AQA A Level Geography- Glacial Systems and Landscapes

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What is an open system?

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

What is a closed system?

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

What is an isolated system?

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

What type of system are glaciers?

Open systems.

What is accumulation?

Glacial inputs as snow.

What is ablation?

Glacial outputs e.g. melting, sublimation.

When have glacial and interglacial periods occurred?

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

When was the last glacial maximum? (Little ice age)

18,000 years ago

Where are polar environments found?

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.

What is the climate like in polar environments?

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

What are soils like in polar environments?

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

What are plants like in polar environments?

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.

How can positive feedback link to plants and soils in polar environments?

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

Where are alpine environments found?

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

What is the climate like in alpine environments?

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.

What are soils like in alpine regions?

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.

What is vegetation like in alpine environments?

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.

Where are periglacial environments found?

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

What is the climate like in periglacial environments?

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

What are soils like in periglacial environments?

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.

What is vegetation like in periglacial environments?

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.

What are glacial environments and where are they found?

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

What is the climate like in glacial 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.

What are soils and vegetation like in glacial environments?

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

How does latitude create glacial characteristics?

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

How does cold air create glacial characteristics?

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

How does global atmospheric circulation contribute to glacial environments?

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

What is the albedo affect?

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.

Why do cold environments have katabatic winds?

Changes in gradient create differences in pressure, creating winds.

Why do periglacial plants have shallow roots?

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

What plants grow in glaciated environments?

Lichen, sedge, cotton grass.

When was the Pleistocene era?

2.5 million years ago to 11,700 years ago.

What happened during the Pleistocene era?

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

When was the last glacial maximum?

21,000 years ago.

Where were polar regions distributed in the Pleistocene era?

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

Where were periglacial environments distributed during the Pleistocene era?

Central and southern Russia, central Europe.

Where were alpine regions distributed during the Pleistocene era?

Northern USA, China, Peru, Bolivia.

Historical periods of glacial advance and retreat.

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.

What was the little ice age?

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

What happened to Mont Blanc glaciers between 1818-1821?

They were the largest they have ever been.

Why did the little ice age pose a threat in the Alps?

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

What is the zone of accumulation?

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

What is the zone of ablation?

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

How do glaciers form?

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

What is the glacial budget?

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

What is the glacier’s equilibrium point?

Where accumulation and ablation are equal.

What is a firn/neve?

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.

What is a snow line?

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

What is Aspect?

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.

What is an example of where Aspect is prevalent?

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

What is the net balance?

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

What is a positive mass balance/positive regime?

Accumulation exceeds ablation- glacial advance.

What is a negative mass balance/negative regime?

Alation exceeds accumulation- glacial retreat.

What is a pressure melting point?

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

What is the pressure melting point of a 200km thick glacier?

-1.27 degrees.

Why do thicker glaciers move and advance quicker?

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

What are the types of glacier?

Warm based and cold based.

Where are warm based glaciers found?

Milder locations- North America, Norway, Southern Iceland.

What are the characteristics of warm based glaciers?

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

What are the melting patterns of warm based glaciers?

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

Where are cold based glaciers found?

Polar areas- Antarctica, Arctic.

What are the characteristics of cold based glaciers?

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

What are the accumulation patterns of cold based glaciers?

Low precipitation- low accumulation rate.

What are the melting patterns of cold based glaciers?

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

What are geomorphological processes?

Any processes that change the shape of the land.

What is internal deformation?

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.

What is rotational flow?

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.

What is basal sliding?

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

How does basal sliding occur?

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

What is extensional flow?

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.

What is compressional flow?

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

What factors affect rates of ice movement?

Temperature, mass, relief.

What are glacial surges?

When a glacier moves forward suddenly.

How are glacial surges caused?

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.

Why are there different rates of movement within a 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.

What is weathering?

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

Why is there little biological/mechanical weathering in glaciated environments?

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

What is freeze-thaw weathering?

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.

What is scree?

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

What is nivation?

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

How does nivation occur?

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.

What is erosion?

Breakdown of rocks as a result of movement displacing solids.

Where is erosion most common?

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

What is abrasion?

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

What are striations?

Scratches on the surface of a rock.

What is rock flour?

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

What is plucking?

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.

What part of the glacier is plucking mainly found at?

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

What is an Arete?

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

Arete example.

Crib Goch, Snowdonia.

What is a pyramidal peak?

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

Pyramidal Peak example.

Matterhorn, on Swiss/Italian border.

What is a corrie?

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.

Corrie example.

Cwm Cau on the peak of Cadair Iris, Snowdonia.

How are corries formed?

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.

What is a Tarn Lake?

A corrie filled with water- postglacial landform.

Tarn lake example.

Red Tarn, Lake District.

What is a glacial trough?

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.

Glacial trough example.

Nant Ffrancon, Snowdonia.

What landforms are associated with glacial troughs?

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