The key factors influencing abrasion and plucking

Question 1

What are the key factors which influence abrasion?

Answer 1

• The quantity of debris available
• The angularity of debris or clasts
• The relative hardness of clasts in bedrock
• Structure and lithology, the amount of
  jointing in rock and overall hardness
• Basal water sliding moves debris faster

Question 2

What are the key factors which influence plucking?

Answer 2

• The thickness of ice
• The presence of basal meltwater
• Higher velocity of ice movement creates greater shear stress
• Highly fractured and jointed rock promotes dilation and freeze-thaw

Question 3

What are the key factors which influence both abrasion and plucking?

Answer 3

• The thermal regime of the glacier
• The semi-permeability of the bedrock leads to maximum meltwater at glacier-bedrock face