Glacial Systems and Landscapes Flashcards
1
Q
What is a system?
A
A set of interrelated components working together towards some kind of process. A system will include imputs, outputs, stores, flows, and boundaries, and generally exists in a state of dynamic equilibrium.
2
Q
What is positive feedback?
A
Where the effects of an action are amplified or multiplied by subsequent knock-on or secondary effects.
3
Q
What is negative feedback?
A
Where the effects of an action are nullified by its subsequent knock-on effects.
4
Q
What are the purposes of using systems in geography?
A
- Simplifies complicated physical and human processes
- Shows how energy is transferred and how components change
- Helps us understand how natural change and human activities impact an environment
5
Q
What are the types of systems?
A
Isolated system
Closed system
Open system
6
Q
What is an isolated system?
A
A system with no interactions with anything outside its boundary i.e. no input or output of energy or matter. These are extremely rare, only existing in things such as a scientific lab experiment.
7
Q
What is a closed system?
A
A system with transfers of energy but not mass outside of its boundary e.g. the water cycle
8
Q
What is an open system?
A
A system where matter and energy can be transferred across the boundary e.g. most ecosystems, a drainage basin
9
Q
What is dynamic equilibrium?
A
Where there is a balance between inputs and outputs in a system, meaning stores stay the same even though flows are ongoing
10
Q
What is feedback?
A
Changes to an equilibrium as a result of one of the elements of a system changing
11
Q
What aspects are linked as part of a landscape system?
A
Landforms
Processes (that create landforms)
The global environmental system that controls them
12
Q
What are the Earth’s major spheres?
A
Atmosphere
Biosphere
Hydrosphere (inlcudes the cryosphere)
Lithosphere (includes the pedosphere)
13
Q
Where are cold environments generally found?
A
Most are found at Earth’s northernmost and southernmost points. Above 55 degrees north permafrost is found, mostly in Canada and Russia. In the Arctic Circle above 66 degrees north pack ice is found as well as ice sheets such as Greenland. Below 66 degrees south Antarctica is covered by an ice sheet and surrounded by pack ice. Cold environments are also found around the world in mountain ranges.
14
Q
What is an ice age?
A
A time period where there are ice sheets and glaciers on Earth
15
Q
What is a glacial period?
A
A time period with unusually extensive polar and mountain ice sheets
16
Q
What is an interglacial period?
A
A time period of warmer average global temperatures, during which ice sheets recede
17
Q
What is an ice sheet?
A
A large, thick layer of ice, especially one that exists for a long period of time, covering more than 50,000 square kilometres
18
Q
What is an ice cap?
A
A covering of ice over a large area, especially on a polar region, covring less than 50,000 square kilometres
19
Q
What are the most recent geologic time periods?
A
Holocene epoch - 11,700 years ago to today (interglacial period)
Pleistocene epoch - 2.6 million - 11,700 years ago (ice age)
Together make up the Quaternary Period
20
Q
What was the climate of the pre-Pleistocene period like?
A
Global average temperatures 8-15 degrees higher than today, though just before the Pleistocene it was warmer, with some ice present.
21
Q
When was the last glacial maximum (LGM) and what were conditions like at the time?
A
Around 22,000 years ago. 25% of the Earth’s surface was covered in ice, as opposed to less than 10% today, including most of the British Isles (by the Devensian ice sheet) and much of North America (by the Laurentide ice sheet).
22
Q
What is the climate of tundra environments like?
A
Long and cold winters with average temperatures of -20 degrees
Summer temperatrures are rarely over 5 degrees
For at least 8 months of the year temperatures remain below 0 degrees
Precipitation is low (less than 300mm per year)
Frequent strong winds
23
Q
What is the vegetation of tundra environments like?
A
Low lying shrubs, mosses, lichen, grasses, and cushion plants
Vegetation is more common where there is meltwater and deeper soils
There are some dwarf birch and willow trees, but no full grown trees
Biodiversity is low
Most flowering plants are perennials
24
Q
What is the soil of tundra environments like?
A
Permafrost is common and contains large amounts of trapped methane and carbon dioxide
Lower down soils are full of peaty undecomposed vegetation and frost-shattered rock
There is a thin, often acidic, organic surface layer
Soils become waterlogged in summer
25
What is the climate of polar environments like?
Temperatures vary from 4 down to -28 degrees on average
Very low precipitation (average of 100mm per year)
Snow storms and cold winds for much of the year
In Antarctica temperatures can be as cold on average as -55 degrees, though coastal areas are warmer (-10 degrees)
26
What is the vegetation of polar environments like?
Limited vegetation as a result of infertile soil
| Mosses and lichens grow in some places without ice and snow cover
27
What is the soil of polar environments like?
Soil is thin and infertile
Soils lack nitrogen and carbon from a lack of decomposition
Soils are frozen most or all of the year
28
What is the climate of alpine environments like?
Cool climates - snow may melt in warmer seasons
Windward sides receive lots of precipitation, usually snow, and wind
Leeward sides receive less precipitation and wind
29
What is the vegetation of alpine environments like?
Low lying shrubs, mosses, and lichen are found at the highest altitudes
Coniferous trees are found at lower levels, below the tree line
30
What is the soil of alpine environments like?
Soil is thin, gravel like, and very infertile from slow rates of decomposition
31
What are glaciers?
