Glaciated Landscapes and Change Flashcards
(79 cards)
1
Q
What do periglacial processes include?
A
- Nivation, frost heave, freeze thaw weathering, solifluction, high winds, meltwater erosion
2
Q
What are 4 unique periglacial landforms?
A
- Ice wedges 2. Patterned ground 3. Pingos 4. Loess
3
Q
What are the three processes of accumulation?
A
- Direct snowfall 2. Avalanches 3. Wind depostion
4
Q
What are the five processes of ablation?
A
- Melting 2. Sublimation 3. Calving 4. Evaporation 5. Avalanches
5
Q
What are the three different processes that are important in the movement of glaciers?
A
- Basal slip 2. Regelation creep 3. Internal deformation
6
Q
What are 5 factors that affect the rate of movement in glaciation?
A
- Altitude 2. Slope angle/gradient 3. Ice thickness 4. Bedrock permeability 5. Variations in mass balance (ice temp, rates of ablation and precip)
7
Q
How and when were ice ages discovered?
A
In 1830s by Louis Agassiz in the Swiss Alps. Identified that they had occurred all over Europe, saw that certain areas had similar features
8
Q
What is the theory of Uniformitarianism?
A
The assumption that the same natural laws and processes that operate in our present day scientific observations have always operated in the universe in the past and apply everywhere in the universe
9
Q
What does glacial and interglacial periods mean?
A
Glacial - period of intense cold
Interglacial - period between glacial periods
10
Q
How have ice cores helped determine past climates?
A
Bubbles trapped in the ice contain CO2 from the atmosphere
11
Q
What epoch are we currently living in?
A
Quaternary epoch
12
Q
What are epochs?
A
Periods of geological time. These relate to times of the past where geological strata were laid down. Epochs denote changes such as mass extinctions
13
Q
What three epochs is the quaternary period divided into and explain them
A
- Pleistocene - covers the beginning of the quaternary period, this is the age we will study in detail 2. Holocene - interglacial period of man 3. Anthropocene - begins from when there was significant human impact on Earth until now, including such things as biodiversity loss and climate change
14
Q
Does the Pleistocene epoch have multiple glacial and interglacial periods?
A
Yes, causes the landscape to remould and reshape each time, this makes it complex to reconstruct the past
15
Q
How many years roughly is there a new glacial or interglacial period?
A
Every 100,000 years
16
Q
Give another way glacial landscapes can be modified other than other glacial periods
A
Geomorphological processes
17
Q
What are stadials and interstadials?
A
Stadials - smaller fluctuations and shorter periods of intense cold
Interstadials - shorter periods of relative warmth
Recent ice core analysis show these to be sometimes quite abrupt changes
18
Q
Give the 5 types of glacial erosion
A
- Quarrying 2. Plucking 3. Abrasion 4. Crushing 5. Basal melting. These all combine with subaerial freeze thaw and mass movement
19
Q
Give the 7 upland erosional features
A
- Cirques/corries 2. Aretes 3. Pyramidal peaks 4. Glacial troughs 5. Truncated spurs 6. Hanging valleys 7. Ribbon lakes
20
Q
Give the 4 landforms due to ice sheet scouring
A
- Roches moutonnees 2. Whalebacks 3. Knock and lochan 4. Crag and tail
21
Q
What is the pleistocene?
A
Covers the beginning of the quaternary period, glacial epoch. around 2,588,000 to about 11,700 years ago
22
Q
What is precession?
A
A gradual change, or wobble, in the orientation of Earth’s axis affects the relationship between Earth’s tilt and eccentricity
23
Q
When did the quaternary period start?
A
2.588 million years ago!!!!!!!! wow
24
Q
How many years of climate can ice cores track back to?
A
800,000 years
25
What is the first milankovitch cycle theory and how often does this happen?
Eccentricity of orbit - happens every 100,000 years
26
How often does axial tilt happen?
41,000 years
27
How often does precession happen?
Every 21,000/22,000 years
28
Spell the volcano in Iceland that sir wants you to spell for some reason
Eyjafjallajokull
29
What are the three reasons for glacial deposition?
1. When the velocity is reduced 2. They become overloaded with debris 3. When ablation increases
30
What are the six ice contact depositional features?
1. Erratics 2. Medial moraines 3. Lateral moraines 4. Recessional moraines 5. Terminal moraines 6. Drumlins
31
What are the two types of till plains (lowland depositional features)?
