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Edexcel A Level Geography - Glaciation Summary Notes
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Glaciation Content DumpMass balance: ablation, ice is lost as more is being removed than added. And accumulation, ice adds on because more is being
gained than lost. Think of it as transfers and stores (and outputs, inputs)
Line of equilibrium splits a glacier into accumulation and ablation, but this can be referred to in a general sense to.
Inputs: river that it started with, avalanches, snow fall called rime ice. Compaction leads to then denser and denser as you go
deeper down.
Outputs: melting to create fluvio-glacial, evaporation from surface, sublimation – occur due to UV rays from sun – heat.
Erosional landforms
A glacier flows downwards: affected by incline, glacial surges: enabled by basal sliding where meltwater on base acts as a
lubricant for glacier to slide. Also ice crystals within deform: internal deformation, also bedrock deformation, where its too
weak and gives way. All enable the downward movement of a glacier.
Creates cirques with lakes called tarn once melted (craters where tributary glaciers, or where glaciers or tributaries originate
from), striations (scars in the rock where a lodged piece of sediment has carved into bedrock, creating lines in the direction of
glacial movement), creation of a v shaped valley as the weight of the ice breaks the rock underneath it. And also aretes: peaked
areas of rock on valley ridges.
By PLUCKING, ABRASION and CRUSHING
Depositional landforms
Glaciers carry material and drop it off when it no longer has the energy to move it
Creates erratics (plucked pieces of non-localised geology, dropped off by a glacier), and other landforms created when till
(unsorted sediment carried by the glacier) gets deposited.
Moraine: a term used for general land features that are created with direct ice contact (upland)
Along with… non ice contact such as till plains, and ice sheet contact drumlins (mounds) – lowland!
Fluvio-glacial
Meltwater from glaciers creates erosional and depositional landforms much like a river would. Also include larger events like:
glacial meltwater lakes called proglacial lakes (+outwash plain, network of rivulets), GLOFS: glacial outburst floods, can be
triggered by volcanism, where an ice barrier melts away, allowing for water or other ice to break free. Major hazard to human
infrastructure, very destructive.
Along with features such as kame terraces (winding deposits of till)
Periglacial environments
These are the areas of a higher/closer to equator latitude that are essentially tundra.
Have a permafrost layer which is very important to be maintained: it is a carbon store (methane and carbon dioxide) and if
melts, releases this carbon which then accelerates the greenhouse effect, enhancing global warming. This will cause many other
issues.
Frost shattering of rock can create ice wedges that create gashes in the ground. Expand over time with continuous melt and
freeze over seasonal periods.
Or Pingos: where accumulation of water in discontinuous permafrost creates an underground lake that bulges up the ground
above it.
Rapidly freezing soils and shattering create patterned soils with lines and stripes of rock.
Climatology
Feedback systems are events that create feedback, either negative which reduces temperature, or positive which increases
temperature. Some examples:
Positive: (loss of) ice albedo: where the ice that normally reflects sunlight back into space melts, less is reflected so Earth’s
surface warms more. Also causes sea level rise as ice melts. Melting of permafrost (as above-mentioned release of greenhouse
gases). Add some more.
Negative: clouds and rainfall – boost plant growth, then increase amount of carbon sequestered, so reduces greenhouse effect.
Also can be positive because they absorb and trap heat. Add some more.
Natural Climate Change
Milankovitch cycles: eccentricity, axial tilt, and orbital cycle
Volcanism: creates ash clouds which reflect sunlight (cooling effect)
Plate tectonics: block off or enable streams of water to move temperature around the globe
Variations in solar output eg sun flares, would create a warming effect
Management of Glacial Landscapes
They have value: value can be constituted in so many ways… tourism, beauty, ecology, biodiversity, culture, art, music,
recreation, energy, resources etc…
The way in which glacial landscapes are managed can be placed on a scale of intervention: “SPECTRUM OF MANAGEMENT
RESPONSE”
Can also be in response to threats that are facing glacial landscapes: both human and natural
Examples…
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