Glaciers are large masses of snow, recrystallised ice, and rock debris that accumulate in great quantities and begin to flow outwards and downwards under the pressure of their own weight.
32
How does snow become ice in glaciers?
Snow --> partially melts, refreezes, and compacts --> névé --> survives a full ablation season and is further compacted --> firn --> further compaction (sometimes over decades) --> ice
33
What are the inputs of a glacier system?
Precipitation, avalanches, windblown snow, and hoar frost - deposit snow, ice, and water through surface accumulation
Throughflow and groundwater flow - deposit rain and meltwater through internal and basal accumulation, which then refreeze
34
What are the stores in a glacier system?
Ice
Snow
Meltwater
Rocks
35
What are the flows and processes in a glacier system?
Freezing, melting, sublimation, deposition (gas to solid)
| Plucking, abrasion, debris transport, deposition
36
What are the outputs of a glacier system?
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Meltwater runoff
Calving
Melting
Sublimation
Subaqeueous frontal melt
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37
What is a glacier budget/mass balance?
The balance between a glacier's inputs (accumulation) and outputs (ablation). If accumulation is higher than ablation, the glacier will advance, while if ablation is higher than accumulation, the glacier will recede. The glacier budget varies in different parts of the glacier: in the upper part, the zone of accumulation, it is gaining mass, while in the lower part, the zone of ablation, it is losing mass. At the equilibrium line, these processes are equal.
38
What is the equilibrium line and what does its elevation depend on?
The line that separates the zone of accumulation and the zone of ablation on a glacier; at this line the processes are equal. Its elevation depends on temperature, precipitation, and the surrounding landscape.
39
Why is it of concern that glaciers are retreating?
Many humans rely on glacial meltwater for drinking and agriculture, especially in Asia, where the Himalayas ('the water tower of Asia') and glaciers on the Tibetan Plateau provide water to billions of people. Some countries, such as Pakistan, are almost entirely dependent on this water, creating a potential for conflict.
Glacial retreat feeds into the ice albedo effect: ice has a high albedo, while the underlying rocks do not, so positive feedback is created.
Flooding risk will be raised.
40
What is the firn line?
The minimum altitude at which firn accumulates on a glacier, marking the transition between the snow covered upper-regions and exposed glacial ice. During the summer melt season, the line migrates up-glacier.
41
Why are glaciers said to be in a state of dynamic equilibrium?
When changes occur in the system (e.g. to inputs or outputs), it responds to establish a new equilibrium. For example, if inputs decrease, it will retreat up the valley (as well as the equilibrium line) until it is in equilibrium again.
42
If a glacier is in retreat, what changes will occur if it is a) approaching equilibrium b) in disequilibrium?
a) The glacier will retreat and thin somewhat at the terminus, while the equilibrium line will shift upwards.
b) There will be substantial thinning along the entire longitudinal profile of the glacier, and no accumulation will occur, as the equilibrium line is said to be above the glacier.
43
What is a geomorphological process?
A natural process that results in the modification of landforms on the Earth's surface
44
Where are geomorphological processes most active in relation to cold environments? Why?
At the margins of cold environments, as precipitation is higher, liquid water is available, and temperatures go both above and below freezing, which all aid geomorphological processes
45
What is weathering? What are the most common weathering processes in cold environments?
The breakdown or disintegration of rock in situ or just below the ground surface. The major weathering processes in cold environments are frost shattering (freeze-thaw, where water expands by 9% when it freezes), carbonation (chemical weathering with carbonic acid in rain), and nivation (geomorphic processes associated with a patch of snow).
46
What is nivation?
The geomorphic processes associated with a patch of snow, most notably frost shattering, meltwater erosion and transportation, and mass movement, usually slumping. Over time this creates a nivation hollow, which can lead to the development of a corrie glacier.
47
What are the main processes of glacial erosion?
Abrasion and plucking
48
What is plucking?
Glacial erosion that takes place when meltwater freezes part of the underlying bedrock to the base of a glacier. Loosened rock fragments are then 'plucked' away as a glacier moves. This process is most common in localised areas of reduced pressure under the ice, which leads to regelation.
49
What is abrasion?
The sandpapering effect of ice as it grinds over and scours a landscape. It occurs from angular, frost-shattered material, especially large rocks carried beneath the oce, which create striations on the bedrock. Over time these transported rocks become pulverised by the weight of ice, so they become fine rock flow, which smooths and polishes the bedrock.
50
What are the main processes of ice movements?
```
Internal deformation - includes inter- and intragranular movement
Rotational flow
Compressional and extensional flow
Basal sliding
Surges
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51
What is internal deformation?
The movement of a glacier as a result of deformation of ice crystals from the weight of the glacier. This is generally only 1-2cm per day and happens most near the bottom of the glacier, where pressure is greatest. There are two types:
Intergranular movement: individual ice crystals slip and slide over each other in the direction of ice movement.
Intragranular movement: ice crystals become deformed or fractured from pressure, causing the mass of ice to move downhill.
This is the only form of movement in cold-based glaciers.
52
What is rotational flow?
The movement of a glacier within a corrie, where ice moving downhill pivots around a point, further eroding and deepening the corrie floor.
53
What is compressional and extensional flow?
Compressional flow - when the gradient of the slope decreases, so movement slows and the glacier 'piles up' and becomes thicker. This closes crevasses on the surface of the glacier
Extensional flow - when the greadient of the slope increases, causing ice to flow faster and thin through internal deformation, potentially causing crevasses to form on the glacier's surface
54
What is basal sliding?
