Geography coastal revision 🌊🌿

• The south downs was weathered and eroded overtime to create V-shaped valleys and hilltops
• Chalk is very porous so it can hold water easily, this means that the soil on top of the chalk is also permeable
• Hydraulic action is when waves crash against a cliff making the rock fall and break off
• Abrasion is when rocks crash against a cliff to break rock off
• Solution is when chemicals wear and break down rocks until they are dissolved and are carried away by the water
• Attrition is when small sediment collide against each other and the cliff until they are broken down
• Erosion is when rock is broken down by a moving force e.g. water
• Transportation is the movement of broken down sediment by water
• Weathering is the break up of rock in one place e.g. freeze thaw
• Deposition is when material is dropped by moving water as it loses its energy
• Mass movement is the movement of material downhill due to gravity
• Rock falls is when a rock has been undercut due to weathering or waves and falls down due to gravity
• Slumping occurs after a long period of rainfall. When the rain seeps through permeable rock and meets impermeable rock and starts to slump along a curved surface
• Mechanical weathering is when repeated freezing and thawing of water inside a crack in a rock happens until rock breaks off
• Chemical weathering is when slightly acidic rain water meets rock and weakens the rock due to chemical reactions e.g. Acid rain
• Biological weathering is when roots of growing plants and burrowing animals widen cracks in rocks and cause cliff faces to weaken
• Traction is when stones roll along the sea bed (this needs the most energy)
• Saltation is when small particles bounce along the sea floor (leap frog movement)
• Suspension is when particles are carried within the water flow
• Solution is when particles dissolve in water (this requires the least amount of energy)
• how are waves formed?

  1. wind blows across the ocean
  2. the wind pushes parts of the water down
  3. this then pushes other parts of the water up
  4. these then start to spin in a cycle and begins to form a wave
• Fetch is the distance a wave travels over the sea to make a wave
• Constructive waves help to build a beach through deposition
• Destructive waves help to destroy a beach through the use of erosion
• Constructive waves have:

  • strong swash
  • weak backwash
  • short fetch
  • low frequency
• Destructive waves have:

  • weak swash
  • Strong backwash
  • long fetch
  • high frequency
• swash is the movement of a wave onto a beach
• Backwash is the movement of a wave off of a beach
• Factors that determine the energy of the waves are:

  1. wind strength
  2. wind duration
  3. fetch
• Discordant coastline: a coastline which has alternating layers of hard and soft rock facing the sea

  
• Concordant coastline: a coastline that has one layer of rock facing the sea (usually hard rock )

  
• What landforms can be created on a discordant coastline?

  1. Headlands and bays
• What landforms are created on a concordant coastline?

  1. Cove
• How is a cove formed?

  Coves are formed at a concordant coastline. Overtime erosion causes a crack to form. This means that soft rock behind it starts to erode forming a cove. As waves enter a cove their energy us lost making them deposit their sediment forming a beach in the cove.
• How is a headland and bay formed?

  Headlands and bays are formed at a discordant coastline. This means that the soft rock is less resistant so it erodes faster. This means the hard rock form a headland and the soft rock form a bay. Overtime there will be a beach in the bay from the waves losing energy at the headlands turning them into constructive waves depositing sediment forming a beach
• Wave cut notches and wave cut platforms?

  1. The waves erode the cliff base by hydraulic action. This is called undercutting.
  2. As erosion occurs a wave cut notch is formed.
  3. As the notch gets bigger the overhang grows and becomes unstable and collapses.
  4. The cliff then retreats back
  5. A wave cut platform forms where the cliff used to be ( made by the collapsed overhang )
• Caves, arches, stacks and stumps?

  1. These are all formed on a discordant coastline
  2. hydraulic action cause cracks in the hard rock
  3. overtime the crack widen and deepen and become caves
  4. erosion on the cliff enlarges the caves and forms an arch
  5. more erosion causes arches to grow and lack of support causes the arch to collapse due to gravity
  6. then the rock left standing is a stack
  7. after biological and mechanical weathering plus erosion break down the top of the stack and then form a stump
• What is longshore drift?

  the movement of material along the coast in a zig-zag pattern
• How to describe longshore drift in an exam question?

  • swash pushes sediment onto the beach at an angle determined by the prevailing wind
  • backwash pushes sediment off the beach at a right angle due to gravity
  • overtime swash and backwash push sediment along the beach in the process of longshore drift
• what would the information in the image be. use the OS map?

  476334