Glaciation is the action of moving ice.
Glacier is a Mass of ice moving outward from an area of accumulation.
glaciers are formed when snow accumulates on the surface, lower layers are compressed to a harder mass resulting in opaque ice due to air bubbles and accumulation of continuous compression lower layers squeezing out air forming glassy ice called a glacier.
Types of glaciers
- Cirque glacier – ice occupying a cirque.
- Valley glacier – Ice confined within a valley
- Piedmont glacier: Glacier formed when valley glaciers converge at the foot of the mountain.
- Ice bergs – Large mass of ice floating in the ocean formed when an ice sheet moves to the sea e.g. in Arctic and N. Atlantic Ocean.
- Ice sheet – Continuous mass of ice covering a large area on the earth‟s surface.
- Ice caps – Ice covering the mountain peak.
- Snow line – Line beyond which there is a permanent snow cover.
Ways of Ice Movement
Plastic Flowage
Movement of ice like a viscous liquid.
it occurs when Great pressure is exerted at the bottom sides and center causing some ice particles to melt slightly and move slowly downhill like a viscous liquid.
Basal Slip
Movement of ice by sliding over the underlying rock.
it occurs when Pressure is exerted on deepest layers of ice in contact with the rock beneath causing melting.
A film of water is created which acts as a lubricant between the ice and the rock causing ice to slip and slide over the rock and move downslope.
Extrusion Flow
Movement of ice by spreading out.
it occurs Ice accumulates building to great thickness at the center causing compression of layers of ice beneath.
The layers beneath are forced to spread out where there is less pressure.
Internal Shearing
Breaking of ice into smaller pieces that move alongside one another.
it occurs when Uneven movement causes ice to develop cracks on the surface.
The glacier breaks into smaller pieces which move alongside each other downslope
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