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glaciated landscapes study guide 3 (proglacial streams (transport a lot of…
glaciated landscapes study guide 3
proglacial streams
transport a lot of sediment,
higher discharges in the summer due to more meltwater produced
lower discharge in the winter as little melting occurs
sediments deposit in the channel meaning the streams split up forming braided streams
kettle holes
may contain lakes that form on the outwash plain
produced of blocks by stagnant blocks of dead ice melting
dead ice becomes buried by the outwash material. once melted overlying sediment causes a depression
depression is filled with meltwater.
eskers
deposition of material carried by subglacial and englacial meltwater streams
stream sediments are laden due to hydrostatic pressure
as the snout retreats > deposition moves back > leaving a exposed sinuous ridge of material on the floor
solufluction
upper layer soil undergoes seasonal thawing
water cannot drain due to impermeable permafrost
encourages down hill movement of the sediments
soils become saturated
stone polygons
ice beneath the rocks expand
stone reach the surface and rolls outwards due to the shape of the landscape
due to capiliary action the stones are pushed upwards
stones have a low specific heat capacity meaning they cool down quicker
ice lens
accumulation of ice beneath the surface.
ice layer forms a lens shape parallel to the ground surface
thickening of ice causes it to heave upwards
pingo formation
water collects in the valley bottoms in area of talik due to gravity
groundwater rises. increases artesian pressure
ice lens forms, rising water freezes and expands pushing sediment
attracts more water from soil by capiliary action. rising lens displaces sediment but if exposed by sun = melting occurs and sediment drops causing a depression which can be occupied by meltwater forming an ognip