2a.Geomorphic Processes

Question 1

Erosion - Plucking (quarrying)

Answer 1

• Melt water seeps into joints of rocks on floor
• Water freezes and rock becomes attached to glacier
• Glacier pulls rock away

Question 2

Erosion - Abrasion

Answer 2

• Debris embedded in glacier scratches against floor and sides, wears them away
• Debris is smooth / worn down (forms rock flour)

Question 3

What influences abrasion

Answer 3

• Debris (size and shape exert pressure proportional to weight)
• Hardness (effective with hard rock)
• Thickness (greater thickness = greater pressure)
• Basal water pressure (melt water reduces friction)
• Sliding of basal ice (abrasion requires this, more sliding = more erosion)
• Movement of debris to base ( frequent debris is needed to replace worn out debris)
• Removal of fine debris (so larger particles can erode)

Question 4

Nivation

Answer 4

• Not classified as erosion or weathering
• Includes freeze thaw, soliflucation, running water transport, chemical weathering
• Responsible for enlargement of hillside hollows

Question 5

Material clasification

Answer 5

Supraglacial
-Debris carried on glacial surface
Englacial
-Debris in the ice. supraglacial material covered by snow or sunk
Subglacial
-Debris embedded in the base of a glacier frim plucking for abrasion or that has moved down

Question 6

Deposition

Answer 6

• Glaciers deposit material if they become overloaded
• AKA, drift
• Also called till when deposited by ice
• Also called outwash when deposited by meltwater
• These are classed as glacio-fluvial material

Question 7

Till

Answer 7

Lodgment till
-Deposited by advancing ice due to downward pressure from ice
-Debris pushed into valley, left behind
-Forms drumlins
Ablation till
-Deposited by melting / retreat
-Most glacial depositional landforms form from this

Question 8

Till characteristics

Answer 8

Angular / sub angular
-Embedded in ice, not eroded by melt water 
Unsorted
-Glaciers wont sort material
Unstratified
-Glacier till dropped in mounds / ridges

Question 9

Transportation

Answer 9

Material comes from:

• Rockfall
• Avalanches
• Debris flows (scree, soil, mud)
• Aeolian deposits (fine material carried and deposited by wind)
• Volcanic eruptions (ash and dust)
• Plucking
• Abrasion