2.6 - Sub-aerial Weathering

Question 1

What are the three different types of weathering?

Answer 1

Biological
Chemical
Mechanical

Question 2

What are molluscs?

Biological

Answer 2

Animals which bore away to find food and survive by eating rock

Question 3

What is salt crystallisation?

Mechanical

Answer 3

Salt is left behind in cracks from hydraulic action as water evaporates
Salt contracts and expands as it crystallises
This puts pressure on the surrounding rock so it cracks and breaks off

Question 4

How does seaweed erode?

Chemical

Answer 4

As it decomposes it produces Suk fruit acid
H2SO4 dissolves the rock
Holes are left behind

Question 5

What is freeze thaw?

Answer 5

Water enters cracks in the rocks
As temperatures drop overnight, the water freezes and expands putting pressure within joints
Joints get wider over time

Question 6

What is oxidation?

Chemical

Answer 6

Rock minerals react with oxygen
E.g. iron = rust
Rock becomes more susceptible to erosion

Question 7

What is carbonation?

Chemical

Answer 7

Rain combines with carbon dioxide to form weak carbonic acid which reacts with calcium carbonate in the rock (limestone/chalk) forming calcium bicarbonate which erodes rock