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GLACIERS - Coggle Diagram
GLACIERS
OVERVIEW
Glaciers as natural systems
Inputs
Energy
-
Kinetic
from wind and moving glacier.
Thermal
from the Sun and
geothermal
heat
from the earth
Atmospheric
-
Snow
from precipitation, avalanche or blown-in.
Condensation
of water vapour.
Sublimation
of vapour directly to ice crystals
Rock debris
from weathering and transportation
Outputs
Energy
through evaporation and sublimation
Meltwater
Water
vapour
through
sublimation
of ice and snow
Icebergs
and
ice
blocks
Glacial
and
fluvio-glacial
sediments
Snow
- blown away
Stores
Accumulated
debris
from weathering, erosional and depositional processes
Ice
of the glacier itself
Meltwater
- stored on and within the glacier (supraglacial lakes are on top of a glacier)
Potential
energy
stored from
movement
of
glacier
Flows
Debris
flow
through glaciers from surface storage to landforms
Kinetic
energy
from movement of glacier
Meltwater
flow
Glacial
movement
through gravity
Nature and Distribution of Cold Enviroments
Polar
Areas of
permanent
ice
The vast ice sheets of
Antarctica
and
Greenland
Periglacial (Tundra)
Literally means on the
edge
of
permanent
ice
Characterised by
permafrost
Canada
,
Alaska
,
Scandinavia
and
Russia
Alpine
Mountain
areas.
The
European
and
Southern
Alps
High
altitude
results in
colder
conditions
, particularly in
winter
Glacial
found at the
edge
of
ice
sheets
, can also be
mountainous
found in
polar
and
mountain
regions
Causes of distribution
Higher
latitudes
(closer to the poles)
receive
less
solar
radiation
per unit area due to the
curvature
of the
Earth’s
surface
.
Sun’s energy hits the Earth at more of an
angle
at
high
latitudes
, so it is spread over a
larger
area
tilt
of
Earth’s
axis
of rotation means
polar
areas
are in
permanent
darkness
for
several
months
each
winter
.
High altitudes
Higher
altitudes
are are
colder
than
lower
altitudes
for every
1000 m
of
height
gained the
temperature falls
by
6.4°C
Air temperatures
decreases
with
increasing altitude
because as the altitude increases the air becomes
thinner
less
of the
Sun’s
energy
reflected
back
from the
Earth
is trapped
adiabatic
/
enviromental
lapse rate
Continentality
The
middle
of
continents
are cold
because they are
far
away
from the
sea
.
In the
summer
, the
land
heats
up
quickly
and the
sea
heats
up
slowly
.
In the
winter
the
land
cools
quickly
and the
sea
cools
slowly
.
Vegetation Development
Plant Adapatations
Needles
-
dark
green
colour
in order to
maximise
the
sunlight
intake and therefore
photosynthesis
Waxy
surface
-
protects
them from
frost
Grow
in
groups
(forests) - to protect them from the
cold
arctic
wind
.
Branches
angled
downwards
- protects them from the
weight
of
heavy
snowfall
Plants dont tend to grow
below
6
degrees
Systems and Processes
Geomorphological processes
Frost shattering
Water
(rainwater or melt water)
seeps
into
cracks
and
holes
(pores) within a
rock
.
Temperatures falls to
0°C
or below, the water turns to
ice
,
expanding
in
volume
by about
9%
This
exerts
stresses
within
the
rock
,
enlarging
cracks
and pores.
As the process
repeats
many times the cracks eventually
split
in
half
causing chunks of
rock
to break away and
pile
up
as
screen
at the foot of the slope.
They become
trapped
under
the
ice
, then they are
joined
together with the
glacier
used effectively as
abrasive
tools
Carbonation
Carbon
dioxide
dissolved
in
water
forms a
weak
carbonic
acid
.
This
reacts
with and
dissolves
calcium
carbonate
in some rocks,
particularly
limestone
, to form
calcium
bicarbonate
.
this is a process of
chemical
weathering
Block fields
Block fields is a
result
of
frost
shattering
forms a
rock
-
strewn
landscape
Scree
piling
up
Frost heave
Only happens in
periglacial
or
tundra
environment where there's
soil
Freezing
water just
below
the
surface
expands
by
9%
and
pushes
up the
ground
above
.
Causing the
ground
to be
bumpy
and
irregular
Nivation
Nivitation covers a
range
of
processes
associated with
patches
of
snow
.
These processes are
most
active
around
the
edges
of
snow
patches
Fluctuating temperatures
these and the
presence
of
meltwater
promote frost shattering
Meltwater
this will
carry
away any
weathered
rock
debris
to reveal an
ever-enlarging
nivation
hollow
Slumping
saturated
debris
(material filled with water)
collapses
due to the
force
of
gravity
Glacial and Interglacial periods
How do ice Cores predict climates?
