Ice Distributions
Geography: Edexcel A Level, topic 2.1.3
Types of Ice Cover
Ice cover is collectively known as the cryosphere. It can be classified into a number of different forms.
Ice sheets, caps and fields
- Ice sheets are large dome-shaped ice masses that completely cover the underlying topography and can be several kilometres thick (e.g. Antarctica and Greenland).
- Ice caps are smaller ice sheets (e.g. Svalbard).
- Ice fields are ice sheets covering a mountain plateau with some mountain peaks showing through (e.g. Vatnajokull, Iceland).
Glacier types
- Valley glaciers are large tongues of ice constrained within a valley (e.g. the Athabasca glacier, Canada).
- Cirque/Corrie glaciers are smaller glaciers occupying a hollow on a mountainside (e.g. there are several in the Swiss Alps).
Thermal characteristics of glaciers
- Cold-based (polar) glaciers have very cold surface temperatures of −20 to –30°C and their base is frozen to the bedrock beneath.
- Neither the pressure of the ice above nor geothermal energy from below is enough to melt the ice base, and so there is little movement.
- Warm-based (temperate) glaciers are not frozen to the bedrock surface they rest on.
- At their base there is a layer of water, allowing the base of the ice to slide and move.
Present-day Distribution
Ice cover is found in the following areas.
High latitude
- Ice is found with the Arctic and Antarctic Circles, more than 65 degrees of latitude north and south.
- These polar regions receive the least concentrated solar radiation, in comparison with other latitudes, so ice is much more likely to form.
- Ice is found mainly in large ice sheets, ice caps, ice fields and in some glaciers.
- Ice is also found on the coastal fringes of high latitude regions.
High altitude
- Ice is found in high altitude mountain ranges, which can happen at any latitude.
- Ice is often constrained within the topology (e.g. mountain valleys as glaciers) or can be unconstrained (e.g ice sheets, and ice caps).
- E.g. the Andes, the Himalayas, the Alps.
Upland landscapes
- The present-day distribution of high altitude glaciated upland landscapes yields a number of features:
- There are over 150,000 valley glaciers and small ice caps.
- Relict landscapes from the Pleistocene period provide evidence of formerly glaciated upland areas.
- In the UK, the Lake District, Snowdonia, the Grampians and the Scottish Highlands are the main areas of such relict features.
- Evidence includes glaciated valleys, corries and other ice-scarred landscape features.
Past vs Present Distribution
The present-day distribution of areas of ice (the cryosphere) is mainly in high latitudes and high altitudes. The distribution in the late Pleistocene covered 45.3 x106 km2 whereas present area covered is around 15.8 x106 km2.
Polar regions
- The past and present distributions of areas covered by ice are very different.
- The following compares the late Pleistocene area to the present in 106 km2:
- Antarctica - 14.5 vs 13.5.
- Greenland - 2.4 vs 1.8.
- Arctic fringes - 16.0 vs 0.35.
- Scandinavia - 6.6 vs 0.004.
High altitude regions
- The past and present distributions of areas covered by ice are very different.
- The following compares the late Pleistocene area to the present in 106 km2:
- Andes - 0.1 vs 0.03.
- Alps - 0.1 vs 0.004.
Test yourself on Ice Distributions
What is the surface temperature of cold-based (polar) glaciers?
What geological period does evidence of formerly glaciated upland areas come from?
Ice is found at north and south latitudes higher than what degrees?
How much ice cover was there in the late Pleistocene?
What do we call the distribution of areas of ice?