Landforms Of Glacial Erosion

Question 1

Formation of corries

Answer 1

Deepened initially by nivation.snow accumulates in the hollow and turns to ice under pressure.
Weight of ice causes it to rotate and move
Ice pulls away from back wall plucking it - steeper
Corrie is overdeepened by rock debris abrading the floor of hollow

Question 2

Features of a corrie

Answer 2

Plucking of back wall
Large crevasse -bergschrund 
Rock lip 
Over deepened basin 
After glaciation corrie may be filled by small lake- tarn ( meltwater)

Question 3

What is an arête

Answer 3

Two or more corries that erode back to back towards each other from opposing sides. Produce a knife edge ridge

Question 4

What’s a pyramidal peak

Answer 4

When three or more corries erode back towards each other

Question 5

u shaped valley - glacial trough

Answer 5

When a river flows down a pre existing river valley as they flow they straighten widen and deepen these valleys

Question 6

Glacial trough formation

Answer 6

Glaciers can erode horizontally as well as vertically so are better able to erode obstructions.
Formed by plucking and abrasion as ice has greater power than water

Question 7

What do glacial troughs look like

Answer 7

Steep sided flat floored valleys

Question 8

Formation of rock basins

Answer 8

Compressional flow over deepens softer parts of valley floor. Can also occur where two glaciers join due to increased mass of ice
Erosion happens at different rates so only occur in certain places

Question 9

What are ribbon lakes

Answer 9

Extra deep sections in valley floor may be filled with water they are long and narrow Lakes - ribbon lake

Question 10

What are truncated Spurs

Answer 10

Cliff like features often at the lower end of an arête and are triangle shaped sharp cut offs

Question 11

Formation of truncated Spurs

Answer 11

Glaciers move down a river and erode valley sides they may remove tips of interlocking Spurs leaving cliff like features

Question 12

Hanging valley description

Answer 12

Found between truncated Spurs
Smaller u shaped valley above main valley
Waterfalls can form when the river returns down to main valley

Question 13

Formation of hanging valleys

Answer 13

Caused by tributary valley glaciers which are smaller
They erode less so have been cut off as glaciers formed a u shaped valley
Floor of main valley is much lower

Question 14

What are corries ( cirques)

Answer 14

Armchair shaped hollows with a steep back wall and over deepened basin.May contain a small lake called a tarn.front may have a raised lip

Question 15

What’s a Roche moutonnée

Answer 15

Mass of more resistant rock which is smooth on top , abrasion may have left behind striations. It has a jagged downstream side due to plucking

Question 16

Formation of a Roche moutonnées

Answer 16

When the glacier moves over a band of harder rock and smooths the upstream side by abrasion,often there are striations Showing direction of ice movement. As ice spilled over top it removes loose rocks by plucking leaving a jagged edge on downstream side( lee)

Question 17

What is a crag and tail

Answer 17

Larger masses of more resistant rock on upslope side and a gently sloping tale which is made of less resistant rock, plucking and abrasion erode to form steel side