Factors Affecting Erosion

Question 1

How does lithology influence the rate of erosion?

Answer 1

Igneous rocks ( granite) are more resistant to erosion and weathering than less resistant sedimentary rock (limestone). Granite recedes at 1mm per year, compared to 2.5cm a year by limestone.
Metamorphic rocks are formed from sedimentary and igneous rocks by intense heat and pressure (marble) so they are very resistant.
Superficial deposits made by rivers, wind and glaciers can overlay bedrock. These are unconsolidated and easily eroded. Glacial till along the coast can have recession rates of 1m.

Question 2

How does vegetation stabilise the coast?

Answer 2

Plant roots bind the sediment together so they are less likely to be eroded.
Plant leaves slow down wind speeds at ground level, reducing erosion and increasing deposition.
As plants lose leaves and die, they add organic material to the sand, which forms soil.