AQA A Level Geography Glacial Systems and Landscapes

Characteristics of a glacial landscape

land permanently covered by ice (glaciers or ice sheets), high snowfall, little/ no soil exposed

Characteristics of a polar landscape

temps never above 10 degrees, winters are below -40 degrees, rainfall is low, soil is thin and nutrient poor, layer of permafrost, few lichen and mosses

Characteristics of a Periglacial landscape

temps frequently below freezing, 380mm or less precipitation, soil thin and acidic with permafrost topped with thin layer of soil that melts in summer, plants grow slowly and not tall

Characteristics of an Alpine landscape

cold area above the tree line, can include glacial and periglacial, snowfall can be high, seasonally exposed soil means plants grow longer.

What is the glacial budget?

It considers the balance of inputs and outputs of a glacier?

What is carbonation?

carbon dioxide dissolved in water forms a weak carbonic acid which reacts with and dissolves calcium carbonate in some rocks to form calcium bicarbonate.

Inputs of a glacial system

snow, condensation, sublimation, rocks/ debris

Stores of a glacial system

ice, meltwater, rock/ debris

Flows of a glacial system

meltwater flow, debris flow

Outputs of a glacial systems

meltwater flows, melting, evaporation, blow away, ice fall off

What end of the glacier is there more accumulation?

the upper end

Equilibrium point

the place on the glacier in which accumulation and ablation are equal

Cold based glaciers

found in places like Antarctica, there is very little melting

Warm based glaciers

occur in milder areas, heat from friction or geothermal heat from the earth creates meltwater that acts as a lubricant, there is lots of movement

What is integranular ice movement?

individual ice crystals slide over each other. they orientate in the direction of ice movement, this allows for sliding

What is intragranular ice movement?

ice crystals become deformed due to the stresses in the ice because of the glaciers mass, it moves downhill in response to gravity

What is the rate of movement of internal deformation?

1-2cm a day

Basal sliding

meltwater underneath the glacier allows the glacier to slide and move

What is the rate of basal sliding?

2-3m a day

Regalation

Where the glacier hits an obstacle in its path and pressure creates localised melting which allows the glacier to slide over it, it then refreezes on the downstream

Rotational sliding

basal slip allows the glacier to rotate in an arc sae in the valley

Extension flow

At the top of the glacier there is as strong gravitational force pulling the ice down, the ice then moves quickly and fractures into layers that slip down

Compression flow

The lower end of the valley is less steep and the top pushes down compression the ice causing it to fracture and slip down

Nivation

Occurs under a snow patch. Snow gets in a hollow and freeze thaw makes frost shattering happen, meltwater then carries these broken pieces away, slopes collapse due to water-logging and material is washed away by meltwater.

What are the two main forms of glacial erosion?

abrasion and plucking

Frost action

water gets into cracks in rocks and when the temp fluctuates around 0 degrees, the water freezes and thaws causing stress on the rock which then breaks apart

Plucking

Ice freezes and thaws around rocks stuck to the valley wall, as the glacier moves it pluck the rock from the wall

Abrasion

debris carried by the glacier can scrape material at the valley walls and floor.

Supraglacial

material carried on top of the glacier

Englacial

material carried within a glacier

Subglacial

material carried underneath a glacier

What are Thaw lakes?

common in poorly drained periglacial areas, form in summer when snow melts with the active layer,

What are taliks?

The dark surface of thaw lakes absorb radiation from the sun this increases the depth of melting creating unfrozen areas- taliks

What is a blockfield/felsenmeer

the boulder strewn landscape creates by frost action that leads to angular scree at the bottom of a mountain

At what temperature is frost action most effective at?

between -4 and -15 degrees

What is ground ice

ice in the ground

What is frost heave?

when ice forms within pores creating ice needles, this can force individual soil particles or small stones upwards

How are ice wedges formed?

cracks formed in the ground by thermal contraction can be filled with water, this then freezes and enlarges

What is solifluction?

the saturated active layer of soil slumps down a hill during summer to form solifluction lobes.

What is frost creep?

The growth of needle ice in loose sediments results in the gradual movement of ice down a hill. Particles raise perpendicular to the ground by frost heave and at dropped due to gravity, this causes it to creep downwards.

What are the 5 factors that affect the extent of erosion by a glacier?

Mass of ice, Gradient, Meltwater, rock debris, underlying geology

How are ribbon lakes formed?

Localised over-deepening due to enhanced erosion caused by weaker bedrock, merging of tributary glacier (more mass) or narrowing of valley

How do corries form?

snow collects in a hollow and compacts into ice, basal sliding abrasion and plucking deepen the hollow

Arete

a sharp ridge formed whet two glacial flow parallel to each other, they erode the side

Pyramidal peak

a point formed when three or more corries form back to back

Glacial troughs

steep sided valleys with flat bottoms formed by erosion of a V shaped valley

Hanging valley

formed by tributary glaciers getting left at a higher level than the main glacier

Truncated Spur

ridges of land 'spurs' are cut off as the main glacier moves past

Tarns

Lakes that form in a corrie after the glacier has retreated

Roche Moutonnee

hard mass of rock on the valley floor, the upstream side is smooth as it was abraded, the downstream is steep due to plucking

Lateral moraine

morraine at the side of the glacier

Medial moraine

formed when two glaciers meet and the medial moraine joins down the middle

Terminal moraine

marks the furthest point of glacial advancement

Ground moraine

found underneath the glacier

Recessional Moraine

marks several points of glacial retreat

Till plain

extensive plain resulting from a large sheet of ice that becomes detached from the glacier, the till levels out topography

Briefly describe drumlin formation

a glacier hits an obstacle in its path and is forced to move over it, the ground moraine collects around the obstacle and a tapered drumlin is formed

How do erratics occur?

