Glaciation 1 Flashcards
(106 cards)
1
Q
what is glacial?
A
A period where there is lots of glaciers and cold temperatures
2
Q
what is inter-glacial?
A
Period of less glaciers due to climate warming
3
Q
what is the quaternary?
A
A period of time referencing the last 2.6 million years
4
Q
when was the holocene?
A
last 11-12,000 years
5
Q
what is the epoch?
A
The smallest category of the geological time periods
6
Q
what is an ice sheet?
A
Large mass of ice found on top of land
e.g. Antarctica
7
Q
how much of earth today is covered in ice?
A
10%
8
Q
what was the extent of ice from Britain’s last ice age?
A
Upto 2 miles deep.
Melted about 11,500 years ago
9
Q
are glaciated landscapes open or closed systems?
A
Open systems.
Energy and matter can enter as inputs and leave as outputs
10
Q
what are the stores in a glacier?
A
- Ice
- Water
- Debris accumulation
- Movement of ice due to gravity
11
Q
what are the inputs of a glacier?
A
- potential energy from height/gravity
- kinetic energy from wind
- thermal energy from sun
- precipitation
- deposition, weathering, mass movements, avalanches
12
Q
what are the outputs of a glacier?
A
- Sediment (deposition and erosion)
- calving
- ablation (melting, evaporation, sublimation)
13
Q
what are the energy inputs in a glacier system?
A
- thermal from sun
- gravitational potential energy
- kinetic energy
- geothermal heat energy (at base of glacier)
14
Q
what are energy throughputs/flows in a glacier system?
A
- gravitational energy (ice moves downhill)
- frictional heat energy (ice movement increase ice temp)
- release of latent heat (when meltwater freezes)
15
Q
what are energy stores in a glacier system?
A
gravitational potential energy stored in rocks
16
Q
what is the energy output in a glacier system?
A
when energy leaves the system in the from of heat
17
Q
what are the material inputs in a glacier system?
A
precipitation
snow/rock debris
18
Q
what are the material throughputs in a glacier?
A
Movement of snow, ice, meltwater and rock debris
19
Q
what are the material stores in a glacier system?
A
storage of ice, meltwater, rock debris above, beneath or below the glacier
20
Q
what are the material outputs of a glacier?
A
water vapour
water
ice
rock debris
moved by aeolian processes
21
Q
what are the flows of solar energy throguh the glacial system?
A
Evaporation and sublimation (output).
without this there would be no snowfall
22
Q
what are the flows of variations in solar energy in a glacial system
A
- determines differences in high latitudes vs low latitude glaciers
- greater snow accumulation, therefore more glacier
23
Q
what are the flows of wind energy in a glacial system?
A
Importance in the role of ‘snow blow’ and snow formation at a local scale
24
Q
what are the flows of gravity in a glacial system?
A
Provide potential energy
Determine flow of kinetic energy as ice/rocks flow downhill
25
what are the flows of geothermal energy through a glacial system?
Influence gravitational energy available, causing uplift
Might also provide meltwater at the base of a glacier, encouraging movement
26
what is system feedback in a glacial system?
Characterised by feedback.
If inputs=outputs then the system is at equilibrium, i.e. a glacier stays the same size.
Glaciers are dynamic equilibrium - self regulates
27
what is positive feedback?
A change creates a response in the system, reinforcing the effect of the original change. This amplifies that change, creating a 'snowball effect'.
28
what is negative feedback?
System will self-regulate to re-establish stability through counteracting the change and maintaining equilibrium
29
what is albedo?
The reflectivity of sun's rays on Earth's surfaces.
Water abosrbs more light (low albedo)
Ice absorbs less light (high albedo)
30
what is mass balance?
The glacier constantly adjusts to the changes in the balance between accumulation and ablation
31
what is positive mass balance?
When accumulation is greater than ablation.
Gain of mass.
i.e. in winter
32
what is negative mass balance?
