Wethering and erosion

• What is the definition of weathering?

  The wearing away of rocks in situ
• How does freeze-thaw weathering occur?


  Water enters cracks, freezes, expands by 10%, and exerts pressure
• What is frost shattering?

  Water gets trapped in pores, freezes, and creates sheer stress
• What is pressure release in weathering?

  The weight causes the rock to expand and fracture
• What are the five ways chemical weathering can occur?

  Oxidation, carbonation, solution, hydrolysis, hydration
• Why can't biological weathering take place in certain conditions?

  It is too cold for animals and plants
• What is the definition of erosion?

  The wearing away of rocks during movement
• What is abrasion in the context of glacial erosion?

  When the base of the ice mass slides over the bedrock, scraping it with rock debris
• What is the definition of plucking?


  When glaciers detach and remove chunks of the bedrock
• What are the steps of plucking?


  Water freezes on the bedrock, and glacier rock is pulled away from well-jointed rocks
• What are the steps of abrasion?

  Glaciers slide over rock, pick up debris, erode sides and floor, and incorporate rock fragments into the base
• What is a Roche Moutonnee?

  Asymmetrical mounds caused by abrasion on the stoss side and plucking on the lee side
• What factors affect glacial erosion?

  Thickness of ice, resistance of rock, basal ice temperature, gradient, rock joint, and velocity
• What factors affect abrasion?

  Hard rock, ice thickness, meltwater, volume of debris, and rock flour
• What are topographical controls in glacial dynamics?

  They affect the size, location, and dynamics of a glacier
• What are geological controls in glacial dynamics?


  Structure, lithology, availability of material, characteristics, and time
• How does meltwater erosion work?

  Meltwater increases in the snout, erodes rock using fluvial processes, and flows faster due to hydrostatic pressure causing solution to occur
• What are the three types of transportation in a glacier?

  Supraglacial (surface), englacial (within the ice), and subglacial (base of the glacier)
• When do glaciers deposit materials?

  When their capacity is reduced, usually as a result of ablation during retreat
• What is Lodgement till?

  Material deposited by the advancing ice
• What is ablation till?

  This material is deposited by melting ice from a glacier in retreat
• What is drift?


  All materials deposited during glaciation
• What is till?


  Materials deposited directly by the ice
• What is outwash?


  Materials deposited directly by meltwater
• What percentage of the Earth is covered in glacial deposits?

  8%
• What are the three characteristics of till?

  Angular, unstratified, and unsorted
• How does rock flour affect the rate of abrasion/erosion?

  It can hinder movement and needs to be removed by meltwater to allow large particles to move and erode
• How does ice thickness affect the rate of abrasion/erosion?

  The greater the ice thickness, the greater the weight and pressure exerted at the base, causing more ablation
• How does debris size and shape affect the rate of abrasion/erosion?

  The larger and more angular the debris, the more effective it is at abrasion
• How does the amount of basal debris affect the rate of abrasion/erosion?

  The rate increases when there is more debris, as pure ice cannot erode solid rock
• When is erosion more effective?

  When there is debris laden, high velocities, temperature glaciers, densely jointed rocks, already weathered, and permeable bedrock