Coasts Flashcards
What are constructive waves?
Swash stronger than backwash. Builds up the coast.
What are destructive waves?
Backwash stronger than swash. Erodes the coast
What is an example of mechanical weathering?
Freeze thaw weathering
What are the 3 steps of freeze thaw weathering?
- Water seeps into cracks and fractures in rocks
- Water freezes and expands 9% and wedges apart rock
- Repeated freeze-thaw cycles causes the rocks to break off
Name 3 landforms resulting from erosion
- Wave cut platform
- Caves, arches, stacks and stumps
- Headlands and bays
Along what type of coastline are headlands and bays formed?
Discordant coastline- alternating hard and soft rock along coast
How are headlands and bays formed?
Soft rock erodes quicker which leaves a section (headland) jutting into the sea. The bay is more sheltered but the headland is subject to extreme erosion.
What types of erosion are most used in forming stacks and stumps
Abrasion and hydraulic action
What i the sequence that it takes to get to a stump?
Wave cut notch-> cave -> arch -> stack -> stump
Name 3 landforms resulting from deposition
Beaches
Sand dunes
Spits and bars
Why are beaches formed in bays?
Bays are sheltered and the waves have to have limited energy for disposition to build up the beach
How are Sandy beaches created vs pebbled beaches
Sandy- low energy bays
Pebbled- waves have higher energy and cliffs being eroded
How are spits formed?
Change in shape of coastline causes deposition to occur. Thin long ridge of material is deposited
How are bars formed?
Sometimes spits grow across a bay and join 2 headlands. They trap shallow lakes behind them called a lagoon
Name 4 types of hard engineering
- Sea walls
- Groynes
- Gabions
- Rock armour
What is a sea wall?
Curved concrete wall that reflects energy of waves and prevents erosion
What is rock armour?
Large boulders at the base of cliffs to absorb energy and break waves
What are gabions?
Rocks in mesh cages in areas affected by erosion
What are groynes?
Wooden structures built at right angles that go into the sea
Give 2 advantages + disadvantages of sea walls
- Effective at protecting cliff base
- Promenades for people to walk on
- Waves still powerful and can erode sea wall
- Expensive- £2000 per metre
Give 2 advantages + disadvantages of rock armour
- Cheaper than sea walls and easy to maintain
- Can be used for fishing
- Look different to local geology
- Expensive to transport
Give 2 advantages + disadvantages of gabions
- Absorb wave energy
- Cheap- £100 per metre
- Not very strong
- Look unnatural
Give 2 advantages + disadvantages of groynes
- Builds beach which encourages tourism
- Traps sediment being transported by longshore drift
- Trapping sediment starves beaches farther down
- Look unattractive
Give 3 types of soft engineering
- Beach nourishment
- Beach reprofiling
- Dune regeneration
What is beach nourishment?
Adding sand onto existing beach to build it up
What is beach reprofiling ?
Sediment redistributed from lower to upper beach
What is dune regeneration?
Adding marram grass onto sand dunes- stabilises dune and traps sand to build them up
Give 2 advantages + disadvantages of beach nourishment
- Blends in with existing beach
- Larger beaches- tourism appeal
- Needs to be constantly repeated
- Sand brought in from elsewhere
Give 2 advantages + disadvantages of beach reprofiling
- Cheap and simple
- Reduces energy of waves
- Works only when wave energy is low
- Needs to be constantly repeated
Give 2 advantages + disadvantages of dune regeneration
- Quite cheap
- Natural looking coastline
- Can be damaged by storm waves
- Areas zoned off from public
