Revision PowerPoint

Use this PowerPoint to help you revise some of the key ideas from this model to help you get ready for

your test.

Don’t forget you can also use Doddle to browse presentations and animations!

What is the Coast?What is the Coast?What do we use it for?What do we use it for?

The Coast is where the land meets The Coast is where the land meets the sea.the sea.

The next slide some of the many The next slide some of the many things we use the coast for.things we use the coast for.

Many people visit the coast for Many people visit the coast for leisure and holidays.leisure and holidays.

People live and work there.People live and work there. Could any of these activities conflict?Could any of these activities conflict?

Could any of these conflict?

The Power of the wavesThe Power of the waves

Waves are changing the coast every Waves are changing the coast every day, they do this by following a day, they do this by following a master planmaster plan

Erode

Transport

Deposit

Waves at WorkWaves at Work

Waves change the coast in 3 ways Waves change the coast in 3 ways

Transport

Deposit

Erode

What do these keywords mean?What do these keywords mean?

Waves Waves erodeerode (wear down) the coast. (wear down) the coast. Waves Waves transporttransport (move) the eroded (move) the eroded

material.material. Waves Waves depositdeposit (drop) this material (drop) this material

in sheltered areas where they lose in sheltered areas where they lose their energy.their energy.

There are 4 types of Erosion By WavesThere are 4 types of Erosion By Waves

erosion

Hydraulic action solution

Abrasionattrition

How do these types of erosion work?

Waves smash against the rock, breaking the rock up over time.Waves smash against the rock, breaking the rock up over time.

Hydraulic ActionHydraulic Action

Waves force water into cracks under Waves force water into cracks under pressure. This helps break up the pressure. This helps break up the rock.rock.

SolutionSolution

Water dissolves soluble material Water dissolves soluble material from the rock.from the rock.

AbrasionAbrasion

Waves fling sand,pebbles and large Waves fling sand,pebbles and large stones against the rock. This acts as stones against the rock. This acts as sand paper wearing away the rock.sand paper wearing away the rock.

AttritionAttrition

Waves knock together the pieces of Waves knock together the pieces of rock broken off by erosion. These rock broken off by erosion. These wear down into smaller and smaller wear down into smaller and smaller pieces. pieces.

The rock wears down into The rock wears down into shingle shingle (Pebbles) (Pebbles) and and sand.sand.

The waves don’t have all the The waves don’t have all the power!power!

Erosion of the cliffs also occur from Erosion of the cliffs also occur from weatheringweathering

What are the different types of What are the different types of weathering ?weathering ?

Water trickles into cracks.In icy weather it freezes, forcing the cracks wider until the rock breaks up.

In hot places, Like deserts, the rock heats up during the day and expands. At night it cools and contracts this weakens the rock. The outer layers of he rock break up- rather like an onion skin.

Plant and tree roots grow in cracks and widen them, causing the rock to break up

Remember Science?

Water reacts with Carbon dioxide in the air. The water becomes slightly acidic. (Carbonic acid). This dissolves the rock.

Erosion of a HeadlandErosion of a HeadlandCaves Arches Stacks StumpsCaves Arches Stacks StumpsThe video link below will help The video link below will help you reacp these land forms:you reacp these land forms:

http://www.bbc.co.uk/learningzone/clips/coastlines-caves-arches-and-stacks/8432.html

Make sure you can describe and explain how these land forms are created.

Remember your P2L, the big picture activity and your diagram?

Geog 2 describes the process of a headland being eroded as shown below:

Crack

Cave

Arch

Stack

Stump

Erosion of a Headland

Longshore driftLongshore drift

Waves transport the material Waves transport the material they erode from the land.they erode from the land.

Much of the material is Much of the material is transported bytransported by

What happen when the waves reach the land?What happen when the waves reach the land?

When the waves reach the beach, When the waves reach the beach, they break and cause a they break and cause a swashswash and and backwash.backwash.

When the water rushes up the beach with lots of

energy this is called the

swash

When the water rushes

down the beach with a

lot less energy this is called the backwash

SEA

Longshore DriftHow the eroded rock moves

around

Direction of longshore drift

Many seaside towns build groynes to stop Many seaside towns build groynes to stop their beaches being washed awaytheir beaches being washed away

The groyne disrupts longshore driftThe groyne disrupts longshore drift

How do groynes work?How do groynes work?

