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Glaciated Landscapes 5 (laurentide ice sheet case study) (negative…
Glaciated Landscapes 5 (laurentide ice sheet case study)
positive feedback loop of the LIS
decreasing temperatures lead to the initial growth of the ice sheet
more of surface covered by ice = higher reflection of sun (albedo
north Americas climate cooled rapidly.
valley glaciers vs the ice sheet
corries
in the valley glacier they vary in size and have small superficial scratches + striations indicate ice flow. whereas in the ice sheet striations develop into mega-scale lineations which also indicate the flow of ice
end moraine are
typically small in the valley glacier.
however in the ice sheet, they are
much larger
and so form
substantial belts of low hills and ridges
drumlins: in the
valley glacier they will vary in size
, whereas in the ice sheet they are much larger
erractis
in the valley glaciers erratics are smaller whereas in the ice-sheet erratics are huge in terms of size and distance traveled.
superficial-deposits: material deposited on top of solid rock geology such as river deposited or windblown sand
ellipsoidal basins are huge lake basins created by erosion, where the ice sheet gouged out deep depressions in the bedrock
summary of the LIS
the LIS eroded due to its sheer scale
the huge depth of ice resulted in high levels of abrasion and plucking
the constant advancing and retreating of the fringes of the ice sheet carved away at less resistant rocks in particular creating the basins and mega-scale lineations
negative feedback loop to illustrate the possible climatic impacts of proglacial dam bursts
global warming leads to the increased glacial melting
proglacial lakes form than a mega flood occurs
meltwater flows into the N Atlantic
water becomes less saline so it cannot sink
GS 'conveyor belt' stops