Coasts Part 1

• How are waves created

  Waves are created by wind which creates friction and changes in pressure. This causes ripples which develop into waves and wind drags the wave as it moves over the surface of the water
• What motion does the water move in

  Water rolls in a circular orbit
• What three factors influence the size and energy of waves

  -the strength of the wind

  -how long the wind has been blowing for

  -distance of ocean the wind blows and the waves build up(fetch)
• Why is the southwest of England a good place to surf


  The fetch has thousands of miles to travel so the waves build up
• What happens as waves move from deeper to shallow waters

  -they slow down

  -get steeper

  -get closer together
• What are the two things that a broken wave produces

  a swash and a backwash
• What is swash


  water that flows towards the coast (deposits material)
• What is backwash


  water flows back towards the sea (removes material)
• What happens when swash is more powerful then backwash

  more material is deposited on the shore than is taken away
• What waves are produced when swash is more powerful the backwash

  constructive waves

  -forms a more gently, wide sloping beach profile
• What happens when the backwash is more powerful than the swash


  more material is removed from the beach then is added
• What waves are produced when the backwash is more powerful than the swash

  Destructive waves

  -forms a steeper, narrow beach profile

  -erodes the beach
• Which direction does the swash arrive at the beach

  at a diagonal

  45 degrees
• Which direction does the backwash leave the beach

  flows straight back due to gravity

  90 degrees
• What process causes sediment to be transported along the beach

  Longshore drift
• What does weathering mean

  The breakdown of rocks by physical or chemical changes in situ (one place).
• What are the three different types of weathering

  mechanical,

  Break-up of rocks without changing their chemical composition, external factors

  chemical

  caused by chemical changes

  biological

  due to the actions of flora and fauna (animals and plants)
• Types of mechanical weathering

  freeze thaw

  salt weathering
• what is freeze thawing

  -during the day water will collect in cracks in a rock from rain or ocean

  -at night the temperature will drop and the water will freeze to form ice. Ice expands which means the crack is enlarged

  -overtime this process will be repeated and eventually the crack becomes large enough to break of and collect as scree at the foot of the rock face
• What is salt weathering

  -seawater contains salt-when the water evaporates it leaves behind salt crystals

  -in cracks and holes these salt crystals grow and expand

  -puts pressure on the rocks, they then disintegrate and flakes break off