Pebbles and sand carried by Pebbles and sand carried by longshore drift are stopped by the longshore drift are stopped by the groyne, so the beach builds up on groyne, so the beach builds up on

this sidethis side

On this side longshore drift carries On this side longshore drift carries on . It moves pebbles and sand away on . It moves pebbles and sand away in the direction of the longshore drift, in the direction of the longshore drift,

so there is less beach material.so there is less beach material.

Wave direction

Direction of longshore drift

..Watch this video clip to see Watch this video clip to see

longshore drift in action.longshore drift in action.

http://www.bbc.co.uk/learningzone/clips/the-coastline-longshore-drift-and-spits/3086.html

Cliff CollapseCliff Collapse

Wave erosion, Weathering and rain Wave erosion, Weathering and rain combine to weaken cliffs. This can combine to weaken cliffs. This can cause them to collapse.cause them to collapse.

Holbeck Hall Hotel in Holbeck Hall Hotel in ScarboroughScarborough

Cliff Collapse

Weathering

Chemical: rain soaks in and dissolves minerals

Freeze- thaw: In winter water freezes in the cracks making them larger

Rain

Soaks into the cracks. It makes clay cliffs

very slippery. The clay can just slide away.

Wave Erosion

Waves attack the cliff through Hydraulic Action, Abrasion,

Solution and Attrition.

If we can reduce the effects of

these processes, we can prevent cliffs falling into

the sea.

Make sure you can describe, explain and evaluate the advantages and

disadvantages of the different methods we use to prevent

cliff collapse.

Rock ArmourRock Armour Heavy rocks cemented in front of the cliff.Heavy rocks cemented in front of the cliff. Absorbs energy from the waves.Absorbs energy from the waves. Creates a barrier protecting the land from attcak by Creates a barrier protecting the land from attcak by

wave erosion.wave erosion. Difficult to transport heavy stonesDifficult to transport heavy stones Interferes with Longshore DriftInterferes with Longshore Drift Ugly, spoils the view and some of the beach is Ugly, spoils the view and some of the beach is

covered.covered. Heavy lorries need to transport the rocks causing Heavy lorries need to transport the rocks causing

traffic problems, noise and pollution.traffic problems, noise and pollution. Needs to be replaced when it has been eroded.Needs to be replaced when it has been eroded.

Drainage PipesDrainage Pipes Pipes that are dug into the cliff.Pipes that are dug into the cliff. Drains away water from the cliff, so it is less Drains away water from the cliff, so it is less

slippery.slippery. It doesn’t spoil the view.It doesn’t spoil the view. Very Effective, especially to protect soft clay cliffs Very Effective, especially to protect soft clay cliffs

that become very slippery when they are saturated that become very slippery when they are saturated with water.with water.

Very expensive to install.Very expensive to install. Noise, pollution and disruption while trenches are Noise, pollution and disruption while trenches are

dug to install the pipes.dug to install the pipes.

Salt resistant vegetationSalt resistant vegetation Plants that can survive in salty conditions near the Plants that can survive in salty conditions near the

coast are planted on the cliff.coast are planted on the cliff. They draw out some of the water from the cliff.They draw out some of the water from the cliff. Their roots bind the soil together, stabilising it and Their roots bind the soil together, stabilising it and

making it less likely to slip.making it less likely to slip. Quite cheap and low maintenance.Quite cheap and low maintenance. Looks natural and could create habitats.Looks natural and could create habitats. Loss of agricultural (Farm) land.Loss of agricultural (Farm) land. Changes the natural habitat of animals and plantsChanges the natural habitat of animals and plants

Wave Barriers/Granite ReefsWave Barriers/Granite Reefs Break the waves away from the coastBreak the waves away from the coast Doesn’t stop Longshore Drift completelyDoesn’t stop Longshore Drift completely Extremely expensiveExtremely expensive

GroynesGroynes Stops Longshore drift causing sand to Stops Longshore drift causing sand to

build up.build up. Ugly and costly to maintainUgly and costly to maintain

Beach ReplenishmentBeach Replenishment Replacing the material moved by waves.Replacing the material moved by waves. Natural effect against erosionNatural effect against erosion Needs constant “Topping up” Needs constant “Topping up”

(replenishment)(replenishment)

There is always a downside…

Knock on EffectsIf we stop erosion and cliff collapses in one

place, longshore drift will not be able to transport the eroded material along the coast

to another place.

The beach there will not be replenished, but it will be transported away by longshore drift.

This means erosion will be worse there as there is less beach to protect the coast

However we protect the coast or try to prevent cliffs

collapsing there will be a disadvantage.