Opinion: Natural erosion of Sidmouth’s cliffs will continue forever

Sidmouth cliffs. Ref shs 03-17TI 5498. Picture: Terry Ife

Sidmouth cliffs. Ref shs 03-17TI 5498. Picture: Terry Ife - Credit: Archant

How is it that the local authority does not understand erosion?

Rain falls and it penetrates the soil, water freezes, and the ice formed expands, thus causing cracks in the cliff. Gravity gets involved and cliffs end up on the beach. Wave action then returns the spoils back into the sea. This cycle is then repeated again and again over many years. It’s called erosion and will continue forever unless the rain stops and gravity is cancelled.

Please explain to me how a very expensive sea defence plan of putting rocks at the shoreline can stop or even halt this natural process?

Note: putting boulders at the base of the cliff makes it worse. As water swirls around these rocks, the velocity of the water increases and will have a higher energy when it strikes the cliff. Hence the erosion effect is greatly increased. You can see this effect by the increased undercutting near the boulders near the Alma Bridge. The boulders are making it worse.

Kinetic energy: E=½mv² - ie the energy is proportional to the square of its velocity.

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Double the speed of anything and the kinetic energy will be increased by a factor of four.

This erosion process is natural and will continue forever into the future. Rock armouring with boulders at the shoreline will have little or no effect on this process.

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John Austin,


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