glacial modification Flashcards
glacier
large natural accumulation of land ice affected by present or past motion, moves in response to gravity so downward. motion occurs because the ice loses its rigidity and becomes plastic
what is the density of water
1 g/cm 3
what are the stages of snow
snowflakes - ice granules - firn - ice
ice age
a period of millions of years characterized by intermittent glacial occupation of large areas of high and mid latitudes
glacial periods
period where glaciers advance, colder and drier than interglacial periods
interglacial period
warmer periods where glacier retreat
phanerozoic 3 major glaciations
andean
karoo
cenozoic
types of glaciers
constrained (mountain/ alpine)
unconstrained (continental)
what is a constrained glacier
shape and flow pattern strongly dependent on underlying topography
what is an unconstrained glacier
shape and flow patter is mostly independent of underlying topography
glaciers move by
internal deformation
basal sliding
zone of ablation
more ice melts than accumulates as snow
till
unstratified mixture of rock fragments of all sizes
types of moraines
- end
- terminal
- recessional
- interlobate
- push/ squeeze
- ribbon
drumlin
oval shaped hills composed of glacial till (look like little speed bumps)
esker
sediments deposited by glacial streams (look like a very big string is under the ground)
glaciolacustrine
sediments originate from glacier and deposited in a lake
glacial lake agassiz
largest of all marginal lakes
contained lake of the woods, lake winnipeg, lake manitoba
glacial pluking
glacier pulls large rocks or boulders from the ground as it moves and drops it later on as it melts out of the glacier (glacier erratics)
