Glaciers
Glaciers
A GLACIER is a
large, slow-moving
mass of ice, formed
from compacted
layers of snow, that
slowly deforms and
flows in response to
gravity and high
pressure.
Glacial Features
Snowline
– Area of a glacier that snow/ice stays all year.
Snowfield
– Motionless mass of permanent snow and ice.
Firn
– Grainy appearance of ice that melts and
freezes (changes overtime).
Explain what happens as snow
accumulates:
Zone of Accumulation
– Area of built up snow and ice on a glacier.
Zone of Wastage
– Area on a glacier that melting is greater than
accumulation.
The growth of a glacier depends on :
The balance between snowfall received
and ice lost by melting and evaporation.
Glacial Features
Types of Glaciers
Valley (Alpine)
– form at high elevations where temperatures remain
cold enough during the summer to keep the previous
winter's snow from melting allowing snow and ice to
accumulate.
Types of Glaciers
Continental Glacier
– form at high latitudes where temperatures remain cold
enough during the summer to keep the previous winter's
snow from melting allowing snow and ice to accumulate.
Zone of
Accumulation
– Area of built up
snow and ice on a
glacier.
Zone of Wastage
– Area on a glacier
that melting is
greater than
accumulation.
Crevasses
– Large cracks in a
glacier (weak areas
of ice).
Describe the processes of
glacial Advance and Retreat
Glacial Advance
– occurs when
the leading
edge of a
glacier is able to
move ahead
faster than it
can melt.
– Animation
Glacial Retreat
– occurs when the
melting of the front
of the glacier
happens faster
than the forward
motion of the
glacier.
Explain movement of Glaciers
Basal Slip
Internal Plastic Flow
– Movement of glaciers
from the slipping of the
bottom edge.
– Movement in which
the ice crystals flow
over one another.
– (ice skates)
– (melting plastic)
Glacier Erosion
Plucking
– It results when glacial ice freezes in the cracks and
crevices of a bedrock projection and eventually pulls it
loose.
Glacier Erosion
Ice Wedging
– A type of mechanical weathering in which rocks are
broken by the expansion of water as it freezes in joints,
pores, or bedding planes. Synonymous with frost
wedging.
Glacial Abrasion
– Scratching of underlying rock.
Glacial Features
Glacial EROSION
Cirques
– Bowl-shaped
depression produced
by a valley glacier.
Cirques
Glacial EROSION
Aretes
– Sharp, jagged ridge
formed between
cirques.
Glacial EROSION
Horns
– Sharp, pyramid-like
peak formed where
several aretes join.
Glacial EROSION
Hanging Valleys
– Small abandoned
glacial valley
suspended on a
mountain above the
main glacial valley.
Hanging Valley Formation
Hanging Valleys
Glacial EROSION
Striations
– Markings on rock from
glacial movement.
Glacial EROSION
Kettle Lakes
– Depression in a glacial
outwash plain.
Kettle Lakes
Glacial EROSION
‘U’-Shaped Valleys
– Glacial formed valley.
U-Shaped Valley Formation
Glacial DEPOSITION
Drumlins
– Long, low tear shaped
mound of till.
Drumlin Formation
Glacial DEPOSITION
Eskers
– Long, winding ridge of
gravel and coarse
sand, deposited by a
glacier.
Esker Formation
Glacial DEPOSITION
Kames
– Irregular shaped hill or
mound formed from
glacial till.
Kames
MORAINES
Glacial DEPOSITION
Moraines
–Lateral
– Deposited along side
of glacier.
Glacial DEPOSITION
Moraines
– End/Recessional
– Secondary terminal
moraine formed during
halt of melting glacier.
Glacial DEPOSITION
Moraines
– Medial
– Two or more valley
glaciers combine and
form along center.
Glacial DEPOSITION
Moraines
– Terminal
– Till at leading
edge of melting
glacier.
Glacial DEPOSITION
Glacial Sediment
– Erratics
– Large boulder
transported and
deposited by a glacier.
Glacial DEPOSITION
Glacial Sediment
– Till
– Unsorted Rock
material deposited by
a glacier.
Till Formation
Glacial DEPOSITION
Glacial Sediment
– Outwash
– deposit of sand and
gravel carried by
running water from the
melting ice of a glacier
and laid down in
stratified deposits.
Glacial Flow Lab
Glacial Flow Lab