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glaciated landscapes summary (outwash plain (flat expense of glacio…
glaciated landscapes summary
glacial definition
periods of very cold + dry climate
large land and sea ice masses grow
valley glacials extend to lower levels
interglacial definition
warmer periods with the extent of the ice masses
valley glaciers begin to retreat
formation of a glacial trough
glacials flow down pre-existing river valleys
they erode the sides and floor of the valley
causing the shape to become wider, deeper and straighter
lodgement till
material is deposited due to an advancing glacier
glacier advances due to basal sliding.
can be enhanced by localised pressure
delta kame
formed by englacial streams emerging at the snout of the glacier
the stream loses energy at the base and deposits its load
or. some form as debris-filled crevasses collapse during the period of retreat
ellipsoidal basins
eroded by ice sheets
surface also being lowered by the weight of the ice mass
outwash plain
flat expense of glacio-fluvial sediments (sands) forms at the snout
proglacial streams transport material due to high discharges
sediments are often deposited within the channel splitting up streams forming braided streams
in the summer streams have a higher discharge and are debris laden
in winter the discharge is lower which results in increased deposition within the channel to form channel bars, splitting the stream
formation of a corrie
nivation forms small hollows in which snow accumulates
rotational movement causes erosion and deepening of the hollow
plucking steepens the backwall and abrasion deepens the hollow
thinner ice at the round is unable to erode creating a corrie lip. may consist of moraine
esker
is a long sinuous ridge of stratified sand. deposited by glacial meltwater
deposited in subglacial tunnels, as the amount of meltwater decreases at the interglacial period
subglacial streams carry a lot of debris, deposition occurs when the pressure is released as meltwater emerges at the snout
as the snout retreats, the point of deposition moves backwards,
arete
form from glacial erosion
steepening of slopes and the retreat of corries
that are back to back or alongside each other
pyramidal peaks
3+ corries develop around a hill or mountain top
if the backwall retreats, remaining mass will be steepened forming the pyramid shape
weathering of the peak may sharpen the shape
kame terrace
ridges of till running along the edge of the valley floor. supra glacial streams pick up and carry the lateral moraine
streams form due to the melting of ice warmed in contact with the valley sides. - friction
compsed of outwash deposits that are rounded and sorted
pingo formation
water from surrounding slopes collects in the valley bottoms in area of talik due to gravity
groundwater rises to surface under artesian pressure
ice lens forms, water freezes and expands pushing the sediments
rises and displaces the overlying sediment. ice lens = exposed to sun creates a depression as the overlying sediment will collapse