Coastal Landscapes

• Stack - A tall column of rock left standing after an arch collapses
• Waves are formed when wind blows over the surface of water, causing ripples that grow into larger waves with height and speed.
• What are the features of constructive waves?

  Low wave height, long wavelength, gentle slope, and the strong swash brings sediments to build up the beach the weak backwash is not strong enough to remove the sediment
• What does the size and energy of the waves depend on?

  The size and speed of waves depend on the wind strength, wind duration, and the distance over which the wind blows (fetch).
• What are the characteristics of destructive waves?

  Destructive waves have a high wave height, short wavelength, weak swash and strong backwash that erodes the beach.
• What is weathering?

  Weathering is the process by which rocks and minerals are broken down into smaller pieces by physical, chemical, or biological means.
• What are mechanical weathering processes?

  Freeze-thaw and biological.
• What is mechanical weathering?

  Mechanical weathering results in rocks being disintegrated rather than decomposed, usually associated with extremes of temperature.
• What is chemical weathering?

  The breakdown of rocks and minerals through chemical reactions.
• What is an example of chemical weathering?

  Carbonation.
• What is carbonation?

  When carbonic acid in rainwater reacts with calcium carbonate in limestone to form calcium bicarbonate. This is soluble, the limestone is carried away in solution.
• What is mass movement?

  Mass movement refers to the downslope movement of weathered material (rock, soil, or mud) under the influence of gravity.
• What is rockfall?

  Rockfall is the sudden and rapid movement of rocks or boulders down a slope or cliff.
• What is sliding?

  A ‘slide‘ is when material moves in a straight path down a cliff in layers.
• What is slumping?

  A ‘slump’ is where saturated soil slumps down a concave slip and rotates outwards forming a curved surface and a ‘toe’ at the bottom of the cliff.
• What is erosion?

  Erosion is the wearing away of rock along the coastline. Destructive wavesare responsible for erosion on the coastline.
• 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 Attrtition?

  This is when rocks hit against each other to become smaller and rounder in shape.
• What is Solution?

  This is when the seawater dissolves sediment e.g. limestone or chalk.
• What is the difference between weathering and erosion?

  Weathering is the process of breaking down rocks and minerals on the Earth's surface, while erosion is the process of transporting and removing the weathered material.
• What is Traction?

  The rolling of large boulders along the sea bed.
• What is Saltation?

  Saltation is the ‘hopping’ or ‘bouncing’ motion of particles too heavy to be suspended across the sea bed.
• What is suspension?

  When particles are carried in the flow of water.
• What is Solution?

  When dissolved chemicals often derived from limestone or chalk are carried in the water.
• What is longshore drift?

  Movement of sediment along a coast due to waves and currents.
• How is material transported by longshore drift?

  Waves approach the coast at an angle because of the direction of prevailing wind. The swash will carry the material towards the beach at an angle. The backwash then flows back to the sea, down the slope of the beach. The process repeats itself along the coast in the zigzag movement.
• What is deposition?

  When eroded material is dropped by constructive waves.
• What factors cause deposition in coastal areas?

  • waves starting to slow down and lose energy
  • shallow water
  • sheltered areas, eg bays
  • little or no wind
• What are the two coastlines?

  Concordant and Discordant.
• How is a concordant coastline structured?

  Bands of hard and soft rock are parallel to the coast.
• How are discordant coastlines structured?

  Bands of hard and soft rock are perpendicular to the coast.
• What are landforms resulting from erosion?

  Headlands and bays, cliffs and wave cut platforms, caves, arches and stacks.
• Headlands and bays formation

  1. Bands of soft and hard rock are perpendicular to the sea

  2. Differential erosion occurs

  3. Soft rock (less resistant to erosion) is eroded quickly forming bays

  4. Hard rock (more resistant to erosion) is eroded slower forming headlands

  5. Wave refraction focuses wave energy on headlands and spreads it out in the bays
• How do cliffs and wave-cut platforms form?

  The sea attacks the base of the cliff between the high and low water mark along a headland. A wave-cut notch is formed by erosional processes such as abrasion and hydraulic action. As the notch increases in size, the cliff becomes unstable and collapses, leading to the retreat of the cliff face. The backwash carries away the eroded material, leaving a wave-cut platform. The process repeats. The cliff continues to retreat.
• How are caves formed?  1. Cracks are widened in the headland through the erosional processes of hydraulic action and abrasion. 2. As the waves continue to grind away at the crack, it begins to open up to form a cave.
• How does an arch form?

  The cave will become larger and eventually breaks through the headland to form an arch.
• How does a stack form? The base of the arch continually becomes wider and thinner through erosion below and weathering from above. Eventually, the roof of the arch collapses, leaving behind an isolated column of rock called a stack.
• How does a stump form? The stack is undercut at the base by wave action and sub-aerial weathering above, until it collapses to form a stump.
• What are landforms that result from deposition?

  Beaches, sand dunes, spits and bars.