1. Ice distribution on Earth has changed over time and varies based on factors like latitude, altitude, and local climate conditions. 2. There are different types of ice masses including ice sheets, ice caps, glaciers, and ice shelves, which vary in size and location. 3. During the last ice age, ice cover was much more extensive, with large ice sheets covering North America and Europe that profoundly shaped the landscape as they advanced and retreated.

1. Present and Past
Distribution of Ice
Lower Sixth

2. What we’ll Learn today
1. That ice distribution was not uniform
2. That ice comes in various types of mass
3. That various glaciers exist
4. Ice is often constrained by several factors

3. Present and Past Distribution of
Ice
• Glaciers are a very sensitive and visible barometer of
climate change as they constantly shrink/retreat and
grow/advance in responses to changes in temperature
Cryosphere – Parts of the earths crust and
atmosphere subject to temperatures below
0oC for some part of the year.

4. Types of Ice Masses
• Ice can be classified into different characteristics such as
size and location:
Types of
Ice Mass
Description Size (sq km)
Ice sheet a layer of ice covering an extensive tract of land for a long period of time. 10 – 100,000
Ice cap miniature ice sheets. form primarily in polar and sub-polar regions that are
relatively flat and high in elevation
3 – 10,000
Ice field A large expanse of ice covering a mountainous region and consisting of
several interconnected glaciers
10 – 10,000
Valley
Glacier
Glacier confined by valley walls 3 – 1500
Piedmont
Glacier
occur when steep valley glaciers flow onto relatively flat plains, where
they spread out into fan or bulb shapes (lobes).
3 – 1000
Cirque
Glacier
are named for the bowl-like hollows they occupy, which are called cirques 0.5 – 8
Ice shelf floating sheet of ice permanently attached to a land mass 10 – 10,000

5. Glacier Types
• Some glaciers are land based such as
those on the Alps (e.g. Mer De Glace)
• Others are marine based – base is below
sea level (e.g. west Antarctic ice sheet)

6. Constraint
• Some marine based ones can go 2000m
below sea level and be frozen directly to the
seabed
• A further morphological contrast is provided
from the degree of constraint.
• Unconstrained glaciers – tend to be larger
forms such as ice sheets and ice caps
• These are thick and extensive and often
submerge the landscape
• Constrained – those that have a physical;
limit such as valley glaciers where the
landscape constrains where they are and tend
to only drain one way

7. 2 Types of Glacier
• Warm based
• Temperate or wet glaciers occur at high
altitude areas outside of polar regions
• Temperatures fluctuate on the surface to
above and below freezing
• The rest below the surface is close to
melting point because the pressure builds
up.
• Because of this water exists as a liquid at
temperatures below 0 degrees

8. Warm Based
• Having liquid at the bottom causes them to
melt continually (Basal ice – ice at bottom
of glacier)
• The ice also has lots of debris at the
bottom also and this creates many
subglacial deposits and landforms

9. Cold Based Glacier
• Polar glaciers where average temperature
is often below 0 degrees with surface
temperatures of -20 to -30 degrees
• Therefore the temperature at the base is
still below freezing even though the ice
could be 500m thick
• Limited surface melt during the polar
summer and so the glacier is permanently
frozen to the bed
• The basal layer therefore has far less
debris within it.

10. Geothermal Gradients of glacier
types

11. Polythermal Glacier
• This is a glacier which is warm based but
the margin cold based
• The upper zone is cold based whilst the
lower zone is warm based
• Due to extending into warmer climate
zones
• An example of this is some of the glaciers
on Svalbard

13. Surging Glaciers
• These can occur within warm based or
polythermal glaciers
• The glacier begins to flow at up to 100m a
day
• Greenland outer glaciers can do this (30m
per day)
• This leads to increased calving

14. Past and Present Ice distribution
• Glacial ice covers over 10% of the earth’s land surface
• It accounts for 75% of all freshwater stores
• 1.8% of all water on the planet

15. Where is it?
• 85% of all glacier ice is contained within
the Antarctica ice (Both west and East ice
sheets)
• The rest is distributed amongst ice caps all
over the world:
• Iceland
• Canada
• USA
• Himalayas
• Andes
• Alps

16. • Glacier exist in the
• High Andes
• Tanzania
• Indonesia
• Even though these are equatorial due to
the height
• The two most important factors governing
where they are is
• Latitude - For polar ice caps
• Altitude - For Alpine glaciers

17. Why?
• At high altitudes the suns rays hit at a
lower angle so the solar energy received
has to heat a larger area
• High altitude impacts on temperature via
the Environmental Lapse Rate (The rate
at which temperature decreases with
altitude at a given time)
• This is approximately 1% for every
100m

18. Local Factors
• Aspect – This determines the amount of
snow that settles.
• Relief and aspect in mountainous areas
combine to affect where cirques form
• Northern Hemisphere
• North and East slopes are more sheltered
and receive less sun therefore better able
to hold snow (Hence North Face)

19. Past Cover
• During the Pleistocene maximum ice cover
was around 3 times what it is today
• The Antarctica and Greenland ice sheets only
covered a slightly greater amount than they do
today
• The major extensions could be found
• North America (Laurentide and Cordilleran ice
sheets)
• Scandinavian Ice sheet in Europe
• Both these grew to a thickness of 3000-4000m
and transformed the landscape
• Other significant areas included S. America,
New Zealand, Siberia and the Himalayas.