Case study - Holderness Coastline Flashcards
Location
East coast of England in Yorkshire
Extends 61km from Flamborough in the North to Spurn Point in South
Holderness erosion rate?
One of Europes fastest eroding coastlines with an annual rate of 2m per year
2 million tonnes of material every year
How much land has holderness lost?
Approximatlety 3 miles (5km) of land has been lost since the roman times
How many towns/villages has holderness lost?
23-29
Holderness geology?
- Underlaying the coastline is bedrock made up of cretaceous chalk
- Most of the coastline is made up of boulder clay deposited from glacial till over 18,000 years ago
- Boulder clay is very soft and easily eroded especially when saturated
Other factors leading to erosion of cliffs (Wind, fetch, wave energy)
- Strong prevailing winds creating lsd depositing material that is facilitates erosional processess at the base of the cliff
- Holderness exposed to winds and waves from northeast with a small fetch of about 500-800km
- Currents circulate around the UK from alantic adding wave energy and increasing the frequency of destructive waves along the coastline at holderness
- Low pressure weather systems and winter storms are intense producing strong winds and rain , low pressure air weight less as well which causes a rise in sea levels and higher tide
- Small enclosed areas generate huge waves
- Sea floor is relativley deeps so waves are not weakened by friction as they approach the beach
The flamborough head
- Headland points out in the north sea and formed of chalk (resistant)
- Several bays along Flamborough head- selwicks bay: most easterly bay and location of the lighthouse
- Bay contains a range of coastal landforms of erosion and depostion
- Cliffs made of chalk which are overlayed by boulder clay
- Stacks ‘stack adam’, cliffs, wave cut platforms, arches
- Small beaches consisting of chalk, boulder clay and sand
LSD and beach material
- The beaches are main problem BC erodes to produce clay particiles which are fine and easily transported out to sea in suspension rather than built up on shore
- Not much sand to stop waves reaching cliff face at high tide
- The tides flow southwards transporting sand south by LSD and leaving the cliffs at holderness poorly protected against wave attack
Predominant direction of LSD
North to South
Spurn point head
- Sand and shingle recurved spit
- 5.5km long reaching across the mouth of the humber esturay
- Sand transported along the coastline by LSD
- Energy of the waves travelling/transporting the material reduces where the North Sea meets the Humber Esturay
- Sanddunes along the spit have been colonised by marram grass
- Saltmarshes have formed behind spurn point from material depoisted by the river humber esturay
Examples of hard engineering at holderness
Hornsea and Withern sea: sea walls protecting the holiday resorts, Reventments protecting the easington gas terminal, Gabions at skipsea, Groyones protecting the coastline at hornsea,withernsea and mappleton
Skipsea erosion
Highlights the human impact of erosion in areas where coastlines are not being defended
Mappleton
- 3km south of Hornsea has rates of 2m per year resulting in access road being only 50m from the cliff edge at closest point
- Mappletone is served by the B1242, main road connecting the settlememts along the holderness coast
- In 1991 a scheme was implemented at the coast with a cost of 2.1 million - the scheme included two rock groynes designed to track beach sediment, a rock revenyment to prevent eorison of the clif, 450m line of defence
- The cliffs were regarded to reduce slumping and there was some beach nourishment
- Terminal groyne syndrone occurs to south of mappleton with increased eorsion of 1.7m - 3.3m terminal scour
Chemical weathering
- Relativley ineffective at holderness except on the chalk of flamborough head
- Mechinical and biological weathering more effective
- Freeze-thaw and alternate wetting and drying of the boulder clau which makes it crumbly during dry periods
