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• Wave

  Oscillations of energy created by friction with the wind
• Wave

  • Wavelength is the distance between 2 peaks
  • Crest is top
  • Trough is bottom
  • Wave height is height
• Period of a wave


  Amount of time it takes for a complete wave to occur = go up then down
• Frequency of a wave


  Number of waves per second
• Energy of a wave

  The energy transferred through vibrations of water particles
• Wave formation

  1. Wind moves across the water surface causing friction

  2. The resistance causes small ripples to form

  3. Over time the ripples become more circular in an orbital motion of water particles = wave

  4. As the sea bed shallows the orbit becomes more elliptical

  5. There is more of a horizontal movement of the wave

  6. Wave height increases but wave length and velocity decrease

  7. Water backs up behind the wave and results in it breaking and surging up the beach
• Factors that affect a waves size and strength

  • Wind (stronger the wind = stronger the wave, wind moves from high to low pressure, pressure changes due to variation in surface heating by the sun)
  • Duration of wind (wind is active for long periods of time, energy builds up and wave increases)
  • Size of fetch (the distance over which the wind blows, larger fetch = more powerful waves)
• As waves approach the shore


  1. Friction causes the wave to slow down

  2. Wave length decreases

  3. Wave becomes steeper = called shoaling

  4. It continues until the wave is too high to be supported

  5. When 1:7 height :length

  6. Wave breaks and surges up the beach
• Swash


  Movement of the wave onto the beach after it breaks
• Backwash


  Movement of the wave back down to the beach
• Constructive wave


  • Swash is stronger than backwash
  • Deposition creates landforms
  • Low waves that surge up a gentle slope
• Destructive wave


  • Remove depositional landforms through erosion
  • Beach size decreases
  • Backwash is stronger than swash
  • High waves plunge onto steep slope beaches
• High energy coastline


  • Powerful waves
  • Large fetch
  • Rocky headlands due to destructive waves
  • Coastline erosion
• Low energy coastline


  • Less powerful waves in sheltered areas
  • Constructive waves
  • Depositional landforms
• Refraction


  1. Waves turn around an irregular shaped headland

  2. Waves drag in the shallow water approaching a headland so the wave becomes high steep and short

  3. The part of the wave in the deeper water moves forwards faster causing the wave to bend

  4. As they turn they lose energy

  5. The wave energy is focussed on the headland resulting in erosion

  6. Energy is lost in bays = formation

  7. Low energy environment = beaches
• Marine erosion

  • Hydraulic action (air is forced into the cracks joints and faults, the high pressure causes the crack to widen, as wave retreats air expands causing rock to fracture)
  • Cavitation (bubbles in water implode under high pressure creating tiny jets of water that over time erode the rock)
  • Corrasion (sand and pebbles are picked up by the sea from an offshore sediment sink, they are hurdled against the cliff at high tide causing it to erode)
  • Abrasion (as sediment is moved along the shoreline, sediment and rocks are worn down in a sandpaper action as they rub together)
  • Solution (water dissolves rock into solution, mildly acidic water causes alkaline rock eg limestone to be eroded)
  • Attrition (wave action causes rocks to hit against each other wear down becoming rounder and smaller)
• Sub aerial processes

  • Weathering: Physical weathering (freeze thaw, salt crystallisation, wetting and drying)
  • Chemical weathering (carbonation, oxidation, solution)
  • Biological weathering (root action, birds, rock boring, seaweed acids, decaying vegetation)
• Mass movement


  • Factors affecting mass movement (slope angle, rock type, rock structure, vegetation, saturation of ground, presence of weathering)
  • Types of mass movement (soil creep, mudflows, rockfall, landslides and rockslides)
• Marine transportation and deposition

  • Traction (large heavy sediment rolls along the seabed)
  • Saltation (smaller sediment bounces along the sea bed)
  • Suspension (carried within the water)
  • Solution (dissolved within the water)
• Deposition


  • When sediment becomes too heavy for the water to carry, or if the wave loses energy. Gravity settling or flocculation. High energy coastline have larger rocks and shingle. Low energy coastlines have smaller sediment
• Sources of beach sediment


  • Cliffs
  • Offshore seabed
  • Rivers
  • Wind
  • Glaciers
  • Human action
• Characteristics of beach sediments


