geography mappleton
1. Why is Mappleton threatened by coastal erosion?
The plain of Holderness did not exist before the Ice Age. It was once a wide bay backed by chalk cliffs running from Flamborough Head to Hessle, west of the city of Hull. Today Holderness is made up of glacial tills – sands and clays deposited by ice sheets during the Ice Age (Figure 4). The tills are soft and unstable and have little resistance to erosion. The low cliffs repeatedly slump down along rotational slip planes, lubricated by water which reduces friction and makes the sands and clays slip easily. The sea washes the slumped material away. This rapid coastal retreat will continue until the old buried cliff-line along the eastern edge of the Yorkshire Wolds is once again exposed. This is composed of much more resistant chalk rock, which will again form impressive white cliffs such as those north of Bridlington.
2. How have human actions contributed to the erosion that destroyed Sue
Earle’s home? Include in your answer mention of the effect human actions have had on the coastal system at Mappleton.
The sea defences constructed at
Mappleton have contributed, unfortunately, to the destruction of
Sue Earle’s home. The £1.9 million scheme, completed in 1991, includes two large rock groynes and a protective barrier of granite boulders laid along the beach close to the cliff base. Although it protects the area of cliff behind the defences, the rate of erosion of the unprotected cliff to the south has trebled. This is because the groynes have destroyed the balance within the coastal system and have stopped the supply of beach material by cutting off the longshore drift. The narrower beach south of the defences means that waves crash against the cliff foot more often and with more energy. 3. (a)What do you understand by the policies of ‘managed retreat’ and ‘beach feeding’? (b) What do you consider to be the advantages and disadvantages of (i) hard sea defences? (ii) managed
The plain of Holderness did not exist before the Ice Age. It was once a wide bay backed by chalk cliffs running from Flamborough Head to Hessle, west of the city of Hull. Today Holderness is made up of glacial tills – sands and clays deposited by ice sheets during the Ice Age (Figure 4). The tills are soft and unstable and have little resistance to erosion. The low cliffs repeatedly slump down along rotational slip planes, lubricated by water which reduces friction and makes the sands and clays slip easily. The sea washes the slumped material away. This rapid coastal retreat will continue until the old buried cliff-line along the eastern edge of the Yorkshire Wolds is once again exposed. This is composed of much more resistant chalk rock, which will again form impressive white cliffs such as those north of Bridlington.
2. How have human actions contributed to the erosion that destroyed Sue
Earle’s home? Include in your answer mention of the effect human actions have had on the coastal system at Mappleton.
The sea defences constructed at
Mappleton have contributed, unfortunately, to the destruction of
Sue Earle’s home. The £1.9 million scheme, completed in 1991, includes two large rock groynes and a protective barrier of granite boulders laid along the beach close to the cliff base. Although it protects the area of cliff behind the defences, the rate of erosion of the unprotected cliff to the south has trebled. This is because the groynes have destroyed the balance within the coastal system and have stopped the supply of beach material by cutting off the longshore drift. The narrower beach south of the defences means that waves crash against the cliff foot more often and with more energy. 3. (a)What do you understand by the policies of ‘managed retreat’ and ‘beach feeding’? (b) What do you consider to be the advantages and disadvantages of (i) hard sea defences? (ii) managed