The movement of a large body of ice, usually in a series of short jerks. It occurs in warm-based glaciers where meltwater lubricates the base of the ice. Movement can be up to 2-3 metres per day.
When the glacier encounters an obstacle, the additional resistance causes increased pressure, which leads to pressure melting of the base, allowing the glacier to move over the obstacle. On the downslope, pressure is lower, so regelation occures.
As movement causes friction and pressure, it can increase temperatures, causing additional melting of basal ice, which lubricates flow in a positive feedback loop.
55
What are surges?
When an excessive build up of meltwater occurs under a glacier, leading to ice moving rapidly forwards, at least 10x faster than normal but sometimes up to 100x times, leading to speeds of up to 250-300 metres per day. This can be hazardous to people living in the glacial valley below.
56
What are the reasons for current cold environments?
Latitude
Continentality
Altitude
Albedo
57
How does latitude affect temperature?
At the equator the Sun's rays hit the Earth at a direct angle, while at the poles this angle is far more oblique, so less solar energy is absorbed per area at the poles. In addition, the Sun's rays have to pass through more of the atmosphere to reach the poles, so more is reflected before reaching the surface.
58
How does continentality affect temperature?
The oceans have a moderating effect on temperatures, as water has a higher specific heat capacity than land, so heats up and cools down more slowly than land. In winter, therefore, the ocean heats coastal areas somewhat, as it still retains some of its heat from summer, while in winter it cools them (though to a lesser extent). The result is that coastal areas are generally warmer than areas inland e.g. the UK has a similar latitude to northern Canada and southern Siberia, but a very different climate.
59
How does altitude affect temperature?
For every 1000m of height gained, the temperature falls by 6.4 degrees, as the air becomes thinner at higher altitudes, so it is less able to reabsorb heat radiated by the Earth (creating a localised version of the greenhouse effect), so it is colder.
60
How does albedo affect temperature?
Areas with lots of ice and snow coverage e.g. Antarctica, the Arctic, and snow-capped mountains have a higher albedo than other land or oceans, so they reflect more heat from the Sun rather than absorbing it, making them even colder in a positive feedback loop.
61
What are the reasons for historical cold environments?
Orbital changes
Volcanic activity
Solar activity
62
How have orbital changes affected temperatures?
Milankovitch cycles:
- Eccentricity cycle: over 100,000 the Earth's orbit changes from circular to elliptical and back
- Axial tile: the Earth is currently tilted at 23.5 degrees, but over 41,000 years it changes from 22.5 to 24.5 degrees and back
- Precession: the Earth wobbles on its axis over a cycle of 26,000
More eccentricity, tilt, and precession means higher temperatures, so all three together creates an interglacial, while a lack of these creates a glacial period.
63
How has volcanic activity affected temperatures?
Large, explosive eruptions produce lots of ash and sulphur dioxide. If these reach the stratosphere, they are spread around the Earth by high level of winds, with ash blocking out the Sun and sulphuric acid (from sulphur dioxide) reflecting solar energy, thereby cooling the Earth temporarily. The 1991 Mount Pinatubo eruption cooled the planet by 0.5 degrees for a year, while the 1815 Mount Tambora eruption led to 'the year without a summer', with 200,000 deaths from famine in Europe.
64
How has solar activity affected temperatures?
Sunspots indicate that the Sun is more active than usual, with lots of sunspots meaning more solar energy is being fired out from the Sun. These follow an 11 year cycle.
65
What is pressure melting point (PMP)?
The temperature at which ice melts at a given pressure. The higher the pressure, the higher the temperature required to melt ice.
66
What is the key difference between temperate and polar glaciers?
Temperate glaciers are warm based: at the base of the glacier the temperature is above the pressure melting point, so meltwater is present, lubricating the flow and allowing basal sliding to occur. In polar glaciers the temperature at the base is well below 0 degrees, so PMP is not reached and the glacier is frozen to the bedrock.
67
Where is glacial movement greatest?
At the equilibrium line, which is where the greatest volume of ice passes; consequently this is the point where there is the most energy available.
In areas of high precipitation and ablation, as this means the mass of the glacier is constantly changing, so the glacier is much more dynamic.
In small glaciers, as they respond more readily to short-term climatic fluctuations.
In areas with steep gradients, as gravity promotes increased movement.
In temperate glaciers, where there is meltwater at the base providing lubrication.
68
What is till?
Unsorted material deposited directly by glacial ice
69
What is a landform?
An individual feature that, together with all other features, makes up a landscape
70
How did the Channeled Scablands form?
16,000 years ago, during the last glacial period, Lake Missoula was a pro-glacial lake of the Laurentide ice sheet. It was dammed by ice, but this gave way, triggering a glacial lake outburst flood (GLOF) with huge erosional power, which carved out the Scablands.
71
What are the characteristics of kettle holes? How do they form?
Kettle holes are depressions found in glacial outwash plains. They are generally quite small, with a diameter of 5-100m and a depth of 1-5m. Most fill with water, becoming kettle lakes; some become acidic as a result of decomposition (kettle bogs) while some are ephemeral, so dry up in summer months.
They form as a glacier recedes, leaving behind blocks of ice (calving). As a result of glacial outwash, these blocks become partially or wholly covered by sediment in outwash plains. The ice then melts, leaving gaps in the sediment.
