UK Evolving physical landscape - 4A - Coastal change Flashcards
Give an example of a hard rock
Granite
Give an example of a soft rock
clay
Why do harder rocks erode slower?
More resistant = erode slower
What is a joint?
small cracks found in a rock
What is A fault?
Larger cracks found in a rock
What is a concordant coastline?
Rock parallel to coast
What are discordant coastlines?
Perpendicular to coast
Headlands and bays formed
What are the 2 different types of wave
Constructive
Destructive
Features of a constructive wave?
Strong swash
weak backwash
deposits sediment
Features of a destructive wave?
Strong backwash
weak wash
Erodes sediment
Describe Longshore drift
Longshore drift transports sediment along coastlines
Waves break at an angle to the coast
Sediment pushed up the beach by swash
Dragged back down at right angles by backwash
How are bays formed?
Soft, less resistant rock is eroded faster
How are heads formed?
Harder, resistant rock is eroded slower
what are the 4 steps needed to create wave-cut platforms?
- Sea attacks base of cliff (abrasion and hydraulic action) creates a wave-cut notch
- Wave-cut notch becomes larger = cliff collapses
- Cliff retreat
- Wave-cut platform formed
How are caves, arches, stacks and stumps formed?
- caves enlarged by hydraulic action
- Arch formed by destructive waves
- Stack = arch eroded and collapses -> stack results
- Stump = Stack eroded by abraision -> stack collapses
How are caves, arches, stacks and stumps formed?
- caves enlarged by hydraulic action
- Arch formed by destructive waves
- Stack = arch eroded and collapses -> stack results
- Stump = Stack eroded by abrasion -> stack collapses
How does a wave form?
Waves are created by winds as they blow over the sea
Shallow water near the coast causes friction with the seabed
The top of the water is travelling faster so it starts to tip forward
The wave then topples forward or breaks
How do spits form
Spits are formed due to deposition
Longshore drift occurs along the coastline but as the wave lose energy the deposit the sediment
Normally due to going into a sheltered area such as behind the headland or a mouth/estuary
The deposit of sediment overtime this creates a spit
How do bar and lagoons form?
- continuation of a spit formation
-Spit grows and joins 2 headlands - lagoon forms
- area becomes infilled by deposition
What are sea walls
Concrete walls placed at the foot of the cliff to prevent erosion. They are curved so they reflect the energy back into the sea
What is rock armour
Large boulders placed at the foor of the cliff. They break the waves and absorb their energy
What are gabions
Rocks which are held in mesh cages and placed in area affected by erosion
What are groynes
Wooden or rock structures built at right angles into the sea
What is beach replenishment
Sand and shingle from the sea bed is moved towards the beach
What is beach reprofiling
Reshaping the beach using existing beach material
What is dune regeneration
Grass planted in sand dunes to stabilise the dunes and helps to trap sand to build them up
What is dune fencing
Fences are built on the sandy beaches, which encourage new dunes to form
Advantages and disadvantages of sea walls
Very effective
Very long lasting
Very expensive £2000 per metre
Very ugly
Advantage and disadvantage of groynes
Not to expensive
Builds up beaches
Starves the beack further down the coast line of sediment
Advantage and disadvantage of gabions
Cheap and easy to mantain £100 per metre
Absorbs wave energy
Not very strong
Looks unatural
Advantages and disadvantages of rock armour
Relatively easy to maintain
Effective at reducing wave energy
Can beshifted if the rock is too small
Expensive to transport
Advantages and disadvantages of beach nourishment
Blends in with the existing beach
Creates wider beaches
Can kill or destroy animal habitats
Expensive and has to be repeated
What are the advantages and disadvantages of beach reprofiling
Provides an effective buffer for the coastline
Looks reasonably natural
Can be expensive
Has to be done regularly
What are the advantages and disadvantages of dune regeneration
Wave energy is absorbed
It is cheap
The protection is limited to a small area
Can be damaged by storms or waves
What are the advantages and disadvantages of dune fencing
Constructed out of natural material
Have minimal minimal impact on natural systems
Can be damaged by storms
Needs maintenance
