coasts

• Prevaling wind - the dominant wind in an area 
• Crest - the top of a wave 
• Swash - movement of waves up a beach 
• Backwash- when waves move down a beach 
• Sub-areial processes - when the face and top of a cliff are attacked
• Marine ersion- waves attack rocks causing them to erode 
• Chemical weathering - When chemicals make a rock erode 
• Biological weathering -An animal or plant makes a rock to erode
• Attrition - Sand and pebbles colliding making beach material rounded
• Abraison - Sand and pebbles in waves atacking the cliff - coastal erosion
• Hydraulic action - Waves being so strong that when they hit the cliff parts of rock break away , also air gets compressed into cracks, blasting fragments of rock
• Fetch - The dictance the wave travels 
• Constructive waves - Low long waves that spill onto the beach ; strong swash ,little backwash

Corrosion- (solution):

Salt water is very corrosive so dissolves soft rocks , like chalk, because of this the size of the cracks in these stones increases. This allows more salt spray to get into the cracks , once the water from the salt spray dissolves crystals are left behind, eventually so many crystals are formed the rock is forced apart.

Wetting/ drying:

Soft rocks , like clay, expand when they are wet and cntract when they dry , this means that they weather easily , therefore they errode easier. 

Erosion weathering   ----------->Transportation-------------->Depositation

material is taken away from places    then moved by waves       then deposited in other places

The reason a wave breaks is because the crest is travelling faster than the base , the energy of the wave breaking makes it travel up the beach,swash, it will continue to travel until it reaches it's highest point and loses it's energy. It then starts to travel down the beach , backwash. Waves cause he most re-shaping of the coastline.

Wave energy isn't the only factor in erosion and landforms , one reason is the type of rock in the area. Strong rocks , like igneous , and rocks with few cracks in are difficult to errode however weaker rocks like clay and those with crack are easy to errode.

Headlands and Bays:

Areas of coastline with hard rock tend to stick out and form headlands , whereas areas with cofer rock tends to cause bays. In bays waves are less powerful as they are more sheltered so depositation tends to occour, this is why areas of soft rock tend to have sandy beaches.

Cosatal erosion leads to clifs being worn away or receding over a period of time. The erosion of a cliff is greatest at its base as that is where hydraulic action occours , this forms and indent called a wave-cut notch, the face of the cliff is also impacted because of the rocks from the breaking waves which are being hauled at it. 

The under cutting gradually becomes larger making the overhanging cliff unstable , meaning it collapses , this continues making the cliff retreat more.

Wave cut platform:

As the undercut gets larger and the cliff reteats more a wave cut platform is made , this is a sloping platform of and pebbles and rocks, which is exposd at high tide

A crack in the cliff surface is widened by hydraulic action making a wave-cut notch , because of abraision and hydraulic action a cave is formed at the base of the cliff. Then the sea caves breaks through the headland and an arch os formed . Because of salt spray and instablility the top of the cliff collapses leaving a stack, which then errodes to become a stump. 

Many coastlines in the UK are soft coatlines , which means they have rocks such as clay which are unstable when wet. This means that when there is a combination of heavy rainfall and the waves attacking the base of the cliff the rock becomes saturated , this may cause slumping and landfalls.

Mass movement: The downhill movement of material due to gravity

Mud flow:When a layer of soil on top of a layer of rock becomes saturated it will fall down.

Rotational slip (slumping): When saturated soil and soft rock slumps on a curved surface

Where :

• Scarbourgh, the hotel had a lot of history and the town is a tourist destination

When:

• Friday the fith of June 1993

Why:

• The area has a mixture of soft and hard rock, there had been a period of dry weather which left cracks in the cliff and meant that water could getinto the cliff easier, when there was a large downfall of rain the weight of the cliff increased. 

Impact:

• It is thought that the damage equated to 3 million pounds as well as the loss of jobs for hotel staff 

Transport - As waves travel up the beach they deposit sediment that they previously picked up 

Coastal deposition - Constructive waves deposit more sediment than they drop so eventually a beach forms

Swash aligned beaches- When waves aproach parralel to the coastline and swash and backwash move sediment up the beach , this makes wide beaches with an event shorline 

Drift aligned beaches - When waves aproch at an angle to the coastline

Longshore drift - Movement of material across a coastline

Spits are caused when the direction of a coastline changes so the material that is transported by longshore drift is deposited in the same direction of the original coastline , or the material is deposited when the sea becomes more shallow and loses wave energy. If there is a change in wind direction the spit will often end up curved as the material is pushed inland. This means that many spits are characterised as hooked or curved end, spits cannot be made on estuaries and often salt marshes form behind them.

Bars:

Sometimes longshore drift may grow and trap a bay making a frsh water lake or lagoon behind it ; making a bar.

Some offshore bars have been made onshore because of the rising sea levels after the last ice age - this is called a tombola.

With the increasing populating in coastal areas more effort must be done to stop coastal erosion whilst still maintaining the sea side view.

In the UK Defra (the department for environment , food and rural affairs) is responsible for maintaining the coastlines, because of their budget they must decide which areas are worth protecting. To make this easier they have split the coast into 11 sediment cells (the borders being natural things like headlands etc.), and within these cells there are subcells. For each sub- cell a plan has been devised to tackle the areas problems.

Their managment criteria is :

• Hold the line - maintain the existing coastline 
• Advance the line - build new defences seaward of pre-exiting ones 
• Managed realigment - Let an area flood and build defence inland 
• No intervention - allow nature to shape the coastline 

Happisburgh :

• There is a soft clay cliff which is retreating at 10-15 metres per year which makesit one of the fastest retreating coastlines in the UK making house prices lower  
• In the past 4,000 tonnes of rocks were used as a rock bund 
• It was decided that the area should be allowed to retreat - which the community is very angry about 

Sea Palling:

• By the 1990's most of the beach had been washed away and the sea wall was under constant attack , there are caravan parks etc. there so it has financial value
• In the past , 1953, a million tonnes of boulders wereplaced as a defense 
• They decided to continue proctecting Sea Palling as otherwise the Norfolk broads would have been flooded and a tourist area would have been lost