Pieces of rock are picked up by glaciers and transported to areas with a different geology

How can meltwater streams cause erosion?

hydraulic action, abrasion, attrition and solution

What do meltwater streams form?

deep troughs in the landscape called meltwater channels, these are wide and deep due to their high erosive powers.

How does a meltwater channel form?

overspill from a lake alongside/ in front of a glacier, high erosive water spills across the landscape and carves a valley

What are the fluvioglacial transport processes?

traction, saltation, suspension and solution

What is different about fluvioglacial deposits than glacial deposits?

they are sorted, the fine sediment is separated from the larger pieces. glacial deposits are just melted.

What is an outwash plain and how is it formed?

it is a layer of gravel, sand and clay that forms in front of where the snout of a glacial used to be. Meltwater flowing out of the glacier carries the sediment with it. They are sorted into layers based on heaviness.

What are Eskers and how are they formed?

They are long winding ridges of sediment that run in the same direction as the glacier. They're deposited by meltwater streams flowing in tunnels underneath the glacier. It shows where a glacial tunnel used to be.

What are Kames and how are they formed?

They are mounds of sediment on the valley floor. Meltwater streams on top of glaciers collect in depressions and deposit layers of debris. When the ice melts the debris is dumped in the valley floor.

What are Kame terraces and how are they formed?

They are piles of deposits left against the valley wall by meltwater streams that run between the glacier and the valley sides. they look like lateral moraines but they're sorted into layers, they deposit their heaviest load first so they have gravel at the bottom and fine stuff at the top.

What are kames deltas?

As meltwater flows into a proglacial lake it deposits its sediment on the ice, these are deltas, when the ice melts these become delta kames.

What are crevasse kames and how are they formed?

some kames result from fluvial deposition of sediments in surface crevasses, when the ice melts they are deposited on the valley floor to form small hummocks.

What are proglacial lakes?

They are lakes that form in font glaciers when the flow from meltwater streams gets dammed by the terminal moraine

What is permafrost?

permanently frozen ground with a top layer that can melt in summer.

How much of the earths surface is permafrost?

20-25%

How is patterned ground formed?

as ice wedges become more extensive, a polygonal pattern maybe formed on the ground with the ice wedges marking the sides

What are stone polygons?

a feature of patterned ground that tends to form on flat ground. frost heave causes the expansion of soil and lifts particles up. Small particles may be moved by wind leaving larger rocks leaving a pattern

What are stone stripes?

a sloped ground can distort the polygons as they slide or roll down hill

What are pingos?

Rounded hills, up to 90m high and 800m across, they have vegetation on the outside and have a solid ice core.

How are closed pingos formed?

a lake infills with sediment that insulates the ground beneath it, liquid is trapped in the talik between the lake and permafrost, this water then freezes and expands and the talik is squeezed, the lake sediment above is then pushed up to form a pingo

How are open pingos formed?

occurs in areas of discontinuous permafrost. the active layer freezes and traps water between it and the permafrost, this creates an ice lens which pushes the land up. water moves through the talik to the ice lens, freezes and pushed it up more

How are terracettes formed?

frost heave causes individual particles to expand upwards then fall back down vertically, on a slope this causes a downhill movement and creates 'steps'

How is thermokarst formed?

when ground ice melts and settles to form a landscape of marshy hollows and hummocks. this varies depending on the vegetation, climate, topography etc

name three reasons why cold environments are fragile

slow ecosystem development and highly specialised habitats, sensitive to change, once damaged it can take a long time to recover.

Name five human activities that impact upon cold environments

oil extraction, fishing, tourism, hydroelectric power production and mining

Impacts of the 1989 oil spill of the coast of Alaska

over 40 million litres was lost, 250,000 birds and fish killed

How many leaks a year were there from the trans- Alaska pipelines from 1977-1994

30-40

Name a fish that is being overfished in the Antarctic

Patagonian toothfish

What is bottom trawling

it catches fish by dragging nets along sea beds, it disrupts eco systems and catches other species

Impacts of hydroelectric power production

block migratory patterns of fish, causes fish population to decrease. Dams heat up the water endangering fish that are cold water adapted

Impacts of mining

can lead to ground and surface water contamination by chemicals or releasing the mined minerals e.g. zinc lead mine in Maarmorilik was closed but levels of zinc are still high in the Fjords. they produce solid and waste water that needs to be disposed of.

Current impacts of climate change on cold environments

melting glaciers and ice sheets, sea level rise, melting permafrost e.g. Alaska. changing migration patterns of species e.g. Caribou

Predicted impacts of climate change on cold environments

sea levels will rise further and cause flooding. melting permafrost releases trapped methane causes temps to rise more and cause more melting. plants that are adapted will find it hard to survive