Lesson Objective:

To know the factors affecting cliff retreat and explain the effects on people

StarterI can see…

I think…

I wonde

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People and Coastal Retreat

Read page 76 of Evolving Planet Explain why erosion and retreat of

coastal cliffs can happen at different rates.

Complete skills builder 5, page 76

The effects of coastal retreat Holbeck Hall landslide, Scarborough The Holbeck landslide, south of Scarborough in North Yorkshire, attracted considerable interest when

it destroyed the four-star Holbeck Hall Hotel between the night of 3 June and 5 June 1993. A rotational landslide involving about 1 million tonnes of glacial till cut back the 60 m high cliff by 70 m. It flowed across the beach to form a semicircular promontory 200 m wide projecting 135 m outward from the foot of the cliff.

The likely cause of the landslide was a combination of: rainfall of 140 mm in the two months before the slide took place; issues related to the drainage of the slope; pore water pressure build up in the slope and the geology.

The first signs of movement on the cliff were seen six weeks before the main failure, when cracks developed in the tarmac surface of footpaths running across the cliffs. These were filled to stop ingress of water to the cliff, but when the cracks reopened, shortly before the main failure, the council closed the cliff paths below the hotel. At this time a small part of the hotel garden was also observed to have suffered a minor movement.

There was originally 70 m of garden between the hotel and the cliff edge. At 6 am on the 4 June a guest saw that 55 m of the garden had disappeared. The hotel was evacuated and the landslide continued to develop, culminating in the collapse of the east wing of the hotel by the evening of 5 June

Use the information provided and page 76,

Evolving Planet, to explain what happened at Holbeck Hall in 1993.

Use the heading-Effects of coastal

retreat.

Case Study- Holderness Use Google Earth to fly to the Holderness

coastline. Explore the different types of land use-

harbours, industry, tourist areas, farmland.

Create a map that shows the key features of the region

Extn. Explore details of a coastal management plan

http://www.hull.ac.uk/coastalobs/media/pdf/Final%20Executive%20Summary%20(September%202007).pdf

HoldernessChalk

Boulder Clay

Label -Headland- Flamborough Head

Spit- Spurn Point

The River Humber

Geology- Chalk, Boulder Clay

Boulder clay

http://www.bbc.co.uk/learningzone/clips/3189.flv

The Holderness coastline is the fastest eroding coastline in Europe. This clip features a farm on the edge of the section of cliff that is eroding the fastest. The farm is being lost to the sea and the owners are set to lose everything as insurance companies refuse to insure the land and property. The erosion has been significantly worse since coastal defences were built further down the coastline at Mappleton.

Holderness Case Study Where is Holderness located? Describe what Holderness is like (page 78 Evolving

Planet) What makes Holderness prone to erosion? What are the options available to people in

Holderness? Read the opinions (page 79) on coastal

management- put them into an order of Strongly for and strongly against coastal management

What are the costs and benefits to managing the coast?

What do you think they should do?

Describe the retreat since Roman times

Describe the changes in the coastline between 1864 and 1994.

Explain why cliff retreat is happening at a fast rate on this coastline. (Page 78 Evolving Planet)

What do people think about the erosion of the Holderness coastline? There are different views about what

should be done to manage cliff erosion

1. Do nothing

2. Use hard engineering

3. Hold the existing defence line by maintaining or improving the protection

4. Strategic realignment- retreat from the existing defence line to allow e.g. caravan parks to move inland.

Plenary

Share your ideas for what should happen to Holderness

Homework- Letter to the Council

M anagem ent of the Holderness Coast A Decision M aking Exercise