Coasts

Question 1

Destructive Waves

Answer 1

• Weak swash and strong backwash
• The strong backwash removes sediment from the beach
• The waves are steep and close together

Question 2

What is the swash?

Answer 2

It is a turbulent layer of water that washes up on the beach after an incoming wave has broken. The swash action can move beach materials up and down the beach, which results in the cross-shore sediment exchange.

Question 3

Constructive Waves

Answer 3

• Strong swash and weak backwash
• The strong swash brings sediments to build up the beach
• The backwash is not strong enough to remove the sediment
• The waves are low and further apart

Question 4

Hydraulic Action

Answer 4

This is the sheer power of the waves as they smash against the cliff. Air becomes trapped in the cracks in the rock and causes the rock to break apart.

Question 5

Abrasion

Answer 5

This is when pebbles grind along a rock platform, much like sandpaper. Over time the rock becomes smooth.

Question 6

Attrition

Answer 6

This is when rocks that the sea is carrying knock against each other. They break apart to become smaller and more rounded.

Question 7

Solution

Answer 7

This is when sea water dissolves certain types of rocks. In the UK, chalk and limestone cliffs are prone to this type of erosion.

Question 8

Longshore Drift

Answer 8

• The movement of material along a coastline due to the angled approach of waves.
• Waves approach the coast at an angle because of the direction of prevailing wind. The swash will carry the material towards the beach at an angle. The backwash then flows back to the sea, down the slope of the beach. The process repeats itself along the coast in the zigzag movement.

Question 9

Ways to prevent Erosion to avoid coastline cliff collapse

Answer 9

• Sea walls - concrete walls that are placed at the foot of a cliff to prevent erosion. They are curved to reflect the energy back into the sea.
• Rock armour - large boulders placed at the foot of a cliff. They break the waves and absorb their energy.
• Gabions - Rocks are held in mesh cages and placed in areas affected by erosion.
• Groynes - Wooden or rock structures built out at right angles into the sea.