Coastal change and conflict Flashcards
What is the coastal zone?
The dynamic, constantly changing zone between the land and sea.
Give one example of and describe 3 features of a hard rock coast.
Lands End, Cornwall
1) Cliffs are high,steep and rugged
2) Cliff face is often bare with no vegetation and little loose rock.
3) A few boulders and rocks have fallen from the cliff at the foot of the cliff face.
Give one example of and describe the features of a soft rock coast.
Scarborough, Yorkshire
1) May be high, but are less rugged and not so steep.
2) May be piles of mud and clay which have slipped down the face of the cliff.
3) At the foot of the cliff, there are very few rocks, some mud and sand.
Name three erosive processes and describe them.
1) Hydraulic action - Water is forced into cracks in the cliff face, this compresses the air so that when the wave retreats the air blasts out which can force the rock apart.
2) Abrasion - Loose rocks called sediment are thrown against the cliff by waves this wears the cliff away and chips bit of rock off the cliff.
3) Attrition - Loose sediment is swirled around by waves, the sediment constantly collides with other sediment and is gradually worn down into rounder smoother sediment.
How is a wave cut platform formed? (4)
1) The sea attacks the base of the cliff forming a wave-cut notch.
2) The notch increases in size causing the cliff to collapse.
3) The process repeats and the cliff continues to retreat.
4) A wave-cut platform is left at the bottom, exposed at low tides.
What is a discordant coastline?
A discordant coastline consists of different layers of rock at right angles (perpendicular) to the coast.
What is a concordant coastline?
A concordant coastline consists of the same rock type along the whole coastline, parallel to the coast.
How are caves, arches, stacks and stumps formed? (4)
1) Weak areas in a headland are attacked by waves and open to form a cave.
2) Cave widened and deepened by erosion and breaks through headland to form an arch. e.g. Durdle door, Dorset.
3) The arch is continually eroded and eventually collapses leaving an isolated stack.
4) The stack is eroded forming a stump.
On what sort of coastline are bays formed and how are they formed?
Give an example of this sort of coastline.
Discordant coastlines, South-West Ireland
Bays are formed when a band of weaker rock is surrounded by two bands of hard rock. The soft rock erodes much faster than the hard rock creating bays, the hard rock is left sticking out as headlands.
On what sort of coastline are coves and cliffs formed and how are they formed?
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What are the characteristics of summer constructive waves? (3)
1) Small, long wavelengths and low amplitudes.
2) Strong swash so transport sand up the beach and deposit it - build up the beach.
3) This creates a gently sloping beach profile.
What are the characteristics of winter destructive waves? (4)
1) Big, shorter wavelength and larger amplitude.
2) They have strong backwash, which erodes sand from the beach.
3) This creates a steep beach profile.
4) The sand is carried offshore by an underwater rip current and is deposited out at sea, forming an offshore bar.
What causes waves?
What does the size of waves depend on? (3)
When wind blows across the sea, friction between the wind and the water surface causes waves.
The size of waves depends on:
1) The strength of the wind.
2) How long the wind blows for.
3) The length of water the wind blows over - called the fetch.
What is backwash?
What is swash?
The movement of a wave retreating back to sea, away from the beach.
The movement of a wave onto and up the beach, when a wave breaks.
Explain the process of longshore drift. (4)
1) Longshore drift is the process by which sediment is carried along a coastline.
2) Waves can break at an angle due to the direction of the prevailing winds.
3) The swash carries material up the beach at an angle and the backwash then flows back to the sea at 90º.
4) Prevailing winds are usually from one direction, longshore drifts are usually in one direction too.