Coastal Weathering and Erosion

Salt Weathering

Seawater gets into cracks in rocks, seawater evaporates, forming salt crystals in cracks.

Chemical Weathering

Breakdown of rock by altering its chemical composition.

Biological Weathering

Living organisms break down rocks eg. plant roots growing into cracks in rocks and pushing them apart

Mass Movement

Shifting of rocks and material down a slope.

Slides mass movement

When loose material shifts downhill along a straight line

Slumps mass movement

When saturated soil and weak rock slump down a curved surface, often after heavy rain.

Rockfalls mass movement

Material breaks up and falls down a slope.

what causes mass movement

• Weathering (especially freeze-thaw and biological weathering)

• Saturation by water (from rainfall)

• Gravity pulling weakened material down

• Human activity (e.g., removing vegetation)

what are the three types of erosion that affect coats

- hydraulic power : Waves compress air in rock cracks, causing erosion.

- abrasion : Eroded particles scrape against rocks, removing pieces.

- attrition : eroded particles in the water collide collide and break into smaller fragments.

Sub-aerial Processes

Weathering and mass movement occurring above water.

Cliff Retreat

Rapid erosion causing coastal cliffs to move back.

What is the Lubricant Effect and how it affects mass movement

Water makes material heavier and facilitates movement enabling more mass movement

what causes coats to rapidly retreat

mass movement

explain the formation of a wave cut platform

1) water attacks the base of the cliff caused by erosion by hydraulic action

2) this forms a wave cut notch and it enlarges as erosion continues

3) the rock above the notch becomes unstable and collapses

4) the collapsed material is washed away and and a new wave cut notch starts to form

5) repeated collapsing results in the cliff retreating

6) a wave cut platform is the platform left behind as the cliff retreats

formation of a bay and headland

the less resistant rock on the discordant coastline is eroded quickly by hydraulic action and abrasion and this forms a bay with a gentle slope

Harder rocks resist erosion and remain as headlands jutting out to sea

how are headlands eroded to form caves, arches and stacks

1) waves crash into the headlands where there is weakness such as a crack and the cracks enlarge

2) the repeated erosion and enlargement of the cracks causes a cave to form

3) continued erosion deepens the cave until it breaks through the headland forming an arch

4)erosion continues to wear away the rock supporting the arch until it eventually collapses

5) this forms a stack, an isolated rock that's separate from the headland

Erosion

Process of wearing away landforms over time.

Concordant Coastline

Coastline with parallel rock bands to shore.

Discordant Coastline

Coastline with alternating rock bands at right angles.

Hard Rock

More resistant rock, erodes slowly over time.

Soft Rock

Less resistant rock, erodes quickly compared to hard rock.

how do joints and faults affect erosion rates

they increase erosion rates

why are erosional landforms like bays and headlands more common on discordant coastlines

because the bands of rock are being eroded at different rates

Destructive Waves

High, steep waves that erode coastlines effectively, they have a stronger backwash, so more material is removed from the beach

Backwash

Water movement returning to the sea after a wave.

Swash

Water movement advancing up the beach from a wave.

how do hotter temperatures affect salt weathering and therefore coastal erosion

the hotter temperatures increase the rate of salt weathering as more water evaporates

Storm Impact on coastal erosion

Increased erosion due to high energy waves caused by strong winds of the storm

intense rainfall causes cliffs to become more saturated increasing mass movement

how does the UK climate affect coastal erosion

The UK's climate is considered to be temperate maritime, (1) meaning summers are warm and wet and winters are mild and wet. (1) The prevailing winds bring frequent rainfall to the country, leading to increased erosion, weathering and mass movement along the coast. (1)

Storm frequency is high, which brings heavy rainfall and strong winds that increase the destructive power of the waves. (1)

During the winter the UK frequently sees temperatures dip below freezing at night and then rise above 0°C by day. (1) This repeated freezing and thawing, results in weathering of cliff faces and headlands adding to erosion and cliff collapse. (1)

Coastal Retreat

Land loss along the coastline due to erosion.

hard rock cliffs are more _______ and soft rock cliffs are more sloping

hard rock cliffs are more VERTICAL and soft rock cliffs are more SLOPING