2.3 - Factors Affecting Erosion (North Antrim)

Question 1

What is lithology made up of?

Answer 1

Rock age
Permeability
Structure e.g. columnar jointing

Question 2

How is rock age important?

Answer 2

White Rocks is made up of basalt and then a chalk (sedimentary) layer on top
Usually sedimentary is very vulnerable to erosion but as it’s aged it’s hardened and now become very resistant so White Rocks doesn’t erode easily

Question 3

How do entablature and columnar jointing affect erosion?

Answer 3

Giant’s Causeway is made up of
Entablature which is resistant and near the top due to fewer cracks
Columnar jointing allows water to permeate easier due to cracks and erode lower layers

Question 4

How do laterite, basalt, and chalk layers affect erosion at Giant’s Causeway?

Answer 4

Laterite is easily eroded so upper layers collapse to fill the space
Basalt is mostly impermeable as it’s not jointed which means chalk underneath is likely to never erode

Question 5

What happens when water can’t get through the entablature?

Answer 5

It builds up pressure as it accumulates
Causes cracks
Gets through to laterite

Question 6

How have tectonics affected North Antrim?

Answer 6

Determine lithology (rock type)
Lava flowed and cooled over chalk at Causeway forming basalt which is very resistant and protects underlying chalk

Question 7

How did tectonics create columnar jointing?

Answer 7

Lava cooled down faster at the top and contracted as it cooled to form the cracks in the columns

Question 8

How does marine erosion factor in?

Answer 8

Destructive waves erode chalk (hydraulic action etc) but if waves were constructive, rock wouldn’t break off

Question 9

How is rock type important?

Answer 9

Causeway has b,sick bass,f which is impermeable to water so processes like salt crystallisation can’t occur and erode the rock