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19 terms

Lesson 30 - Glacial Processes and Landforms

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Types of glaciers
1. Mountain glaciers: Glaciers that form in mountainous areas.
• Highland icefiels
• Valley glaciers
• Alpine glacier
• Cirque glacier
2. Continental ice sheets: Glaciers from in non mountainous areas. The two main types are Antarctica and Greenland.
Accumulation
Addition of Ice by accumulation of snow
Glacial abrasion
Bedrock is worn down by the rocks being dragged along in the moving ice
Isostasy
term used in geology to refer to the state of gravitational equilibrium between the earth's lithosphere and asthenosphere such that the tectonic plates "float" at an elevation which depends on their thickness and density.
Glacial plucking
- Process of glacial erosion.
- Rock fractures open up beneath the glacier because of the weight of the ice and because of the freezing and thawing of water in cracks.
- The stress exerted by lowing glacial ice plucks rocks fragments loose and transports them in the direction of glacier flow.
- Particularly effective on leeward slopes and in well-jointed bedrock.
Drift
General term for all material moved by glaciers
Till
Rock debris deposited directly by moving or melting of ice, with NO meltwater redeposition involved
Moraine
- Process of glacial deposition
- General term for glacier-deposited landforms compsed entirely or largely of till.
Outwash plain
Smooth, flat alluvial aprons deposited beyond recessional or terminal moraines by streams issuing from the ice.
Glacial trough
- Glaciers move down valleys with more effectiveness than a stream.
- A valley shaped by valley glaciers and ice streams within ice sheets that has a distinct trough form.
Accumulation Zone
- Upper portion of a glacier.
- Here the amount of new ice added by snowfall exceeds the amount lost by melting an d sublimation
Ablation Zone
- Lower portion of a glacier.
- The amount of ice added is less that the amount lost
Terminal moraine
A ridge of till that marks the outermost limit of glacial advance
Glacial advance/retreat
Getting bigger or smaller due to relation between ablation and accumulation.
Glacial flow
Displacement of ice movement downslope. Always happen even when glacier is retreating
Glacial erosion
- Plucking
- Abrasion
Glacial landforms
- Horns
- Cirques
Roche moutonnée
Troughs
• U-shaped Valley
• Hanging valley
• Fjord
Glacial transportation
- Rock flour/loess
- Till
- Erratics (huge rock)
Glacial deposition
- Moraine
- Drumlin (elongated, linear feature-opposite of roche moutonnée)
- Outwash plain (sorted material)
- Kettle lakes (big chunk of ice melted)