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GEOGRAPHY A LEVEL REVISION - LVI > Glaciated Landscapes > Flashcards

Glaciated Landscapes Flashcards

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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
Q

Summarise the formation of glacial ice.

A
  • 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
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26
Q

How deep is true glacial ice found?

A
  • 100m
27
Q

What is firn?

A
  • Snow that has survived one summer

- AKA neve

28
Q

What is the term for the formation of glacial ice?

A
  • Diagenesis
29
Q

What are the two types of glacier?

A
  • Valley glacier/warm-based

- Ice sheet/cold-based

30
Q

Define an ice sheet and give two named examples.

A
  • Accumulations of ice greater than 50,000km^2

- Greenland, Antarctica

31
Q

Outline the size of the Antarctica ice sheet.

A
  • Area - 13.6 million km^2
  • Volume - 30 million km^3
  • Depth - 4700m
32
Q

Outline typical size of a valley glacier.

A
  • 10-30km long

- 1km thick

33
Q

Give four characteristics of valley glaciers.

A
  • High altitude
  • Steep relief
  • Basal temps at PMP
  • Rapid movement - 20-200m per year
34
Q

Give four characteristics of ice sheets.

A
  • High latitude
  • Low relief
  • Basal temp below PMP
  • Slow movement - <10m per year
35
Q

Define pressure melting point (PMP).

A
  • Temperature where ice is about to melt
36
Q

What five factors impact movement of glaciers?

A
  • Gravity
  • Gradient
  • Thickness of ice
  • Internal temperature
  • Glacial budget
37
Q

What are the two typical zones of glacial ice movement?

A
  • Upper zone - brittle

- Lower zone - deforms

38
Q

What type of glacier moves by basal sliding?

A
  • Warm-based/valley glaciers
39
Q

What is basal sliding?

A
  • Basal temp at PMP
  • Thin meltwater reduces friction
  • Ice moves down valley
40
Q

What mechanisms are involved in basal sliding?

A
  • Slippage
  • Creep
  • Bed deformation
41
Q

How much movement is basal sliding often responsible for and what is the extreme of this?

A
  • Often 45%

- Extreme - 90%

42
Q

Why is basal sliding rarely seen in cold based glaciers/ice sheets?

A
  • Basal temp too low
43
Q

What are the two components of internal deformation?

A
  • Intergranular flow

- Laminar flow

44
Q

What is inter granular flow?

A
  • Individual crystals re-orientate and align
45
Q

What is laminar flow?

A
  • Movement of layers of ice within glacier
46
Q

What is extending flow and when does it occur?

A
  • Ice moving over steep slope fractures
  • Ice unable to deform fast enough
  • Leading ice pulls away from ice behind
  • Forms crevasses
47
Q

What is compressing flow and when does it occur?

A
  • Gradient of slope decreases
  • Ice thickens
  • Flowing ice moves over slower ice
  • Layers called planes - slip planes
48
Q

What is a glacial surge and what can cause it?

A
  • Rapid movement - 100s meters per day
  • Steep gradient and large inputs of snow
  • Tectonic activity
49
Q

Name an example of a glacial surge.

A
  • Disko Island, Greenland

- Moved 10km between 1995-1999

50
Q

What are the three types of weathering?

A
  • Physical
  • Chemical
  • Biological
51
Q

Define physical weathering.

A
  • The breakdown of rock into smaller fragments with no chemical alterations
52
Q

Why are some weathering processes not significant in glacial landscapes?

A
  • Temperatures are too low

- They are ineffective

53
Q

What are the three main physical weathering processes in glacial landscapes?

A
  • Freeze-thaw
  • Frost shattering
  • Pressure release
54
Q

Outline the process of freeze-thaw.

A
  • 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
Q

Outline the process of frost shattering.

A
  • Very low temperatures
  • Water in rock pores expands
  • Stress causes disintegration
56
Q

Outline the process of pressure release.

A
  • Weight of overhead ice lost due to melting
  • Rock under expands and fractures parallel to surface
  • AKA dialation
  • Exposes underlying rock
57
Q

Define chemical weathering.

A
  • Chemical reaction between elements in weather and minerals in rocks
  • It may reduce rock to constituent chemicals or alter composition
58
Q

What are the five main chemical weathering processes?

A
  • Oxidation
  • Carbonation
  • Solution
  • Hydrolysis
  • Hydration
59
Q

Outline the process of oxidation.

A
  • Minerals eg iron react with oxygen in air/water
  • Becomes highly acidic
  • Structure destroyed
60
Q

Outline the process of carbonation.

A
  • 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
Q

Outline the process of solution.

A
  • mineral dissolves in water
62
Q

Outline the process of hydrolysis.

A
  • Chemical reaction between minerals and water to make secondary minerals
  • e.g. Feldspar in granite reacts with hydrogen to form kaolin (china clay)
63
Q

Outline the process of hydration.

A
  • Water molecules mix with minerals to make larger volume minerals
  • e.g. Anhydrite forming gypsum

GEOGRAPHY A LEVEL REVISION - LVI (23 decks)

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