Coast GW1(Coastal processes+Coastal landforms)

Coast GW1(Coastal processes+Coastal landforms)

1. Coastal processes

   • Coastal Erosion
     • Hydraulic action
       • Waves traps air in the rock joints and is compressed by oncoming waves,exerting presssure on joints,cause joints to weaken & rocks shatter
     • Abrasion/Corrasion
       • Sediments are carried by waves and are hurled against the coast.Loosened sediments knock and scrape against coastal cliffs.Weakens surface and breaks down the coast.Powerful enough to undercut a cliff.
     • Attrition
       • Rocks break down into smaller pieces & become smoother and more rounded over time.
     • Solution/Corrosion
       • Sea water react chemically with water-soluble minerals in coastal rocks.For exp,limestone are easily eroded by carbonic acid.Weakens rocks and rocks will eventually disintegrate.
   • Sediment Transport
     • Longshore drift
       • Beach drift
         • Resultant Zig-Zag movement of the sediments
       • Longshore current
         • Currents that flow parallel to the coast
   • Sediment deposition
     • Low wave energy like constructive waves allows the deposition of sediments.It vary in type and size,resulting a variety of beaches

2. Coastal landforms

   • Depositional coast
     • Beaches
       • Form from loose sand,gravel,pebbles,broken shells etc.
       • Fine sand = gentler gradient;Coarse sand = steeper gradient
       • Constructive waves
     • Spits&tombolos
       • Longshore Drift > direction of coastline changes abruptly > LSD continue to transport sediments from original direction > Sediments accumulated appear above water surface > spit > continue to extend from mainland to another island > Tombolo
   • Erosional coast
     • Cliff & shore platform
       • Cracks/Joints > Notch > Cave > Roof of cave collapse > steep cliff > Abrasion/Hydraulic action attack base > Overhanging cliff > Overhanging cliff collapse > Cliff retreat inland > Gentle sloping sloping shore platform formed
     • Headland & bay
       • Less resistant rock
         • Bays
       • More resistant rocks
         • Headlands
     • Caves,arches & stacks
       • Joints and faults > Hydraulic action > Cave > Join caves to form arch > roof of arch collapse > Stack

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