Geomorphic processes

• The 4 types of geomorphic processes:

  • weathering
  • Erosion
  • Transportation
  • Deposition
• the 3 types of weathering

  • chemical
  • biological
  • mechanical
• mechanical weathering is the breakdown of rock without changing its chemical composition

  • one example is freeze-thaw weathering
• freeze thaw weathering

  1. temperatures alternate above and below 0˚C
  2. water gets into rock without changing its cracks
  3. water freezes and expands, putting pressure on the rock
  4. water thaws, releasing pressure
  5. this repeats, breaking up the rock
• chemical weathering is the breakdown of rock by changing its chemical composition
• chemical weathering

  1. rainwater has carbon dioxide in it, making it a weak carbonic acid
  2. acid reacts with rock that contains calcium carbonate
  3. rocks slowly dissolved by rain
• biological weathering is the breakdown of rocks by living things

  • plant roots grow into cracks and push them apart
• mass movement is the shifting of rocks and loose material down a slope

  • it causes coats to retreat rapidly
• there are 2 types of mass movement:

  • slides
  • slumps

  
• there are 4 types of erosion

  • hydraulic action
  • abrasion
  • attrition
  • solution
• Hydraulic action 


  1. Waves crash against rocks
  2. Forces air into the rock, building pressure
  3. Repeated compression causing rock to break off
• abrasion

  1. eroded particles in the water scrape against sea bed or cliffs
  2. removing small pieces of them away
• attrition 


  1. eroded particles smash into each other, breaking into smaller fragments
  2. this keeps happening until they are tiny
• solution

  1. dissolved co2 makes water slightly acidic
  2. reacts with rocks
  3. dissolves them
• 4 types of transportation:

  • traction
  • Saltation
  • Solution
  • Suspension
• transportation is the movement of eroded material
• Traction

  Large particles like boulders are pushed along the river bed or sea floor by force of water
• saltation

  pebble-sized particles bounce along river/sea bed by force of water
• suspension

  small particles are carried along by water
• solution (transportation)

  soluble materials dissolve in the water and are carried along
• Deposition is the dropping of material. It occurs when the water carrying sediment loses velocity so that it isn’t moving fast enough to carry so much sediment
• coastal deposition

  waves that deposit more material than they erode are called constructive waves

  • low and long
  • swash is powerful, backwash is weak
• river deposition

  this occurs when

  • volume of water in river decreases
  • amount of eroded material in water increases
  • river reaches the sea or lake at its mouth