Glaciation Flashcards
(99 cards)
1
Q
What are the two short term climatic events?
A
Loch Lomond Stadial (11,500 yrs ago) (glacial temp = 6-7 drop) (drainage of proglacial lake = lake agassiz)
Little Ice Age (1550-1750) (curling = nat sport scotland and abandonment of upland farms, river and nyc harbour froze!!)
2
Q
What are the long term factors leading to climatic change?
A
Milankovitch Cycles
3
Q
What are the short term factors leading to climate change?
A
- Solar forcing
2. Volcanic eruptions
4
Q
How much sulfur dioxide was released from Tambora 1815?
A
200 million tonnes
5
Q
What are the ice masses I gotta know?
A
- Valley glacier
- Cirque glacier
- Ice Sheet
- Ice fields
6
Q
What are the factors affecting distribution of ice cover?
A
- Latitude (sun’s rays hit ground at lower angle etc…)
2. Altitude - ELR
7
Q
Periglacial conditions: now VS Pleistocene?
A
Now = 20% Pleistocene = 33%
8
Q
How much of Earth experiences permafrost conditions?
A
25%
9
Q
Factors affecting permafrost?
A
- Amount of moisture avalible
- Slope of angle orientation
- Vegetation prescence
10
Q
What are the four periglacial processes?
A
- Contraction and cracking of rapidly freezing soils = ice wedges, and frost heaving = patterned ground
- Migration of the sub-surface water to the freezing front by suction = segregated ice = ice lens = pingos
- 9% expansion of water on freezing = block fields and screes
- Mass movement of the active layer downslope = lobes and terraces
11
Q
What are the three periglacial landforms?
A
Patterned ground
Ice Wedge Polygons
Pingos
12
Q
Examples of the three periglacial landforms?
A
Patterned ground = Banks on the River Till
Ice Wedges Polygons = Tinto Hills
Pingos = Vale of Llanberis
13
Q
What occurs during Freeze Thaw Weathering?
A
- Summer = meltwater = erosion of river and stream channels
2. Winter = deposition = braided channels
14
Q
What are the inputs of the glacial system?
A
- Energy from the sun
- evaporates water
- form precipitation
- air masses
- snowfall = INPUT - Masses
- energy due to elevated position
- e.g. debris/snowfall
- energy used up as glacier moves, melts, or warms
15
Q
Glaciers currently in retreat, case studies?
A
- Around 95% of Himalayan glaciers = rapid retreat
- On Eastern slopes of Rocky Mountains, all of the glaciers have lost between 25% and 75% of all their mass since 1850!!
16
Q
What is the Khumbu glacier retreat?
A
5km since 1953!
17
Q
What is the Antarctic ice loss?
A
250 billion tonnes a year! :O
18
Q
What is the positive feedback loop of ice which is causing further melting?
A
- Less ice
- Loss of reflectivity (white)
- More dark surfaces exposed
- More heat absorption
- Further warming of the Earth
19
Q
What rivers rely on meltwater from Himalayas?
A
Ganges
Mekong
Yangtze
20
Q
Global warming on hydrological cycle?
A
Loss of supply of meltwater (mainly in early spring and summer)
Huge implications for populations of China & India
High demands of water for development as emerging superpowers - for industry & development & people’s quality of life
21
Q
Management of the glaciated areas?
A
- Do nothing
- Business as usual
- Sustainable exploitation
- Sustainable management
- Total protection
22
Q
Glaciated landscape - human threats?
A
- Industry
- Tourism
- Construction
23
Q
Visitors in Antarctica?
A
2012 = 34,000 2018 = 42,000
24
Q
3 What is sustainable exploitation?
A
- Development for profit
2. Mandatory insistence on env. regulations
25
4 What is sustainable management?
1. Resources for benefit of community
2. Without destroying environment
3. Conserving resources for future gen's
26
1 What is 'do nothing'?
1. Total exploitation
| 2. Supported by TNC's, developers, industrialists
27
2 What is 'business as usual'?
1. Leaving an area as it stands
| 2. May include pre-exisiting sustainability/ regulations
28
5 What is 'total protection'?
1. Complete conservation of environment
| 2. Environmentalists, researchers, locals
29
What is ANWR?
Artic National Wildlife Refuge
30
What did Trump do in ANWR?