Alternatively, a glacial lake outwash flood occurs, depositing large amounts of sediment onto an outwash plain, including sediment-rich ice. This then melts, again leaving holes on the plain.
72
What are the characteristics of braided streams? How do they form?
Braided streams are narrow, fast flowing bodies of water emerging from the snout of glaciers. They are split into multiple channels divided by islands of deposited material, called eyots.
They form as a glacier melts, releasing large amounts of fast flowing, sediment rich meltwater. This loses energy as a result of friction, causing sediment to be deposited, which blocks the stream. As the stream lacks the power to erode this, it instead diverts around it, splitting into separate channels.
73
What are the characteristics of outwash plains? How do they form?
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Outwash plains (or sandhurs) are large (5-80km long), mostly flat areas of layered glacial sediment, found after the terminus of a glacier. The sediment is often stratified, with the largest pieces closest to the terminus. Often landforms such as kettle holes, varves, and braided streams, are present. Example: Skeidararsandur, Iceland.
They form as meltwater from a glacier transports sediment eroded or weathered and transported by the glacier into the plain. As the meltwater loses energy, it deposits this sediment, causing the plain to enlarge over time. They can also grow quickly as a result of GLOFs or jökulhlaups.
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74
What are the characteristics of varves? How do they form?
Varves are annual layers of deposited sediment. They are found in glacial lakes and are generally 1mm-20cm thick, with two distinct parts: a coarse sand layer and a fine clay layer.
They form as meltwater streams deposit sediment into glacial lakes. During summer months discharge is higher so more sediments flow into the lake, creating the wider layer, while in winter months discharge is lower, creating the thinner layer.
75
What are the characteristics of kames? How do they form?
Kames are irregularly shaped mounds of glacial sediment, up to 50m wide and 3-5m high. Unlike e.g. moraine, the sediment is stratified, with the largest sediment at the middle of the landforms. There are three types: kame terraces, which are ridges found on the side of valleys, kame deltas, which are small, mound-like hills on the valley floor, and crevasse kames, which are small hummocks on the valley floor.
They are formed when glacial streams carry sediment to supraglacial lakes, where it is deposited. The glacier then melts, leaving the pile of sediment behind. Kame terraces are formed as a result of a lake on the side of a glacier, kame deltas are formed as a result of a lake on the surface of a glacier, and crevasse kames are formed when streams flow into crevasses on the surface of a glacier, depositing their sediment inside them.
76
What are the characteristics of eskers? How do they form?
Eskers are long, narrow ridges of sediment running in the direction of ice advance. They have a sinuous (winding) form and are about 10-50m wide, 5-20m tall and 0.5-150km in length. They are made of sorted coarse material, which is stratified according to grain size. Today many eskers are discontinuous as a result of erosion by glacial meltwater and post-glacial rivers. Example: Esker Riada, which runs 200km from Dublin to Galway in Ireland.
They start as subglacial, englacial, or supraglacial streams or rivers. Englacial channels are able to flow uphill as a result of hydrostatic pressure. These rivers carry large amounts of sediment, which is deposited as the glacier starts to melt, causing velocity to fall. When the glacier completely melts, only the sediment is left behind.
77
What are the characteristics of meltwater channels? How do they form?
These are channels cut into ice, rock, or sediment by channels in, under, on, or in front of a glacier by meltwater. E.g. the Channeled Scablands
78
What are periglacial regions?
Periglacial regions exist in high latitude areas not permanently covered by snow or ice. Permafrost conditions are found.
79
What is the definition of permafrost?
Ground that continually remains below 0 degrees for two or more years
80
What are the types of permafrost?
Continuous permafrost: found in the coldest periglacial regions, reaches deep into surface layers (in Siberia, it reaches an estimated 1,500m deep), and with an uppermost layer that hardly melts in the coldest areas.
Discontinuous permafrost: found in slightly warmer areas, reaches less far into the ground (on average 20-30m deep), and has gaps under rivers, lakes, and near the sea.
Sporadic permafrost: found where mean annual temperatures are around or just below 0 degrees, with permafrost only in isolated spots where the local climate is cold enough that soil cannot completely thaw in summer.
81
What are the key periglacial processes?
Nivation
Frost heave
Solifluction
82
What is frost heave?
The movement of material upwards as a result of freezing and thawing. There are two parts to this: 1. as stones are more thermally conductive than soil, they cool down faster, so the area under the stone is colder than the surrounding soil. Small amounts of moisture in the soil beneath the stones then freeze and become ice lenses, expanding by 9% as they do so. This causes the stones above them to rise. When the ice melts, the place the stone once was is replaced by soil, and the process repeats, gradually heaving stones upward.
2. As soil freezes from the top down, ice reaches and 'grabs' stones, pulling them up by the vertical expansion above them. Soil then fills the place the stone once was, preventing it from moving back down when the soil below freezes.
83
What is solifluction?
Mass movement of soil affected by alternate freezing and thawing. In the summer, the active layer thaws, releasing lots of meltwater. This cannot percolate downwards (as the ground below is frozen) so it saturates the soil, reducing the internal friction between particles so making it highly mobile. Without substantial vegetation to bind the soil, it can flow even on lopes of very few degrees. In the winter, the active layer refreezes, leaving behind rounded, tongue-like lobes.
