Physical Landscapes - Coastal Landscapes

Question 1

Explain the formation of a cliff by erosion.

Answer 1

• cliffs are formed by wave action undercutting land that meets the sea and occurs at high tide level
• a notch is cut and as the land recedes, the cliff base is deepened by wave erosion
• at the same time the cliff face is continuously attacked by weathering processes and mass wasting such as slumping occurs, causing the cliff face to become less steep
• when high, steep waves break at the bottom of the cliff, the cliff is undercut forming a feature called a wave-cut notch
• continual undercutting causes the cliff to eventually collapse
• as this process is repeated, the cliff retreats leaving a gently sloping wave- cut platform

Question 2

What factors affect the size of waves?

Answer 2

• the speed of the wind
• the length of time that the wind has been blowing for
• the distance over the sea it has travelled

Question 3

Explain what hydraulic action is.

Answer 3

Hydraulic action is the sheer force of waves crashing against the shore and cliffs. The power of the waves forces air into cracks, compresses it and blows the rock apart as the pressure is released.

Question 4

Explain what attrition is.

Answer 4

Attrition happens when rocks and pebbles carried by the waves crash into each other, wearing each other away and gradually becoming smaller, rounder and smoother.

Question 5

Explain what solution is.

Answer 5

Solution is when chemicals in the seawater dissolve minerals in the rocks causing them to break up.

Question 6

Explain how headlands and bays are formed.

Answer 6

When resistant rocks alternate with less resistant rocks along a coast under wave attack, the resistant rocks form headlands while the less resistant rock is warm away to form bays.

Question 7

Which is more vulnerable to erosion? Headlands or bays?

Answer 7

Headlands

Question 8

Explain the formation of caves, arches and stacks.

Answer 8

• caves are formed when waves attack cliffs with resistant rock along lines of weakness such as faults and joints
• the waves undercut part of the cliff and can cut right through the cave to form an arch
• continual erosion causes the arch to widen- eventually the roof of the arch collapses to leave a piece of rock left standing called a stack.

Question 9

How are beaches formed?

Answer 9

From material that is deposited by the sea.

Question 10

What factors affect beaches?

Answer 10

• wave energy
• the steepness of its gradient
• the seasons of the year
• whether sand or shingle is deposited

Question 11

What is a split?

Answer 11

A split is a long narrow ridge of sand which projects into the sea from the coastline.

Question 12

Explain the formation of a split.

Answer 12

• material is transported along the coastline by long- shore drift
• splits form in shallow, sheltered water when there is a change in direction of the coastline
• deposition happens resulting in the accumulation of sand and shingle
• the largest material is dropped first as the waves have less energy
• finer material is then deposited which builds up the split
• as the split grows outwards a change in wind direction can result in the split changing direction, forming a curved end.

Question 13

Explain the formation of a sand bar.

Answer 13

• sometimes a split grows the whole way across a bay
• a sand bar develops parallel to the shore and the waves and wind move it towards the shore until it joins the mainland
• behind the bar a lagoon is formed where water is trapped and eventually the lagoon may become a salt marsh, then finally be filled in by deposition.

Question 14

Explain longshore drift.

Answer 14

• a pebble or sand particle is carried up and along the beach by the swash (strength of waves and the angle at which the waves strike the shoreline is determined by the prevailing wind)
• it is then pulled down the beach, carried by gravity and the waves backwash
• this process is repeated over and over again and the particle moves along the shoreline.