In 2017, he passed the provision of opening up the 1002 area of the ANWR for oil and gas drilling
31
CNN Alaskan oil division?
59% support it
| 39% oppose it
32
Homes of Arctic tribes? (ANWR)
Inuit ppl
33
ANWR stakeholders/players? support
SUPPORT:
1. National government
2. Major oil companies
3. Local people/local government (jobs, incomes)
34
Oil in ANWR?
Estimate of 10.4 billion barrels of oil!
35
ANWR stakeholders/players? against
AGAINST:
1. Local/ national/ international pressure groups
2. Native people
3. Environmentalists
36
2 types of legislative frameworks to 'protect and conserve glaciated landscapes'?
1. International
- 1959 ATS treaty (effective = 1961)
- continent of peace and science
- 54 parties
- 12 signatories
- four separate international agreements formed by ATS: inc CCAS and CCAMLR
- Arctic issue: surrounded by 2 superpowers = USA & Russia
- 4 million people live in Arctic
- not just ice, ice and tundra !
- Arctic Council (8 members) - 1996
- only 15% of arctic is protected
- ISSUE OF ARCTIC COUNCIL:
+ 'peace and security issues were left out of it's mandate'
+ climate change and melting of sea ice = water ways and energy resources are more accessible e.g. USA, Alaska, 1002 area
+ territorial disputes =
+ EEZ issue e.g. Russia and USA, Bering Strait and Chukchi Seas
+ NOW: some suggest peace and security issues should be brought to agenda
2. National
- ANWR
- 1960
- many animal species like caribou, bears, snow geese
- ranngeee of stakeholders here e.g. major oil companies, tourists, locals, governments
37
ANTARCTIC AGREEMENT NAMES?
1. CCAS
Convention for the Conservation of Antarctic Seals
2. CCAMLR
Convention for the Conservation of Antarctic Marine Living Resources
38
Examples of global systems for conservation?
1 INDIVIDUAL SPECIES
- CITES
- 1973
- many Arctic species e.g. polar bear, walrus
- issue of ppl not sticking to this, e.g. Japan whaling
```
2 IUCN (international union for the conservation of nature)
- 'Red List' = endangered species = polar bears
```
3 UNESCO, WORLD HERITAGE SITES
- Wrangel Island (arctic), 2004 = 23 endemic species
39
What is the issue of global systems for conservation?
1. Without real n strong enforcement
2. Growing economic demands > oil etc... moving away from conservation
3. Increasing nationalistic view and world on self serving motives e.g. Japan - withdrawals from global systems...
40
What is climate warming amplified by?
Positive feedback!
1. More dark surfaces
2. Melting of permafrost
41
Futures of glaciated landscapes?
1. Water insecurity will increase for some (Asia)
2. Losses in carbon store from permafrost, peat etc...
3. Predicted sea level rise of 0.5-0.75m by end of 21st century
4. Complex changes in food webs
42
What mitigation do we need for climate warming?
LOCAL, NAT AND INTERNATIONAAAL COOPERATION BABYYYYY
1. Local = planning, recycling, transport
2. National = energy, transport, taxation
3. International = strategies e.g. COP21 Paris 2015, Kyoto 1997
43
Factors affecting rate of glacial ice movement?
Ashley Tisdale Grinds Little Shit
1. Altitude
- high altitudes = higher potential energy = increase glacial movement
2. Temp of ice
- warm based = quicker (equlibrium shit) and ALTITUDE!
3. Gradient
- steeper = encourages quicker movement = move gravity = larger downslope force = pulls from bedrock and moves
4. Lithiology
- more easily eroded rock = deformations = slow down ice movement
5. Size of glacier
- rapidity of response
- large glacier = slow movement = needs a larger downslope force to move
44
Glacial movement?
Shear stress > resisting forces
Weight of snow and ice exerts downslope force due to gravity
Glacier pulls from bed rock and moves
45
What does speed of glacier depend on?
Degree of imbalance/gradient btwn zones of acc and ab
46
Types of glacial deposition?
```
FLAD
FLOW
LODGEMENT
ABRASION
DEFORMATION
```
47
Glacial entrainment?
SUPRAGLACIAL (valley glaciers)
SUBGLACIAL (mainly ice sheets)
ENGLACIAL (valley glaciers)
48
Factors affecting glacial erosion?
