Coastal Environments

Mechanical Weathering

rocks being disintegrated rather than decomposed, e.g. freeze-thaw weathering

Chemical weathering

Rocks decomposing after rainwater hits it

Biology weathering

Plants or animals break up rocks

Mass movement

downward movement of rock, mud or soil due to gravity

Sliding

material slides quickly downwards in a straight line

Slumping

material slides with a rotation over a curved slip plane

Rock fall

rocks breaks apart and fall, due to freeze-thaw weathering

Hydraulic Action

Waves hit the base of cliffs and compress the air in the cracks and the rocks break apart

Abrasion

Waves containing rocks fragments wear away the base of a cliff or headland

Attrition

Rocks bump into each other and break up, becoming smaller

Solution

Seawater dissolves soluble minerals in rocks

Longshore drift

movement of sediment along the coast by waves

Traction

large pebbles and rocks are rolled along the seabed

Saltation

small pebbles bounce along the seabed

Deposition

when sea loses energy and drops eroded materials, beaches are deposited sediment

Headland 

a narrow piece of more resistant rock which projects outwards from the coast

Bay

a crescent-shaped indentation in the coastline found between two headlands

Wave-cut platforms

Erosion at base of a cliff forms wave-cut notch → cliff collapses and the erosion repeats leading to the cliff retreating creating a wave-cut platform

Beaches 

Deposits of sediment that lie between the high and low tide levels made by constructive waves

Spits

long stretches of sand/ shingle that extend from the land, formed where the coastline changes shape

Bars

forms where a spit joins two headlands together, trapping the water in a lagoon behind it

Hard engineering

man made structures to reduce erosion: sea walls, groynes, rock armour, gabions

Sea walls

concrete walls built at the edge of a beach, reflects waves back to the sea

+well-maintained walls can last for years; Prevents erosion

-They are expensive to build and maintain; made out of concrete, which bad for the environment

Groynes

Wood barriers built at the front of the beach to trap sediment and prevent longshore drift

+they are cheap; effective at preventing erosion

-carries sediment further down the coast

Rock armour

large rocks placed along the coastline to absorb the power of waves

+they are cheap, quick to build and easy to maintain

-Look unnatural and not pleasant

Gabions

wire cages filled with rocks to act as a buffer against wave erosion

+cheap, can become vegetated and blend into the landscape

-can erode within 10 years, if broken can be dangerous

Soft engineering

work with the natural environment to protect coastal areas: beach nourishment and dune regeneration

Beach nourishment 

sand/ shingle from elsewhere is added to beach

+creates wider beaches which slows waves

-expensive( £500,000 per 100m)

Dune regeneration

dunes are created/ restored by adding more sand

+form an effective barrier between land and seas; help maintain natural habitats

-expensive and requires a lot of maintenance

Managed retreat (coastal realignment)

allows land to become naturally flooded, creating an area of marshland to protect inland ares

Coastal Management: Holderness 

1991, £2million spent on coastal management, rock armour and groynes

Groynes at Mappleton prevented sediment movement down the coastline

Bridlington, 4.7km long sea wall to protect the seafront from erosion and tourists