AQA A Level Geography- Glacial Systems and Landscapes

Where matter and energy can be transferred across a system boundary.

Where energy can be transferred across a system boundary, but matter cannot.

Where neither matter nor energy can be transferred across a system boundary.

Open systems.

Glacial inputs as snow.

Glacial outputs e.g. melting, sublimation.

During Pleistocene glaciations (1.6 million- 12,000 years before present)

18,000 years ago

At the poles of the Earth within the Arctic Circle (66°N) and the Antarctic Circle (66°S). 10°C isotherm- in the hottest month, the average temperature stays below 10°C.

Temperatures consistently below freezing, little rainfall. Winter averages of -40 degrees, precipitation rarely exceeds 100mm/year.

Climate leads to slow nutrient cycles, so soil is nutrient deprived and frozen. Have a lack of decomposers.

Cold climate and low precipitation means only highly adapted vegetation can grown, such as moss and lichen. Plants rarely decompose, as there is a lack of decomposers and temperatures slow this process.

Lack of soil nutrients limits nutrient rich plant growth, limited nutrient rich plant growth leads to a lack of soil nutrients.

Found at high altitude, mountainous regions, above the treeline, at any latitudes.

Temperatures fluctuate annually, summers are frequently above 0 degrees. Average low -20, average high 12. High snowfall in winter, high rainfall and meltwater in summer.

Higher summer temperatures cause thawing of soil, so more vegetation can grow. Fertile soil develops when these decompose. Soils freeze in winter, so less plants grow.

Vegetation adapted to alpine climate thrives in the summer and usually dies in winter. Climate allows for a short nutrient cycle, encouraging decomposition and short growing times.

Found at high latitudes and altitudes, usually on the edge of colder environments.

Temperatures are consistently below freezing, precipitation is low. Winters in higher latitudes last longer with less daylight hours, so are colder.

Lower ground is frozen all year round, active layer thaws during higher summer temperatures. Soil is usually waterlogged due to thawing, making it deoxygenated so plants cannot survive, and nutrients are leached away.

Only highly adapted plants can survive cold temperatures and little rainfall. Leads to a slow nutrient cycle, and lack of nutrients can lead to soil infertility. Permafrost makes it hard for plants to grow as roots cannot penetrate the soil.

Areas of land permanently covered by glaciers or ice sheets. Found in both polar and alpine regions.

Are cold enough for ice to be present all year round, summer temperatures may produce meltwater. Most have high snowfall, but cold based glaciers have little snowfall.

No exposed soil, very few plants, though algae and moss may grow on the surface during summer.

Low levels of insolation as suns energy is distributed over a larger area, causing a distinct lack of seasons.

Cold air holds less water vapour/moisture, so less precipitation occurs.

Glacial systems found in high pressure areas, leading to low precipitation levels.

Ice reflects 90% of sun’s energy. As ice is lost, less of the sun’s energy is reflected, so leads to more ice melting.

Changes in gradient create differences in pressure, creating winds.

Permafrost in the ground prevents their death, so they do not need the stability roots provide.

Lichen, sedge, cotton grass.

2.5 million years ago to 11,700 years ago.

Most recent major ice age- fluctuations in global temperatures leading to glacial and interglacial periods.

21,000 years ago.

UK and northern Europe, Northern Russia, Canada, Alaska, Northern USA.

Central and southern Russia, central Europe.

Northern USA, China, Peru, Bolivia.

Glaciers have advanced and retreated in correlation with the world’s glacial and interglacial periods. Majority of glaciers are currently retreating due to increasing temperatures.

The most significant global cooling in recent history, between 1300 and 1870.

They were the largest they have ever been.

Heavy avalanches and snowfall were common and posed a risk to life.

Glacial inputs exceed outputs, usually in the upper part of the glacier.

Glacial outputs exceed inputs, usually in the lower part of the glacier.

Snow is compressed and crystallised forming ice. These crystals grow over time, and eventually larger crystals are compressed so there are no air pockets.

The balance between accumulation and ablation over a year. Shows whether the mass of ice in the system has increased or decreased.

Where accumulation and ablation are equal.

When snow accumulates, the lower layers of snow get compressed by the upper layers. As layers get compacted, the mass changes colour from white to blue, indicating air has been expelled from layers.

The lower edge of the permanent snow cover in upland areas. As temperatures drop, snow line moves downslope.

Direction glaciers are facing in Northern Hemisphere: Southern facing slopes receive more solar energy due to movement of sun. Northern facing slopes- receive less solar radiation, lower temperatures, higher chance of snow and accumulation.