1. Lodgement till 2. Ablation till
32
Explain the eccentricity of orbit as a primary cause of climate change. 4 points
1. Elliptical earth orbital cycle to circular every 100,000 years 2. Amount of solar radiation received in high eccentricity orbit varies greatly, increase in magnitude of seasonal changes 3. Low eccentricity leads to low seasonality - promotes glaciation 4. As a result, temps at high latitudes in northern hemisphere increase
33
Explain obliquity as a primary cause of climate change. 5 points
1. Axial tilt varies from 21.8 degrees to 24.4 degrees, currently at 23.5 , 2. 41,000 year timescale 3. Impacts intensity of light received at poles - seasonality of Earth 4. Less tilt=warmer winters but cooler summers - glaciers do not melt in summer - advance, low obliquity=low seasonality 5. Glaciers will reflect more of incoming solar radiation further cooling planet
34
Give four different characteristics of glacial and fluvioglacial deposits
1. Stratification 2. Sorting 3. Imbrication 4. Grading
35
Give three formations of fluvio-glacial ice contact features
1. Kames 2. Eskers 3. Kame terraces
36
Give four fluvio-glacial proglacial features
1. Sandurs 2. Pro-glacial lengths 3. Meltwater channels 4. Kettleholes
37
Explain precession as a primary cause of climate change in 5 points
1. The earth wobbles on its axis changing the point in time the earth is nearest the sun (21,000/22,000 year cycle) 2. Means that the North Pole points both towards and away from the sun increasing the variation in the irradiation of the Northern Hemisphere 3. Causes variation in summer and winter temperatures and so causes variations in ice volume 4. Precession (tilt direction) works in conjunction with eccentricity to control the level of insolation at 65 degrees north 5. Glaciation is favoured when the direction of the tilt is such that N.hemisphere summers are at the largest earth-sun distance
38
How much do the Milankovitch cycles affect the temperature by?
1 to 1.5 degrees
39
How many degrees change does there need to be for ice to form?
5 degrees
40
Give an example of positive feedback
Small increases to snow and ice cover can raise surface albedo (the quantity of reflection of sunlight) - more solar radiation is reflected back into space - could lead to more snow and ice cover
41
Give two examples of negative feedback
1. Increases global warming and industry leads to more evaporation which increases cloud cover - increased cloud cover reflects solar energy back into space - reducing the intensity of global warming 2. Ice sheet dynamics disrupt thermal heating circulation - warming waters in the Arctic disrupts ocean currents - less warm water from the gulf stream creating global cooling in N.Europe
42
Explain solar forcing in 4 points
1. Energy emitted by the sun varies due to sunspots. Cycling every 11 years, date back to 400yrs
2. 1645 to 1715 - Maunder Minimum
3. 950 to 1250 - Medieval Warm Period
4. Seen as contributing to 20% of global warming in 20th Century
43
Explain volcanic causes as a short term fluctuation for climate change in 4 points
1. Many past examples where volcanoes alter temp
2. VEI 7+ volcanoes eject huge amounts of Sulphure Dioxide, CO2 and water vapour into atmosphere
3. These block out sunlight
4. 1815 - Tambora in Indonesia caused temps to drop by 0.4 to 0.7 for 2-3 years
44
Explain the Loch Lomond Stadial in 6 points
1. When Lake District formed, occured 11,700BP to 12,900 BP
2. Ice sheets began to melt at 18,000BP
3. Rapid deglaciation 15,000BP ago. Similar temps to today
4. 12,500 BP glacial conditions reoccurred and by 11,500BP temps were 6-7 degrees lower than today
5. Glaciers readvanced all over the world including Scotland, Lake District and Snowdonia
6. Reason: Believed to be due to the draining of Lake Agassiz into Atlantic disrupting THC by cutting poleward heat from the gulf stream
45
Explain the Little Ice Age in 7 points
1. Proxy records tell us that between 1350 to 1900 there was a trough of cold temperatures having many impacts
2. Abandonment of many hill farms in Northern Europe
3. Glaciers advanced down valleys
4. Arctic sea ice spread further south with Polar Bears found in Iceland
5. Rivers froze in the UK, lowland Europe and New York
6. Curling developed as a sport in Scotland
7. Never developed into a full stadial due to Industrial Revolution
46
Why are glaciers a visible barometer of climate change?
They constantly shrink/retreat and grow/advance in response to changes in temperature
47
What is the cryosphere?
Part of the earth's crust and atmosphere subject to temperatures below 0 degrees celcius for some part of the year.
48
What are the two distinct roles of the cryosphere?
1. It helps to regulate climate via the albedo effect
2. It is also a global store of freshwater
49
What is an ice sheet?
A layer of ice covering an extensive tract of land for a long period of time
50
What is an ice cap?
Miniature ice sheets, form primarily in polar and sub-polar regions that are relatively flat and high in elevation
51
What is a valley glacier?
Glacier confined by valley walls
52
What is a cirque glacier?
