Coasts Flashcards
What is swash?
When a wave breaks and water rushes up the beach
What is backwash?
When water runs back down the beach towards the sea under the force of gravity
What factors affect the amount of energy a wave has?
- How far wind travelled (fetch)
- Energy of the wind
- The length of time the wind blew for
What are the features of constructive waves?
- Low in height
- Weak
- Made in calm weather
- Strong swash and weak backwash
- Leaves material on the beach
What are the features of destructive waves?
- Tall height
- Powerful
- Breaks downwards
- Weak swash and strong backwash
- Takes material from the beach
How are waves created?
Wind
How can you spot a destructive wave?
It rolls
What makes a wave strong?
Large fetch
What is weathering?
The natural process which causes the breakdown of rocks and minerals by chemical, biological or physical agents
What is mass movement?
Erosion, transport and accumulation of material that occur on both gentle and steep slopes mainly owing to gravitational forces
What are the 3 types of weathering?
- Chemical
- Mechanical
- Biological
What is chemical weathering?
Carbonic acids attack rocks, changing their structure, causing them to dissolve and wash away in solution.
What is mechanical weathering?
Freeze thaw weathering happens when water enters a crack and freezes and expands, causing the crack to widen.
How much does water expand when it freezes?
9%
What is biological weathering?
Burrowing animals and plants attack rocks. For example a rabbit can burrow into a crack in a rock, expanding the crack. Or a root widening a crack.
What are the types of mass movement?
- Rock falls
- Rotational slumping
- Soil creep
What are rock falls?
Fragments of rock are eroded and weathered until they separate and fall from the cliffs
What is rotational slumping?
A large area of land moving down a slope. Usually occurs on clay cliffs that become saturated during heavy rainfall
What is soil creep?
Slow, down-slope movement of materials under the influence of gravitation
What are the 4 erosional coastal processes?
- Abrasion
- Hydraulic action
- Attrition
- Solution
What is Abrasion?
The waves pick up sediment and hurl it at the cliffs, chipping away at the cliffs
What is hydraulic action?
Water is forced into the cracks into the rocks, trapping air in the cracks and compressing it. This forces the rocks apart
What is attrition?
Rocks and pebbles from the cliffs continually collide with each other and break, becoming smoother
What is solution? (erosion)
Acids in the sea dissolve rocks like chalk and limestone