Glaciated Landscapes Flashcards

1
Q

What is a glacier’s bed load?

A
  • Sediment dragged along the base of a glacier then deposited over a large area
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2
Q

What is the accumulation zone?

A
  • Net accumulation is greater than net ablation

- Top part of a glacier

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3
Q

What type of system are glaciated landscapes?

A
  • Open system

- Both energy and matter cross the system’s boundaries

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4
Q

Explain what a closed system is.

A
  • A system with inputs and outputs of energy

- No movement of materials across system boundaries.

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5
Q

Name 4 glacial inputs, throughputs and outputs.

A
  • Inputs: precipitation, meltwater, debris, thermal energy
  • Throughputs: snow, ice, debris, meltwater
  • Outputs: water vapour, debris, meltwater, thermal energy
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6
Q

What is a glacial mass balance?

A
  • AKA glacial budget

- Difference between accumulation and ablation over one year

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7
Q

What is the ablation zone?

A
  • Where net ablation is greater than net accumulation

- Lower part of glacier

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8
Q

What is the equilibrium line in terms of a glacier’s mass balance?

A
  • Where accumulation is equal to ablation

- Dynamic and theoretical

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9
Q

How would you calculate the annual budget of a glacier?

A
  • Subtract total ablation from the total accumulation
  • Positive values means net accumulation
  • Negative values means net ablation
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10
Q

What are aeolian processes?

A
  • Erosion, transportation and deposition carried out by wind
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11
Q

How can lithology influence glaciated landscapes?

A
  • Lithology - physical and chemical composition of rocks
  • Rocks with weak lithology (eg clay) have little resistance to erosion
  • Basalt has strong lithology so is resistant and forms prominent landforms
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12
Q

How does structure of rocks affect glaciated landscapes?

A
  • Concerns jointing, bedding, faulting and permeability

- Angle of dips of rocks which can influence valley side profile

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13
Q

How does latitude influence glaciated landscapes?

A
  • At 66.4º N and S - cold, dry climates, little seasonal variation
  • Glaciated landscapes develop through large, stable ice sheets
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14
Q

Define lithology.

A
  • The physical and chemical composition of rocks
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15
Q

How does lithology impact the formation of landforms?

A
  • Weak lithology rocks easily eroded e.g. clay

- Strong lithology rocks rarely eroded e.g. basalt

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16
Q

Define structure.

A
  • Properties of individual rock types including jointing, bedding and faulting
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17
Q

How does structure affect the formation of landforms?

A
  • Some rocks are permeable, like limestone, while granite is impermeable
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18
Q

How does relief affect the formation of landforms?

A
  • Steeper relief causes greater acceleration due to gravity so more erosion
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19
Q

How does aspect affect the formation of landforms?

A
  • If facing away from sun, temperatures remain below zero for longer so less melting occurs and ice forms
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20
Q

What are the components of a system?

A
  • Inputs, throughputs and outputs, stores and flows
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21
Q

What are the flows of energy of a glacial system?

A
  • Kinetic energy in the movement of ice and material
  • Potential energy in the vertical height of material
  • Thermal energy in the absorption of solar energy
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22
Q

How does climate impact a glacial system?

A
  • Inputs of precipitation increase the mass of a glacial system
  • Small inputs restrict growth
  • Large seasonal variation causes large variation in glacial mass
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23
Q

Define latitude.

A
  • Measurement of distance north or south of Equator
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24
Q

How can altitude impact a glacial system?

