Glaciers

Question 1

Corrie Basin

Answer 1

• Snow collects in hollow on side of mountain, usually on North facing slopes in Northern hemisphere
• Snow doesn’t melt in summer, cold and sheltered
• Collects more snow every year, compacted, air is squeezed out leaving ice
• Back wall gets steeper due to freeze thaw weathering and plucking
• Base of Corrie gets deeper due to abrasion
• Gets heavier and moves down hill. Moves out of hollow in circular motion called rotational slip
• Due to less erosion at the front of the glacier a corrie lip is formed
• After melting a lake forms in hollow

Question 2

Arete

Answer 2

• 2 corries meet back to back
• glaciers erode either side of ridge, edge becomes steeper and ride narrower
• Freeze thaw may steepen knife edged ridge, water enters cracks and when frozen expands by 9%
• Repeated freezing and melting creates pressure on rock
• E.g - striding edge - Lake District

Question 3

Pyramidal Peak

Answer 3

• back walls of three Corries form at top of mountain
• Glaciers erode back towards each other, carves out rock by plucking and abrasion
• Freeze thaw weathers summit, creates a sharp point
• E.g - Mount Blanc, France

Question 4

U shaped valley

Answer 4

• Snow accumulates in north/NE hollow, compacts to form nevee then ice
• During periods of glaciation when glacier accumulates, advances to fill V shaped valley
• Glacier has greater power to erode than river due to size, allows glacier to carve out own route as it moves due to gravity
• Glacier bulldozes through valley, removes truncated spurs
• Ice freezes as it travels onto rocks - plucked away - makes sides deeper. Rocks in ice (sandpaper, deeper)
• Freeze thaw makes scree (falls on glacier, abrades base)
• Temp increases and ice melts and retreats. Erratic deposited and scree falls into valley making UsV.
• River turns into misfit stream

Question 5

Ribbon Lake

Answer 5

• U shaped valley formation
• Ribbon lake can form where softer bedrock on floor of valley eroded deeper than surrounding area
• Ribbon lakes form where terminal/recessional moraine creates a dam
• E.g - Lake Windermere

Question 6

Terminal Moraine