Geography- Coastal Zone Flashcards
How are waves formed?
Friction between the wind and the surface of the water causes ripples to form.
These develop into waves
What is fetch?
The stretch of open water over which the wind blows
The longer the fetch the ………… powerful a wave can become
More
What is swash?
The water that rushes up the beach
What is backwash?
The water that flows back towards the sea
What happens to waves as the water becomes shallower?
The top of the wave (the crest) begins to move faster, which causes the crest of the wave to rise up and eventually topple onto the beach .
What are constructive waves?
powerful waves that surge up the beach with a powerful swash
How do constructive waves change a beach?
They carry large amounts of sediment and construct the beach, making it more extensive.
How are constructive waves formed?
By distant storms, which can be hundreds of kilometres away.
What are the characteristics of constructive waves?
Well spaced apart
Powerful when they reach the coast
What are destructive waves?
Waves that destroy the beach as they have little swash when the wave breaks (as they rear up to form towering waves before crashing down into the beach) but a powerful backwash. Therefore this explains the removal of sediment and the destruction of the beach
How are destructive waves formed?
By local storms close to the coast
What are the characteristics of destructive waves?
Closely spaced, often interference with each other producing a chaotic, swirling mass of water.
What is a cliff?
A steep or vertical face of rock often found at the coast
What is mechanical weathering?
Involves the disintegration of rocks without any chemical changes taking place
What is rockfall?
The collapse of a cliff face or the fall of individual rocks from a cliff, often due to freeze thaw.
What is freeze thaw weathering?
Involves water collecting in cracks or holes in the rock. At night the water freezes and expands. This expansion creates stress within the rock, widening any cracks that already exists. When the temperature rises the water seeps deeper into the rock and the process repeats.
What type of rock is freeze thaw weathering particularly effective in?
Porous (contains holes)
Permeable (allows water to pass through it)
What is exfoliation?
Where the heating and cooling of a rock causes it to expand and contract, eventually leading to the outer layer of the rock flaking off.
What is chemical weathering?
Slight acidic rain dissolves the calcium carbonate slightly to form calcium hydrogen carbonate which is soluble, and over time this process dissolves the rock away.
What is biological weathering?
Plant roots are effective at growing and expanding in cracks in the rocks. Animals such as rabbits can be effective at burrowing into weak rocks such as sands.
What is mass movement?
The downhill movement of material under the influence of gravity
What is a landslide?
Block of rock slide downhill
What is mudflow?
Saturated soil and weak rock flows down a slope