84
What is talik?
A layer of year-round unfrozen ground in permafrost areas. It is often found below lakes and rivers. There are three types: open talik, which is surrounded by permafrost on some but not all sides, found below small lakes; through talik, which has no permafrost underneath, found below large lakes; and closed talik, which is surrounded completely by permafrost.
85
What are the characteristics of thermokarst? How does it form?
Thermokarst is a land surface characterised by marshy hollows and small hummocks. It forms as permafrost begins to thaw, waterlogging the soil and creating lakes on the surface. Ice lenses collapse as they thaw, creating depressions which contribute to the uneven surface of thermokarst.
86
What are the characteristics of patterned ground? How does it form?
Patterned ground refers to the geometric formations (e.g. circles, polygons, or stripes) found on permafrost subject to significant amounts of frost action. There are two types: ice-wedge polygons (20-30m across) and stone polygons (usually less than 10m across):
Ice-wedge polygons form when water inside fissures in the active layer freeze. This then expands the fissure, pushing the ground apart, and each year the wedge also grows, as water flows into it in summer then freezes again in winter. Over time ice wedges therefore expand, which develop in polygonal patterns
Stone polygons form as a result of frost heave, which moves significant amounts of stones to the surface. As they collect on the surface, larger stones are pushed towards the edge of the pile by gravity and land expansion, while smaller ones and sand and silt remain in the middle, creating polygons.
87
What are the characteristics of solifluction lobes? How do they form?
Solifluction lobes are semicircular shaped protrusions that extend downhill on the side of a slope. They form as ice melts in the active layer in the summer, waterlogging the soil as it cannot evaporate (too cold) nor penetrate deeper. This lubricates it, causing it to move downslope. In colder months the active layer freezes in place, causing soil to become immobile, so it stays as a lobe.
88
What are the characteristics of terracettes? How do they form?
Terracettes are small, narrow ridges that run horizontally along th eside of a slope. Each 'step' is usually only tens of centimetres wide.
The main theory about terracette formation is that they are formed by a combination of creep, the process by which soils move downhill, solifluction, and frost action. Their formation is probably accentuated by animals grazing on the slope, which helps erode them into a staircase form.
89
What are the characteristics of blockfields? How do they form?
Blockfields are surfaces covered by boulder or block-sized angular rocks. They typically have little vegetation aside from a few plants between the rocks and very little soil.
They form as a result of frost heave, which brings rocks to the surface. Once at the surface, they are broken apart by frost shattering, creating the smaller, angular rocks characteristic of the landscape.
90
What are the characteristics of pingos? How do they form?
Pingos are ice-cored hills, usually conical in shape and between 10-60m tall and 50-600m wide. If the ice within them melts, they can collapse, creating a depression within them which often fills with water. There are two types: open and closed.
Open pingos form in discontinuous permafrost in an area of through talik. Here an ice lens can form, which will then expand as water is drawn to it by capillary action and hydraulic pressure, raising the ground around it and forming the pingo.
Closed pingos form in an area of talik in continuous permafrost, below a lake. The lake can then drain into the talik, and, without the insultation the lake provided, the talik can then freeze, creating an ice lens. More water is then drawn in through hydrostatic pressure, which then freezes, expanding the ice lens and forming the pingo.
91
How fast do various glacial landforms form?
Fastest: small erosional landforms e.g. striations (1 day)
Fairly fast: depositional and fluvioglacial landforms e.g. till, meltwater channels, eskers, moraine (1-100 years)
Slow: larger erosional landforms e.g. roches moutonnees (1000 years), corries and U-shaped valleys (tens of thousands of years
92
What are the characteristics of glacial troughs (U-shaped valleys)? How do they form?
Glacial troughs are large valleys with a flat floor and steep sides, usually 0.5-3km wide. If they meet the ocean, they can fill with water, becoming fjords. Ribbon lakes may be present as a result of overdeepening of the valley floor.
They form as a result of abrasion and plucking as a glacier moves through a valley, carving out a wide path with steep sides. Previously the valley would be V-shaped, created by a river, before being widened by the glacier.
93
What are the characteristics of hanging valleys? How do they form?
Hanging valleys are smaller side valleys left 'hanging' above the main U-shaped valley. Very often a waterfall will flow from the hanging valley into the main trough.
They form as a result of a tributary glacier, which connects perpendicularly to the main valley glacier. As the main glacier is much bigger, heavier, and contains more material, it has a far greater erosional power, so will create a far deeper valley than the tributary valley. Once the glaciers recede, this difference becomes obvious, as the hanging valley is left far higher than the main trough.
94
What are the characteristics of truncated spurs? How do they form?
Truncated spurs are ridges which descend towards a valley floor from a higher elevation and which end abruptly in a flat, inverted-V shaped face.
They form initially as interlocking spurs, where a river meandered around patches of resistant rock in its upper course and through vertical erosion created a series of spurs. When a glacier forms in this valley, it has the erosional power to erode away the ends of these spurs through abrasion and plucking. This material is transported away, leaving only the truncated part of the spur once the glacier recedes again.
95
What are the characteristics of roche moutonnees? How do they form?
Roche moutonnees are monds of rock with a gently sloping, smooth (with some striations) stoss side and a steep, jagged lee side. They are generally 1-10m tall and 3-30m long.
