Cold Environments

POLAR

In Winter, temperatures often drop to -50 degrees celsius. Despite these snowy conditions they are often very dry with low amounts of precipitation. There are also large areas of sea ice, which is a layer of permanent ice on the sea. Antarctica, Greenland, Spitzbergen

ALPINE

Mountainous areas that experience very cold winters with heavy snow. Due to the high altitude the temperature can drop to -10 degrees celsius. However, in the summer the temperature can even exceed 20 degrees celsius. Alps, Rockies, Himalayas

PERIGLACIAL

At the edge of a glacier. These areas experience permanent permafrost. During their brief warm summers the ground surface layer thaws enabling plants to grow. Parts of Siberia

GLACIAL

Specifically associated with glaciers. The heavy winter snowfall provides the ice to feed the glaciers. Then in summer meltwater lubricates the glaciers. Mer de Glace, France

INPUTS - Snow, Sleet, Avalanches -> TRANSFERS - Moving ice

STORES - As glacier ice -> OUTPUTS - Melting ice, calving, direct evaporation

Zone of Accumulation - The upper part of the glacier where mass is added

Zone of Ablation - The lower part of the glacier where mass is lost

Zone of Equilibrium - The area where mass added is equal to mass lost

Net Glacial Balance - The overall mass lost or gained by a glacier

Positive mass balance - In Winter, there is more accumulation than ablation. Mass is added so glacier advances

Negative mass balance - In Summer, there is more ablation than accumulation. Mass is lost so glacier retreats

The glacier balance year - There is a zero net balance if the positive balance and the negative balance are equal.

The glacier system - It is an equilbrium if the accumulation wedge balances the ablation wedge

Niche Glacier - Small patches of glacier ice found on upland slopes. Mainly found on north facing slopes in the northern hemisphere. Very little effect on topography

Cirque Glacier - Small masses on mountain slopes which gradually erode armchair shaped hollows. If they become too large they spill over the lip to feed a valley glacier

Valley Glacier - Larger masses that flow from icefields or a cirque. Often follow preglacial river valleys, developing steep sides as they erode their course.

Piedmont Glacier - Large lobes of ice formed when glaciers spread out. They may merge on reaching lowland lands

Ice Caps - Huge flattened, dome shaped masses of ice that develop on high plateaus. Less than 50,000km2 in area

Ice Sheets - Huge flattened, dome shaped masses of ice that develop on high plateaus. Greater than 50,000km2 in area. Only ones on Earth are two in Antarctica and one in Greenland

Ice Shelves - Extensions of ice sheets that reach out over the sea. Can be up to 1000m thick.

Warm based glaciers - Where water is present throughout the ice mass

Cold based glaciers - Where ice is frozen to the bedrock

Internal Flow

This occurs when ice crystals orienate themsleves in the direction of the glacier's movement and slide past each other. As surface ice moves faster, crevasses develop. Internal flow is the main feature of the flow of polar glaciers as, without the presence of meltwater, they tend to be frozen to their beds

Basal slippage

When the base of the ice reaches pressure melting point the ice melts. This leaves a thin layer of water between the ice and bedrock, thus allowing the ice to slide down the hill as frictional drag is reduced

Regelation slip

On the `upglacier' side of the obstacle, pressures in the ice build up sufficiently to cause pressure-melting locally. The water thus formed trickles around and over the obstacle, where it refreezes in the normal pressure conditions on the `downglacier' side of the obstacle. If the ice temperature is below the melting point, this process cannot operate. This only tends to operate on obstacles less than 1m in length

Creep

Occurs where there is little or no regelation slip. Plastic deformation that occurs within ice when its course is impeded by larger obstacles. These obstacles increase stress in the ice and cause it to become plastic in behaviour so it creeps or flows around an obstacle

Extensional Flow

This is the extension and related thinning of the ice in zones where velocity increases. Velocity increases near the ELA as down valley ice is constantly pulling away or where the slopes steepen

Compressional Flow

This is the type of flow where velocity decreases and a glacier increases in thickness. Velocity decreases below the equilibrium line as ice from the upper valley pushes against down valley ice, where the gradient is less

Surges

Extremely fast movements of ice up to 300m a day caused by excessive meltwater in subglacial resevoirs where snowfall is exceptionally high and the glacier reacts quickly

• Steepness of the slope - There is more kinetic energy so it speeds up the movement
• Permeability of the surface - The more rainwater that can soak into the surface, the more likely it will move
• Temperature - The warmer it is the more likely glacial slippage will occur
• Thickness of the ice - There is more pressure so more water at the bedrock, so slippage is more likely to occur
• Amount of meltwater - There will be less friction so will move much faster
• Proximity to equilibrium line - Extensional flow occurs so the closer it is to the equilibrium line the faster it will go
• Amount of precipitation - The rain could freeze and give it mass speeding it up

Weathering - The breakdown of rocks in situ which produces finer particles that can then be moved by agents of erosion such as wind and running water

Freeze thaw/Frost shattering - Occurs when water enters exposed cracks during the day, which then freezes at night. This expands creating pressure on the surrounding rock. Repeated freezing and thawings widens the cracks and causes the rock to break off.

