Geography

• Swash 


  The force of breaking waves moving up the beach.
• Backwash 


  The movement of water down the beach by the action of gravity.
• Destructive waves

  Backwash is stronger than swash, allowing them to remove material from the beach.

  • Frequent in number
  • Tall waves, meaning they have greater distance to fall when they break. This causes them to scour out beach material.
  • Creates a steep, narrow beach
• Constructive Waves 


  Swash is much stronger than backwash, causing the beach to be built up by the deposited material.

  • less frequent
  • long waves so they roll onto the beach rather that crashing.
  • Create a wide, gentle sloping beach.
• Longshore drift

  Prevailing winds blow onto the coastline at an angle. This cause the waves to hit the beach at an angle dragging sediment with it.

  • The backwash returns to the sea at 90 degrees due to gravity dragging sediment with it.
  • The zigzag pattern moves sediment along the coast in a process known as longshore drift.
• Where do headlands and bays form?

  Form where there are layers of hard and soft rock perpendicular to the sea.
• How do bays start?

  Soft rock erodes fastest as it is less resistant forming a bay.
• How do headlands start?

  The hard rock erodes much slower as it is more resistant forming the headland.
• How are sand dunes formed?

  • Sand dunes form when strong onshore winds blow sand from the beach inwards.
  • where no vegetation is present the sand will continue to be blown inward.
  • The sand forms mounds, held together by long rooted grasses such as marram.
  • In some places grasses are planted or fences built in an attempt to stabilise the dunes.
• How are spits and bars formed?

  • Spits form in shallow, sheltered water with large amount of sediment.
  • Longshore drift transports sediment along the coast and where the coast changes direction, continues to deposit material in the original direction.
  • Overtime this builds up forming a spit. If the direction of wind changes, longshore drift will changed direction causing a curved end.
  • Salt marshes and mudflats will develop behind the spit where it is sheltered.
  • If the spit grows across a bay to join to headlands a bar is formed.
• How is slumping formed?

  • The waves attack the base of the cliff through hydraulic action.
  • Overtime this will cause a wave cut notch.
  • At the same time water soaks into the top of the cliff making it heavy.
  • Eventually the cliff above the wave cut notch becomes to heavy and collapses. A slump is left behind.
• How are meanders formed?

  
• Waterfalls?


  Waterfalls form in areas of the upper course where hard rock and soft rock are next to eachother.

  Hydraulic action erodes the soft rock fastest as it is less resistant.

  This erosion continues until a drop forms as so much soft rock has eroded.
• Waterfall pt2? 


  This leads to an overhang of unsupported hard rock. At the base of the waterfall a plunge pool is formed by hydraulic action.

  Eventually, gravity cause the overhang to collapse, meaning the waterfall retreats. Pebbles are added to the plunge pool where abrasion speeds up erosion and the undercutting of the hard rock e.g. High force falls, river tees.
• Threats of deforestation: Population?

  Population growth has resulted in the loss of tropical rainforest as land is cleared.
• Farming?


  Large areas are cleared for pastoral farming. As global demand for meat has increased, many cattle farms have opened in the Amazon Basin for beef farming.
• Logging? 


  Tropical rainforests are cut down so that valuable trees like mahogany can be accessed and sold for timber to make furniture. Other trees are cut down to make paper products.
• Mining?


  The Amazon Basin is rich in natural resources such as iron ore, copper, tin, aluminium, manganese and gold. This has lead to development of mines, which resulted in the clearance of rainforests.
• Roads? 


  The construction of access roads for farmers, loggers and miners resulted in large parts of the tropical rainforest being destroyed.

  The creation of hydroelectric power stations in the Amazon Basin has resulted in large areas getting flooded to create the reservoirs and dams.