Ice On The Land Flashcards
Environmental impacts of unreliable snowfall
40% less snow in the areas under 1000m above sea level over the last 50 years - led to greater pressure on high-altitude ski slopes, which are environmentally sensitive areas ( fragile alpine environments)
The chemical additives used in snow-making affect the natural vegetation
Why does deposition by glaciers occur?
When the ice carrying the material melts, the material is left behind on the valley floor
It also occurs when the glacier has reached its carrying capacity
How are drumlins formed?
A drumlin is an egg-shaped hill made from boulder clay (till). They usually occur together as a swarm
When the competence of the glacier is low, this encourages deposition of sediments
The melting glacier meets small obstacles which are enough to encourage deposition of boulder clay from the ice at the side of the obstacle, facing up-valley. This forms the stoss end
As the glacier continues to move, the boulder clay at the bottom of the glacier is moulded into shape around the obstacle. This forms the lee end.
Over time, the drumlin is re-shaped by further ice movements
What is subglacial moraine?
Material carried along the base of the glacier
What was the extent of maximum ice cover in the northern hemisphere during Pleistocene?
Around 20,000 years ago 30% of the Earth’s land surface was covered by ice
70m km3 of ice over North America, Europe and Asia
How are drumlins formed?
The competence of the glacier is low because it is filled with sediment which encourages deposition of sediment. Melting glaciers meet small obstacles and deposits boulder clay, creating the stoss end because ice deposits more sediment when facing up valley.
The glacier continues to move and the boulder clay moulded into shape around the obstacle, creating the lee end.
Some facts about the Athabasca glacier
6km long, 6km2 area, one of the most visited glaciers in the world because of its proximity to a major highway (Icefields Parkway)
What is the glacial budget?
It is the balance between accumulation and ablation in a glacier. Its determines whether the glacier will advance or retreat.
What are interglacial periods and how long do they last?
Warmer periods when the ice retreats to cover less of the Earth’s surface. Each one lasts around 10,000 years
Where are rates of abrasion highest?
Where there is a large amount of debris in the glacier
Where the ice is thick so there is more pressure
Where the rock debris is more resistant than the bedrock
What is the name given to the formation of glaciers?
Glaciation
What is an ice age, when was the last ice age called and when was it?
Ice ages are cold periods that last for millions of years when large masses of ice cover parts of the Earth’s surface Pleistocene that began around 2.6m years ago
What are adaption strategies in fragile environments?
Maintain ski tourism - artificial snow, develop on higher terrain, change slope design
Subsidies - annual or single government contributions.
Alternatives to ski tourism - non-snow related winter activities, all year tourism
Fatalism - carry on as usual or cancel ski tourism.
Economic impacts of glacial retreat
Lower ski resorts shutting down
Once a glacier has completely retreated, the amount of meltwater decreases - the industries that rely on the supply of meltwater e.g. agriculture for irrigation and HEP for electricity production, will make less money and could shut down
What are glacial periods and how long do they last?
Cooler periods when the ice advances to cover more of the Earth’s surface. Each one lasts about 100,000 years
Negative environmental impacts of Chamonix tourism
Large number of tourists cause a lot of traffic which increases pollution - a study from 2002 to 2004 showed that traffic pollution was worse in the Chamonix region than in the centre of Paris
Mountain footpath erosion
Farm animal gates left open - harm to animals
Litter can end up in the glacier - glass bottles are a safety hazard
A huge amount of energy is used to run the facilities for tourists e.g. the hotels, ski lifts and snow-making machines - increases CO2 emissions, which increases global warming
What is a glacier?
A glacier is a long standing mass of ice that moves very slowly downhill.
Economic impacts of unreliable snowfall
Making artificial snow, 15% of French ski resorts are covered by snow canons - in some resorts, making snow consumes more power than running ski lifts
If skiing is the main attraction, when there is too little snow it can be unsafe or not possible to ski. If there is too much snow, slopes are unstable increasing the possibility of an avalanche - both reduce tourists numbers
What is a long term glacial budget change?
Climate change (Ice ages, glacial and interglacial periods, etc.)
Positive social impacts of Chamonix tourism
Improvement in transport and health care
Job availability
Locals supplied with good facilities and activities
Clean, safe pedestrianised streets
Social impacts of glacial retreat
The Alps is the source of three main rivers of Europe; the Rhine, the Rhone and the Po. Glacial retreat will lead to unreliable freshwater supply to the region
Distributions to power supplies from HEP could leave some people with an unreliable power
If businesses shut down, local people will have to move away to find work
If an area’s population declines, local services and recreational facilities will also shut down
The ice will no longer be available for local people e.g. for trekking and ice climbing
Give some examples of natural causes of global temperature change.
