AS Unit F761 - Managing Physical Environments (GLACIERS)
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Notes that cover Glaciated Landscape
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AS Unit F761 - Managing Physical Environments (GLACIERS)
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OCR
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OCR A-level Geography Workbook 1
This pack contains responses to short answer questions, that cover the Glaciated Landscapes unit in OCR A Level Geography. The Short answer questions were all awarded full marks. This pack is useful for both teachers and students. Students can use it for helping in homework tasks, aiding the unders...
A Level OCR Geography Notes For The Changing Spaces, Making Places Unit
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AS Unit F761 - Managing Physical Environments (GLACIERS)
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A Level Geography
Topic 1.1.2 – Glaciated Landscapes
Practice Questions
1. Describe the components that make up a glaciated landscape system [8].
A system is a set of interrelated processes which are interdependent from one another and work together
to form a working unit. A system is composed of inputs, processes and outputs. Glaciated landscapes achieve
this definition as they are an open system consisting of inputs, processes, stores and outputs.
Firstly, inputs such as precipitation and thermal energy start the glacier process and determine the outputs.
Those inputs are then stored in a medium such as water, snow, ice or debris. The different stores then
facilitate different processes from occurring. For example, if ice is the stores then freeze thaw weathering is
possible. Conversely if meltwater is present than hydrolysis will occur in the glaciated landscape. Other
processes which also occur in glaciated landscapes include plucking and abrasion. The processes will then
create glaciated landscapes which would be the output. An example of a system would be reduced thermal
energy (input) leading to accumulation and creation of ice (store). The ice would then move downslope
leading to abrasion of the bedrock underneath. The shear stress generated would lead to plucking (process)
hence forming an erratic (output).
In a glaciated system – inputs can change (eg in summer – increased thermal energy produces more
meltwater). This changes the outputs until the input returns to what it originally was – glacier systems fit this
model and thus they are a system which undergoes dynamic equilibrium. Furthermore, glaciated systems are
based on negative feedback since they have dynamic equilibrium.
As the glaciated system produces different outputs depending on the inputs then that highlights how
interlinked the system is. Inputs are also controlled by outputs since the output (formation of corries) then
dictates what inputs can be created in the first place therefore highlighting the interdependence between the
system – without one of these processes then the entire system will not work.
2. Explain the term ‘dynamic equilibrium’. [3]
Dynamic equilibrium is a form of negative feedback which states that when the equilibrium of a system is
disturbed then the system will institute changes that restore that previously established equilibrium.
3. Describe the flows of energy and material through glaciated systems [4].
Glaciated systems move their material through either Kinetic, Thermal or potential energy. Kinetic energy
describes the movement of ice or meltwater – kinetic energy is facilitated by the shape of the landscape.
, Kinetic energy allows glaciers to move. Thermal energy is dictated by seasonality and pressure exerted by
overlying ice. Thermal energy can create meltwater that in the case of corries allows for rotational slip to
occur and thus for glacial systems to move. Finally, gravitational energy is created when the glacier is at a
position of the slope with a high angle – the force of gravity creates this potential energy.
Glacier systems contain these energy stores and energy is transferred throughout the system. For example,
in the creation of a corrie, freeze thaw weathering from rocks above leads to rock fall as the potential
energy of gravity causes the weathered material to fall. As the material becomes incorporated into the ice –
the ice base begins to melt since energy has transferred from potential to thermal and also as the pressure
of overlying rock causes melting. This melting allows for rotational slip and movement of ice – the ice moves
by the surrounding landscape- hence energy is transferred from thermal to kinetic energy.
4. Explain how the glacier mass balance of a glacier may change temporally and spatially [8].
The glacier mass balance is an equation which determines if glaciers have been retreating or accumulating
per annum. It is calculated by subtracting the amount of accumulation with the amount of ablation;
whichever figure is bigger thus determines if the glacier has accumulated or melted. The glacier mass balance
changes spatially and temporally.
Throughout the year there are temporal changes – in winter months because of the reduced soalr radiation
– there is less warmth and creation of meltwater reduces whilst ice accumulates – this creates a net
accumulation. In contrast in the summer month – the high summer months results in high baltion rates
which In turn reduce the ice leading to a glacier mass loss. In a typical year since winter and summer months
are equal in their duration – then glacier overall balance does not change since the opposing season
counteracts the changes that the other season makes.
However, with climate change – increased temperatures in the winter thus means that accumulation rates
are not that significant and, in each year, – there is a net loss/ablation of the glacier mass balance. A net loss
means the glacier will retreat. Overall, regarding temporal changes – the glacier mass balance may become
more negative over time.
Concerning spatial variations – accumulation would be greater in areas of high latitude (Antarctica) or high
latitude (Himalayas). These areas are subject to colder conditions facilitating for the accumulation of ice in
these regions than in other areas. This would create spatial variations with high latitude and altitude areas
having a positive mass glacier balance whereas other areas may not have a positive mass glacier balance.
5. Explain how precipitation patterns influence glaciated landscape systems [4].
High precipitation patterns means an increase in the input, which when in tandem with high solar radiation
can produce a high volume of meltwater. Meltwater is influential is the formation of glacial landforms since
water contains carbon dioxide meaning that the rate of erosion can increase – the erosive property of
meltwater can thus make erosional landforms. In converse – if precipitation patterns can also form ice and if
temperatures are low then ice is formed – ice forms the basis of glacial landforms – such as in creating
corries.
When precipitation levels are low such as in high latitude locations such as Vostok, Antarctica – there is a
lack of an increase in inputs since precipitation makes the basis of snow, meltwater etc – this means that the
glacier mass balance doesn’t change, and so precipitation levels dictate the volume of inputs that in turn
dictates what glaciated landscapes could be formed.
6. Explain the difference between ‘structure’ and ‘lithology’ [4].
Structure concerns the properties that the rock has such as bedding planes, fractures and joints, as well as
the porosity and permeability of rocks. If a rock contains these properties, then that increases the water
infiltration into the rock. If temperatures fall below 0 then freezing of that water may occur and freeze thaw
weathering may be possible – increasing the likelihood of till sheet or corrie formation.
Whereas structure is about the individual properties of rock types – lithology describes the physical and
chemical composition of rocks. Rocks such as clay are incompetent rocks which have a weak lithology since
their cohesion between grains is low and so they are subject to more extensive weathering and erosion. In
contrast – Basalts and granites are composed of interlocking crystals and are resistant to weathering and
erosion – This allows these rock types to dominate higher altitude areas and thus help form Aretes and
pyramidal peaks.
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