Ice on the Land

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Ice on the Land
Glacials and Ice Ages
In the last 800,000 years, 1015 glacials have occurred.
The average global temperature only needs to decrease about 2 for an ice age to occur.
The last ice age was the Pleistocene Epoch. It began about 2 million years ago and ended
around 96009700BC.
The maximum extent of glaciation occurred about 18,000 years ago. 30% of the world was
covered in ice including large parts of North America and Europe and most of Britain.
Currently, there are only two large ice sheets: covering Antarctica (south) and covering
Greenland and Arctic Canada (north).
Glacial period: A period of ice advance associated with falling temperatures.
Interglacial: A period of ice retreat associated with rising temperatures.
Ice Sheet: A large body of ice over 50,000km2.
Ice Cap: A smaller body of ice usually found in mountainous regions.
Glacier: A finger of ice usually extending downhill from an ice cap and occupying a valley.
Tundra: An environment which is frozen during winter, where only lowlying frost resistant plants
can grow.
Glacier Movements and its Causes
If the inputs to
the glacier are
greater than
the outputs,
then the
advances and
vice versa.
Ablation is
greatest at the
snout and the
surface as the
is highest there.
The amount of ice present depends on the glacial budget. This has seen a loss since 1950 and
there are seasonal changes due to fluctuations in temperature.
Accumulation: Inputs to the glacier budget, e.g. snowfall and avalanches.
Ablation: Outputs from the glacier budget, e.g. melting.
Snout: The front of a glacier.
Glacier Budget: The balance between the inputs and outputs of the glacier.
A Retreating Glacier: South Cascade Glacier
Located in Washington, USA.
It's retreating rapidly: the net water loss between 1985 and 2005 was 18.91 metres.
However, it has had short periods of glacial advance in 1991, 19967, 19982000 and 2002.
Between 1958 and 2009 South Cascade Glacier lost nearly a half of its volume.
The main cause of the glacier's retreat is climate change due to the greenhouse effect.
Temperatures have been increasing and therefore so have melting rates.

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Causes of Glacial Retreat & Advance
Sun spots: The output of the sun slightly varies over decades due to sunspots. High levels of
sunspot activity reduce annual ablation rates.
Volcanic Eruptions: Volcanoes can eject km3s of dust into the atmosphere. This acts as an
insulator of the earth from the sun's rays, causing temperatures to fall and short periods of glacial
Global Warming: The increasing usage of fossil fuels has lead to a measurable increase in
global temperatures.…read more

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This provides lubrication, allowing the glacier to slide over the surface
(this is basal sliding).
This type of movement in corries results in rotational slip.
Gravity causes the movement of the glacier to be downhill.
Basal Sliding: Meltwater acts as a lubricant, allowing glaciers to slide down surfaces.
Internal Deformation: The weight of the ice causes the ice crystals to change shape under
pressure. The crystals act like plastic and `flow'.
Bulldozing: The pushing of deposited sediment at the snout of a glacier.…read more

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Eventually, the glacier melts and a misfit stream or ribbon lake occupies the valley. The
hanging valley creates a waterfall.
Ribbon Lake: A long narrow lake on the floor of a glacial valley which is often blocked by a
terminal moraine.
Identifying Glacial Features on an OS Map
As corries are rounded hollows, they look like a horseshoe shape of contour lines on the
map. Remember tarns can be found within them. Corries can also be known as coire, cwm,
cirque or cove.…read more

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Reduces 200 tonnes of emissions per year
Economic Effects Environmental Effects
Provides lots of jobs in the Deforestation
resort and in hotels etc. So less Noise pollution ­ affects hibernating animals and
young people move away to find residents
jobs. Carbon emissions from building and flights ­ a cause
Brings lots of tourists to the of global warming
area. Decreases biodiversity of local environment
Transport is improved. Light pollution as night skiing is available.…read more

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Situated in Weheka in the Westland National Park.
The glacier was advancing from 19852005, but is now retreating. These changes in
movements are caused by varying amounts of accumulation and ablation.
Activities available there include hiking tours, helicopter rides, ice climbing and ski diving.
The weather patterns are sudden and varied due to the mountainous area. Temperatures
can range from 025. On average, the township receives 5m, the lower glacier receives
11m, and the upper glacier receives 15m of rainfall per year.…read more

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