2.6. Factors affecting coastal erosion

Question 1

How do waves affect coastal erosion?

Answer 1

• The size and type of waves affects erosion

-Most erosion happens during winter storms when destructive waves are at their largest and most powerful

Question 2

How does rock type (lithology) affect coastal erosion?

Answer 2

• Tough, resistant rocks e.g. granite, erode at very slow rates compared to weaker clays and shales.
• In the UK, some of the fastest rates occur on the Holderness coast where unconsolidated glacial till deposits have eroded 120mm over the last 100 years
• In the same time, the granite coastline at Land’s End has eroded 10cm

Question 3

How does geological structure affect coastal erosion?

Answer 3

• Cracks, joints, bedding planes and faults create weaknesses in the cliff that can be exploited by erosive processes
• Large scale- variations in rock type and geological structure can lead to the formation of headlands and bays

Question 4

How does the presence or absence of beach affect coastal erosion?

Answer 4

• Beaches absorb wave energy and reduce impact of waves on a cliff
• If a beach is absent, a cliff may experience increased erosion as it is more vulnerable to wave attack

Question 5

How do subaerial processes affect coastal erosion?

Answer 5

• Weathering and mass movement will weaken cliffs and create piles of debris that are easily eroded by the sea, potentially increasing erosion rates.

Question 6

How does coastal management affect coastal erosion?

Answer 6

• The presence of structures such as groynes and sea walls will have an impact on sediment transfer and patterns of wave energy along a coastline.
• Groynes trap sediment moved by longshore drift and may deprive beaches of sediment further down.
• Sea walls may deflect energy elsewhere along the coast.