They form as a glacier moves over a patch of more resistant rock. This results in an increase in pressure, as the glacier cannot simply erode it but must move uphill in order to pass over it. As a result, more meltwater forms, allowing the glacier to move over it. Striations are created as the rock is abraded. On the other side of the rock, once the glacier has crested the hill, pressure sharply decreases again, causing regelation to occur. Rocks are therefore plucked from this side, creating an angular, jagged face.
96
What are the characteristics of corries? How do they form?
Corries are armchair shaped hollows found on the sides of mountains. They are generally 0.5-1km wide and have a steep back wall of 100-400m, usually between 60 degrees to vertical in angle. Often, as a result of overdeepening and the despositing of moraine on the lip of a corrie, it is able to fill with water, forming a tarn.
They form initially as a result of nivation from a snow patch on the side of a mountain. As meltwater transports eroded and weathered sediment away from the patch, it becomes deeper, allowing a small glacier to form. This then begins to move through rotational flow, eroding the back wall and floor through abrasion and plucking. Weathering also deepens the back wall, over time creating the distinctive shape of the corrie.
97
What are the characteristics of aretes and pyramidal peaks? How do they form?
Aretes are narrow ridges that separate two valleys. They can be up to 2km long and form either when two glaciers erode parallel U-shaped valleys, or when two corries form back to back. In both cases, they are steepened by frost shattering.
Pyramidal peaks are angular, sharply pointed mountain peaks. They form when three or more corries erode towards one another, creating the steep peak, which is again steepened by weathering.
98
What are the characteristics of drumlins? How do they form?
Drumlins are elongated, teardrop shaped hills, with widths between 25-600m, lengths from 50-1.2km, and heights of 15-50m. They have a steep stoss side and a gently sloping lee side.
There are many theories for the creation of drumlins. One involves catastrophic subglacial floods, which scour cavities into the bed of the glacier. These then fill with sediment deposited by meltwater streams below the glacier, creating drumlins which remain when the glacier recedes.
Another is the deforming bed model. This argues that the sediment below the glacier deforms as a result of the extreme amount of pressure it is put under. Stronger, coarses pieces of sediment resist this more, while finer pieces deform more. The weaker sediment is then able to flow around the more static, stronger sediment, which explains the coarser core of drumlins surrounded by finer, streamlined till.
Once formed, drumlins are then narrowed and straightened by the movement of the glacier.
99
What are the characteristics of erratics? How do they form?
Erratics are glacially deposited rocks which differ in size and character from the surrounding geology. They range in size from pebbles to large boulders.
They are plucked by a glacier from their original landscape and transported vast distances, often hundreds of kilometres, before being deposited. As a result, they can often be used to determine glacier movement.
100
What are the characteristics of moraine? How does it form?
Moraines are accumulations of glacial till. There are several types, all with their different method of formation:
Terminal moriane marks the furthest extent of glacial advance. It is deposited once a glacier begins to recede, as it lacks the power to continue transporting all its material.
Recessional moraine is deposited behind terminal moraine, where a glacier pauses during its retreat, allowing sediment to be deposited.
Lateral moraine is found on the sides of a glacial valley. It forms from material weathered from the valley sides by frost shattering or carbonation, or which flows off the surface of the glacier.
Medial moraine forms when two glaciers meet each other and merge, combining their lateral moraine into one line.
101
What are the characteristics of till plains? How do they form?
Till plains are large, flat plains of unsorted glacial material. They form when a sheet of ice detaches from the glacier and melts in place, depositing its sediment in one place.
102
What is a fragile environment?
One with sensitivity and on the edge of survival, where even the slightest change can have significant effects.
103
Why are cold environments fragile?
Processes such as weathering and erosion happen very slowly, so if material is lost, it will take a long time to be replenished
Plants and animals are highly specialised to the specific environment (e.g. lack of daylight, strong winds, lack of rainfall, frozen soil etc.) so are very sensitive to change and would not be able to survive in a different one
There are lots of positive feedback loops present in cold environments (e.g. ice albedo, permafrost melt), so minor changes can have big effects
104
What are some current human impacts on cold environments?
Oil spills - ground and water pollution, death of plants and animals
Introduction of invasive species - through climate change and tourism
Global warming - disruption to migratory patterns, ice melt, disruption of ocean currents
Fishing - loss of biodiversity
Tourism (skiing and other adventure sports) - soil erosion and deforestation
Mineral extraction
Settlements - permafrost melt
105
How is global warming affecting cold environments?
Average Arctic temperatures have risen 1-2 degrees since the 1960s, making it the fastest warming place on Earth.
Arctic sea ice is declining at a rate of 12.5% per decade, with the potential for an ice-free Arctic summer by 2030-50
Leading to species decline - polar bears in the southern Beaufort Sea have declined by 40% from 2001-10
Increased permafrost melt leading to land subsistence and positive feedback
Potential for the Northwest Passage to become open year round, shortening shipping times, especially for ships too heavy to transverse the Panama Canal
Decreased precipitation and higher temperatures in alpine environments forcing ski resorts to shut earlier
106
How is pollution affecting cold environments?
Usually coems from resource extraction e.g. oil spills, as the areas are resource rich - there are 90 billion barrels of oil equivalent in the Arctic
Since opening in 1977, the Trans-Alaska Pipeline has leaked on at least four occasions, and the Russian oil industry spills more than 30 million barrels on land each year
The 2020 Norilsk oil spill, the second largest in Russian history, was caused in part by melting permafrost, which caused foundations to collaps
107
How is infrastructure development affecting cold environments?