Erosion - The wearing away of land

Transportation - Substances being moved from one place to another

Deposition - When substances are dropped

Abrasion - Angular material is embedded in the glacier as it rubs against the valley sides and floor gradually wearing it away. The scratching action may leave striations as well as smooth gently sloping landscapes

Plucking

This occurs where the glacier freezes onto rock outcrops after which ice pulls away masses of rock. As the pressure melting point causes ice to melt upstream of an obstacle and refreeze downstream material is more easily attached to the main ice flow and removed. It is likely that previously loosened material is removed. Plucking generally creates a jagged landscape

Rotational movement

As with rotational slumping in landslides, this is a downhill movement of ice pivoting around a central point of rotation. This process is most effective where temperatures flunctuate around 0 degrees celsius allowing frequent freeze thaw to operate and in areas of jointed rocks

Armchair shaped hollow that has steep sides and a deep hollow which holds a tarn - Cwm Cau, Snowdonia. Average height/depth - 100 -> 400m

• Snow falls and collects in a hollow high up on the mountainside
• Freeze thaw around the hollow causes the surrounding rocks to disintegrate. This debris is then washed away when the snow melts so the hollow becomes bigger
• As more snow falls and collects in the hollow it gets compressed and becomes glacial ice. Abrasion and plucking gradually makes the hollow even bigger
• Gravity causes the ice to move in a circular motion and is known as rotational slip. This can then cause the ice to pull away from the backwall creating a crevasse
• Plucked debris from the backwall causes further erosion through abrasion which deepens the cirque
• Some of this debris is deposited at the edge of the cirque, building up the lip
• These processes create a rounded armchair shaped hollow with a steep backwall
• After the ice has gone, a circular lake is often formed at the bottom of the hollow, known as a tarn

Arete - A sharp, narrow, often pinnacled ridge, formed as a result of glacial erosion from both sides - Nevado Jirishanca, Peru

Pyramidal peak - A steep sided pyramid shaped peak, formed as a result of the backward erosion of cirque glaciers on three or more sides - Matterhorn

A glaciated valley often characterised by steep sides and a flat bottom, resulting primarily from erosion by strongly channelled ice, average length 1 -> 50km - Valley of Lauterbrunmen

• Ice occupies a former river valley
• The ice removes the interlocking spurs of the former river valley, via processes of abrasion and plucking at the base especially and bulldozing as the material is pushed out of the way
• Thus, the valley widened and deepened but the latter to varying extents due to the prescense of extensional and compressional flow

Truncated spur - Former spur eroded away in its lower part by the power of a valley glacier

Roche Moutonnee - A rocky hillock with a gently inclined smooth up valley facing slope, resulting from glacial abrasion and a steep rough down valley facing slope resulting from glacial plucking

A tributary valley whose mouth ends abruptly part way up the side of the main valley, as a result of the greater amount of glacial down cutting of the latter. Average height 10 -> 15m - Mitre Peak, New Zealand 

During a glacial period ice fills valleys previously occupied by rivers. The main valley glacier is the largest glacier causing large amounts of erosion subsequently deepening the valley considerably. Tributary valleys will host smaller glaciers which erode to a smaller extent. As a result post glaciation a hanging valley is left as the main valley has been eroded to a greater depth than the tributary valley

Misfit Stream - A small stream flowing at the base of a glacial trough. The stream is too small to have created the valley

Ribbon Lake - A long narrow lake filling the base of a glacial trough. These form where compressional flow took place and over deepened the valley due to the extra erosion taking place - Lake Windermere, Lake District

Glacial Till - Unsorted sediment such as Clay, Silt, Sand, Gravel

Moraine - A landform created when material carried by a glacier is deposited

• Glacial sediment is created by plucking and abrasion
• The ice carries material from further up the valley and brings it down to the snout
• As the glacier begins to slow at the lower margin, thrusting occurs and much of the moraine is pushed through the ice and deposited at the snout
• If the glacier stands still a ridge will form
• Sometimes this material overlies a core of ice that makes the ridge stand sharply up from the landscape. Over time this can collapse and form a much less delineated feature
• The moraine ridge can be held together by subsequent vegetation growth

Lateral Moraine - Debris deposited along the side of a glacier, comprising both rockfall debris from above and debris ground up by ice marginal processes, Vadret du Tschierva, Switzerland

