Coastal Landforms

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  • Coastal Landforms- Erosion
    • Arches/Stacks
      • 3.  The geo is widened over time into a cave. A cave is also cut into the opposite side of the rock due to the wave refraction. These meet in the middle to form an arch.
      • 1. Waves hit a headland and refract taking the shape of the coastline and find a weakness in the hard rock, such as a crack.
      • 2. The crack is widened into a geo by abrasion and hydraulic action as well as weathering processes like freeze-thaw.
      • 5. Exposed to erosion, the stack eventually is reduced to a stump.
      • 4. Weathering such as salt crystallisation, biological, chemical and freeze-thaw act on the arch  roof. Attrition, abrasion and hydraulic action act on the base. The arch collapses, leaving a sea stack.
    • Headlands/Bays
      • 1. Form on discordant coastlines where bands of rock alternating between soft and hard are perpendicular to each other.
      • 3. Also form on concordant coastlines where bands of hard/soft rock run parallel to the coast. The sea breaks through a weakness in the hard rock, and accelerates erosion of the soft rock behind.
      • 4. The soft rock's erosion creates a bay or cove with a narrow opening due to the hard rock band in front. Beaches form at the back of the bay due to constructive waves. These deposit sediments because of increased friction from the larger distance needed to reach the coast.
      • 2. Differential erosion by hydraulic action causes the soft rock to be eroded faster than the hard, forming bays. Where the hard rock juts out, headlands are found.
    • Blowholes
      • 1. Waves are forced into a cave in the cliff face. If there is a weakness at the top of the cave, the water erodes this rock by hydraulic action and abrasion.
      • 2.Eventually, the waves will erode all the way through the rock, making a hole in the top of the cave.
      • 3. When large waves enter the cave, water sprays through the blowhole.
    • Cliffs/Wave-cut Platforms
      • 2. This process repeats, so over time the platform gets bigger. The large platform creates more friction for the waves, so the energy is dissipated, meaning the process slows down. Consequently, platforms never exceed 0.5km as the waves lose nearly all energy.
      • 1.  Destructive waves erode a cliff face, creating a notch. This undercuts the cliff by weathering and erosion, eventually causing the cliff to collapse from the weight of the overhang, leaving a flat platform.
      • 3. Wave-cut platforms are never smooth as the waves transport the material from the collapsed cliff across the platform. This wears depressions into the rock by the process of abrasion.


chiedza tasosa

this is so good,thank you !

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