Coasts

• The stronger the wind the longer it blows, the longer the fetch the larger the waves will be and more energy they'll have.
• Swash - the water that rushes up the beach when a wave breaks.
• Backwash - the water that rolls back down a beach after a wave has broken.
• Backwash more energy than the awash = the waves eat at the land.
• Swash more energy then the backwash = materials left on the land.

• The moon attracts the sea and pulls it upwards and the rise and the fall of the sea gives us the tides.
• High tide - is when the tide is in at the coastal town
• Low tide - is when the tide is out, leaving the boats resting on mud.
• High tides occur about every twelve and a half hours, with low tides in between.

• Waves erode the coast
• Waves deposit in sheltered areas
• Waves transport eroded material

Erosion

• Waves hammer against the rock over time this breaks the rock up.
• Hydraulic action - waves force water into cracks in the rock under pressure, this breaks the rock up.
• Solution - Water dissolves soluble materials from the rock.
• Abrasion - Waves fling sand pebbles and large stones against the rock. They wear it away like sandpaper.
• Atrtrition - Chunks of rock get knocked together and worn into smaller bits.

• Deposition - if waves carry more material on the land a beach forms.

• Headland - hard rock erodes more slowly than soft rock, forming an headland.
• Bay - softer rock has been eroded away.
• Eroded material is carried along the coast by longshore drift. If longshore drift is interrrupted you get a spit.
• Salt marsh - Silt and mud build up in a sheltered area.

• Cliffs are eroded by waves and weakened by weathering.
• It winter the ice makes the cracks bigger.
• Heavy rain means the cliffs are full of water.
• The more water in cliffs the weaker they are.
• Clay cliffs are the worst, huge blocks of clay slide down the slope.
• One way to solve the problem is to bury pipes in them so they carry the water away.
• This is expensive and pipes don't last forever.
• You can use rock armour to stop the cliffs from collapsing.

How can we stop the coast eroding?

• Sea walls
• rock armour (Soak up the waves energy)
• Build barriers out at sea to make the waves break away from the shore
• Build groynes to stop sand being carried away because the sand protects the coast
• Beach replenishment by adding more sand