Geography - CoastsBy Charlotte Hayward

Contents• Introduction• Headlands• Bays• HAAC Processes• Parts of a Wave• Types of Waves• Cave, Arch, Stack Formation• Wave-cut Platforms• Wave-cut Notches• Predicted Erosion Rates• Quiz• Key Words• Summary

IntroductionAs you know, a coast is a narrow stretch between land and see. This Power Point will be your revision aid, it will contain all you need to know about coasts and include quizzes, pictures, matching games and much more.

If you ever need to return to the home page click on the home button which will appear on the screen next.

HeadlandsA headland is made out of a band of alternate rock perpendicular to the coastline. The hard rock along a coastline is usually made out of rocks like chalk, meaning it gets eroded slower than the softer rock like clay. This hard rock sticks out into the sea; known as a headland.An example of a headland are the White Cliffs of Dover.

The soft rock that gets eroded fasterthan a headland is called a bay…

BaysA bay is also formed from a band of alternate rock perpendicular to the coastline. The soft rock along a coastline is usually made out of rocks like clay, meaning it gets eroded faster than the hard rock like chalk. This soft rock sticks into the land; known as a bay.An example of a bay is Hudson Bay.

For headlands and bays to beformed certain types of erosionoccur.

HAAC ProcessesThere are four main types of erosion called the

HAAC processes.

Hydraulic Action - The force of the river against the banks can cause air to be trapped in cracks and crevices. The pressure weakens the banks and gradually wears it away.

Attrition - Rocks being carried by the river smash together and break into smaller, smoother and rounder particles.

Abrasion - Rocks carried along by the river wear down the river bed and banks.

Corrosion – Water dissolves minerals from the rocks and washes them away.

Parts of a WaveA wave is made up of four distinct parts,

these are:

Crest – The top of the wave.

Trough – The bottom of a wave.

Wavelength – The length of one complete wave cycle.

Amplitude – The distance from crest to crest.

Types of WavesDestructive Waves:

• Destructive waves are create in storm conditions.• They occur when wave energy is high and the wave has

travelled over a long fetch.• They tend to erode the coast.• They have a stronger backwash than swash.• They have a short wave length and are high and steep.

Constructive Waves:• They are created in calm weather and are less powerful than

destructive waves.• They break on the shore and deposit material, building up

beaches.• They have a swash that is stronger than the backwash.• They have a long wavelength, and are low in height.

Cave, Arch, Stack FormationCave:

Occur when waves force their way into cracks in the cliff face. The water contains sand and other materials that grind away at the rock until the cracks become a cave. Hydraulic action is the predominant process.If the cave is formed in a headland, it may eventually break through to the other side forming an arch.Arch:The arch will gradually become bigger until it can no longer support the top of the arch. When the arch collapses, it leaves the headland on one side and a stack (a tall column of rock) on the other.Stack:The stack will be attacked at the base in the same way that a wave-cut notch is formed. This weakens the structure and it will eventually collapse to form a stump.One of the best examples in Britain is Old Harry, a stack found off a headland in the Isle of Purbeck.

Wave-cut Notches

A wave-cut notch is formed when a headland gets eroded further at the bottom of the headland where the waves and HAAC processes attack it.A wave-cut notch is an indent in the headland, this process causes a Wave-cut Platform later on.

Wave-cut Platforms

Wave-cut Platforms are formed from Wave-cut Notches.When the pressure above a Wave-cut Notch becomes too much for the rock to hold and it collapses leaving a wave-cut platform.

Predicted Erosion RatesPhysiographic Regions Treatment Average Erosion Rate (tons/acre/year)

Ridge and Valley Bulldozing 13.70

Sand Mountain KG-blade 4.00

Southern Piedmont ChoppingChop and burnKG-bladeBulldozingDisking

0.220.381.804.101.90

Southern Coastal Plain ChoppingChop and burnKG-bladeDiskingBulldozing

0.240.410.650.460.66

Blackland Praires, AL and MS KG-bladeDisking

1.203.30

Most Popular Type of Coast

Most Popular Type of Coast

BayCoveCapeGulfPeninsula

Quiz

Name an example of a Headland that you have learnt about from this

PowerPoint.

ANSWERANSWER

The White Cliffs of Dover

Quiz

What are the four parts of a wave called?

Quiz

ANSWERANSWER

Crest, Trough, Wavelength and Amplitude

Quiz

What type of rocks are baysusually made out of?

Quiz

ANSWERANSWER

Soft rock like clay and sandstone

Quiz

What does HAAC stand for?

Quiz

ANSWERANSWER

Hydraulic Action, Abrasion,Attrition and Corrosion.

Quiz

Conserving Coasts