The albedo effect means the whiteness of the surface of the earth. The white surface is (i.e. the more ice)The more sheet is reflected. The more the ice melts, the dark seawater will absorb heat instead causing the temperature to rise. Volcanic winter caused by Yellowstone volcano means ash will blackout the sun and cause global cooling.
Long term avalanche responses
Rules are stricter Skiers made to wear Avalanche transceiver Instructors warn skiers Rescue is free More equipment
Chamonix winter attractions
Skiing, snowboarding Mountain climbing Ice skating Sledging Spas Access to slopes via cog railways or cable cars Museums 60,000 tourists
What are fragile environments?
Environments that are easily unbalanced and damaged by natural or human factors. Alpine environments are fragile environments and need careful, sustainable management
Name some factors that affect the movement of a glacier.
Slope, snowfall and meltwater at the base of the glacier.
Environmental impacts of glacial retreat
Increase in natural hazards - rapid melting can cause flooding, rockslides and avalanches. These hazards destroy habitats and disrupt food chains
Meltwater from retreating glaciers contributes to rising sea level which destroys coastal habitats by causing flooding and erosion
Lots of fish species are adapted to live in cold meltwater that comes from glaciers - when the glaciers have completely melted, there’s no cold meltwater so these fish species may die out
Harmful pollutants can be trapped in glacial ice e.g. the pesticide DDT that was used from the 1940s to 1980s - rapid melting releases them into the environment, polluting streams and lakes
What is scree?
Material that has been deposited, weathered or eroded. Deposits of angular rock fragments found at the foot of rocky features. Scree itself is not a landform.
What is a positive and negative budget?
If accumulation is larger than ablation this is a positive budget. This means the glacier will advance. This usually happens in winter or glacial periods. If ablation is greater than a accumulation, this is a negative budget and the glacier will retreat. This usually happens in summer or interglacial periods.
Explain how glaciers form
A glacier is a system with inputs (accumulation) and outputs (ablation).
The snow falls and becomes compacting, releasing air, turning firn into ice crystals.
The ice crystals become denser and become clearer glacial ice
Avalanches can also be a source of accumulation when they release snow
Ablation happens mostly at the snout of the glacier where the ice melts because it’s warmer
Calving is when ice breaks off at the snout
Another output is by evaporation or sublimation
Why does Chamonix need management? (environmental reasons)
Accumulation of fresh snow has halved in the past 40 years - Mer de Glace has lost 65m in depth and 300m in length in the last 20 years
15% of French ski areas are covered by snow canons to preserve summer skiing - noise and visual pollution + cooling agent Snomax is added which can pollute the local environment
Cigarette litter - toxins contaminate water
Hotels have an inefficient use of energy - large carbon footprint and surrounding hillside is eroded as more hotels are built
High use of private vehicles, difficult to arrive by rail as no direct service from closest airport - source of 80% of carbon emissions in Chamonix
The Alps is the source of three main rivers of Europe: the Rhine, the Rhone and the Po - Glacial retreat will lead to unreliable fresh water supply in the region (social)
Global warming leads to melting of the permafrost, increasing the risk of landslides
Negative environmental effects of avalanches
Trees uprooted
Biodiversity disrupted
Positive economic impacts of Chamonix tourism
Local employment - 2500 people work as seasonal workers every year in the tourism industry
Helps local businesses - Compagnie du Mont Blanc is a company that runs ski lifts and rail transport
Good for local economy
Where are rates of plucking highest?
Where the bedrock is well-jointed
Where there are large amounts o meltwater
Where the ice is thick so there is more friction
When was the last glacial period?
It began around 100,000 years ago and ended around 10,000 years ago
What is bulldozing?
When the ice pushes loose material in front of it
Explain how a corrie forms
A Corrie is an armchair shaped hollow with a steepened back wall.
Snow accumulates in a hollow and compacts into ice over thousands of years.
The glacial ice starts to flow downhill in a rotational slip, causing abrasion and the steepening of the back wall as the process of plucking rips the rock off.
Freeze-thaw weathering on the back wall adds more rock material to the glacier causing further abrasion at the base of the hollow, deepening it.
Where the gradient is less, erosion occurs less, forming a rock lip near the end of the glacier
When the glacial period has passed, and the corrie is left,a tarn can form in the hollow, which is a small lake.
What is the fossil evidence for changing global temperatures?
The remains of some organisms are preserved when they die, creating fossils.
Fossils show the distribution of plants and animals that are adapted to warm or cold climates at different times in the past - from this we can tell which areas were warmer or colder in the past