Ice
forms
over time after
consecutive
snowfalls
. The
deeper
the ice, the
older
the ice
Antarctica
has the
oldest
and
thickest
ice sheets
Ice cores are
drilled
and
analysed
, and the
trapped
air
bubbles
provide insight into the
ancient
atmosphere
.
Scientists measure the
greenhouse
gas
levels
and
predict
what the
climate
might have been like back in the
past
.
Milankovitch
cycles
- The earth's
orbital
changes
The earth's orbit is
elliptical
(
oval
)
orbit changes between a more
circular
orbit where the earth is
closer
to the
sun
a more extreme
elliptical
orbit
where at times the
earth
is much
further
away
from the
sun
The transition
between
these
cycles
takes approximately
100
thousand
years
As the earth's orbit becomes more
elliptical
and the earth is
further
from the
sun
some
global
temperatures
decrease
triggering
an
ice age
.
Ice Movements
Errosion
Plucking
As a glacier moves through a valley,
pressure
is exerted on the
sides
and
bottom
of the
valley
This generates
friction
and
heat
, causing the
edges
of the glacier to
melt
This meltwater
freezes
around
rocks
and
stones
under
the
glacier
As the glacier moves
forward
, it '
plucks
' this ice,
pulling
the
rock
away
Abrasion
:
Rocks
,
stones
and
boulders
stuck
in the ice,
grind
against the
rock
below
the
glacier
wearing it away and producing rock flour
Striation
(scratch) marks arise when rocks beneath the glacier are
transported
across
the
bedrock
The
weight
of the
ice
in a glacier
forces
it to advance
downhill
,
eroding
the
landscape
as it moves
Ice advances in a
circular
motion called a
rotational
slip
, which
hollows
and
deepens
the corrie
Deposition
Glaciers transport material such as
clay
,
rock
, and
sand
in the
body
,
base
and
surface
of the glacier over
long distances
The
front
of a glacier is called the '
snout
' and
acts
as a
bulldozer
pushing
loose
rocks
and
debris
(
glacial till
) downhill by the sheer
force
of the
moving
ice
Supra glacial
- predominantly
weathered
material
carried
on top of ice
Englacal
- supraglacial material
buried
by
snowfall
and carried
within
the ice.
Subglacial
- material is carried
beneath
the
ice
, dragged and pulverised by the
overlying
glacier
Internal Deformation
- how ice moves under gravity
Inter
granular movement
Individual
ice
crystals
slip
and
tumble
over one another
The Ice particles
orient
themselves in the
direction
of
ice
movement
allowing them to
slide
past
one
another
Intra
granular movement:
Individual ice crystals become
deformed
or
fractured
due to the
intense
stresses
within the ice
Gradually the ice
deforms
and moves
downhill
under the
influence
of gravity
Regalation
Surge
- Lots of
pressure
,
lubrication
and a
steep gradient
As ice moves
over an obstacle
,
pressure
and
stress
builds up
in the glacier
.
Consequently the
base
of the
glacier
reaches
pressure
melting
point
and
melts
.
The meltwater
lubricates
the
base
of the
glacier
allowing
basal
sliding
.
When the glacier flows
downslope
from the obstacle,
pressure
is
reduced
, leading to the
refreezing
of the
ice
.
Extensional and Compressional flow
Extensional Flow
This creates
crevasses
Occurs when theres a
sudden
increase
in
gradient
The ice
flows
faster
, then
stretches
and
thins
Compressional Flow
A
reduction
in
gradient
will cause the glacier to
slow
and '
pile
up
'
And become
thicker
Controlling factors of ice movement:
Gravity
: The
downhill
force
that encourages the ice to move. The
steeper
the
gradient
, the
greater
the
influence
of
gravity
Mass of Ice
: The
heavier
the
ice
, the more
potential
energy
it has to move. However,
more
force
will need to overcome the
increased
friction
that comes with
extra
weight
.
Friction
: If the ice as a whole is to
move forward
,
friction
with the
ground
needs to be
overcome
. The
gradient
and
angularity
of the bedrock can
increase/decrease friction
Meltwater
:
Lubricates
the
base
of the
glacier
increasing basal flow
through
basal sliding
. It also helps
overcome friction
.
Temperature
of the ice: In polar (
cold-based
) glaciers the ice is so cold that the ice is
frozen
to the
bedrock
These glaciers move
slowly
.
Warm base
glaciers move more
rapidly
through
basal siding
from
meltwater
The glacial budget
The glacial budget considers the
balance
between the
inputs
and
outputs
.
Glacial mass balance means
equal
inputs
and
.
