glaciation Flashcards
nivation
erosion of ground around a slope of snow due to freezing and thawing
frost heave
uplift of soil due to expansion of groundwater when freezing
freeze thaw
water falls through cracks in rocks, freezes, expands and breaks the rock
weathering
wear away from the long exposure to the climate and atmosphere
solifluction
movement of wet soil / material down a slope
zone of accumulation
snow is added
zone of ablation
removal
positive mass balance
glaciers gain more mass than they lose
basal slip
glacier sliding over bed due to meltwater under ice increasing movement
revelation creep
melting and refreshing of ice which affects slippage
internal deformation
when the weight of the ice causes deformation of ice crystals , usually at the glacier bed where pressure is at its highest
erosion
wearing away by wind water and other natural agents
entrainment
responsible for the erosions and movements of rocks
transport
movement of debris away from the glacier
deposition
the mixture of unsorted sediments carried by the glacier, often forming moraines
abrasion
when rocks become embedded in the glacier and rub against the bedrock whilst the glacier moves.
Causes the wearing away of the landscape, producing smooth surface.
Scratches on surface which result = striations
quarrying
occurs within valley glaciers where pieces of bedrock are transported and eroded
plucking
same as quarrying
occurs when rocks become frozen to the glacier and are plucked from ground as glacier moves forwards.
Jagged landscape left behind
crushing
crushing and scraping of glacier as it moves causes erosion along soil and rock it sits on.
Weight of glacier may cause physical stress to ground whilst often plucking up boulders which are then deposited downstream
basal melting
melting point of water decreases under pressure, water melts at a lower temp under thicker glaciers.
Can lead to basal sliding where glacier ‘floats’ above a layer of meltwater which acts as lubricant- moves faster
subaerial freeze thaw
water stuck in the cracks of rocks, freezes then expands by 10%.
This repeated action puts pressure on rock, eventually causing it to shatter
mass movement
Can happen quickly due to basal slipping so danger.
A sudden movement of large mass down long distances.
corries
deep rounded hollows which capture snow.
Plucking/erosion steepen back wall.
Aretes
Separates two glaciated valleys.
From erosion of 2 corries