TOPIC COASTLINES Jq03NBao

In this unit we will look at how the sea shapes the coastline by processes of erosion, transportation and deposition.We will also see how man has had an important impact on the coastline ( coastal management ) It is the action of waves and the nature of the geology that shapes the British coastline. COASTS

Local Geology The coastline of the British Isles is not smooth. Why ? The nature of the rocks is important. Some are very hard but some are very soft and are eroded easily.

Wave Action Destructive Waves Winds generate waves. Strong winds build powerful waves with lots of energy. Gentle winds produce gentle waves with low energy. Destructive waves have a very strong backwash and a weak swash. They remove beach material. Tend to create steep, shingle beaches waves

Constructive Waves. These waves deposit material at the coast. They build up the coastline. The strong swash pushes sand / shingle up the beach. Tend to be gentler, sandy beaches

Features / Landforms produced by EROSION. What are the processes of EROSION ? Remember the H.A.C.A HYDRAULIC ACTION. ABRASION CORROSION ATTRITION. erosional landforms

Bays and Headlands Cardigan Bay: Wales 1.Describe what has happened in these sketches. 2.Explain what has happened in these sketches.

Cliffs and wave cut platforms These are the Seven Sisters On the south coast between Brighton / Eastbourne. Look for the point where the cliff line used to be. Notice the cliff line today.

A great example of a wave cut platform!

DURDLE DOOR in DORSET What will be formed when the arch collapses?

Headland Erosion. OLD HARRY ROCKS The headland itself is eventually broken down by erosion. Remember the sequence of events : CAVES ARCHES STACKS + STUMPS

Case study / Example OLD HARRY ROCKS in Dorset

What is Longshore Drift ? Waves approach at an angle. Material is moved along the beach. Is longshore drift a good thing / bad thing ? Why ?

Spit Formation Key Terms : EROSION TRANSPORTATION DEPOSITION Draw arrows to label the places on the sketch.

Spit animation Watch how material is transported along the coastline by longshore drift. The coastline changes direction and the material is moved out to sea and deposited. Case study : Spurn Head

Longshore Drift also creates…. SPITS This is Spurn Head the largest spit in the British Isles.

What features are produced as a result of Longshore Drift ? The sand has moved along the coastline and formed a BAR. A bank of sand across the estuary.

Why is Longshore Drift a problem? Longshore drift moves material along the coast. Places can be left with no sand / shingle to protect the coastline. The waves can easily attack / erode the cliffs. Case study of Holderness

Where is the Holderness Coast?

Holderness Coast In this photograph you can see that the beach is narrow and the cliff is open to attack from the waves. The house on the cliff top is under threat of collapse into the sea.

Now watch some film clips of the Holderness Coast to see the effects of interfering with the natural process of Longshore Drift.

Coastal Management

Coastal Protection Coastal Protection only goes ahead if the value of the land at risk exceeds the cost of the coastal defences. Which parts do we protect? Coastal towns/cities that have high populations and high land value Tourist resorts which rely on coastal attractions Important transport links, roads railways Industry – factories or ports – power stations. MANAGED RETREAT – in areas of low economic value the sea is allowed to erode and flood the land. winter storms take toll on UK coastline

What are Groynes ? Longshore Drift moves material along the coastline leaving some parts unprotected. How can we stop Longshore Drift ? Wooden Groynes trap beach material

Examples of Groynes Look at how the waves approach at an angle to the shoreline. Note how material builds up on unevenly between the groynes.

Are Groynes a good or bad thing? Good Points : Groynes Trap material and it builds ups protecting the coast. Case study Bournemouth Beach. Bad Points The natural movement of material is stopped and other places along the coast do not get the sand / shingle to protect the coastline. Case study Holdermess What has happened in this photograph ?

Coastal Protection Some parts of our coastline are protected from erosion. Why? To protect towns that have large populations and whose local economy depends on tourism or fishing or industry.

Coastal Protection

Rock Armour and curved sea wall. Gabions are rocks held together with Wire netting. They stabilise cliffs.

Coastal Protection Rip Rap wooden barriers hold rocks together Look at this sketch to see what defences have been built on Brighton Seafront.

What is Managed Retreat? It can cost millions of pounds to build sea defences. Low value land is not worth protecting. Nature is allowed to take its natural course. Birling Gap near Eastbourne in Sussex Will not receive any money for coastal protection. This low value farmland will be allowed to flood.

Hemsby Bangladesh New Orleans

Case study of Bournemouth Bournemouth Seafront is heavily defended. Wide sand / shingle beach.Wide Promenade / Concrete sea wall. Gabions. Grass banks stabilise the soil.

Bournemouth Facts. Population million visitors a year. Tourists spend over £130million a year jobs in tourists sector. Bournemouth has: 7 miles of golden sands. Bournemouth receives 7.7 hours of sunshine on average every day.