Periglacial processes

Parts of the Arctic that are not permanently frozen, where the less extreme climate means that ice and snow melt for a period during the summer months, are described as being periglacial.

Periglacial Nunavut

Nunavut, the most northerly territory of Canada, is located in the periglacial Arctic.

Nunavut landscape
Nunavut landscape
Qikiqtarjuaq
Qikiqtarjuaq community, Broughton Island, Nunavut
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Climate data for Nunavut

MonthAverage temperature (°C)Precipitation (mm)
January-26.422
February-27.119
March-23.621
April-1528
May-4.729
June2.826
July758
August6.262
September1.652
October-5.143
November-1332
December-22.120
  • Use the data above to draw a climate graph for Nunavut, in the Arctic periglacial region. Annotate the key features that you think makes this climate distinctive. Consider, for example, the length of the growing season and the amount and distribution of precipitation throughout the year.
  • What characteristics do you think vegetation would need to be able to grow in these conditions?

Tundra

In the summer months, temperatures in periglacial areas such as Nunavut rise above freezing, and the top layer of soil thaws, although it remains underlain by permanently frozen ground (permafrost).

The thin layer of unfrozen soil above the permafrost supports vegetation typical of the tundra biome. The name ‘tundra’ comes from the Finnish word for a barren or treeless land. Tundra vegetation has adapted to growing in thin, nutrient poor soils which are often waterlogged due to poor drainage: water is prevented from infiltrating through the frozen permafrost beneath it. In the tundra of Nunavut, species such as mosses, sedges, grasses and saxifrages have adapted to the conditions in the following ways:

  • Low-growing and cushion-like form for protection and insulation from the strong winds
  • Hairy stems to retain heat
  • Thick waxy leaves to reduce transpiration
  • Shallow roots that grow in the thin layer of soil above the permafrost
  • The ability to flower and produce seeds in a short period of time to take advantage of the short growing season, which may be only 50-60 days long
  • The ability to photosynthesise in low temperatures.
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Aaju talks about the summer flowering of the tundra, and the extremely small trees. “If you get lost in the forest, just stand up!”

In Nunavut, animal species such as the caribou are reliant on the summer food options provided by the tundra vegetation. In winter, hardy lichens provide an important food source. Herbivores in turn support predatory species such as the Arctic wolf; in total 20 species of mammal inhabit the Canadian tundra, including of course the polar bear.

  • How are the animals living in the tundra adapted to the conditions here?

Periglacial processes and landforms

The cyclical freezing and thawing that occurs each year in periglacial regions results in a set of unique landscape processes and features.

Pingo and ponds
Canadian Arctic tundra with kettle ponds and small pingo.
Pingo
A pingo is a mound of earth-covered ice found in the Arctic.
  • Did you know, the largest (and oldest) pingos in the world are found on the MacKenzie Delta in northern Canada? They are over 50 m high and 300 m wide.

What features might you find in periglacial regions?