Mass balance
More
accumulation
over a year and the glacier has a
positive regime
or
positive mass balance
The glacier will
gain mass
and advance in response to
high accumulation
in the
upper zone
A
negative mass balance
or regime is when there is
less accumulation
than ablation (usually during the
summer months
)
The glacier will
lose mass
and retreat in response to
low
accumulation
in the
upper zone
Dynamic equilibrium
is when the
overall
amount
of
ablation
and
accumulation
balances
over a year
Glaciated landscape development
Periglacial processes and landforsms
exists at the
end
of
polar
and
glacial
environments
.
they
don't
have
permanent
covering
of
ice
, they experience
extreme
cold
for most of the year with
penetrating
frosts
and
periodic
snow
cover
.
Thaw lakes
Common in
poorly
drained
periglacial
areas
Form in the
summer
when
snow
melts
together with the
active
layer
Water
retains
its
warmth
and its
relatively
dark
surface
absorbs
radiation
from the
sun
This warmth will
increase
the
depth
of
melting
of the
underlying
permafrost
forming
unfrozen
zones
called
taliks
Solifluction lobes
Mass movement
-
downward
movement
of
material
,
downslope
under the
influence
of
gravity
.
Saturated
soil
(the
active
layer
)
slumps
downhill
in the summer when it has
thawed
, to form
solifluction
lobes
.
Only the
top
active
layer
that
thaws
in the
summer
has the
mobility
to move this way.
The
frozen
permafrost
below
remains
solid
Terracettes
Particles are
raised
to the
surface
by
frost
heave
, these are then
dropped
down
vertically
(due to
gravity
) on
thawing
.
Repeated
cycles
cause the
soil
particles
to gradually
creep
downslope
.
Frost heave
forces
soil
particles
to the
surface
, they then due to gravity move
down
slope
and that is
frost
creep
and that creates
terracettes
Ice
wedges
Cracks
in the
ground
caused by
thermal
contraction
in winter become
filled
with
water
in the summer
This water then
freezes
in
winter
and
enlarges
the
crack
.
Over many years an
ice
wedge
is
formed
which can be
3m
wide
at the surface and
10m
deep
.
Frost heave
The
thermal
conductivity
of
stones
is
greater
than that of
soil
.
The
area
under
the
stone
becomes
colder
than the
surrounding
soil
and
ice
crystals
form.
The
ice
lenses
force
the
stones
ab
text
ove them to
rise
until eventually they reach the
surface
.
Stones
are
pushed
and
rolled
over
uneven
ground
Patterned ground
Ice
wedges
and
lens
grow in autumn as the
active
layer
of soil
repeatedly
freezes
and
thaws
on a
daily
basis
.
This creates
un
uneven
soil
layer
above
The ice wedge/lens
grows
and
pushes
the
stones
up
above it through
frost
heave
.
Fine
sediments
fill
the
gap
preventing it from
falling
back
down
.
Pingos
Lake
infills
with
sediment
, insulating the
ground
beneath
==
Liquid
water
is trapped in the
unfrozen
ground
(
talik
between the
lake
sediment
and
permafrost
.
Water
freezes
as
climate
cools
to form
ice
core
.
Ice
expands
due to
increased
hydrostatic
pressure
and the
talik
is
squeezed
.
Lake
sediment
pushed
up to form a
pingo
In summer, part of the
ice
core
may
collapse
and
fill
with
water
.
Fluvioglacial
landscapes associated with
flowing
water
that is
melted
from
glaciers
Contemporary landscapes
Glaciers
are
still
present
in
shaping
the
landscape
Relic Landscapes
Landscapes
shaped
from
previous
glaciers
(no longer there)
Reasons
for
meltwater
:
Warm
summers
,
warmer
surface
temperature
of ice
Pressure
melting
point
Snout
of glacier
melt
(due to
lower
altitude
)
Nivation
, edges of snow patch melt
Outwash plain
Large
area
of
land
where
deposition
occurs from
glacial
rivers
,
braided
meltwater
streams (Well sorted sediment)
Sorted sediment:
Heavy
rocks are
deposited
closer
to the
glacier
, because the
river
doesn
;t have enough
energy
to
carry
them.
lighter
rocks are
deposited
further
along
the outwash plain as the
river
has
enough
energy
to
carry
them.
Subglacial stream
A
stream
flows
beneath
the
glacier
, which usually
cuts
into the
ice
above
to form a
tunnel
Eskers
A long,
commonly
sinuous (
bending
) ridge of
sand
and
gravel
this is
deposited
by a
stream
in a
subglacial
tunnel
Long
ridges
of
material
running
in the
direction
of
ice advance
They are often
stratified
(
layered
).