Tamara Taylor Licks Shit
1. Thickness of ice
- thicker ice
- more pressure exerted on bedrock
- more likely to tear away
- thicker ice = more erosion
2. Thermal regime
- warm based = debris and meltwater (facilitates erosional processes)
- warm based = more erosion
3. Lithiology
- softer rock = eroded more easily
- harder rock = eroded less easily
4. Speed of glacier
- faster = erodes more = high velocity = high energy = high erosive potential!
49
Types of glacial erosion?
ABRASION
PLUCKING
DILATION
MELTWATER EROSION
50
Abrasion?
Scraping or wearing away of individual clasts which leads to microfeatures e.g. striations.
The rock flour also polishes the underlying bedrock by sandpaper actioooon
51
Glacial trough?
A steep sided flat floored straight valley
52
What is hanging valley resulted from?
Differential rates of erosion
| - main valley glacier erodes fast
53
Things to enlarge corrie?
1. Nivation
2. Positive feedback
3. Plucking and abrasion = overdeepening
54
What can be left after a glacier melts from a corrie?
A tarn (lake)
55
Glacial depositional landforms?
1. Erratics
2. Moraine
- medial
- lateral
- recessional
- terminal
3. Drumlin
56
Longer term causes of climate change?
Milankovitch Cycles, 1920's
1. Eccentricity
- elliptical to more circular and back again: 100,000 years
- amount of radiation recieved by sun
2. Axial tilt
- 21.8 to 24.4
- now 23.5
- over 41,000 years
- changes intensity of sunlight @ poles, seasonality of earth's climate
- bigger tilt: bigger diff between summer and winter
3. Precession/wobble
- changes point in year where earth is closest to the sun
- over 21,000 period
- WHEN diff seasons occur
57
Negative feedback?
^ evap
^ global cloudy skies
^ inc pollution from industrialisation adds to cloud cover
^ global dimming
^ reflect solar energy back to space = white
^ cooling
58
Why does warm water in Arctic disrupt THC?
- less warm water drawn north to arctic
| - cooling in northern europe
59
Maunder Minimum?
1645-1715
| longer period w no sunspot activity
60
Tambora ejection?
200 mil tonnes of sulphur dioxide
61
What does cyrosphere consist of?
Lake ice, sea ice, ground ice (permafrost), glaciers, ice shets, snow cover
62
Ice masses I gotta know?
1. Ice sheets
- large masses of glacial ice that cover entire landscapes
- antarctica: 14 mil sqkm2!
2. Valley glaciers
- confined btwn valley walls and terminating in a narrow tongue
- e.g. Athabasca, Canada
- 3-1500km2
- from ice cap/sheet or cirque
3. Cirque glaciers
- occupying hollow, corrie on mountain side
- e.g. Hodges South Georgia
- 0.5-8 sqkm2
4. Ice field
- large area of interconnected glaciers
- colder climates
- higher altitudes
- moutaneous region
- patagonia icefield (chile & argentina)
- less than 50,000sqkm2
63
WARM BASED GLACIERS?
1. TEMP OF SURFACE LAYER MOVES ABOVE AND BELOW FREEZING
2. INCREASED PRESSURE = WATER = LIQUID BELOW 0 DEGREES
3. BASAL ICE MELTING CONTINOUS = @ PMP
Why isn't glacier frozen to bed? Due to effects of:
1. Percolation
2. Geothermal energy
3. Pressure
64
COLD BASED GLACIERS?
1. EXTREME SURFACE TEMP = -20 TO -30
2. LITTLE SURFACE MELT = LITTLE MELTWATER PERCOLATES DOWN
3. FROZEN TO BED
65
Glacial ice coverage?
10% of Earth's land area
| 85% in Antarctica
66
Periglacial: before and after?
Pleistocene: 33%
Now: 20%
67
Factors affecting distribution of ice cover?
1 LAT
- suns rays hit ground @ lower angle = heat a larger area = a lot of ice coverage = sun cannot physically heat a larger area
2 ALT
- ELR
- rate of atmospheric temp decreasing with altitude at a given time and location
- colder at high alts = little solar energy = ice cover high = no heating :(
68
Ice cover: Pleisto V now?
Ice cover was X3 greater in Pleistocene than present day!!!!
69
Periglacial characteristics?
