COLD: Landforms of erosion

Question 1

How are cirques formed?

Answer 1

• Hollow on the north facing slope allows SNOW TO COLLECT as temperatures are LOWER as receive LESS solar energy.
• Freeze thaw ENLARGES the hollow.
• Hollow deepens, more snow collects.
• GLACIER ICE begins to SLIDE OUT of hollow under its own weight.
• MOVING ICE DEEPENS hollow by ABRASION and ice at the back PLUCKS at the headwall of cirque, making it STEEPER.

Question 2

How are aretes formed?

Answer 2

• Formed when two neighbouring corries run back to back.

- As each glacier ERODES either side of the RIDGE, the edge becomes STEEPER and the ridge becomes NARROWER.

Question 3

How are U shaped valleys formed?

Answer 3

• Characterised by STEEP SIDES and relatively FLAT BOTTOM.
• Result from CHANNELLING OF ICE through valleys, combining freeze thaw, plucking, abrasion.
• Before glaciation, freeze thaw under PERIGLACIAL PROCESSES weakens the floor and sides of the valley. At end of glacial period, there will be PRESSURE RELEASE EXPANDING the rock. EROSION results in the U shape.

Question 4

How are truncated spurs formed?

Answer 4

• Begin as interlocking spurs.
• As glaciation occurs, the ends of the interlocking spurs are ERODED away through plucking and abrasion, as they lie in the path of the oncoming glacier.
• The DESTRUCTIVE effect is what forms the truncated spurs.

Question 5

How are fjords formed?

Answer 5

• Glacial troughs below/partly below sea level.
• More likely to be U shaped than land based glacial troughs.
• Have a long profile and are very DEEP, suggesting there was a lot of glacial erosion to construct the landform.

Question 6

How are hanging valleys formed?

Answer 6

• Cirque glaciers develop and join at a point together.
• Merging INCREASES WEIGHT and EROSION.
• River tributaries cut down to MEET main river.
• Tributary ICE will cut down so it can SLIP INTO main glacier.
• Ice DISAPPEARS, tributary glacial valley left HANGING.