration at a total of 1,350.

Pingos can collapse due to the melting of the supporting ice and give rise to a depression in the landscape showing an inverse shape (horizontal mirror).

[9] These pingos are found in flat, poorly drained areas with limited groundwater available such as shallow lakes and river deltas.

[10] This type of closed system pingos is formed in an area where a lake has been infilled with sediment.

However, during summer months the ice core of the pingo begins to melt which causes the mound to cave in.

[10] Hydraulic (open-system) pingos result from groundwater flowing from an outside source, i.e. sub-permafrost or intra-permafrost aquifers.

Hydrostatic pressure initializes the formation of the ice core as water is pushed up and subsequently freezes.

[2] The groundwater is put under artesian pressure and forces the ground up as it makes an expanding ice core.

These conditions allow an ice core to form, but also provide it with a supply of artesian ground water.

[9] The thickness of the permafrost at Disko Bay is around 150 m (490 ft) deep, providing for ideal conditions for the development of closed system pingos.

[13] The Tuktoyaktuk Peninsula is an area with a marine tundra environment on the shores of the Arctic Ocean in the Northwest Territories, Canada.

The Kadleroshilik Pingo is 54 m (177 ft) in height, but is continuing to rise in elevation by a few centimeters a year.

[14] In Siberia, an area containing a high density of close system pingos can be found near Yakutsk located on the Lena River.

[9] For example, the Tibetan Plateau has pingos at above 4,000 m (13,000 ft) in elevation due to its permanently frozen terrain.

Some depressions found in Jutland, and some circular lakes in the Finnmarksvidda plateau may be remnants of collapsed pingos.

[20] Pingos are vulnerable to surface disturbance given the considerable amount of ground ice stored within them.