Coasts

• What is the term for the distance the wind blows across the water?

  Fetch
• What is the term for the water that moves up the beach?

  Swash
• What is the term for the water that comes back down the beach?

  Backwash
• What are the characteristics of constructive waves?

  • Low waves that surge up the beach
  • Stronger swash than backwash
  • Carry in deposits of sand and pebbles
  • Usually formed by storms far away
• What are the characteristics of destructive waves?

  • Higher waves with larger backwash than swash
  • High steep profiles
  • Plunge downwards and pull back sediment
  • Formed by local storms close to the coast
• What are the four main types of coastal erosion processes?

  1. Hydraulic power
  2. Abrasion
  3. Attrition
  4. Corrosion
• What is hydraulic power in coastal erosion?

  Hydraulic power is when water enters cracks in the cliff, compressing air and exerting pressure on the rock.
• How does abrasion contribute to coastal erosion?

  Abrasion occurs when rocks in the water bash against cliffs, wearing them away.
• What is attrition in the context of coastal erosion?

  Attrition is when rocks and pebbles in the sea hit against each other and break down.
• What is corrosion in coastal erosion?

  Corrosion is when weak acids in seawater dissolve the rocks along the coast.
• What are the two types of weathering in coastal processes?

  1. Chemical weathering

  • Carbonation
  • Hydration

  1. Mechanical weathering

  • Physical breakdown of rocks
• What is hydration in chemical weathering?

  Hydration is when water swells the structure of the rock.
• What is freeze-thaw weathering?

  Freeze-thaw weathering is when water enters cracks in rocks, freezes, and exerts pressure on the rock.
• What are the types of mass movement in coastal processes?

  1. Landslides
  2. Slumping
  3. Rock falls
• What are landslides in coastal processes?

  Landslides occur when layers of rock dip towards the sea and blocks fall.
• What is slumping in coastal processes?

  Slumping occurs in areas with alternating layers of hard and soft rock, causing them to slump down.
• What causes rock falls in coastal processes?

  Rock falls are caused by quick erosion leading to rocks breaking off cliffs.
• What is longshore drift?

  • The process where pebbles are carried along the beach
  • Pebbles are moved straight by backwash and at an angle by swash
  • Repeats continuously as waves move
• When does deposition occur in coastal processes?

  Deposition occurs when waves lose their energy and drop sediment.
• What are the erosional landforms created by coastal processes?

  1. Cliff and wave-cut platform
  2. Headlands and bays
  3. Caves, arches, and stacks
• How is a wave-cut notch formed?

  A wave-cut notch is formed as waves erode the base of a cliff, causing cracks to form.
• What creates headlands and bays?

  Headlands are formed from hard rock that remains while soft rock is eroded, creating bays.
• What happens to waves as they enter a bay?

  Waves lose energy and deposit material, forming a beach.
• What are caves, arches, and stacks in coastal erosion?

  Caves are formed in headlands, which can erode to form arches, and when the roof collapses, stacks are created.
• What are the types of depositional landforms?

  1. Sandy beaches
  2. Pebble or shingle beaches
  3. Sand dunes
  4. Spits
  5. Tombolos
  6. Sandbars
• How do sandy beaches form?

  Sandy beaches form in sheltered bays where constructive waves dominate.
• How do pebble or shingle beaches form?

  Pebble or shingle beaches occur on more exposed parts of the coastline where destructive waves wash away finer sand.
• What are the stages of sand dune formation?

  1. Embryo dune
  2. Fore dune
  3. Yellow dune
  4. Grey dune
  5. Mature dune
  6. Dune slack
• What is a spit in coastal geography?

  A spit is formed when longshore drift moves material across a coastline, creating a sheltered area behind it.
• What is a tombolo?

  A tombolo is where an old island is connected to a headland by a spit.
• What is a sandbar?

  A sandbar is formed when sediment moves straight across a bay, turning it into a lagoon.
• What are the hard engineering coastal defenses?

  1. Seawall
  2. Groins
  3. Rock armor
  4. Gabions
• What is the purpose of a seawall?

  A seawall is a concrete barrier that reflects waves and protects the coast.
• What are the advantages of seawalls?

  Seawalls are effective at protecting the coast and often include promenades for tourism.
• What are the disadvantages of seawalls?

  Seawalls can be obtrusive, expensive, and require high maintenance due to erosion.
• What are groins in coastal defenses?

  Groins are structures built out to sea that trap sediment to prevent longshore drift.
• What are the advantages of groins?

  Groins are not too expensive and help keep beaches in place.
• What are the disadvantages of groins?

  Groins can cause increased erosion elsewhere and may be considered unattractive.
• What is rock armor in coastal defenses?

  Rock armor consists of large boulders placed at the foot of cliffs to absorb wave energy.
• What are the advantages of rock armor?

  Rock armor is cheap to maintain and can provide habitats for marine life.