coast

• What is weathering?

  The breakdown of rocks in situ.
• What are the two types of weathering?

  Mechanical and chemical weathering.
• What is mechanical weathering?


  The breaking of rock without changing its chemical composition.
• Freeze thaw weathering

  Occurs when temperatur alternates between 0 degrees. Water enters rock with a crack, when the water freezes it expands which puts pressure on rock, when it thaws it contracts and releases the pressure, overtime this widens the cracks and causes it to break up.
• What is chemical weathering?


  The breakdown of rock by changing its chemical composition.
• What is mass movement?

  The sliding of rocks and loose material down a slope.
• When does mass movement occur?

  When the force of gravity exceeds the force supporting the slope.
• How does water affect mass movement?

  Water acts as a lubricant, making the material behave like a fluid.
• What creates waves?

  Wind blowing over the surface of the sea.
• What is fetch in relation to waves?

  The distance the wind blows over the sea.
• What are storm surges?

  Temporary sea level rises caused by strong winds pushing water onshore.
• How do constructive waves differ from destructive waves?

  Constructive waves deposit material, while destructive waves erode it.
• What is hydraulic action?

  Waves crashing against rock compress air in the cracks.
• How does abrasion contribute to erosion?

  Eroded particles scrape and rub against rock, removing small pieces.
• What is attrition in the context of coastal erosion?

  Eroded particles collide, break into smaller pieces, and become more rounded.
• How does longshore drift transport material along the coast?

  Waves carry material up the beach in the direction of the waves, then backwash carries it down at right angles.
• What is traction in coastal transportation?

  Large particles like boulders are pushed along the sea bed by water.
• What is suspension in coastal transportation?

  Small particles like silt and clay are carried along in the water.
• What is saltation in coastal transportation?

  Pebble-sized particles are bounced along the sea bed by water.
• What is solution in coastal transportation?

  Soluble materials dissolve in water and are carried along.
• When does deposition occur?

  When water carrying sediment loses energy and slows down.
• What happens when deposition exceeds erosion?

  Coasts build up.
• What increases deposition on a coast?

  Lots of erosion elsewhere, transport of material, and constructive waves dropping more material than they remove.
• How do discordant coastlines differ from concordant coastlines?

  Discordant coastlines have alternating bands of hard and soft rock at right angles to the coast while in concordant coastlines the bands are parallel to the coast.
• What forms headlands and bays along discordant coastlines?

  Alternating bands of resistant and less resistant rock.
• What happens to more resistant rock along a coastline?

  It erodes slower than less resistant rock.
• What are some examples of coastal landforms in Dorset?

  Durdle Door, Lulworth Cove, Chesil Beach, and Swanage Bay.
• What is the aim of coastal management?

  To protect people and the environment from erosion and flooding impacts.
• What are the two types of coastal defences?

  Hard engineering and soft engineering.
• What is managed retreat in coastal management?

  Removing current defences and allowing the sea to flood the land behind.
• What happens to the land behind in managed retreat?

  It becomes marshland, which protects the land from flooding and erosion.
• What are the benefits of managed retreat?

  It is cheap, requires no maintenance, and creates new habitats.
• What are some issues caused by managed retreat?

  It can flood farmland and affect farmers' livelihoods.
• Headlands and bays form along discondant coastlines. The less resistant rock erodes faster forming a bay with a gentle slop. The more resistant rock erodes slower and juts out forming a headland with steep sides
• Waves crash into the headland and enlarge cracks (by hydraulic action and abrasion). Repeated erosion and enlargement of cracks causes a cave to form, the cave deepens until it breaks through the headland and causes an arch. The rock supporting the arch is eroded until it collapses forming a stack.
• Waves cause the most erosion at the foot of a cliff, forming a wave cut notch. Repeated erosion causes the rock above the notch to become unstable and collapse. Collapsed material is washed away and a new wave cute notch starts to form. The cliff retreats, leaving a wave cut platform
• Beaches are formed by constructive waves depositing material. Sand beaches are created by low energy waves and have a long gentle slope. Shingle beaches are created by high energy waves and have a steep slope.
• Spits form when sediment is carried by longshore drift. When there is a shift in the coast deposition occurs. Overtime, a long, thin ridge of material forms. A hooked end can form if there is a change in wind direction. Water behind the spit is sheltered so salt marshes can form
• A bar is when a spit grows across a bay and connects to headlands together. Shallow lakes can be trapped behind the bar, these are lagoons
• Hard engineering is the use of man-made structures to control natural processes.

  • Sea wall - concrete walls placed at foot of cliff, curved to reflect waves.
  • Rock armor - large boulders placed at the foot of a cliff, absorb wave energy.
  • Groynes - a wall built perpendicular to the sea to trap sediment being transported via longshore drift.
  • Gabions - rocks held together in a metal mesh.