Ablation is greater than accumulation
Loss of ice i.e. in spring
33
what is equilibrium?
Accumulation = ablation
Glacier remains stable.
34
what are the two zones a glacier can be divided into?
Accumulation zone
Ablation zone
Seperated by equilibrium line
35
what is accumulation zone?
Where accumulation exceeds ablation
36
what is ablation zone?
Where ablation exceeds accumulation
37
what are the factors influecning the growth of ice sheets?
- accumulation of snow and ice formation
- climate (cold winter, hot summer)
- further snow (gradually snow turns into ice)
- aspect (direction glacier is facing)
38
what are the factors affecting influecing the decay of ice sheets?
- ablation
- summer temp is higher
- output exceed input
- loss of ice resulting from calving
39
what is sublimation?
When ice changes directly from ice to water vapour without being a liquid
40
what are temporal differences in mass balance?
Change
Short term variations
Long term variations
41
what are shortm term variations in mass balance?
Instant, day, month, year
Mass balance varies throughout year (more accumulation in winter)
42
what are long term variations in mass balance?
100s, 1000s of years
Give detailed infromation about climate change
43
what does glacier analysis show?
The vast majority of European glaciers are receding, with rate of recession accelerating since 1980s
44
what is precipiation levels in high latitude areas?
High pressure areas/bands with low levels of clouds and low precipitation
45
what is precipiation levels in high altitude areas?
Increase in altitude means clouds may condense and result in precipitation
46
what is lithology?
What rocks are made of
47
what are the types of cracks in rocks?
Jointing (stress)
Bedding (water build up in between layers)
Faulting (techtonic movement)
48
what are the climate impacts on glaciers?
Wind
Precipitation
Temperature
49
How does wind affect a glacier?
Can carry erosion, transportation and deposition.
Known as aeolian processes
50
how does precipitation affect glaciers?
If temp rises above 0, there will be increase in ablation and higher outputs.
51
what are joints in rocks due to?
Stress
52
what are faults in rocks due to?
Techtonic movement
53
what is the impact of geology on glaciers?
Lithology refers to physical and chemical composition of rock.
Structure is the properties of individual rocks
54
what is the impact of latitude on glaciers?
- high latitude means cold dry climate, little seasonal variations and large stable ice sheets
- low lat but high alt means variable temp and high precipitation, more dynamic glaciers
55
what is the impact of altitude on glaciers?
- glaciers can be found in high latitudes due to reduction in temp with altitude
- decreases at 6C/km gained
56
how much does temp decrease by with altitude?
6C/km gained
57
what is the impact of relief on glaciers?
Steeper relief means more potential energy (gravity) and glacier will have more energy to move downslope
58
what is the impact of aspect on glaciers?
If slope is facing away from sun, temp might never go above 0C
- less melting
59
what is the snowline?
Where snow starts on a mountain
60
what are ice sheets?
Ice features above 50,000km2
96% of worlds ice held in Greenland and Antartica
61
what are ice caps?
Huge dome shaped masses of ice on high plateaus
62
what is a valley glacier?
Glacier confined by valley sides.
10-30km long
63
what are the types of glaciers?
- ice sheets
- ice caps
- mountain ice caps
- ice field
- valley glacier
- corrie glacier
- piedmont glacier
- ice shelf
64
how is ice made?
Snow traps air when it falls and has low density (0.1g/cm3)
Snow accumulated and starts to compress. Forces air out. ice formation begins
65
how long does it take ofr glacial ice to form in alaska?
5 years
66
how long does it take for glacial ice to from in antarctica?
150-200 years
67
what is polar?
A cold environment, mainly convered in snow
68
what is temperate?
A climate with no extreme temperature
69
what is an example of a cold based glacier?
Meserve Glacier in Antarctica
70
what are characteristics of a cold based glacier?