According to one estimate, there will be 1 trillion dollars of infrastructure investment in the Arctic over the next fifteen years, through expanding urban area and the construction of roads and pipelines
Pipeljines can obstruct migration routes and melt snow and permafrost with their heat
Construction workers can trample the landscape, which takes a long time to recover
108
How is tourism affecting cold environments?
Tourism occurs frequently in alpine environments and in growing numbers in polar and periglacial areas
Tourists can trample soil, disrupt wildlife, and introduce invasive species (as a result of climate change invasive species are more likely to survive and thrive in these environments)
Illegal ski resorts have sprung up in countries such as Bulgaria, leading to deforestation and disturbance of wildlife
109
How is fishing and whaling affecting cold environments?
Though commercial fishing is banned in much of the Arctic, illegal fishing still occurs, which ignores all regulations
Fishing is legal in Antarctic waters, and fishermen often use longlines or bottom trawling, two hugely environmentally damaging methods, as they work indiscriminately
Though commercial whaling was banned in 1986, though some countries such as Iceland continue to practice whaling under the loophole of scientific research, while others such as Norway and Japan ignore the IWC ban (Japan withdrew in 2018)
110
How did humans use cold environments in the past?
Home for indigenous people e.g. the Inuit, who practiced extensive nomadic farming of animals in a sustainable manner
Whaling, until its ban in 1986 - in the late 1930s more than 50,000 whales were being killed every year
Exploration
Oil spills in the late 20th century e.g. Exxon Valdez in 1989 (11 million gallons)
Attempts of governments to culturally integrate indigenous groups into the national culture, with negative impacts for the groups
111
What is the population and location of Old Crow?
Population: ~300 Vuntut Gwitchin
Location: on the Porcupine River in Yukon, Northwest Canada
112
What is the climate and environment of Old Crow like?
Climate: fairly mild summers (average temperature ~10 degrees) and very cold winters (average temperature ~-30 degrees). Low precipitation, almost all as snowfall.
Discontinuous permafrost, with mostly small shrubs and lichen growing. There is some evergreen forest found near Old Crow. The Porcupine River freezes in the winter and has several oxbow lakes.
113
What are the opportunities present in Old Crow?
Large native population of Porcupine caribou which migrates throught the area, providing food for the Vuntut Gwitchin
Modern technology (e.g. snowmobiles and rifles) allows the easier hunting of caribou
Caribou meat can last through winter with adequate storage, providing food year round
A gravel airstrip provides access to the community, allowing supplies and diesel fuel to be flown in
A gravel quarry employed 12 people in its construction, but now only 2 people seasonally. It provides material for infrastructure
There are government/First Nation jobs like a co-operative grocery store and a school
Strong community bonds in the Vuntut Gwitchin and a "spiritual connection" to the land
Oil is present in the nearby Arctic National Wildlife Refuge, though this does not stand to benefit the community, as it will disrupt the breeding grounds (the 1002 lands) of the caribou
114
What social problems are present in Old Crow?
Very high dependency ratio, as many working age people move away in search of better opportunities, leaving children and elderly people behind
Issues with food security as a result of the earlier defrosting of the Porcupine river, which is disrupting caribou migration, as well as oil drilling in the ANWR, legalised by the federal US government in 2017. The Porcupine caribou population is rapidly declining despite mitigating efforts by the Vuntut Gwitchin
Very isolated community
115
What economic problems are present in Old Crow?
Trade is limited, as the only access to the community is through the airstrip, to which flights are infrequent
Imported food is very expensive
Very few jobs are available, with government work being the only option for most people in Old Crow
The community is not likely to benefit economically from oil extraction, as it is taking place across the border in Alaska
116
What environmental problems are present in Old Crow?
The average annual temperature in Old Crow has risen by 3.5 degrees from 1948 to 2016, triple the global average, causing officials in Old Crow to declare a national emergency
Porcupine numbers are in signficant decline as a result of climate change, oil drilling, or overhunting
117
How have the Vuntut Gwitchin responded to the increasing challenges of their region?
Hunting caribou for longer hours and in more extreme conditions in order to have enough food to eat, but stopping as soon as they have as many as they need
Only hunting male caribou to try to slow population decline
118
What is a hollistic approach?
One that takes into account all factors (e.g. environmental and socioeconomic) and stakeholders Very few management strategies benefit everybody - there are almost always winners and losers, but holistic approaches try to maximise utility in as many areas as possible
119
What are some traditional and modern management strategies of the Arctic?
The Inuit lived in small communities based around small family units, spread over a large area, so as not to put large amounts of pressure on scarce resources. Often they were nomadic
Using all parts of prey i.e. for food, clothing, and shelter to further minimise impact
Constructing smaller buildings and elevating them, allowing heat to dissipate to lessen permafrost melt
Building larger buildings and roads on aggregate pads, 1-2m thick layers of coarse sand and gravel which insulate the permafrost
Building pipes above ground in insulated boxes (utilidors)
Using low-pressure Rolligon tyres to transverse soft ground in the Tundra
120
What are some adaption strategies to climate change in alpine environments?
Opening ski resorts for less of the year
Building ski resorts at higher altitudes
Using fake snow to fill in resorts (very expensive)
Monitoring sites more closely where avalanches are likely - using the hazard management cycle to plan for these
121
What is ecosystem-based management? What are its pros and cons?
