L9 - waves geology and rock structure

• wave fetch

  the horizontal distance between two crests
• fetch

  the distance the wave travels across open water
• trough

  the bottom of a wave
• swash

  the movement of waves up the beach
• crest

  the top of a wave
• wave height

  the vertical distance from trough to crest
• backwash

  the movement back down the beach
• wave frequency

  the number of waves breaking per minute
• what causes waves

  waves are caused by wind blowing over the surface of the sea and creating friction. as waves approach the coast, the bottom is slowed down by friction with the sea bed, whilst the top is still moving forward faster - this makes the wave bigger and causes it to break
• what affects the strength of a wave

  • speed of the wind
  • time the wind has been blowing
  • fetch
• strong winds result in stronger waves because more energy is transferred to waves from the friction on the surface
• the longer the wind has been blowing the more friction and energy
• the longer the fetch, the more area for the wind to blow over the waves creating friction and transferring energy
• constructive waves are long but destructive waves are short
• constructive waves have a low wave height but destructive waves have a high wave height
• constructive waves occur 6-9 times a minute but destructive waves occur 10-15 times a minute
• the swash of constructive waves is weaker and the swash of destructive waves is stronger
• the backwash of constrictive waves is weaker and the backwash of destructive waves is stronger
• the process of constructive waves is deposition and the process of destructive waves is erosion
• constructive waves are common in summer and destructive waves are common in winter
• constructive waves happen on a wide sandy and gentle sloping beach and destructive waves happen on a steep, pebbly and narrow beach
• geology is the type of rock, softer rock will be eroded faster than harder rock
• rock structure is how rocks are aligned with the coast, they can be concordant or discordant but both have alternating bands of hard and soft rock
• softer rock is less resistant to erosion than harder rock which is more resistant to erosion
• discordant coastlines run at right angles to the coast
• concordant coastlines run parallel to the coast
• an example of soft rock is chalk
• an example of hard rock is limestone