Glaciation

• weathering

  The breakdown of rocks 'in situ' by physical and chemical processes.
• As the glacier moves, it erodes the land beneath it by grinding against rocks and other materials on its path.
• Glaciers are formed when snow accumulates over many years, compressing it into ice.
• erosion


  the wearing away of land by material carried by rivers, glaciers, waves and wind. It produces sediment that is moved from its initial location.
• plucking


  when the glacier slides down a valley, pressure is exerted on sides and bottom, generating heat. The ice melts, creating small amounts of water which freeze around loose particles. These are then "plucked" and carried within glacier, as it moves along.
• abrasion


  as this material is carried down in the glacier is carried along the valley, it rubs against the sides and bottom and, like sandpaper, wears it away (also breaking larger bits off).
• freeze-thaw weathering


  water enters crevice in rock. Water freezes into ice, expanding the hole and putting pressure on the rock, repeatedly. Rock breaks due to the pressure the ice puts on it.
• ribbon lake

  A large, narrow lake occupying a u-shaped valley. It forms in a hollow when a glacier has more deeply eroded, less resistant rock.
• misfit streams

  Meander through the flat, wide U-shaped floor, did not erode the valley, formed in the valley after glaciation had carved out the U-shaped valley, when the ice had melted
• u-shaped valleys

  Flat floor and steep sides, formed by glaciers widening, steepening, and deepening a v-shaped valley through plucking and abrasion
• corrie

  Deep rounded hollow with a very steep back wall and a rock basin, formed at the beginning of the Ice Age in cold rock hollows and can spread or feed into valley glaciers
• Formation of corrie


  1. Glaciers formed in hollows move down the face of a mountain or hill, plucking any grass or rocks in its way, to create steep back walls

  2. Abrasion from the ice in the hollow then deepens the corrie, wearing the bottom away like sandpaper

  3. Ice gathers at the bottom of the corrie and, once the Ice Age ends, melts, resulting in a small lake or "tarn"

  4. Moraine acts as a stopper for the water
• Arete


  Knife-edge formed when two corries form adjacent to each other and erosion occurs
• Pyramidal peak


  Pointed peak formed when three or more corries form adjacent to each other and erosion occurs
• Types of moraine

  • Ground moraine - disorganised piles of rocks of various shapes and sizes, deposited under a glacier
  • Lateral moraine - moraine deposited at the sides of a glacier
  • Medial moraine - moraine deposited in between two glaciers
  • Terminal moraine - moraine deposited at the terminus/end point of a glacier
  • Recessional moraine - deposited before the terminus of the glacier, along its route
  • Hummocky moraine - a big part of the glacier breaks of and comes to a stop, dropping all the sediment it was carrying
• erratic

  A rock which differs in size or type from the environment which it is found in and has been deposited by a glacier
• Front end of glacier

  1. Acts like a bulldozer

  2. Shifting and removing soil

  3. Plucking rock from interlocking spurs

  4. Truncating interlocking spurs
• truncated spurs

  Interlocking spurs without the land that interlocks. The front end of the glacier acts like a bulldozer, shifting and removing soil, plucking rock from interlocking spurs and truncating them
• hanging valleys

  when smaller tributary glaciers join with the main glacier, creating a valley which hangs over the larger u-shaped valley.
• zone of accumulation


  the part of a glacier that, when viewed as a system, has more inputs than outputs.
• zone of ablation


  the part of a glacier that, when viewed as a system, has more outputs than inputs.
• snout


  front end of a glacier
• freeze-thaw weathering process

  • Water gets into a crack in a rock
  • Freezes and ice expands, widening the crack
  • Ice melts, allowing more water to enter
  • Process repeats until rock splits
  • Remains called scree
  • Can only happen in temperatures fluctuating around 0, so water can melt and freeze
• onion-skin weathering

  when rock is repeatedly heated and cooled, causing expansion and contraction, and making pieces of the rock peel off. This process is common in desert areas where it is hot in the day but cold at night.
• label the glacial landforms

  A) arete

  B) pyramidal peak

  C) arete

  D) rock lip

  E) corrie

  
• transportation


  the movement of sediment or fragments from one location to another
• deposition


  the dropping of transported material when energy is lost
• the formation of a glacier


  • snow accumulates through around four years
  • the weight begins to compress the ice/snow at the base, squeezing air out and hardening the structure
  • this produces firn
  • as the firn is placed under more pressure from accumulation, air will be squeezed out and the structure hardened
  • this makes ice
  • eventually due to its weight and gravity the ice will begin to move downhill – it now is termed a glacier.
• label the glacial system

  A) precipitation

  B) avalanches

  C) zone of accumulation

  D) zone of ablation

  E) evaporation

  
• zone of ablation

  occurs at the snout of the glacier, where outputs exceed inputs, leading to meltwater
• zone of accumulation

  occurs at the head of the glacier, where inputs exceed outputs, leading to more snow compacting
• glacier


  a large mass of compact ice that moves slowly downhill under its own weight
• zone of equilibrium


  when the amount of inputs and outputs are equal in a glacier
• scree


  the fragments of rock produced by freeze-thaw weathering
• inputs - precipitation, avalanches

  outputs - meltwater, evaporation