2.2.1
Periglacial Processes
Periglacial Locations
Periglacial Locations
Periglacial environments are currently widespread in high altitude and high latitude locations.
High latitudes
High latitudes
- Periglacial environments are found at high latitudes, especially in the Arctic.
- They are less common in the Southern Hemisphere because of the absence of land masses between 60°S and 70°S - it is mostly ocean!
High altitudes
High altitudes
- Periglacial environments are found at high altitudes because temperatures are low (they fall by 1°C for every 100 m of height).
- E.g. the Himalayan Plateau.
- Periglacial environments are also found in continental interiors, away from the moderating influence of the sea.
- E.g. Siberia.
Permafrost
Permafrost
Permafrost is permanently frozen ground, of which there are three types.
Types of permafrost
Types of permafrost
- Continuous permafrost covers the largest areas with air temperatures below -5°C. The ground can be frozen to depths of several hundred metres.
- Discontinuous permafrost occurs over smaller areas with mean air temperatures between -5°C and -1.5°C. Its depth is much shallower, up to 35m.
- The surface tends to melt in summer and rivers and lakes cause the permafrost to be absent around them due to their ‘warming’ effect.
- Sporadic permafrost covers the smallest areas where mean air temperatures are between -1.5°C and 0°C. Permafrost occurs only in markedly cold spots.
The active layer
The active layer
- Permafrost has a seasonal (summer) active layer.
- This is the upper layer which seasonally melts.
- The depth varies from a few centimetres to several metres, depending on the average summer temperature.
- This layer can become waterlogged (due to meltwater not being able to drain away).
- This can cause it to be unstable and move, even on low angle slopes.
Periglacial Processes
Periglacial Processes
Periglacial environments are widespread in high altitude and high latitude locations today. They are characterised by distinctive processes.
Freezing and thawing
Freezing and thawing
- Major periglacial processes are highly seasonal and are dependent on annual cycles of freezing and thawing.
- Nivation is the collection of seasonal snow in hollows which encourage frost weathering beneath them.
- Frost heave is the upward movement of soil due to the growth of lenses of ice in the soil. The lenses grow due to capillary movement of water in the soil.
- Freeze-thaw weathering is the alternate freezing and thawing of water in cracks and crevices within rocks which causes them to split.
Other processes
Other processes
- Solifluction is the downslope movement of saturated soil, on slopes with a gradient as low as 1 degree.
- Erosion by high winds describes fine particles that may be blown away by strong winds on featureless plains.
- Meltwater erosion describes strong flows of meltwater in the spring and summer washing away weathered material as well as eroding river banks.
1Tectonic Processes & Hazards
1.1Tectonic Processes & Hazards
1.2Natural Disasters
1.3Natural Disaster Case Studies
1.4Trends & Patterns
2Option 2A: Glaciated Landscapes & Change
2.1Glaciated Landscapes Over Time
2.2Periglacial Landscapes
2.3Glacial Processes
2.4Glacial Landforms
3Option 2B: Coastal Landscapes & Change
3.1Coastal Landscapes
3.2Coastal Erosion & Deposition
3.3Coastal Risks
4Globalisation
4.1Globalisation
4.2Negatives of Globalisation
4.3Global Shift
4.5Culture
4.6Measuring Development
5Option 4A: Regenerating Places
5.1Types of Economies
5.2Function of Places
5.3Regeneration
5.4Regeneration Case Studies
6Option 4B: Diverse Places
6.1Population Structure
6.2Past & Present Connections
6.3Urban & Rural Spaces
6.4Diversity
6.5Urban & Rural Case Studies
6.6Case Study - Tower Hamlets
6.7Case Study - Sturton-le-Steeple
7The Water Cycle & Water Insecurity (A2 only)
7.1Hydrological Processes Global to Local
7.2Influences on the Water Cycle
7.3Water Insecurity
8The Carbon Cycle & Energy Security (A2 only)
8.1The Carbon Cycle
8.2Energy Consumption
8.3Alternative Energy
8.4Growing Demand for Resources
9Superpowers (A2 only)
9.1Superpowers
9.2Hard & Soft Power
9.2.1Hard & Soft Power
9.2.2Emerging Powers - China Rivalry
9.2.3Emerging Powers - Chinese Sources of Power
9.2.4Emerging Powers - Brazil
9.2.5Emerging Powers - Russia
9.2.6Emerging Powers - India
9.2.7Theories of Development
9.2.8Power Case Studies: Chinese One Belt One Road
9.2.9Power Case Studies: Pakistan Nuclear Arms
9.2.10Power Case Studies: OPEC
9.3IGOs, TNCs & Alliances
10Option 8A: Health & Human Rights (A2 only)
10.1Human Development
10.2Role of Governments & IGOs
10.3Human Rights
10.4Interventions
11Option 8B: Migration & Identity (A2 only)
11.1Globalisation & Migration
11.2Consequences of Migration
11.3Nation States
11.4Responses to Global Migration
Jump to other topics
1Tectonic Processes & Hazards
1.1Tectonic Processes & Hazards
1.2Natural Disasters
1.3Natural Disaster Case Studies
1.4Trends & Patterns
2Option 2A: Glaciated Landscapes & Change
2.1Glaciated Landscapes Over Time
2.2Periglacial Landscapes
2.3Glacial Processes
2.4Glacial Landforms
3Option 2B: Coastal Landscapes & Change
3.1Coastal Landscapes
3.2Coastal Erosion & Deposition
3.3Coastal Risks
4Globalisation
4.1Globalisation
4.2Negatives of Globalisation
4.3Global Shift
4.5Culture
4.6Measuring Development
5Option 4A: Regenerating Places
5.1Types of Economies
5.2Function of Places
5.3Regeneration
5.4Regeneration Case Studies
6Option 4B: Diverse Places
6.1Population Structure
6.2Past & Present Connections
6.3Urban & Rural Spaces
6.4Diversity
6.5Urban & Rural Case Studies
6.6Case Study - Tower Hamlets
6.7Case Study - Sturton-le-Steeple
7The Water Cycle & Water Insecurity (A2 only)
7.1Hydrological Processes Global to Local
7.2Influences on the Water Cycle
7.3Water Insecurity
8The Carbon Cycle & Energy Security (A2 only)
8.1The Carbon Cycle
8.2Energy Consumption
8.3Alternative Energy
8.4Growing Demand for Resources
9Superpowers (A2 only)
9.1Superpowers
9.2Hard & Soft Power
9.2.1Hard & Soft Power
9.2.2Emerging Powers - China Rivalry
9.2.3Emerging Powers - Chinese Sources of Power
9.2.4Emerging Powers - Brazil
9.2.5Emerging Powers - Russia
9.2.6Emerging Powers - India
9.2.7Theories of Development
9.2.8Power Case Studies: Chinese One Belt One Road
9.2.9Power Case Studies: Pakistan Nuclear Arms
9.2.10Power Case Studies: OPEC
9.3IGOs, TNCs & Alliances
10Option 8A: Health & Human Rights (A2 only)
10.1Human Development
10.2Role of Governments & IGOs
10.3Human Rights
10.4Interventions
11Option 8B: Migration & Identity (A2 only)
11.1Globalisation & Migration
11.2Consequences of Migration
11.3Nation States
11.4Responses to Global Migration
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