Are named for the bowl-like hollows they occupy, which are called cirques
53
What are unconstrained glaciers?
Tend to be larger forms such as ice sheets and ice caps. These are thick and extensive and often submerge the landscape
54
What are constrained glaciers?
Those that have a physical limit such as valley glaciers where the landscape constrains where they are and tend to only drain one way
55
What is a warm based glacier in 6 points?
1. Temperate or wet glaciers occur at high altitude areas outside of polar regions
2. Temperatures fluctuate on the surface to above and below freezing
3. The rest below the surface is close to melting point because the pressure builds up
4. Because of this water exists as a liquid at temperatures below 0 degrees
5. Having liquid at the bottom causes them to melt continually
6. The ice also has lots of debris at the bottom and this creates many subglacial deposits and landforms
56
Describe cold-based glaciers in 4 points
1. Polar glaciers where average temperature is often below 0 degrees with surface temperatures of -20 to -30 degrees 2. The temperature at the base is still below freezing even though the ice could be 500m thick 3. Limited surface melt during the polar summer and so the glacier is permanently frozen to the bed 4. The basal layer therefore has far less debris within it
57
What is pressure melting point?
The temperature at which ice begins to melt under a given amount of pressure
58
Describe past and present ice distribution
1. Glacial ice covers over 10% of the earth's land surface 2. It accounts for 75% of all freshwater stores 3. 1.8% of all water on planet
59
Where are places glaciers can be found?
85% of all glacier ice is contained within the Antarctica Ice. The rest is distributed amongst ice caps all over the world; Iceland, Canada, USA, Himalayas, Andes, Alps
60
What are the two most important factors governing where ice is found?
Latitude - For polar ice caps
Altitude - For Alpine glaciers
61
Why does the solar energy received at high latitudes have to heat a larger area?
The sun's rays hit at a lower angle
62
How does increasing altitude impact temperature via the Environmental Lapse Rate?
Increasing altitude means decreasing temperature - approximately by 1% for every 100m
63
What is the Environmental Lapse Rate?
The rate at which temperature decreases with altitude at a given time
64
What does aspect determine in a glacier?
The amount of snow that settles
65
What two factors combine to affect where corries form?
Relief and aspect
66
Why do north and east slopes have a better ability to hold snow?
More sheltered and receive less sun
67
Describe the past ice cover in the pleistocene
Ice cover was around 3 times what it is today. The Antarctica and Greenland ice sheets only covered a slightly greater amount than they do today. The major extensions of ice could be found in North America, Scandinavia - both of these grew to a thickness of 3000-4000m and transformed the landscape.
68
Where is the Mer De Glace?
French glacier located on the Mont-Blanc massif
69
What are the size and threats of the Mer De Glace?
Covers an area of 30km squared, and reaches a thickness of 300m - it is the largest glacier in France. Climate change is causing rapid thawing of the glacier - each year it shortens by 30 to 40m and loses 4 to 5m of thickness downstream. Since 1850, it has withdrawn by 2km and scientists predict another 1.2km retreat by 2040
70
What is the importance and impact of the Mer De Glace?
Plays a crucial role in regulating hydrologic flows and global climate. Contribute to rising sea levels - if glaciers were to disappear, the consequences would be disastrous for biodiversity - including humans
71
What are the rights of nature for the Mer De Glace?
Despite current vulnerability, glaciologists estimates that it has favourable odds of survival if we manage to mitigate global warming. By adhering to climate commitments, the glacier could retain up to 70% of its current volume by the end of the century. However, without action, it may lose over 90% of its volume
72
What is the ecosystem impact of the Mer De Glace?
The glacier's balance affects the entire surrounding alpine ecosystem
73
Where does accumulation occur?
At the top of a glacier
74
Where does ablation occur?
At the snout of a glacier
75
What is the zone of equilibrium in glaciers?
A balance between accumulation and ablation
76
What factors affect the movement of the zone of equilibrium?
The rates of accumulation or ablation. The time of year/season. A glacier will retreat when ablation>accumulation. A glacier will advance accumulation>ablation
77
What are the 4 processes of accumulation?
Snowfall, avalanches, windblown snow (snow blowing onto glacier) and hoar frost (formation of ice crystals)
78
What are the 4 processes of ablation?
Snow being blown off glacier (windblown snow), avalanches (snow falling of glacier), sublimation, and calving
79
Give four points as to why understanding the glacial system is important
1. Allows us to understand any changes in rates of accumulation or ablation 2. Help explain why glaciers are retreating or advancing 3. Can show us how the changing zone of equilibrium can be impacted upon by changes to the climate 4. Helps to understand both seasonal, annual and long term changes in glacier movements
