2.4.2
Erosional Landforms
Glacial Erosional Processes
Glacial Erosional Processes
A range of glacial erosional processes have created a variety of distinctive large landforms in many upland glaciated areas around the world.
Plucking and quarrying
Plucking and quarrying
- If the bedrock beneath a glacier has been weathered in periglacial times, or if the rock is full of joints (well-jointed), a glacier can detach large particles of rock and take them with it. This is called plucking.
- Quarrying is an extreme form of plucking, creating steep and angular rock cliff faces.
Abrasion
Abrasion
- Abrasion happens when sharp rock fragments embed themselves in the base and sides of the ice.
- These grind down the bedrock as the glacier moves over the rock like sandpaper, making it smooth and wearing it away.
- This leaves scratches on the rock in the direction of ice movement called striations.
Crushing and basal melting
Crushing and basal melting
- Crushing is erosion caused by the sheer pressure exerted by rock fragments embedded at the base of a glacier.
- Basal melting is abrasion by meltwater, acting under great pressure, at the base of the glacier.
Sub-aerial processes
Sub-aerial processes
- Freeze–thaw weathering on the rock slopes above valley glaciers is a constant source of angular rock fragments that build up to form scree.
- Mass movement (rock falls and landslides) is a source of rock material which falls onto the surface of ice and is incorporated into it.
Corrie Formation
Corrie Formation
A corrie is an armchair-shaped, steep-sided hollow at the head of a glaciated valley.
Features
Features
- Corries are armchair-shaped and often N or NE facing in the northern hemisphere as this direction will receive the least sunlight.
- They are in the lee of prevailing winds, causing the snow to accumulate for longer.
- Size varies but they are often around 0.5km in diameter with a back wall up to 1000m in height.
Process 1
Process 1
- The hollow is deepened initially by nivation.
- As the ice accumulates it is deepened more by rotational slide, enhancing the abrasion process due to increased compression in the base of the hollow.
- Ice pulls away from the back wall, plucking rocks already loosened by freeze-thaw weathering.
- This creates a crevasse (bergschrund) which forms where the ice starts to pull away from the back wall of the corrie.
Process 2
Process 2
- Material falls down this crack and is embedded in the base of the ice.
- This then causes more abrasion and deepens the hollow
- Where the pressure and erosion are lower (at the front edge of the hollow) there is deposition of moraine.
- This is called the lip of the corrie, which often allows water to accumulate behind it in a post-glacial period, forming a tarn.
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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