Glaciers Flashcards
what is a glacier
mass of ice originated ON LAND by the recrystallization of snow AND shows evidence of past and present MOVEMENT
______ exceeds ______ in glaciers (snow fall vs snow melt)
snow fall EXCEEDS snow melt
four environmental significances of glaciers
- powerful agent of geomorphologic change
- source of freshwater (77% of all freshwater)
- release nutrients locked up in rocks
- contribute to changes in sea level
two terms associated with changes in sea level
- isostatic sea-level changes (related to land position)
- eustatic sea-level changes (related to water volume)
how is the sea level affected by the formation of glaciers and ice sheets
- eustatic FALL in the sea level (water is being taken out of the ocean and moved to land)
how is the sea level affected by the further growth of sea sheets
isostatic depression of land (land is being pressed DOWN because of the pressure above it) and a rise in sea level
how is the sea level affected by the melting of ice sheets
the eustatic rise in sea level (mass of glaciers on land is melting INTO the sea = decrease of freshwater on land)
how is the sea level affected by the decline of ice sheets and glaciers
- isostatic uplift of the land
- decrease in sea level BUT at the same time there is an eustatic rise in the sea level
the first year of snow for the glacial ice formation can be described as
mostly aid (not very dense)
what happens to the snow over the years in the formation of glacial ice
it begins to become compacted and denser (becomes firn) until it becomes glacial ice
describe the colour of glacial ice and why it is so
blue hue - based on it allowing light to pass through it and ONLY being able to absorb short light wavelengths (like blue light)
three major Canadian glacier locations
- Coridllera
- Baffin island
- Queen Elizabeth Islands
2 main types of glacier
- continental
- alpine
continental glaciers AKA
ice sheets
describe the area covered by ice sheets
it is extensive
does the ice cover the topography in an ice sheet
YES
describe the flow of ice sheets
unconfined due to gravity
example of ice sheets
- Greenland
- Antartica
- Laurentide ice sheet
are ice caps constrained
NO
what is smaller: ice sheets or ice caps
ice caps (have to be smaller than 50 000 km2)
describe the appearance of ice caps
dome-like surface or circular
locations of ice caps
polar and sub-polar regions
(Yukon, Canadian Arctic…)
describe the appearance of ice fields
NO dome-like surface
do ice field show restraint
YES
what are often produced by ice fields
outlet glaciers
ice shelves
where glaciers float out onto oceans
ice shelves are a mix of
fresh ice AND sea ice
true or false
ice shelves are not sensitive to climate change and thus good indicators
false - are sensitive to climate change
where do ice shelves ORIGINATE
on LAND
true or false
valley glaciers only appear on some of the continents
false- appear on ALL of them
where are valley glaciers contained
the flow is contained to the valley between two peaks
what are valley glaciers commonly seen as (steep or gradual)
steep
cirque glaciers
piedmont glacier
tidewater glaciers
the movement of glaciers is driven by
weight and gravity
inputs of glacier processes are the
accumulation zones (snow, ice, rain, avalanches)
output of glacier processes are the
ablation zones (meltwater, debris, icebergs)
together the outputs and inputs of glacier processes form the
mass budget (which forms the equilibrium line)
equilibrium line altitude (ELA)
the highest elevation that a snowline reaches at the end of SUMMEr
what can be used to track the glacier health and change
ELA (equilibrium line altitude)
what is the terminus area
the lowest end of a glacier
how does ice behave
in a plastic manner (by deforming and flowing under pressure)
where does freeze and thaw take place in a glacier
at the base (regelation)
how can ice behave in a brittle manner
by breaking and formin crevasses and ice falls
what is the importance of water BELOW the glacier
lubrication (helps the glacier have spurts have rapid movement)
crevasses are
cracks in the surface in response to stress
what are some stresses that can cause crevasses
tension
friction with walls
compression
does the ice flow always balance out with snow accumulation
NO
surges are the
high speed movement to get ride of express mass
erosion of material by ice can be by
- scarping
- polishing
- plucking
- bulldozing across surfaces
polished rock
debris in ice with a smooth surface
cirques
originated curved site of a small glacier
tarns
small mountain lakes in former glacier hollows
u-shaped valleys and fjords
past presence of glaciers
aretes and horns
remnants of backwards erosion (it is a pyramid-shape or knife-edge ride)
hanging valleys
glacial valleys above one another (tributary glacier valley)
examples of glacial erosion
- polished drock
- ciruqes
- tarns
- u-shaped valleys and fjords
- aretes and horns
- hanging valleys
tarn
u shaped valley glacier
Fjords
horns
horns show remnants of erosion on ____ sides and are where _____ come together
three or more AND cirques
aretes have erosion on _____ sides
both (2)
aretes are _____
ridges separating two adjacent glacier valleys OR cirques
aretes glacier
hanging valley glacier