Landforms caused by erosion

Define a corrie

an arm chair shaped hollow with steep sides and a base wall that results in glacial erosion

Describe the formation of a corrie

1. Accumulation in the hollow

2. Backwall gets steeper due to erosion

3. Rotational movement deepens hollow

4. Thinner ice is unable to erode

5. Higher lip is formed

Define a tarn

a small lake occupying a hollow eroded out by ice or dammed by a moraine

Define an aretes

this is a narrow steep sided ridge between two corries

Define a pyramidal peak

where 3 or more corries develop around a hill or mountain top

What is a glacial trough?

a glaciated valley/fjord that is a strongly channelled ice

Where do some glaciers flow down?

Pre-existing river valleys under gravity

Describe the formation of a glacial trough

1. V shaped valley builds up with ice

2. Freeze thaw and plucking

3. Ice moves downhill and the mass of ice erodes the valley sides and floor

4. U shape valley, scree slopes and truncated spurs are formed

Define subglacial

materials underneath a glacier

Define englacial

materials inside the glacier

Define supraglacial

material on the surface of the glacier

Define drift

materials deposited during glaciation

Define glacial till

materials deposited by the ice

Define outwash

materials deposited by meltwater

Define lodgement till

material that is deposited directly from the moving ice beneath the moving glacier

Define ablation till

material deposited at terminus as the ice deposits

Define Rochee Moutonnees

these are asymmetrical mound caused by abrasion on the stoss side and plucking on the lee ward side

Explain the formation of Roche montonnees

• Passing ice advances over projections of resistant rock on the valley floor, causing localised pressure on the stoss side (up valley) - compressing flow

• This leaves a smooth and streamlined shape caused by abrasion. This leaves striations

• On the lee side (down valley) pressure is reduced and meltwater re-freezes resulting in plucking and steepening - extending flow

What does Roche moutonnees tell us?

the direction of ice movement

What is a hanging valley?

• Hanging valleys with waterfalls and truncated spurs are a feature of the U-shaped valley landform.

• They are visible within this glacial trough, and form as a smaller glacier from another valley has created a U-shaped valley which then enters the larger valley.

• As the hanging valley’s glacier is smaller, it is less powerful, so it does not reach the base of the larger glacial trough valley.