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62 Cards in this Set

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ice in glaciers 3
paleorecords, 7 million cubic miles, over 10% of land area
nunatak
Peaks above the snow mass
ice shelf
Thick, nearly flat sheet of floating ice fed by land glaciers
cirque
scooped out bowl shaped recess at head of glacier
piedmont glacier
Broad lobe of ice that terminates on open slopes beyond a mountain front
ice is rock
metamorphic, it changes
Recrystalliaztion
Summer air penetrates, evaporates the snow points Empty pore space disappears
Recrystallizes, changing from snow to firn, which is granular
Than keeps compresssing and recrystallizing to become glacial ice
snow to ice transformation time depends on
temp and precip
mass balance of glacier
input is accumulation
output in ablation zone, melting (surface, base and internal), deflation and calving, and sublimation
Equilibrium Line
Boundary between Accumulation and Ablation zones
Where mass loss = mass gain
Firn line
lowest level to retain fresh snow through the summer
two types of movement
internal: like a deck of cards also called creep
and basal slip: water as lubricant
Glacial Surge
Probably results from separation of the glacier from its bed
Hydrostatic pressure (water)
Velocities up to 12 km/year
col
saddle like depression or pass
from eroding cirques
Aretes
sawtooth, serrated ridges in glaciated mountains
also from eroding cirques
Tarn
small (cold) mountain lake
Paternoster
chain of small (cold) mountain lakes
Roche moutonnee
asymmetrical hill of exposed bedrock
Abrades the upslope side
Plucks the downslope side
Glacial drift
general term for all glacial deposits, both sorted and unsorted
Unstratified drift
material deposited directly by ice
Unsorted
Unstratified
Stratified drift
material deposited directly by glacial meltwater
Sorted
Erratics
large rocks, of different origin than the local rocks
Till
random mixture of rock fragments
Glacialmarine drift
like till, on seafloor
Moraine
drift, unrelated to bedrock
Ground Moraine
widespread, relatively flat, deposited beneath a glacier
End Moraine
ridgelike accumulation of drift along the end of a glacier
Lateral Moraine
ridgelike accumulation of drift along the side of a valley glacier
Medial Moraine
ridgelike accumulation of drift composed of two lateral moraines
3 types of stratified drift
Outwash: sediment washed out beyond the glacier
Outwash plain: wide field of deposit
(unconstrained by river)
Valley trains : wide field of deposit
(constrained by river)
Esker
curving, narrow ridge of coarse sand and gravel, a startified drift
stratified drifts
Esker: curving, narrow ridge of coarse sand and gravel
Drumlin: elongated teaspoon shape
Kame: conical hills deposited by meltwater flowing into funnel shaped holes in the ice
4 Unstratified Depositional Features
Erratics
Till
Glacialmarine drift
Moraine
5 moraines
Ground
Lateral
Medial
Terminal
Recessional
Stratified Drift 6
Outwash plain
Valley trains
Esker
Drumlin
Kame
Kettle
Periglacial Landscapes
Areas along the margin of glaciers
High elevation
High latitude
Permanent (semi-permanent) ice
Seasonally snow free
Presently > 20% of total land area
Permafrost
Any permafrost area not covered by glaciers is considered Periglacial
2 types of permafrost
Continuous Permafrost: Not present under deep lakes and rivers
and discontinuous
Active zone of permafrost: thaws daily/seasonally
Talik
thaws daily/seasonally
unfrozen ground
ground ice
frozen in ground, Affects the landscape through Frost Action
Frost Action 5
Block Field (Felsenmeer):angular rock blocks shattered by freezing
Frost heaving: vertical movement
Frost thrusting: horizontal movement
Cryoturbation: churning of sediments

Ice wedge: ice frozen in ground cracks, expands over time
Pingo
Palsa
Patterned ground
heaved-up, circular, ice-covered mound
rounded mound of peat, containing thin ice lenses
frost moved accumulations of surface rocks arranged in polygons
Solifuction 3
A form of mass wasting
Thawed active layer flows down hill
Referred to as gelifluction when ground ice is present
Thermokarst Landscapes
Results from thermal subsidence and the ice wedge melting
The thawing of ground ice results in uneven, boggy topography
Ice age
a cold period with at least one glaciation
Isotope Record
The light isotope (O16) evaporates easier
Rain is enriched in O16
The ocean becomes enriched in O18
The O18/O16 ratio can tell you how much ice there is
whats isotopes mean
Hence, as glaciers expand, O16 rich precipitation is stored as glacial ice, and the O18/O16 ratio of the remaining sea water increases slightly.
More O18 than O16 in water means.
More O16 in glaciers and more ice.
Paleoenvironmental Reconstruction
4 types
Pollen
Lake levels
Ice rafting
and glacial records
Younger Dryas
11,000 –10,000 BP
A return to the cold
“the Ice-age’s last gasp”
Pluvial and interpluvial
pluvial: wet, other dry
Pluvial due to?
Probably due to migration of the polar jet stream, which moves south during cold periods
Little Ice Age
Medieval Warm Period
1200-1900 AD
800-1200AD
Why These Changes?
(little ice age etc
Probably due to astronomical effects
Milankovitch Cycles(precession of equinoxes.)
Results in changes in the amount of heat received from the sun
Eccentricity
how elliptical earth's orbit is, 400k and 100k year cycles
tilt
of the axis to sun period of 41k years
precession
change in equinoxes, alters lengths of seasons in relation to how close to the sun and therefore how fast earth is moving in each season.
Feedback
Changes in solar insolation alone are NOT enough to explain the temperature fluctuations (40 –100 C)
Possible positive feedback mechanisms:
3
Albedo (snow fields, lack of vegetation)
Dust
Greenhouse gases
Long-term variation might be due to 3
Continental drift
Ocean spreading
Long term volcanic variability
Greenhouse Gases
Greenhouse gas concentrations correlate with glacial/interglacial periods
glaciation is
slow,
deglaciation is rapid