Flashcards in The Coastal Zone Deck (23):
What are the two types of weathering?
What is mechanical weathering?
The breakdown of rock without changing its chemical composition
What is chemical weathering?
The breakdown of rock by changing its chemical composition
What is mass movement?
Shifting of rocks and loose material down a slope which happens when the force of gravity acting on a slope is greater than the force supporting it
What are destructive waves?
A high frequency (10-14 per minute)
High and steep
Backward is more powerful than their swash
Formation of a wave cut platform
Waves cause erosion at the foot of the cliff
This forms a wave cut notch which is made bigger as erosion continues
The rock above notch collapses
This is washed away and a new wave cut notch starts to form
This being repeated results in cliff retreating
A wave cut platform is left behind as cliff retreats
Where do headlands and bays form?
Where erosion resistance is different
The formation of caves, arches and stacks
Headland are made out of resistant rocks that are weak
Waves crash into them and make the cracks bigger
This is done by hydraulic action and abrasion
Erosion continues and deepens the cave until it breaks through the headland forming an arch
Eruption continues and wears away rock supporting arch until collapses this forms a stack
What is longshore drift?
Waves go in the direction of prevailing wind
Hit the coast at and an angle not a right angle
The swash carries material up beach same direction of winds
Backwash carries material down the beach at right angle and towards sea
Zigzags along the coast
Formation of a beach
Found at coasts between high water mark and low water mark
Formed by constructive waves depositing sand and shingle
How do splits form?
Form at sharp bends in the coastline
Longshore drift transports sand and shingle past the bend and deposits in the sea
Waves and winds can curve the end of a spit
The sheltered area behind the spit is protected from waves
Material collects there and plants grow
Over time a marsh forms
How are bars formed?
Formed when a split joins two headlands together
The bar cuts off the bay between the headlands from the sea a lagoon can form behind the bar
Why is sea level rising?
Because of global warming
2mm a year
The rapid rise in global temperatures over the last 100 years
Coastal flooding impacts
Loss of tourism- cause tourist attractions to close and it can put people off visiting
Loss of housing and jobs- people become homeless and certain coastal industries are shut down because of damage to equipment etc and jobs are lost
Vegetation killed- the force of flood water uproots tees and plants
Coastal flooding case study
1.5 m above sea level
Coastal erosion case study
From Flamborugh Head to Spurn Head
1.8 m of land lost each year
What were the impacts on the Maldives?
Loss of tourism- the main airport couldn't work because the flooding
Less freshwater available- supplies of freshwater is already low and the sea is polluted and salty
Loss of beaches- wears away beaches on the islands at a rapid rate
Impacts of coastal erosion (Holderness)
Homes near the cliffs are at risk of collapsing into the sea
Property prices have fallen
Accessibility has been affected as roads are near the cliffs
Main reasons for rapid erosion
Easily eroded rock- made up of boulder clay which is easily eroded
Naturally narrow beaches- less protection
People worsening the situation- coastal defences called groynes have been built to stop material moving fighter down coast which means beaches are narrower
Hard engineering methods
Sea wall- made up of hard material like concrete that reflects waves back to the sea
Rock armour- boulders that are piled up along the coast
Groynes - wooden or stone fences that are built at right angles to trap material transported by longshore drift
Soft engineering methods
Beach nourishment- sand and shingle from elsewhere that's added to beaches
Dune regeneration- creating or restoring sand dunes by other nourishment or planting vegetation to stabilise the sand
Managed treatment- removing existing defence and allowing the land behind it to flood
Coastal habitat case study
Studland Bay (Dorset)