Medial Moraine - Distinct ridge of debris occuring on the surface of a glacier where two streams of ice merge, Koskawulsh Glacier, Canada

Terminal Moraine - A prominent ridge of glacial debris formed when a glacier reached its maximum limit during a sustained advance, Cordillera Hughhuash, Peru

Recessional Moraine - Ridge of debris representing a stationery phase during otherwise general retreat, Steigletscher, Switzerland

Push Moraine - A complex landform ranging from a few metres to tens of metres in height comprising assorted debris that has been pushed up by a glacier during an advance, Thompson Glacier, Canada

Ground Moraine - Collection of glacial till deposited below the glacier

Asymmetrical elongated mounds of glacial deposits, gives a 'basket of eggs' topography, longer than wide, steeper stoss side, 50 -> 60m high, 25 -> 600m wide, 800 -> 1500m long

• The most widly accepted view is that the ice became overloaded with material, reducing its capacity (ability to carry material)
• The reduced competence may be due to the melting of ice or reduction in velocity
• Once the material is deposited it is then moulded and streamlined by later ice movement, similarly to the fomation of a roche mountonee without a plucked face

OR

• Alternative ideas suggest that they are subglacially deformed masses of pre existing sediment to which more sediment may be added by the melting out of debris (Evans)

Fluvioglacial - River like process and features associated with glaciers

How did meltwater move through a glacier? 

• Supra-glacially
• En-glacially
• Sub-glacially
• Marginally

Moulin - The point where the surface water enters the glacier

Meltwater discharge - Amount of water passing through a given point at any time

Glacial Deposits

• Unstratified - Difficult to identify layers
• Unsorted - Random sorting as the ice melts and deposits material regardless of size
• Material is angular - From physical weathering and erosion and various shapes and sizes

Fluvioglacial Deposits

• Stratified - Vertical layering due to seasonal variations in sediment accumulation
• Sorted - Larger rocks and boulders are deposited first as the meltwater loses energy
• Material is smooth and rounded - Due to attrition it is sorted and graded

Rounded mounds of ill sorted materials as they collapse when the supporting ice melts. Kame Terraces are better sorted material formed by meltwater streams flowing along the edge of the glacier where it meets the valley wall - Max width 50m, height up to 5m

There is the suggestion that hollows on the surface of a melting glacier would fill up with sediment and then gradually go down to lower levels as the ice melted - ultimately forming a mound on the ground surface, these collapse when the ice melts

Kame Terraces are formed when a gap between the valley side and the ice margin is filled with glaciofluvial deposits, leaving behind a terrace when the ice melts

Kettle hole - An enclosed depression on a landscape. It can fill with water to form a kettle hole lake

Formed when a glacier is melting and a piece of ice is isolated from the rest of the glacier. It is buried by outwash debris. It subsequently melts and the resulting subsidence causes a small hollow in the outwash plain - Diameter 5m -> 100m, depth 1m -> 5m

Outwash plains - Areas that may have been glaciated by ice sheets and then affected by meltwater or they may be areas in front of the snout

Formed when the material it is carrying is deposited - the largest particles first often forming an alluval fan at the end of the glacier. When a number of these merge an outwash plain is formed. Length 5km -> 80km, depth 1m -> 75m

Esker - Winding/sinious ridges of often coarse sands and gravels that are deposited by meltwater as it flowed in a channel beneath the glacier. They run parallel to the glacier and are composed of sorted sands that are subrounded to rounded due to water erosion

Flow is under pressure and the streams can carry a lot of material. This is dropped when the meltwater reduces in winter and exposed when the glacier melts. Length 5m -> 20m for small and up to 400km for large (Munro Esker, Canada)

Meltwater channel - The original course followed by a river before glaciation may be blocked by ice or as an overflow from a proglacial lake. The large amounts of meltwater had a lot of energy to erode and carve out deep gorges, that today are occupied by streams too small to have created the valleys they flow in

Braided streams - Seasonal variation in meltwater discharge lead to flunctuations in the sediment load. Excess material is deposited during times of lower discharge and may obstruct flow

Varves - Glaciolacustrine sediments that are deposited annually. Alternating layers of sediment deposited in a proglacial lake. Coarser, lighter coloured sediment is deposited in late spring and summer when the meltwater has more energy, whereas finer darker sediment is deposited in winter

Proglacial lakes - Bodies of water that develop next to or in front of glaciers

Periglacial - Near to or at the fringe of an ice sheet, where frost and snow have an impact on the environment

Permafrost - Permanently frozen ground, it occurs where soil temperatures remain below 0 degrees celsius for at least two consecutive summers

Continuous Permafrost - Found mainly within the Arctic Circle where the mean annual temperature is below -5 degrees celsius. Here winter temperatures may fall to -50 degrees celsius and summers are too cold to allow anything but a superficial melting of the ground

