Pingos and Ice-wedge polygons

Pingos and ice-wedge polygons are large scale landforms found in periglacial regions and are responsible for some of the most striking features in periglacial environments today.


From the Inuit word ‘hill’, pingos are dome-shaped hills found in periglacial environments.

Pingos can be up to 500m in diameter and 50m high (see Figure 1 for an example) and are generally found in permafrost regions (where ground temperatures have remained below 0°C for at least 2 years) of Arctic North America and northern Asia 1.

Figure 1: Pingos near Tuktoyaktuk, Northwest Territories, Canada. Photo credit: Emma Pike, Public domain, via Wikimedia Commons.

FUN FACT: The highest concentration of pingos is located in the Tuktoyaktuk Peninsular, on the Mackenzie Delta, Canada, home to 1350 identified examples! 2.

Formation of pingos

Generally, two types of pingo exist. Firstly we have ‘closed- system’ (hydrostatic) pingos and second we have ‘open-system’ (hydraulic) pingos 4 (Figure 2).

Both types of pingo can rupture through the surface and collapse, to leave behind relic pingos, identifiable by circular ramparts generally filled with water (Figure 1b).  

Open system pingosClosed system pingos
Open system pingos occur in areas with discontinuous permafrost. Here, islands of frozen ground are separated by small pockets of unfrozen ground. As a result, open system pingos are generally found in valley bottoms.

  Open system pingos develop as groundwater flowing down through permeable soils is forced to the surface by artesian pressure and freezes, forming an ice lens 5.
Closed system pingos occur in areas of continuous permafrost. Here the ground only melts superficially (on the surface). As a result, closed system pingos are generally found in lowland regions.

In closed systems, water confined in unfrozen material within the permafrost – known as talik – freezes to form an ice lens. This ice lens is forced to the surface through upheave activity of the permafrost beneath2.
Table 1: Types of pingos found in periglacial environments; open system and closed systems.
Pingo formation in periglacial environments
Figure 2: Diagram to illustrate the formation of open-system and closed-system pingos, showing the effect of artesian pressure and hydrostatic pressure on the ice lens. Credit: Encyclopaedia Britannica.

Ice wedge polygons

Ice wedge polygon formation in periglacial environments
Figure 3: Diagram to illustrate the development of ice wedges over time, with repeat cycles of freeze and thaw. Credit: Caroline Taylor.

In short, ice wedge polygons are the result of repeat frost cracking and ice-vein growth occurring over hundreds to thousands of years. The process of ice wedging happens exclusively in the upper horizons of permafrost, resulting in striking landforms.

Firstly, water held within surface cracks freezes in the winter to form an ice vein. In doing so the crack expands. Then in the following spring, these veins thaw, before refreezing the following winter.

Over time, this cycle of freeze and thaw expands the cracks significantly to form ice-wedges (Figure 4).

Irregular Polygons

As a result of the repeat freeze-thaw activity described above networks of interconnected ice wedges develop beneath the ground. However on the surface, they appear as irregular polygons (Figure 4). Generally, irregular polygons are between 5 and 40 m in diameter 6 and are one of the most recognisable landforms found in periglacial landscapes today.

Examples of periglacial landforms
Figure 4: Left: Example of an ice wedge on Garry Island, Northwest Territories, Canada. The wedge is about 2 m wide and 6 m deep. Credit: 7. Right: A net of vegetated low-centre ice-wedge polygons with a typical diameter of 30 m, on Banks Island. Photo credit: Worsley, 2014.



1. Grosse, G. & Jones, B. M. Spatial distribution of pingos in northern Asia. Cryosphere 5, 13–33 (2011). 

2. Bennett, M. R. Pingos. in Encyclopedia of Earth Sciences Series 331–335 (Springer Netherlands, 2009). doi:10.1007/978-1-4020-4411-3_187. 

3. Wolfe, S. A., Morse, P. D., Parker, R. & Phillips, M. R. Distribution and morphometry of pingos, western Canadian Arctic, Northwest Territories, Canada. Geomorphology 431, 108694 (2023). 

4. Mackay, J. R. Pingo growth and collapse, Tuktoyaktuk Peninsula area, western arctic coast, Canada: A long-term field study. Geogr. Phys. Quat. 52, 271–323 (1998). 

5. Berry, T. W., Fish, P. R., Price, S. J. & Hadlow, N. W. Periglacial geohazards in the UK. in Geological Society Engineering Geology Special Publication vol. 29 259–289 (Geological Society of London, 2020). 

6. Morse, P. D. & Burn, C. R. Field observations of syngenetic ice wedge polygons, outer Mackenzie Delta, western Arctic coast, Canada. J. Geophys. Res. Earth Surf. 118, 1320–1332 (2013). 

7. Mackay, J. R. Thermally induced movements in ice-wedge polygons, western arctic coast: A long-term study. Geogr. Phys. Quat. 54, 41–68 (2000). 

8. Worsley, P. Ice-wedge growth and casting in a Late Pleistocene, periglacial, fluvial succession at Baston, Lincoinshire. Mercian Geol. 18, 159–170 (2014). 


I am a glaciologist and natural hazard scientist at Newcastle University. My research focusses on the risk of Glacial Lake Outburst Floods (GLOFs), to help communities better prepare for, respond to, and live alongside hazards.

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