Yr9 geography

• Waves are formed by the wind dragging on the surface of the water
• 1. Wind blows on the surface of the water
  2. This causes the water to move in circular motion=waves
  3. Friction from the beach slows the lower half of the wave
  4. Upper part of the wave continues to move at same pace
• The fetch is the distance of open water over which the wind blows
• 3 main wave factors

  1. Wind strength
  2. Wind duration
  3. Fetch
• Longer periods mean more energy so bigger waves
• The swash is the movement of waves up the beach same angle as the prevailing wind
• The backwash is the movement of waves back down the beach at 90° to the coast
• Constructive waves

  1. Calm weather
  2. Les powerful due to limited energy
  3. Strong swash, limited backwash
  4. Deposits material
• Destructive waves

  1. Stormy weather
  2. Waves are more powerful with lots of energy
  3. Limited swash, strong backwash
  4. Erodes material from the beach
• Tides are formed by the gravitational pull of the moon which causes a daily rise and fall of sea levels
• 2 high tides

  2 low tides
• 6.15 hours between high and low tides
• 2 tides a day
• Erosion - the wearing away of land, Cliff by the sea
• Transportation- movement of eroded Beach material by wave(longshore drift)
• Deposition- when waves lose their energy they drop material
• Hydraulic action - air becomes trapped in joints& cracks on cloud face. Wave hits trapped air is compressed and weakens the cliff
• Abrasion - bits of rock and same in the waves grind down cliff surfaces like sandpaper
• Attrition- waves smash Pebbles on shore into each other so sharp edges break of and pebbles become smaller, smoother and rounder
• Solution

  Acid contained in sea water dissolves some types of rock such as chalk
• Coastal transportation

  Movement of material from one place to another
• Coastal transportation

  1. Waves approach at the same angle as the prevailing wind
  2. Swash carries material up and along the beach
  3. Backwash carries material
  4. Moves along the beach in longshore drift
• Coastal deposition

  Sea loses energy drops sand, rock particles and pebbles
• Coastal deposition occurs when

  1. Swash runs out of momentum and backwash cannot move material
  2. When longshore drift enters calm water