European Alps. Adret slope- more habitable southern facing. Ubac slope- inhospitable northern facing slope.

The difference between accumulation and ablation. If summer and winter budgets balance each other out, glacier stays stationary.

Accumulation exceeds ablation- glacial advance.

Alation exceeds accumulation- glacial retreat.

The temperature at which ice melts under pressure. Deeper means higher pressures, so more friction and lowered PMP.

-1.27 degrees.

Lower PMP, so creates meltwater that acts as a lubricant, aiding the movement of glaciers.

Warm based and cold based.

Milder locations- North America, Norway, Southern Iceland.

Fluctuating, warmer climate; lots of meltwater, high erosion from basal sliding. Between 5 and -10 degrees.

Summer temperatures cause melting, meltwater present acts as a lubricant for erosion, deposition, and transport. All ice is near melting point.

Polar areas- Antarctica, Arctic.

Consistently dry and cold, very little meltwater, internal deformation only.

Low precipitation- low accumulation rate.

Ice is well below PMP and frozen to bedrock, so movement is slow and erosion is limited as there is little/no melting.

Any processes that change the shape of the land.

The deformation of layers of ice or individual ice crystals caused by the pressure from the weight of the ice. This causes some layers to move faster than others, so different parts of the glacier can be further advanced.

The ice slides in the armchair-shaped hollow about a central point of rotation. This is a downhill flow of ice which pivots around a point producing a rotational movement and erosion.

Glacier sliding over the bedrock. This is due to meltwater providing lubrication for the glacier to move.

Pressure and friction increases when there is an obstacle. Stress builds up, ice behaves like a plastic and flows around or over the object.

When ice meets a steep downhill gradient, gravity forces the ice to increase in velocity. Friction causes the ice to thin out and extend, creating crevasses.

When ice hits a shallower gradient, friction causes the ice to slow down, build up and compress. This causes ice to get thicker.

Temperature, mass, relief.

When a glacier moves forward suddenly.

Excessive build up of meltwater under glacier leads to rapid movement of 250-350m/day. Normally due to basal sliding, Represent a hazard for those at snout of glacier.

Side and base of a glacier move at a slower rate due to friction with the valley sides and floor. Ice cracks and extending flow produce crevasses in these areas.

Breakdown of rock/debris in situ (until removed by later erosional processes)

The environment is far too cold for plants/animals and chemical reactions to occur.

Water gets into the cracks of rocks, freezes and then expands by around 10%. This repeated action puts pressure on a rock, eventually causing it to shatter and break off.

A collection of rock material at the base of a steep cliff.

Processes that operate underneath patches of snow in hollows. Most common in North and East facing slopes.

Rock disintegrates under snow due to freeze thaw weathering. During snow melt, rock particles are removed from the hollow and flushed downslope. More debris accumulates creating nivation hollows, which can lead to corries.

Breakdown of rocks as a result of movement displacing solids.

Upland areas- warm based glaciers move faster so have more erosive power.

Material the glacier is carrying rubs away at the valley floor and sides. Coarser material leaves striations on the rock.

Scratches on the surface of a rock.

Debris worn down to a fine material, which is carried by meltwater and turns milky. Created due to abrasion.

Rocks attached to bedrock or sides become frozen to the glacier. When the glacier moves, the rocks are pulled from the landscape, leaving a jagged surface.

Base of glacier- where pressure and friction create a build up of meltwater.

A sharp, narrow, pinnacled ridge, formed as a result of glacial erosion from both sides.

Crib Goch, Snowdonia.

A steep-sided, pyramid shaped peak, formed where three aretes meet.

Matterhorn, on Swiss/Italian border.

An armchair shaped hollow with steep sides and back wall, formed as a result of glacial erosion on a high mountainside, and often containing a rock basin with a tarn.

Cwm Cau on the peak of Cadair Iris, Snowdonia.

Nivation creates nivation hollows, which are widened and deepened by the forces of erosion. Rotational flow then over-deepens the corrie. This leads to the armchair shape and causes a rock lip to be formed.

A corrie filled with water- postglacial landform.

Red Tarn, Lake District.

A u-shaped valley formed by a glacier eroding through a river valley. The glacier has enough force to erode away a river’s interlocking spurs. This leaves truncated spurs on the valley sides and a wide, flat valley floor.

Nant Ffrancon, Snowdonia.

Rock basins, hanging valley, truncated spurs, fjords, roche moutonnees.