Coasts Flashcards
What is swash?
A wave that travels towards the beach.
What is backwash?
A wave going back out to sea.
What is the fetch?
The distance a wave travels.
What is the prevailing wind?
Strongest, dominant wind direction.
How is a wave created?
- The wind blows over the sea.
- This creates ripples.
- These ripples become bigger swells.
- The swells eventually approach the land.
- The sea becomes shallower as the land gets nearer.
- The bottom of the wave slows due to friction.
- The top keeps going and forms a crest.
- The crest topples over forming a breaking wave.
What is a destructive wave?
Created by a large fetch. They are big, strong waves with high energy. Erode the coastline. Backwash is stronger than swash. 14 waves per minute.
What is a constructive wave?
Created by a short fetch. Small, gentle waves with low energy. Deposit sediment. Swash is stronger than the backwash. 7 waves per minute.
What is biological weathering?
Weakening and disintegration of rocks by plants, animals and microbes. For example, growing plant roots can exert pressure on the rock.
What is chemical weathering?
Erosion or disintegration of rocks caused by chemical reactions. For example, solubles such as acid rain dissolve and break down the cliff faces.
What is mechanical weathering?
The process of breaking big rocks into little ones. Freeze-thaw action is when water enters cracks and expands overnight, separating the rock.
What is hydraulic action?
Erosion of the cliffs caused by the force of water and air in the waves colliding against them.
What is abrasion?
Erosion pf the cliffs as waves throw particles and rocks against them.
What is attrition?
Erosion of the material carried by waves. The material in the waves is smoothed as it bumps into each other.
What is solution/corrosion?
Minerals are dissolved in the water and carried along in solution.
What is a headland?
An area of hard rock protruding out into the sea.
What is a bay?
An area of soft rock creating an inlet or embayment.
How are headlands and bays formed?
The soft rock, such as sand and clay, erode quicker than hard rock (chalk). This means that they form bay as the hard rock doesn’t erode at the same pace.
What is a wave cut notch?
When the sea attacks the base of the cliff and creates an indent.
What is a wave-cut platform?
When weathering attacks the top of the cliff and eventually falls because of the wave-cut notch. The sediment gets carried towards the sea by the backwash, creating a wave cut platform.
How do stumps form?
Waves erode weaknesses in the rock, called faults. Over time a cave will form along the greatest line of weakness.
The size of the cave is increased by further erosion until the headland is opened at both sides.
Wave erosion at the base of the arch led to the collapse of the roof, forming a stack.
The stack is separated from the rest of the land and is eventually eroded down into a stump.
What’s an example of these erosional landforms?
Swanage bay.
How is a spit formed?
- Longshore drift transports sediment down the coast in the direction of the prevailing wind.
- A change in the shape of the land (caused by the estuary) means longshore drift begins to deposit sediment out away from the coast.
- A long tongue of sediment builds up known as a spit. The end is curved by a prevailing wind.
How are salt marshes formed?
They develop in the sheltered area behind the spit (eg. Keyhaven Marshes behind Hurst Castle spit.)
What is a bar?
A bar of sediment in front of a bay, joining two headlands.