Discontinous Permafrost - Found further south in the northern hemisphere, and corresponds to those areas with a mean annual temperature of betwen -1 and 5 degrees celsius

Sporadic Permafrost - Found where mean annual temperatures are just below freezing point and summers are several degrees above 0

Active layer - Formed when summer temperatures rise above freezing point for the surface layer to thaw

Talik - The unfrozen layer beneath the permafrost

Frost heave - Occurs when water freezes in the soil, pushes the surface upwards and churns it. Ice lensing refers to the growth of ice crystals in the soil

Solifluction - Means flowing soil. In winter, water freezes in the soil causing it to expand and seperate into individual soil particles. In spring the ice melts and water flows downhill. It can't infiltrate into the soil because of the impermeable permafrost. As it moves over the permafrost it carries segregated soil particles and deposits them further downslope

Nivation - Freeze thaw weathering under a snow bank. The broken material is removed in spring and summer by the melted snow

Cambering - The process whereby segments of rock are dislodged from the main body of rock and begin to move downhill

Series of polygons together, boundaries marked by small piles of gravel, formed through frost heave when they're forced to the surface

The thermal conductivity of stones is greater than soil so the area under a stone becomes colder. Further expansion by the ice widens the capillaries forcing the stones to rise until they reach the surface. The stones move down the hill because of gravity

Ice wedges - An ice wedge is a crack in the ground formed by a narrow or thin piece of ice that measures up to 3–4 metres in length at ground level and extends downwards into the ground up to long meters meters. During the winter months, the water in the ground freezes and expands

• Occurs mainly between north and east facing slopes beneath patches of snow in hollows of bare rock. 
• It is frost action affecting the land beneath a blanket of snow
• Freeze thaw causes the underlying rocks to disintegrate
• During the spring thaw the weathered particles are moved downslope which may be a step in cirque formation

• During summer the ground thaws releasing a lot of meltwater
• Due to the permafrost this water cannot percolate downwards
• The water saturates the soil, reducing internal friction between particles
• A lack of vegetation to fix the soil means the soil begins to flow
• Where vegetation is sparse, stones heaved to the surface are pushed to the front of a lobe

Mound of sediment up to 500m in diameter, 50m high

• Freezing of water in the upper layer of soil where permafrost is thin or discontinuous leads to the expansion of ice within soil
• This causes overlying sediments to heave upwards into a dome

The Tundra - One of the most northerly ecosystems covering a huge amount of land. Winters are long and cold with temperatures being as low as -25 degrees celsius. It is fragile because there is a short growing season so no time for plants to recover and decay is slow due to temperatures so pollution is broken down very slowly

Vuntut Gwitchen

• Indigenous population of 7500 found in northern Canada
• Originally Nomads
• 300 in Old Crow
• Hunt Caribou with spears, they are sustainable because they use up the whole animal so there is no waste and they don't use any finite sources

Trans-Alaskan Pipeline

• 800 mile pipeline taking oil from Prudhoe Bay to Valdez
• Goes over 3 mountain ranges and 3 earthquake zones
• Zig zag pattern allows the pipe to contract rather than break
• 420 miles is above ground so won't melt permafrost
• 550 animal crossings to allow caribou to migrate naturally

Tourism

• Landscape, traditional cultures, winter activities, fishing --> can cause footpath erosion, littering, pollution, conflict

Race for Arctic Oil

• Oil under Arctic seabed, countries nearest to it arguing over their claim to it
• Could cause oil spills

The Antarctic covers an area larger than Europe but has no permanent residents. It is almost completely covered by ice fields and is surrounded by ice shelves, layers of ice floating on the sea water that are fed by the flow of ice off the continent

Fishing and Whaling - No commercial sealing has been carried out since the 1950s. Whaling used to be very common, before it started there were over 275,000 blue whales in the world, but this decreased to 1000. Since a ban was introduced in 1960 there are now 5000 so the species is recovering

Mining - There has never been any mining, and mineral extraction would be very expensive and dangerous anyway. Coal, Iron ore, Chromium and gas has been found but is hard to source

Climate change - Temperatures in the Antarctic Peninsula have risen by 3 degrees celsius in the past 50 years, and the Larsen Ice Shelf broke apart in 2002

Only 100 tourists at any one location per day are allowed and new specialist clothes must be worn to prevent the spread of foreign diseases so the local area isn't pressurised as much

Antarctic Treaty

Signed in 1961, list of 14 articles to protect Antarctica. Some points are that no military action allowed, no ownership of the land and complete freedom of scientific investigation

Marine Protection Areas

The CCAMLR protect the water area and meet annually to set the framework for the conservation of the area. This is achieved by having no fishing activities or garbage disposal. It also includes important foraging areas for the Adelie penguins