Glacier Movement Flashcards
Why do glaciers move?
Gravity Weight Surges Meltwater Internal deformation Basal sliding
How does gravity cause a glacier to move?
If a glacier is on a slope it will be pulled by gravity
How does weight cause a glacier to move?
Most of the accumulation takes places in the upper part of the glacier. This additional weight at the upper end which gradually pushes the glacier downhill
How do surges cause a glacier to move?
These rapid advancements can occur when water stored under the ice bursts out and causes the glacier to move suddenly.
How does meltwater cause a glacier move?
The weight on top of the ice causes the PMP to be reached and meltwater to be produced. This acts as a lubricant which helps the glacier move.
Why do glaciers sometimes exhibit the appearance of moving uphill?
Because of the weight pushing the glacier from behind
Where is the most velocity within a glacier?
Where there is the least amount of friction with the valley sides and floor.
What is internal deformation?
This involves the ice crystals slipping and sliding over each other in order to change their orientation in response to gravity and the direction of movement.
Where does internal deformation take place?
In the upper part of the glacier
Which type/s of glacier does internal deformation take place?
Warm and cold based
What are the 2 processes included in basal sliding?
Regelation slip
Basal creep
When does regelation slip occur?
When a large block of ice reaches smaller obstacles - usually less than 1m
What happens during regelation slip on the upslope?
On the upslope the ice applies additional resistance which causes an increase in pressure. This leads to localised melting (pressure melting) which creates meltwater. The meltwater enables the ice to flow up and over the obstacle as it acts as a lubricant.
What happens during relelation slip on the downslope?
On the downslope the meltwater refreezes and some of the rock is broken away as the meltwater gets into cracks and causes frost shattering erosion.
What is the texture of the upslope?
Smooth