Kames
Mound
of
sediment
deposited
by a
river
Delta kame
A river
flowing
off
the
surface
of a
glacier
As the river flows into a
glacial
lake
it
deposits
sediment
forming a
mound
Terrace kame
Sediment
sliding
of the
edge
of the
valley
(
lateral edge
)
deposits
at the
edge
of the
glacier
Kettle holes
large
blocks
of
ice
calve
from the
main
glacier
onto an
outwash
plain
As the
glacier
retreats
the
block
of
ice
is left
stranded
When the
temperature
increases
the
ice
block
melts
leaving a
depression
in the
ground
that the
ice occupied
Kettle lakes
Where the
depressions
subsequently
fill
with
rainwater
Depositional landforms
Moraine
-
Material
left
behind
by a
moving
glacier
Lateral
(side to side)
moraine
A
ridge
-
shaped
moraine that is
built
up at the
side
of a
glacier
composed of
material
eroded
from the
valley
walls
by the
moving
glacier
.
Recessional
moraine
Small
ridges
left as a
glacier
pauses
during
its
retreat
.
Terminal
(end) moraine:
A
ridge
of
sediment
piled
up at the
furthest
extent
of an
advancing
glacier
Medial
Moraine
Produced when
two
valley
glaciers
(
Lateral
moraines)
meet
to form
one
larger
glacier
Ground
Moraine
Material
dragged
under
the
base
of the
glacier
(subgl
text
acial transport) and deposited over a
wide
area
on the
valley
floor
.
It forms an
irregular
‘
hummocky
’
surface
topography
.
Till
(rocks carried by the glacier)
plains
An
extensive
plain
resulting from the
melting
of a large
sheet
of
ice
that became
detached
from the
glacier
This till
levels
out the
topography
which
eventually
creates a
flat
landscape
Over time this plain becomes a
fertile
farmland
as
minerals
enter the soil in a
temperate
climate
Erratics
Typically a
small
boulder
that has been
deposited
by the
glacier
Useful in showing the
direction
of
ice
flow
, if you can match up the
rock
type
to rocks
further
up the
valley
you can tell where it has
come
from
Drumlins
Oval-shaped hills
, largely composed of
glacial drift
formed
beneath
a glacier or
ice
sheet
and
aligned
in the
direction of ice flow
They typically have a
rocky
core
with
sediment
moulded
around
them with a
glacial
till
therefore we can assume
meltwater
has a
key
role
.
They form
hundreds
of
metres
under
the
surface
Deforming bed Model
- Drumlins
Sediments
at the
bed
of the glacier are
weaker
so they
deform
due to the
stress
of the
ice above
If parts of this
deforming
layer
vary
in
strength
, then the
stronger
, stiffer portions will
deform less
and remain
static
, while the
weaker
portions will
deform more
rapidly and become
mobile
This links to the
core
of
drumlins
, which are
stronger
and more
coarse
grained
till
surrounded
by more
easily
deformed
till
, responsible for the
streamlined shape
Landscapes of Glacial
erosion
Arêtes
and
Pyramidal Peaks
An arête is a
knife-edge ridge
Formed when
two
corries
run
back
to
back
, as these glaciers
erode
each side of the
ridge
, the edge slowly starts to become
steeper
&
narrower
A
pyramidal
peak
is formed where
3
or
more
corries
meet
The glacier
erodes
backwards
towards
each other,
carving
out the
rocks
through
abrasion
&
plucking
.
Freeze
thaw
occurs at the
top
creating a
pointed
shape
.
Glacial Troughs
(u-shaped valleys)
Glaciers cut
distinctive
U-shaped valleys
, or troughs, with a
flat floor and steep sides.
Processes of
plucking
and
abrasion
,
widen
,
steepen
and
deepen
the
V-shaped
valleyt to then create a
U-shaped
valley
Ribbon lakes
As glaciers flow
over the land
, it flows over
hard
rock &
softer
rock.
Less
resistant
rock means the glacier will
carve
a
deeper
trough
.
Once the glaciers has
retreated
precipitation
will
collect
in the
deeper
area, creating a
long
thin
lake
(ribbon lake)
Hanging valleys
They are created where
smaller
valleys
meet the
main
glaciated
valley
.
The glaciers in the
smaller
valleys
were
not
so
powerful
, so they didn't
erode
such
deep
valleys.
This means the
smaller
valleys
are left hanging
above
the
floor
of the main valley.
A
waterful
can often be seen
Trunkated spurs
Areas of land
projecting
from the
river
-
valley
side
(spurs) have been
removed
(
cut
through
) by the
glacier
,
Glaciers tend to
straighten
the
valley
,
cutting
off
spurs
and leaving
cliffs
called
truncated
spurs
.
Roche Moutonnees
They form where a
glacier
moves
over a
band
of
harder
rock
often leaving
striations
to show the
direction
of
movement
.
Smooth
on one side (where
abrasion
is taken place) then more of a
jagged
down-side
by
plucking
.
