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Coast (Factors influencing coastal environment (Waves (Erode coasts,…

- - - - When waves are approaching the beach, it collapse and breaks, trapping air in the wave, forming white foams.
      - Swash brings and deposits sediments to the coast.
    - - When going up the beach, the wave loses energy slowly and is pulled by the gravity perpendicularly back into the sea.
      - Backwash erode and take away sediments from the coast. :question: abrasion and hydraulic action are all done during swash. Attrition and solution can occur at any time.
  - - - Stronger swash and weaker backwash
      - Lower wave height, longer wave length
      - Lower wave frequency
      - Mainly brings and deposit sediments
      - Swells and spilling breakers
    - - Weaker swash and stronger backwash
      - Higher wave height, shorter wave length
      - Higher wave frequency
      - Mainly erode and transport the sediments
      - Plunging and surging breakers
- - - - Constructive waves \ destructive waves ( cause erosion due to strong backwash)
    - - Sheltered (bay)\ Open (headland) ( exposed to prevailing wind and wave energy is higher, thus more erosion)
    - - More joints - more lines of weakness for waves to attack - more erosion.
    - - Less resistant rocks - more soluble - more erosion
    - - With protection measures: slower erosion
- - - - Due to hydraulic action and abrasion, the line of weakness on the rocks is attacked, causing a notch.
      - The notch is further eroded, forming a cave.
      - When the cave is eroded deeper, the roof of the cave cannot stand the weight and collapse, forming a cliff. The sediments are accumulated at the base of the cliff.
      - 4.The waves carry the sediments and attack the base of the cliff further,(corrasion) causing the cliff to retreat inland. A gently slopping lowland at the base of the cliff is formed known as the shore platform.
    - - Waves attack the line of weakness to form notch at the base of a headland.
      - Continual erosion, especially hydraulic action and abrasion, enlarges notch to form a cave.
      - Cave enlarges after prolonged erosion and cuts through headland to form an arch.
      - Further erosion causes the collapse of arch, leaving behind an isolated pillar of rock called stack, which is separated from the headland.
      - Continual erosion reduces stack to stump which is submerged during high tide.
    - - Alternative bands of more and less resistant rocks occur at right angle to the coast.
      - Continuous erosion will cause the less resistant rocks to erode more rapidly.
      - The less resistant rocks form bay, a wide inward curve of the coast.
        The more resistant rocks form headland, a steep rock face protruding into the sea.
      - Wave refraction:
        
        The waves may bent when approaching the coast.
        
        Waves converge at the headland, increasing the wave height, resulting in greater erosive energy, causing more erosion.
        
        Waves diverge in the bay, decreasing in wave height, resulting in less erosive energy, causing more deposition.
        
        Over time, the uneven coastline will be straightened.
        
        And all over again.
  - - - 1. Longshore drift transports sediments along the coast.
      - When there is an abrupt bent of the coastline, the longshore drift continues to transport the sediments in the original direction for some distance.
      - The sediments are deposited and overtime, the sediments accumulate and rise above the sea level, a spit is formed. It is a long narrow ridge with an end attached to the land.
      - Due to water refraction, the spit may curve at the tip, forming a recurved spit.
    - - Sometimes, a spit may continue to grow with continuous deposition of sediments. Eventually, a spit may join the nearby island, forming a tombolo.
    - - A beach is a zone of sediment deposition
      - waves erode and transport the sediments
      - When the waves lose energy and become constructive waves, they deposit sediments on the coast
      - Overtime, the deposition form a beach