1. Low precip = under 600mm a year
2. Intense frosts in winter and on any snow free ground in summer
3. Temp below -10 for at least 6 months and below 0 for at least 9 months
4. Temp's rarely rise above 18dc, even in summer!
70
Periglacial processes to create upland landforms?
1. Mass movement of active layer downslope
- ice creep
- solifluction
- lobes and terraces
2. Freeze thaw weathering
- block fields and screes
- perfect temp = -4 to -15
3. 'Contraction and cracking of rapidly freezing soils'
- ice wedges
- and frost heave: patterned ground
71
Freeze thaw weathering temp?
Perfect = -4 to -15
72
Types of permafrost?
1. Continous
- hundreds of metres
- air temps of -6
2. Discontinous
- more fragmented and thinner
3. Sporadic
- few m deep
- air temps = freezing
73
Active Layer?
Top layer of soil in permafrost *** environments that melts during summer and freezes during winter
74
Periglacial
Areas of freezing and thawing
75
Why are periglacial landscapes more vulnerable to climate change?
1. melting of permafrost
2. no glaciated are: albedo
3. both are: positive feedback loops
76
Permafrost temp increase?
Every 1 degree temp rise, there could be a 1.5 million sq mile of permafrost loss through thawing
77
Factors affecting permafrost?
1. temp and amount of moisture avalible: degree, depth, prescence
2. slope of angle orientation: amount of radiation: continous vs discontinous = dis = more radiation
78
What is nivation?
Occurs when both weathering AND erosion takes place around and below a snowpatch
- w and e
79
What to remember about Sandurs?
Biggest material deposited first
80
Blockfields?
Acc of angular frost shattered matieral
- flat plateau surfaces
- frost heaving of joint bedrock and ftw
81
Tor?
Free standing rock outcrop
82
Screes?
When rock fragments fall & acc on base/lower slopes of cliffs
BASE OR LOWER SLOPES !!!!!!
83
Glacial ice formation?
1. Accumulation of permanent snowfield
2. Compacted
3. Granular (0.1gcm of density)
4. Compressed
5. Neve/firn
6. Density increases: PIM and refreezing of water into gaps
7. Deeper layers of firn transported into glacial ice (0.9gcm of density)
8. Outwards or downwards by extrusion flow
84
What is glacial ice?
Primarily compacted snow, with other contributions from precip e.g sleet/hail
85
Neve/firn?
Crystalline or granular snow where it hasn't been compressed to ice
86
Mass Balance?
Gains or losses of the ice store of the glacial system
87
Eskers: ice contact fluvioglacial
Sinous ridges of sand and gravel deposited by meltwater flowing thro tunnels
Obstruction of subglacial/englacial tunnel causes fluvioglacial matieral to be deposited upstream
Blakeney Esker, Norfolk
88
Processes of water movement?
1. Supra
2. En
3. Sub
89
Cyrosphere?
Parts of Earth's surface subject to temps below 0 degrees for at least part of each year
90
Solifluction?
Gradual movement of soil saturated with meltwater downslope over a permanently frozen ground in tundra regions
91
Example of block fields?
On the summit of Derry Cairngorm
92
Freeze thaw weathering for dummies?
FEEM
1. Water into crack
2. Freezes
3. Ice expands > enlargening crack
4. Ice melts
5. More water comes in and same thing happens!
6. Continues to happen until rock breaks
93
Pingo diameter?
100-500m
94
Regimes in the summer?
Negative regime
- more ablation than accumulation
- glacier shrinks and snout retreats
95
Regimes in the winter?
Positive
- few days above 0 degree
- more acc than ab
- glacier grows and snout advances
96
Health of glacier?
1. Altimetry
- surface elevation> thickening thinning expanding shrinking
2. Gravimetry
- gravt attraction = changes in mass
3. Mass budget method
- compares snowberg ice calving density with snow acc
97
Benchmark glacier?
A designated glacier in which it's accumulation and ablation rates are measured annually used standardized techniques to monitor impacts of CC
e. g. Sperry --> Montana
e. g. Gulkana --> Alaska
98
Cause of ice movement?
Gravity
- weight of snow and ice cause an increased downslope force due to gravity
- then sheer stress over comes the resistive forces, glacier pulls from bedrock and moves
99
Speed of glacier depends on?
1. Degree of imbalance or gradient between zone of accumulation and ablation
