COASTAL PROCESSES

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Weathering processes - chemical weathering
- Caused by chemical changes. - Rainwater, which is slightly acidic, very slowly dissolves certain types of rocks and materials, such as alkaline rock (e.g. chalk, limestone). - Produces chemical reaction causing rocks to slowly dissolve.
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Weathering processes - mechanical weathering
- The disintegration (break up) of rocks. - Where this happens, piles of rock fragments, called 'scree', can be found at the root of cliffs.
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Types of mechanical weathering - freeze thaw
-Water collect in crack or holes (pores) in the rock.-At night, this water freezes and expands, +makes cracks in rock bigger.-When temp. rises and ice thaws, water will seep deeper into rick.-This repeats, fragments of rock may break off.
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Types of mechanical weathering - salt weathering
- Sea water contains salt. - When the water evaporates, it leaves behind salt crystals. - In cracks and holes, these salt crystals grow and expand - this puts pressure on the rocks and flakes may eventually break off.
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What is mass movement?
- Downhill movement of weathered material under the force of gravity. - The speed can vary considerably.
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Mass movement - rockfalls
- Material breaks up and falls down slope.
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Mass movement - slides
- Material shifts in a straight line.
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Mass movement - slumps
- Material shifts with a rotation.
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Erosion - hydraulic power
- Waves crash against rock and compress the air in the cracks. - Puts pressure on rock. - Repeated compression widens the cracks and makes bits of rock break off.
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Erosion - abrasion
- Eroded particles in the water scrape and rub against rock, removing small pieces.
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Erosion - attrition
- Eroded particles in the water smash into each other and break into smaller fragments. - Their edges also get rounded off as they rub together.
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What is transportation?
- The movement of eroded material.
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Transportation - longshore drift
-Waves follow direction of prevailing wind.-Usually hit coast at oblique angle (any angle not a right angle).-Swash carries material up beach, in same direction as waves.-Backwash carries material down beach at right angles, back towards sea.-Zigzag.
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What is deposition?
- Occurs when material being transported by the sea is dropped due to the sea losing energy. - The water slows down so that it isnt moving fast enough to carry so much sediment.
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How are coastal ares built up?
- Coasts are built up when the amount of deposition is greater than the amount of erosion
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How is deposition on on area of coast increased?
- There's lots of erosion elsewhere on the coast, so there's lots of material available. - There's lots of transportation of material into the area.
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What are low energy waves?
- I.e 'slow waves'. - Carry material to coast but theyre not strong enough to take a lot of material away - lots of deposition and very little erosion.
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What are constructive waves?
-Waves that deposit more material than they erode.-Have low frequency.-Low+long.-Swash is powerful+it carries material up the coast.-Backwash is weaker+it doesnt take a lot of material back down coast, so material is deposited on coast.
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What are destructive waves?
- Carry out erosional processes. - Have high frequency. - High+steep. - Backwash is more powerful than their swash, so material is moved from coast.
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Card 2

Front

Weathering processes - mechanical weathering

Back

- The disintegration (break up) of rocks. - Where this happens, piles of rock fragments, called 'scree', can be found at the root of cliffs.

Card 3

Front

Types of mechanical weathering - freeze thaw

Back

Preview of the front of card 3

Card 4

Front

Types of mechanical weathering - salt weathering

Back

Preview of the front of card 4

Card 5

Front

What is mass movement?

Back

Preview of the front of card 5
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