2A.5 Flashcards
How does lithology alter the rate of glacier movement
In temperate zones, movement is faster over impermeable surfaces than permeable, because basal meltwater is retained – aiding slippage. However, if bedrock is permeable then the meltwater may be able to soak away (percolate), slowing the movement of a glacier. Furthermore, easily eroded rocks (e.g. sandstone, heavily fractured metamorphic rock) are more prone to bed formation and warm-based glaciers can reach great velocities when they move over deformable sediment.
How does altitude effect the rate of glacier movement?
Affects precipitation and temperature. At higher altitudes there will be a greater supply of snow and ice due to greater precipitation and lower temperatures thus increasing the mass balance. This will cause gravity to have a higher effect on increasing the rate of movement
How does gradient/gravity effect the rate of glacier movement?
If the gradient angle is higher it will cause a greater pull in gravity and as gravity encourages ice to move the the stepper the gradient the faster the ice movement will occur
How does ice temperature effect the rate of glacier movement?
In some environments an example being Antarctica the temperature is so low. That the ice is frozen to the bedrock thus meaning the ice move more slowly as it can)t deform as easily compared to warmer climates. Moving slower than the temperate glaciers
How does ice thickness/mass effect the rate of glacier movement?
When ice is greater than 50 meters thick plastic flow begins,so greater thickness creates more pressure in the ice which causes faster movement. An increase in ice thickens can lead to a negative feedback cycle thicker ice will lead to an increase in pressure melting and basal slip so ice moves faster but in turn will reduce ice thickness and therefore lead to reduced pressure melting point and basal slip
The heavier the ice the more is needed to overcome increased friction caused by extra weight
How does the rate of ablation effect the rate of glacier movement?
The more meltwater there is the faster the movement basal slippage increases. Meltwater acts as a lubricant on the base of the ice enabling it to slip downhill
