Erosional processes, outside influences and landforms

Hydraulic action/wave quarrying

• Force if waves compresses water and trapped air into faults and joints in the rock.

• Pressure forces the cracks open meaning more air is trapped

• This eventually causes blocks of rock to erode from the cliff

Abrasion (corrasion)

• Sediment is picked up by the breaking waves and is thrown at the cliff face

• The sediment chips away at the cliff, gradually wearing it down and removing rock particles

What is attrition?

• when already eroded sediment is moved by waves they collide with each other and chips away

• This causes sediment to become smaller and rounder overtime

What is solution (corrosion)

• carbonate rocks (limestone) are vulnerable to rain and salt water (spray) and dissolve

• This can cause overhang

Influence of lithology on erosional processes

Hydraulic action

• heavily jointed/fissured sedimentary rocks are vulnerable

• In very hard igneous rocks HA might be the only erosional process operating

Abrasion

• loose sediment must be available

• Softer sedimentary rocks are vulnerable

Attrition

• softer rocks are rapidly reduced in size

Solution

• mainly effects limestone

What landforms occur due to erosion.

• headlands

• CCAS

• Geo

• Blowhole

• Wave-cut notch/platform

What is a blowhole?

A vertical fault hat has been widened by a wave attack

What is a geo?

• Wave refraction concentrates on both sides of a headland.

• Erosion focuses on weaknesses and a cave is formed

• The cave becomes deeper and supports the roof less and less

• Finally, due to gravity the roof collapses to form a geo

Formation of crack-cave-arch-stack