  • Types (cobbles, coarse sand, fine sand, mud)
  • Particle distribution on a beach (finer = more erosion and deposition, finer moved further eg in spit)
• Sediment cell


  Coasts can be split into sediment cells, often ordered by headlands, within them sediment is almost contained meaning it acts in a dynamic equilibrium, maintains a natural balance despite the constant change of state, it has the tendency to counteract any changes, so input and output is constantly changing to remain in balance
• Transportation of sediment


  • Longshore drift (along beach with prevailing winds)
  • Up and down the beach (swash and backwash)
  • In relation to sediment size (smaller moves further as requires lower energy wave to be transported)
  • In relation to wave energy (higher = more erosion)
• Where and why sediments are deposited


  • Along/near a coastline
  • Low energy which can no longer support the sediment load
  • In estuaries due to change in water velocity or flocculation
  • On beaches due to constructive waves, lower wave energy in bays
• Development of cliffs


  1. Type of material (chalk, granite, limestone, strata)

  2. Dip (angle it comes down at), strike layers

  3. RHS is less likely to erode as fast

  4. LHS is likely to have mass movement and increased erosion from waves at the bottom of the cliff
• Steep cliffs


  • High energy environment
  • Resistant rock
• Gentle cliffs


  • Weaker rock which is less resistant
  • Short fetch
  • Low energy environment
• Rate of cliff retreat

  • Fetch, beach, wave energy = marine factors
  • Subaerial processes, geology, rock strength = terrestrial factors
  • Most likely to retreat = unconsolidated rock and sands
• Development of wave cut platforms


  1. Waves erode the cliff at the high tide line by hydraulic action and corrasion

  2. Creates a wave cut notch

  3. It becomes deeper into cliff face before unstable

  4. Collapses and falls under its own weight

  5. Leaves a platform

  6. Repeats

  7. Exposed at high tide
• Development of caves, arches, stacks and stumps


  1. Waves enter the faults and cracks in headlands

  2. This causes erosion by hydraulic action and abrasion

  3. Eventually forms a cave

  4. Over time it widens and breaks through the headland to form an arch

  5. It widens until it can't support itself and falls under its own weight to form a stack

  6. Marine erosion continues to erode the base of stack and eventually collapses into a stump
• Beach


  A depositional landform that stretches from low to high tide and is created when waves lose energy and deposit sediment
• Development of swash aligned beaches


  1. Waves approach parallel to coastline

  2. Sediment doesn't travel far along the beach

  3. Wave refraction may reduce speed of high energy waves = shingle beach with larger sediment
• Development of drift aligned beaches


  1. Wave approaches at an angle

  2. Longshore drift causes sediment to travel up beach at an angle

  3. Larger sediment at start, smaller at end

  4. Leads to spit
• Development of spits


  1. Longshore drift causes beach to extend out to sea

  2. Angled swash and backwash back down

  3. Material builds up

  4. Due to change in direction of coastline

  5. Can form a compound spit with a curved end abandoned by the new spit
• Development of tombolos


  1. Spit that connects mainland to an offshore island

  2. Wave refraction off of the coastal island reduces wave velocity
• Development of offshore bars


  1. Sand is deposited off shore as the wave didn't have enough energy to carry sediment to shore

  2. The wave breaks early

  3. Deposits sediment

  4. Or destructive waves have a strong backwash that removes sediment from the beach
• Development of barrier beaches


  1. Beach or spit which extends across 2 headlands to join them

  2. The water trapped behind becomes a brackish lagoon
• Development of dunes


  1. Prevailing winds blow sediment to the back of the beach

  2. Needs a large tidal range and lots of sand

  3. Pioneer species such as sea rocket grow and help dunes stabilise

  4. Decaying organic matter = nutrients and humus for marram grass to grow

  5. As dunes develop, height increases, nutrients and humus content increases, water content decreases, pH decreases = more acidic
• Development of salt marshes


  1. In sheltered bays or behind spits, salt minerals build up

  2. Vegetation grows stabilising the salt marsh

  3. Fine sediment deposited

  4. Algal stage and roots bind together

  5. Pioneer species = cord grass which stabilises the mud

  6. Saltmarsh grass grows = carpet and increase in height

  7. Salt rarely gets submerged between marsh and more grows eg scurvy grass

  8. Climax = vegetation submerged once or twice a year