Geography coasts

• Factors influencing wave size:

  • Fetch: how far a wave has traveled
  • Strength of the wind
  • Duration of the wind blowing
• Wave Types:

  • Swash: water that flows towards the beach when a wave breaks
  • Backwash: the water that flows back
• Destructive waves characteristics:

  • Weak swash, strong backwash
  • Strong backwash removes sediment from the beach
  • Waves are steep and close together
• Definition of Destructive waves:

  • Waves that remove material from the beach
  • Swash is weaker than backwash
• Coastal deposition:

  • Occurs when the sea loses energy and drops sand, rock particles, and pebbles it has been carrying
  • Happens when the swash is stronger than the backwash and is associated with constructive waves
• Conditions that encourage deposition:

  • Waves enter an area of shallow water
  • Waves enter a sheltered area like a cove or bay
  • Little wind present
  • Good supply of material available
• Formation of a beach:

  • Sea erodes cliffs, rocks fall into the sea
  • Rocks are eroded into smaller pebbles
  • Pebbles are ground down into sand grains forming a beach
• Processes of sediment movement:

  • Solution: minerals dissolved in sea water and carried invisibly
  • Suspension: small particles like silts and clays suspended in water flow
  • Saltation: small shingle or large sand grains bounced along the sea bed
  • Traction: pebbles and larger material rolled along the sea bed
• Longshore drift:

  • Sediment moved by the longshore current within the surf zone
  • Also known as littoral drift
• Spits are created by deposition and are extended stretches of beach material that project out to sea and are joined to the mainland at one end
• Spits are formed where the prevailing wind blows at an angle to the coastline, resulting in longshore drift
• An example of a spit is Spurn Head, found along the Holderness coast in Humberside
• Longshore drift moves material along the coastline in the direction of the prevailing wind, with the angled swash bringing material onshore and the backwash removing the material in a straight line, perpendicular to the coastline, creating a zigzag movement along the coast
• If the coast changes direction, material will continue to be deposited in the original direction in a shallow sea, leading to the build-up of material known as a spit
• A spit requires a constant supply of material, or it will be removed by tides
• Over time, a spit grows and develops a hook if wind direction changes further out, creating a sheltered area where silt is deposited and mud flats or salt marshes form
• Longshore drift is when eroded material in the sea is carried along the beach in a zigzag course
• Hydraulic Action is the force exerted by water as it hits the shoreline or cliffs, causing them to break apart.
• The main types of coastal erosion are hydraulic action, abrasion, corrosion, attrition, solution, mass movement, and biogenic processes.
• Wave cut notches occur at the base of cliffs due to wave attack, which can lead to undercutting and eventual collapse of the cliff face.
• Solution involves the dissolving of soluble minerals from rocks by seawater.
• Beaches are areas of sand or pebbles near the shoreline, often found adjacent to dunes.
• Erosion from water widens cracks in the rock to form caves
• Erosion from water continues to erode an arch until the weight of rock causes the roof to fall into the sea, forming a stack
• Cracks in the rock erode through abrasion
• Caves occur when waves force their way into cracks in the cliff face, with hydraulic action and abrasion as predominant erosion processes
• If a cave is formed in a headland, it may eventually break through to the other side, forming an arch
• The arch will continue to be eroded (attrition) and will gradually become bigger until it collapses, leaving a stack on one side and a headland on the other
• The stack will be attacked at the base, weakening the structure until it collapses to form a stump
• A wave-cut notch is an area of erosion at the base of a cliff formed by the waves
• Erosion is the wearing away of rock along the coastline by destructive waves, with erosion types including hydraulic action, abrasion, attrition, and solution
• A wave-cut platform is the bedrock left behind as the cliff retreats, smoothed by abrasion from the backwash carrying rubble towards the sea
• Soft rock erodes more quickly than resistant rock, forming headlands and bays along the coastline
• A headland is a stretch of the coast made of rock that juts out into the sea, usually of harder rock left due to surrounding softer rock erosion
• Spits are elongated ridges of sand that extend out into the sea from headlands.
• Caves, arches, stacks and stumps

  
• Bays are areas between two headlands where sediment accumulates due to shelter provided by the headlands.
• Salt marshes are wetlands found on low-lying coastal land, often protected by dikes or seawalls.
• Headlands and bays
• Erosion types