Management that recognises the full array of interactions in an ecosystem, including humans, rather than looking at single species or issues in isolation.
It is flexible and adaptable, so able to respond to the changing nature of ecosystems. It takes into account ecological and socioeconomic factors, although the ecosystem is the most important factor, as it underpins all others.
It is only a framework rather than a set of measures, so cannot by itself solve problems. Potential to create conflict, as many human activities are hugely harmful to ecosystems but have significant amounts of supporters e.g. the oil lobby.
122
What is the Arctic Council?
An intergovernmental forum made up of the Arctic states (the Nordic countries, the US, Russia, and Canada), as well as 13 observer states such as India, China, and the UK, which sit in on meetings but have no voting rights as they have an interest in the Arctic through matters such as fishing and shipping. Indigenous groups are able to raise issues but have no voting rights. It was founded in 1996 to promote environmental protection but today is the leading forum for co-operation on Arctic issues (e.g. pollution, biodiversity, sustainability, and protecting the rights of indigenous people), with a permanent secretariat and the ability to issue binding commitments. Controversially, the Council does not deal with matters of military security, a key issue in the Arctic, given that there are various disputed territories and ocean rights there, e.g. the Beaufort Sea, claimed in part by both Canada and the US. However, it has achieved some successes, such as the decline of illegal fishing from 100,00 tons in 2005 to almost 0 since 2010.
123
How is Antarctica currently managed?
The Atlantic Treaty System sets out international laws governing Antarctica. Antarctica is a condominium, with some countries (e.g. the UK) claiming parts of the continent, others (e.g. the US and Russia) reserving their right to make a future claim, and others (e.g. China) believing it to be a global commons. Nevertheless, certain factors are agreed under the ATS: military activity is banned and commercial mining is banned until at least 2048 under the Madrid Protocol, with scientific cooperation and environmental preservation encouraged.
124
What is the potential for oil extraction in the Arctic?
There are an estimated 90 billion barrels of oil not yet discovered in the Arctic, making it a very lucrative venture, especially as existing reserves are running out.
However, drilling for oil in the Arctic is dangerous, inaccessible, and expensive, so it is highly dependent on the price of oil. At the moment it is mostly in the exploratory stage, rather than full scale extraction.
The potential increased following the legalisation of oil and gas drilling in the Arctic National Wildlife Refuge in Alaska in 2017
125
What issues are present concerning oil exploitation in the Arctic?
Oil tankers struggle to navigate through fast and pack ice
Climate change has caused permafrost melt, making onland transportation more difficult
Pipelines must be constructed above ground to prevent further permafrost melt
The inaccessible location means leaks are hard to detect and clean up - it often takes days or weeks to respond to a spill
Permafrost makes land very difficult to drill into
126
What are some environmental and social impacts of oil exploration in Alaska?
Oil drilling in the 1002 lands of the ANWR could disrupt caribou breeding
Possibilty of the Alaskan government invoking eminent domain, forcing people to relocate to make way for oil drilling. If applied to indigenous groups, this would disrupt their generations long way of life
Despite the TAPS being constructed to limit environmental impact (with 420 out of 800 miles elevated from the ground and built in a zigzag pattern to resist earthquakes), it has leaked at least 4 times since construction e.g. in 1978 16,000 barrels of oil were leaked
127
What are some benefits of oil exploration in Alaska?
The construction of the TAPS created a boomtown effect in many towns along the pipeline, with house prices increasing by 10x in some towns e.g. Fairbanks
The oil and gas industry accounts for 1/3 of jobs in Alaska and 89% of the state's revenue stream
Oil revenues fund the Permanent Fund Dividend, a yearly payment of $1000-2000 to all Alaskans, and there is no state income or sales tax
128
What was the Exxon Valdez oil spill? What were its consequences?
The 1989 Exxon Valdez oil spill was the splilling of 11 million gallons of crude oil into Alaskan waters after an oil tanker of the same name struck a reef. Hundreds of thousands of animals were killed e.g. seabirds, otters, and seals, and the area is still recovering, with pockets of crude oil still present in some areas. There was significant disruption to the fishing industry as a result. The total economic loss was estimated at $2.8 billion.
129
What management strategies are in place with the Trans-Alaska Pipeline?
420 miles (of 800) are elevated to allow animal migration and prevent permafrost melt
The pipeline has a zigzag shape and can shift, allowing it to resist earthquakes such as the 2002 Denali Earthquake, where the pipeline moved but did not burst
The pipeline has survived wildfires but has leaked on several (at least 4) occasions
Alaska and the owner of the pipeline (the Alyeska Pipeline Service Company) both now have rapid response units to respond to damages to the pipelines, and significant oil spills must be reported to the authorities so they can help with cleanup
130
Where is Easedale?
In the centre of the Lake District, around two miles west of the village of Grasmere. The Lake District is the second largest national park in the UK, found in Cumbria.
131
What landforms can be found in Easedale?
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U-shaped valley/glacial trough
Roche moutonnes
Tarn (Easedale Tarn)
Hummocky moraine
Varves
Hanging valleys - with waterfalles (e.g. Sour Milk Ghyll)
Till
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132
How is hummocky moraine formed?
A debris-covered glacial snout thins as it melts, gradually depositing its material over the land
