Section C

• Explain the 4 processes of erosion.

  Hydraulic Action - water and air forcing themselves into cracks in the cliff to break away bits of rock.
• Attrition - rocks being knocked against one another by waves, causing them to wear down
• Solution - rainwater containing carbon dioxide dissolving limestone and chalk cliffs
• What is abrasion?


  Eroded rock scraping against the cliff face, breaking off bits of rock.
• Describe the formation of headlands and bays.

  Headlands and bays form along discordant coastlines which have alternating bands of hard and soft rock. The less resistant rock (soft) is eroded much faster as it is weaker which forms a bay with a gentle slope. However, the more resistant rock eroded a lot slower as it is stronger so it juts out forming a headland with steep sides.
• Describe the formation of a WAVE CUT PLATFORM.

  Waves cause the most erosion at the base of the cliff with hydraulic action and abrasion creating a wave cut notch. As the erosion continues at the base of the cliff, the notch becomes larger and deeper until the rock above gets too heavy and unstable causing it to collapse. This material is transported away and erosion begins to take its course again creating another wave cut notch and the process repeats. This repeating process makes the cliff RETREAT and leaves a WAVE CUT PLATFORM.
• Describe the formation of SAND DUNES.

  Sand dunes are formed when sand is deposited by long shore drift - the movement of sediment along the beach. Obstacles on the beach cause the wind speed to decrease so sand is deposited, forming EMBRYO DUNES which are colonised by plants such as marram grass. The roots of the vegetation stabilises the sand encouraging more sand to build up to accumulate there to form FORE DUNES and eventually MATURE DUNES. New embryo dunes form in front of stabilised dunes.
• Describe the formation of SPITS.

  Spits form at sharp bends in the coastline and long shore drift transports sand and shingle past the bend and loses energy therefore depositing the sediment into the sea. Overtime this sediment builds up forming the start of a spit. Strong winds and waves can curve the end of the spit forming a recurved end. The area behind the spit is shelter from waves so vegetation can grow as material is accumulated and eventually this can become a mud flat or a salt marsh.
• Describe the formation of BARS.

  A bar forms when two spits join two headlands together through long shore drift. The bay between the joining spits is eventually cut off from the sea meaning a lagoon can form behind it.
• How are offshore bars created?

  Offshore bars can form if the coast has a gentle slope. Friction with the sea bed causes waves to slow down and deposit sediment off shore which creates a bar not connected to the coastline.
• How are meanders formed?

  The current is faster on the outside of the bend because the river channel is deeper as there is less friction to slow the water down so more erosion takes place on the outside of the bend forming river cliffs. The current is slower on the inside of the bend because the river channel is shallower so there is more friction so the eroded material is deposited on the inside of the bend forming slip off slopes.
• How are Ox-Bow lakes formed?

  Erosion causes the outside of the bend to get closer until there is only a small bit of land between the bends. The river breaks through the land usually during a flood and the river flows along the shortest course. Deposition eventually cuts off the meander forming an ox-bow lake.
• Describe the transportation method traction.

  Traction is large particles like boulders are pushed along the river bed by the force of water.
• Describe the transportation method of suspension.

  Suspension is the movement of small particles like silt and clay are carried along by the water.
• Describe the transportation method of saltation.

  Pebble-sized particles are bounced along the river bed by the force of the water.
• Describe the transportation method of solution.

  Solution is the movement of soluble particles dissolved in the water and carried along.
• How is a waterfall created?

  Waterfalls form when a river flows over an area of hard rock followed by an area of softer rock. The softer rock is eroded by hydraulic action and abrasion more than the hard rock creating a 'step' and as the water flows over the step it erodes more of the softer rock and a steep drop is eventually created which is called a waterfall.
• describe the characteristics of a constructive wave

  • gentle beach profile
  • builds up the beach
  • low wave length and long waves
  • low frequency
• give the characteristics of a destructive wave

  • tall breaker
  • short wave length and high waves
  • erodes the beach
  • high frequency