Coastal processes

• What does the size and energy of a wave depend on?

  The fetch, the strength of the wind, how long the wind has been blowing for.
• What does the fetch mean?

  How far the wave has travelled
• How many type of waves are there?

  2
• What is swash?

  The water flowing towards a beach when a wave breaks.
• What is backwash?

  The movement of water down the beach.
• What are the features of a destructive wave?

  Weak swash and strong backwash

  the strong backwash removes sediment from the beach

  the waves are steep and close together

  A) Strong backwash

  B) Weak swash

  C) A tall breaker

  D) wave

  E) length

  
• What is a constructive wave?

  strong swash and weak backwash

  the strong swash brings sediment which builds up the beach

  the backwash is not strong enough to remove sediment

  the waves are low and far apart

  A) Weak backswash

  B) Strong swash

  C) wave

  D) length

  
• Processes called erosion, mass movement, and weathering break down and remove material from the coast
• Material from the coast is moved along the coastline by the sea and deposited when there is energy loss
• Exposed rocks along the coastline can be broken down by different types of weathering:

  • Freeze-thaw weathering:

  1. Occurs when rocks are porous or permeable

  2. Water enters cracks in the rock, freezes, and expands causing the crack to widen

  3. The ice melts and water makes its way deeper into the cracks, repeating the process until the rock splits entirely

  • Biological weathering:

  1. Plants and animals weaken the rock structure until it breaks away

  2. Plant roots get into small cracks, grow, and cause the cracks to become larger, leading to small pieces of rock breaking away

  • Chemical weathering:

  1. Rainwater and seawater, acting as weak acids, can dissolve rocks like limestone or chalk over time
• What is rock fall?

  Bits of rock fall off the cliff face, usually due to freeze-thaw weathering.

  
• Label

  A) Cliff Face

  B) Scree

  
• What is scree?

  a mass of small loose stones that form or cover a slope on a mountain
• What is mudflow?

  Saturated soil (soil filled with water) flows down a slope.

  A) Soil

  B) Stream

  C) Saturated soil

  D) Lobe

  E) Bedrock

  
• What is a landslide?

  Large blocks of rock slide downhill.

  A) Slide Plane

  B) Detached rock

  
• What is rotational slip?

  Saturated soil slumps down a curved surface.

  A) Head

  B) Scarp

  C) Foot

  D) Toe

  E) Curved slip plane

  
• How many types of erosion are there?

  Four
• What is hydraulic action?

  This is the sheer power of the waves as they smash against the cliff. Air becomes trapped in the cracks in the rock and causes the rock to break apart.
• What is abrasion?

  This is when pebbles grind along a rock platform, much like sandpaper. Over time the rock becomes smooth.
• What is attirition?

  This is when rocks that the sea is carrying knock against each other. They break apart to become smaller and more rounded.
• What is solution?

  This is when sea water dissolves certain types of rocks. In the UK, chalk and limestone cliffs are prone to this type of erosion.
• How many types of transporation are there?

  Four
• What is solution in terms of transportation

  When minerals in rocks like chalk and limestone are dissolved in sea water and then carried in solution. The load is not visible.
• What is suspension in terms of transportation?

  When small particles such as silts and clays are suspended in the flow of the water.
• What is saltation?

  Where small pieces of shingle or large sand grains are bounced along the sea bed.
• What is traction?

  where pebbles and larger material are rolled along the sea bed.
• What is longshore drift?

  The movement of material along a coastline due to the angled approach of waves.
• What is deposition?

  When the sea loses energy, it drops the material it has been carrying. 
• What leads to deposition?

  • waves starting to slow down and lose energy
  • shallow water
  • sheltered areas, eg bays
  • little or no wind
• Step 1 of a wave cut platform:

  A wave cut platform is formed by the sea attacking the cliff face though different types of erosion e.g. abrasion and hydraulic action. Abrasion is where cliffs are worn down from destructive waves and the throwing of material in the waves.
• Step 2 of a wave cut platform:

  Hydraulic action occurs when the waves enter cracks within the cliff at the high tide mark, compressing the air within and resulting in expansion of the crack as the wave retreats. This then has the effect of creating a notch which slowly becomes larger and larger, forming a small cave. 
• Step 3 of a wave cut platform:

  As erosion continues to occur, the weight of the cliff eventually cannot support itself and collapses as a result with the material being deposited and then carried out to sea. Through repetition of these processes, a wave cut platform is formed.