The Work of Ice

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  1. Plastic Flowage: Ice has plastic qualities and may flow en-masse like a viscous liquid
  2. Basal Slip: The process through which ice slips and slides over the underlying rock.
  3. Internal Shearing: Movement similar to rock faulting involving differential sliding along planes.
  1. Plucking: Parts of the underlying rock are frozen into the base of the ice and pulled away.
  2. Glacial Abrasion: The grinding process where stones frozen in the ice scrape and scratch against the underlying rock.
  3. Sapping: The breaking of rocks by the alternate freezing and thawing of the ice at the bottom or sides of the mass.

Landforms of Glaciation

Landforms of Glaciated Highlands

  1. Cirques: Steep sided rock basins semi-circular in plan. Could develop into corrie lakes called Tarns.
  2. Aretes: Steep sided knife edged ridge separating two cirques.
  3. Pyramidal Peak: Jagged peak formed by the steepening of the back walls of several cirques on the sides of a mountain. Also called horns.
  4. U-Shaped Valley: A broad flat-bottomed steep-sided valley with a U shape. Also called a glacial trough.
  5. Fjord: A deep narrow arm of the sea with steep sided parallel walls.
  6. Hanging Valley: A tributary of a U-Shaped Valley ending abruptly high above the floor of the U shaped valley and separated from it by an almost vertical slope.

Landforms of Glaciated Lowlands

Erosional Landforms

  1. Rouche Moutonee: An outcrop of resistant rock smoothed by ice on the upstream into a gentle slope and plucked on the downstream end to give a steep jagged edge.
  2. Crag and Tail: A knob of resistant rock (crag) which protects a weaker rock (tail) from ice erosion on the downstream slope.
  3. Ice-Eroded Plain: An extensive area once covered by an ice sheet which smoothed off the original landforms to give a rounded topography.

Depositional Landforms

Those formed by unsorted materials:

  1. Boulder Clay Plain: A monotonous hummocky plain made of clay and boulders and deposited haphazardly by ice sheets over a surface.
  2. Drumlins: Elongated ovoid low hummock made of boulder clay.
  3. Terminal Moraine: Ridge like feature made of boulder clay marking the edges of the ice.

Those formed by sorted fluvio-glacial materials:

  1. Esker: Steep sided ridge made of gravel and sand.
  2. Kame: An irregular shaped mass of stratified material formed as a delta on the surface of a stationery glacier.
  3. Outwash: Made of gravel and sand and developed outside of the terminal moraine by melt waters from the ice depositing sorted materials.

Course Notes