- high latitude
- low relief
- glacier is frozen to bed (PMP not met so no meltwater)
- move few metres a year
71
how do cold based glaciers move?
Internal deformation:
- intergranular flow
- laminar flow
72
what are the characteristics of warm based glaciers?
- high altitude
- steeper gradient
- basal temp aroud 0C (meet PMP_
- meltwater
- move 2-3 metres a day
73
how do warm based glaciers move?
basal slippage
74
what does basal slippage result in?
Regelation slip
Creep
Glacial surge
75
details of the Meserve Glacier in antarctica?
- 7km long
- basal temp is -17C
- silt rich basal layer
- slow movement
76
what is an example of a warm based glacier?
Athabasca glacier (canada)
77
what are the details of the Athabasca glacier in canada?
- moves 2-3 metres a year
- 6km long
- 90-300m thick
- basal temp at PMP
78
what is intergranular flow?
When individual ice-crystals re-orientate and move in relation to each other
79
what is laminar flow?
The movement of individual ice layers within the glacier. (Between annual accumulation layers)
80
what is regelation slip?
Glacier melts to go over and obstacle, then refreezes on the other side due to pressure
81
what is creep?
If ice encounters a obstacle on the floor, its put under strain, so deforms plastically and flows or creeps around the obstacle
82
what is bed deformation?
When ice is carried by saturated bed sediments moving beneath it. The water is under high pressure, carrying the ice above it
83
what is sheer?
Pressure from above, along with slip
84
what causes crevasses?
- friction between glacier and valley sides and bed
- tensions within the ice when there is a change in gradient
85
what are crevasses?
A deep tensional crack which can form in glacial ice.
Rarely more than 30m deep
86
what are the different types of crevasses?
- marginal
- transverse
- longitudinal
- radial
87
what are marginal crevasses?
Results from friction along valley sides as ice advances
88
what are transverse crevasses?
Extend across the glacer at steepening of gradient.
Common at 'ice falls'
89
what are longitudinal crevasses?
Valley becomes wider and ice surface widens to fill the valley
90
how much does water expand when frozen?
8-9%
91
what is frost shattering?
Water trapped in rock pores will freeze and expand at very low temperatures.
Expansion causes stress which causes rock to disintegrate to small bits
92
what is pressure release?
As melting causes a reduction in weight of overlaying ice, the underlying rock expands.
It fractures parrallel to the surface
These fractures are known as pseudo-bedding planes
93
what is chemical weathering?
Weathering through chemical reactions can produce weak residues of materials from rock which is then easily removed by erosion
94
when is chemical weathering particularly important?
When meltwater is present and in contact with rock
95
what are teh types of chemical weathering?
Oxidation
Solution
Carbonation
Hydration
Hydrolysis
96
what is carbondation?
when carbonic acid reacts with calcium carbonate in rock (limestone) to produce calcium bicarbonate
97
what is oxidation?
Minerals in rocks react with oxygen, either in water or air
98
what is hydrolysis?
Minerals in rock can undergo a chemical reaction when in contact with water.
It's the hydrogen in water that causes this
99
what is solution?
Any process where a mineral dissolved in water is known as solution.
Some become soluble when water is more acidic
100
what is hydration?
When water molecules are added to rock minerals, they create minerals of a larger volume.
Causes flaking of rocks.
101
How likely is biological weathering in glacial areas?
Generally low due to limited plant/animal activity due to low temp
102
What are two types of biological weathering?
Tree roots
Chelation (organic acids)
103
how are tree roots biological weathering?
The roots grow into cracks/joints in the rock, the exert pressure, forcing the rock apart
104
how is chelation biological weathering?
As plant and animal litter decomposes, organic acids are released. It causes soil to become more acidic. Reacts with minerals and breaks rock down
105
what is dynamic equilibrium?
Refers to a state of balance where the system adjusts to chnges in inputs and outputs. It maintains a long term balance but with fluctuations in the short term
106
