Erosional Landforms

Question 1

What are the factors affecting erosion?

Answer 1

• Wave strength - controlled by the fetch and the wind speed. Longer fetches and stronger winds create bigger, more powerful waves that have more erosive power
• weathering creates weaknesses in rocks that are exploited by the processes of erosion
• human activity - dredging can remove material that would otherwise dissipate wave energy. Coastal management can reduce rates in one location, but increase them down the coast.

Question 2

What are concordant Coastlines?

Answer 2

• have layers which run parallel to the coastline

Question 3

What are discordant coastlines?

Answer 3

• have layers of rock which run perpendicular to the coastline

Question 4

Formation of a Cove?

Answer 4

• formed in concordant Coastlines
• a more resistant “outer” band of rock is eventually breached (possibly with the aid of a river)
• erosion speeds up when waves reach the less resistant bands of rock behind. It can also spread laterally
• once harder rock is reached again erosion slows down
  E.g. Lulworth Cove

Question 5

Formation of headlands and bays?

Answer 5

• the less resistant rock erodes more quickly and retreats to form a bag
• the more resistant rock erodes slowly leaving the rock sticking out to sea as a headland
• a beach develops in the bay because waves are constructive (low energy). Also, eroded soft rock is broken down by attrition.
• wave refraction is important because it concentrates wave energy on the headland. This encourages deposition in the bay - further developing the beach.

Question 6

Formation of cliffs and wave-cut platforms

Answer 6

• over time wave action is concentrated at the base of the cliff, forming a wave cut notch
• sub aerial processes (e.g. freeze-thaw or carbonation will weaken the rocks at the top of the cliff).
• eventually, the wave cut notch will increase in size until the cliff can’t be supported. It will collapse through mass movement.
• material that has fallen off the cliff will be broken down by attrition and also smooth the wave cut platform through abrasion

Question 7

Formation of a Headland?

Answer 7

• lines of weakness are exploited by hydraulic power and cavitation, eventually being made wider and taller
• where erosion continues vertically upwards, a blowhole is formed
• over time, continued erosion and under cutting of the cliff creates a cave
• the cave increases in size until it has eroded through the other side of the headland creating an arch
• a combination of marine erosion and sub-aerial processes have weakened the arch to the point of collapse
• a tall, isolated column of rock is left behind (stack)
• a wave cut notch forms at the base of the stack, eventually causing it to topple over and collapsed leaving behind a stump