erosion

• What is coastal erosion?

  The removal of sediment and rocks by waves.
• What are the three main types of coastal erosion?

  Hydraulic power, abrasion and attrition.
• Describe the process of hydraulic power.

  As waves crash against a cliff, air trapped in the cliff's cracks is compressed. The repeated force of pressure and release widens the cracks and breaks the rock apart.
• Describe the process of abrasion.

  Sand, shingle and sediment are hurled against rocks by breaking waves. The rock is eventually worn down by this repeated rubbing and scraping.
• Describe the process of attrition.

  Rocks and boulders transported by waves collide and break up into smaller pieces. This wears them down into smaller and more rounded fragments over time.
• Where do headlands and bays form?

  Where there are alternating bands of soft and hard rock.
• Describe what a discordant coastline is.

  A discordant coastline is one where bands of soft and hard rock run at right angles to the coast, so the rocks erode at different rates. The protruding bands of isolated rock are called headlands.
• How long can the formation of headlands and bays take?

  Thousands of years.
• Describe the formation of wave-cut platforms.

  1. Waves and rocks crash against the foot of a cliff face.

  2. The base of the cliff is eroded away, leaving a wave-cut notch.

  3. The unstable cliff collapses. With repeated erosion, the cliff retreats to form a wave-cut platform.
• Headlands are gradually eroded to form...

  ... caves, arches and stacks.
• Describe how headlands erode to form caves.

  Waves crash repeatedly into the headland, causing faults and joints to erode and develop into cracks and small caves.
• Describe how headlands erode to form arches.

  Constant erosion causes the caves to get bigger until their back walls are eroded away completely, creating natural arches. The arches widen as more rock is eroded away through weathering.
• Describe how headlands erode to form stacks.

  The arches eventually collapse, leaving an isolated pillar known as a stack. Further erosion of the stack will leave a shorter stump.