A
  • Higher inputs
  • More seasonal variation
  • Some glaciers near Equator
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25
Summarise the formation of glacial ice.
- Fresh snow (0.05 g/cm^3) - Firn (0.4 g/cm^3) - one year - Glacier ice (0.83-0.91 g/cm^3) - 30-1000 years
26
How deep is true glacial ice found?
- 100m
27
What is firn?
- Snow that has survived one summer | - AKA neve
28
What is the term for the formation of glacial ice?
- Diagenesis
29
What are the two types of glacier?
- Valley glacier/warm-based | - Ice sheet/cold-based
30
Define an ice sheet and give two named examples.
- Accumulations of ice greater than 50,000km^2 | - Greenland, Antarctica
31
Outline the size of the Antarctica ice sheet.
- Area - 13.6 million km^2 - Volume - 30 million km^3 - Depth - 4700m
32
Outline typical size of a valley glacier.
- 10-30km long | - 1km thick
33
Give four characteristics of valley glaciers.
- High altitude - Steep relief - Basal temps at PMP - Rapid movement - 20-200m per year
34
Give four characteristics of ice sheets.
- High latitude - Low relief - Basal temp below PMP - Slow movement - <10m per year
35
Define pressure melting point (PMP).
- Temperature where ice is about to melt
36
What five factors impact movement of glaciers?
- Gravity - Gradient - Thickness of ice - Internal temperature - Glacial budget
37
What are the two typical zones of glacial ice movement?
- Upper zone - brittle | - Lower zone - deforms
38
What type of glacier moves by basal sliding?
- Warm-based/valley glaciers
39
What is basal sliding?
- Basal temp at PMP - Thin meltwater reduces friction - Ice moves down valley
40
What mechanisms are involved in basal sliding?
- Slippage - Creep - Bed deformation
41
How much movement is basal sliding often responsible for and what is the extreme of this?
- Often 45% | - Extreme - 90%
42
Why is basal sliding rarely seen in cold based glaciers/ice sheets?
- Basal temp too low
43
What are the two components of internal deformation?
- Intergranular flow | - Laminar flow
44
What is inter granular flow?
- Individual crystals re-orientate and align
45
What is laminar flow?
- Movement of layers of ice within glacier
46
What is extending flow and when does it occur?
- Ice moving over steep slope fractures - Ice unable to deform fast enough - Leading ice pulls away from ice behind - Forms crevasses
47
What is compressing flow and when does it occur?
- Gradient of slope decreases - Ice thickens - Flowing ice moves over slower ice - Layers called planes - slip planes
48
What is a glacial surge and what can cause it?
- Rapid movement - 100s meters per day - Steep gradient and large inputs of snow - Tectonic activity
49
Name an example of a glacial surge.
- Disko Island, Greenland | - Moved 10km between 1995-1999
50
What are the three types of weathering?
- Physical - Chemical - Biological
51
Define physical weathering.
- The breakdown of rock into smaller fragments with no chemical alterations
52
Why are some weathering processes not significant in glacial landscapes?
- Temperatures are too low | - They are ineffective
53
What are the three main physical weathering processes in glacial landscapes?
- Freeze-thaw - Frost shattering - Pressure release
54
Outline the process of freeze-thaw.
- Water enters cracks in rock - Expands 9% when freezing - Pressure makes cracks expand - Continued changes causes breaks - More temp changes makes it more effective
55
Outline the process of frost shattering.
- Very low temperatures - Water in rock pores expands - Stress causes disintegration
56
Outline the process of pressure release.
- Weight of overhead ice lost due to melting - Rock under expands and fractures parallel to surface - AKA dialation - Exposes underlying rock
57
Define chemical weathering.
- Chemical reaction between elements in weather and minerals in rocks - It may reduce rock to constituent chemicals or alter composition
58
What are the five main chemical weathering processes?
- Oxidation - Carbonation - Solution - Hydrolysis - Hydration
59
Outline the process of oxidation.
- Minerals eg iron react with oxygen in air/water - Becomes highly acidic - Structure destroyed
60
Outline the process of carbonation.
- Rainwater combines with CO2 in atmosphere forming carbonic acid - Acid reacts with carbon carbonate forming calcium bicarbonate - process is reversible - precipitation forms stalactites and stalagmites
61
Outline the process of solution.
- mineral dissolves in water
62
Outline the process of hydrolysis.
- Chemical reaction between minerals and water to make secondary minerals - e.g. Feldspar in granite reacts with hydrogen to form kaolin (china clay)
63
Outline the process of hydration.
- Water molecules mix with minerals to make larger volume minerals - e.g. Anhydrite forming gypsum