Topic 2- Glaciation

Question 1

How old is the earth?

Answer 1

4.6 billion years old

Question 2

What two states has the planet been fluctuating between?

Answer 2

Greenhouse earth and icehouse earth

Question 3

What is a greenhouse earth?

Answer 3

A greenhouse Earth occurs when there are not continental glaciers on the planet as a result of warming processes such a higher levels of greenhouse gases in the atmosphere. The cause of this warming may be increased volcanic activity.

Question 4

What is an icehouse earth?

Answer 4

A global ice age, when large ice sheets are preset on the Earth. During this time, the climate fluctuates between cooler glacials, when ice advances, and warmer interglacials, when ice retreats.

Question 5

How many glacial periods have there been in the last 1 million years?

Answer 5

Around 10.

Question 6

How many ice ages have their been in the Earth’s history?

Answer 6

There have been 5 in the Earth’s history.

Question 7

What is the most recent ice age on Earth?

Answer 7

The quaternary ice age.

Question 8

When did the quaternary ice age start and how long did/is it go/gone on for?

Answer 8

2.6 million years ago and extends up to the present day.

Question 9

What are the two epochs of the quaternary ice age?

Answer 9

The Pleistocene epoch(lasted approx 11,500-12,000 years ago).
The holocene epoch(began 10,000 years ago and continues to the present day).

Question 10

What is the division of geological time?

Answer 10

Periods(quaternary), epochs(Holocene)

Question 11

What is the last glacial maximum known as, and how long ago did it occur?

Answer 11

The Devensian, approx 18,000 years ago.

Question 12

What is the last glacial maximum known as, and how long ago did it occur?

Answer 12

The Devensian, approx 18,000 years ago.

Question 13

What was the last glacial advance known as, and how long ago did it occur?

Answer 13

The Loch Lomond Stadial, 12,000 and 10,000 years ago.

Question 14

What are the three main characteristics of the pleistocene epoch?

Answer 14

There were many ice advances and retreats over the 2 million years that it lasted; not just a single ice age.

The extent to the ice advance during each glacial was different.

There are fluctuations within each major glacial. These are relatively short-lived pulses of ice advance are known as stadiums, and warmer periods of retreat known as interstadials.

Question 15

What is the difference between a stadial and interstadial?

Answer 15

A stadial is when ice advances as it is cool and an interglacial is when ice retreats because it is warmer.

Question 16

What is the difference between the Devensian and the loch Lomond Stadial?

Answer 16

The Devensian is the last glacial maximum and the the Loch Lomond Stadial was the last glacial advance.

Question 17

What is the primary cause of oscillations between glacial and interglacial conditions?

Answer 17

The long-term changes in the Earth’s orbit around the sun. Milankovitch cycles.

Question 18

What are the three main characteristics of the Earth’s orbit as part of the milankovitch cycles?

Answer 18

The obliquity cycle
The eccentricity cycle
Precession of the equinoxes

Question 19

What is the difference between the obliquity cycle, the eccentricity cycle and the procession of the equinoxes?

Answer 19

The obliquity cycle focuses on the tilt of the Earth’s axis which varies between 21.5˚ and 24.5˚ over 41,000 year cycles and this changes the severity of seasons. However, the eccentricity cycle focuses on the shape of the Earth’s orbit which varies from circular to elliptical over 100,000 year cycles-the Earth will receive less solar radiation during the elliptical orbit(aphelion). Furthermore the procession of the equinoxes is the Earth’s wobble as it spins on its axis, which means that the season during which the Earth is nearest to the sun(perihelion) varies. At the moment the northern hemisphere winter occurs in perihelion, this varies over 21,000 year cycles.

Question 20

What is the difference between the obliquity cycle, the eccentricity cycle and the procession of the equinoxes?

Answer 20

The obliquity cycle focuses on the tilt of the Earth’s axis which varies between 21.5˚ and 24.5˚ over 41,000 year cycles and this changes the severity of seasons. However, the eccentricity cycle focuses on the shape of the Earth’s orbit which varies from circular to elliptical over 100,000 year cycles-the Earth will receive less solar radiation during the elliptical orbit(aphelion). Furthermore the procession of the equinoxes is the Earth’s wobble as it spins on its axis, which means that the season during which the Earth is nearest to the sun(perihelion) varies. At the moment the northern hemisphere winter occurs in perihelion, this varies over 21,000 year cycles.

Question 21

What is the obliquity cycle?

Answer 21

The tilt of the Earth’s axis varies between 21.5˚ and 24.5˚ over 41,000-year cycles. This changes the severity of seasons.

Question 22

What is the eccentricity cycle?

Answer 22

The shape of the Earth’s orbit varies from circular to elliptical and this varies over 100,000-year cycles. The Earth receives less solar radiation in the elliptical orbit when the Earth is farthest from the sun(aphelion).

Question 23

What is the procession of the equinoxes?

Answer 23

The Earth wobbles as it spins on its axis, which means that the season during which the Earth is nearest the sun(perihelion) varies. At present, the northern hemisphere winter occurs in perihelion, i.e. milder conditions than previous winters in aphelion. This varies over approx 21,000 year cycles resulting in changes in the intensity of the seasons.

Question 24

How great of an impact do the orbital variations effect the temperature change of Earth?

Answer 24

Individually, the orbital variations of axil tilt, eccentricity and wobble have a limited. Impact on Earths weather but over a 100,000 year cycle these oscillations combine to cause major temperature changes leading to dramatic variations in global ice volumes.

Question 25

By how much can the impact of orbital changes effect global temperatures?

Answer 25

Combined orbital changes on solar radiation amount and distribution is small, probably only enough to change global temperatures by between 0.5 and 1˚C.

Question 26

What can explain large temperature changes of up to 5˚C?

Answer 26

The large temperature changes of up to 5˚C lead to vast expanses of ice to form, or alternatively melt, climate feedback mechanisms are responsible for this.

Question 27

What are climate feedback systems?

Answer 27

The effects are those that can either amplify a small change and make it larger(positive feedback) or diminish the change and make it smaller(negative feedback). A number of interacting Earth systems are involved.

Question 28

What does a positive feedback system do?

Answer 28

A positive feedback system increases the warming or cooling rates. In terms of cooling it can increase in snow/ice raise surface albedo(reflectivity) so more solar energy is reflected back into space, leading to further cooling, which could lead to further snowfall and ice cover.

The melting of snow/ice cover by carbon dioxide emissions decreases albedo; methane is emitted as permafrost melts, and warming seas lead to calving of ice sheets, which all lead to loss of snow/ice cover and of surface albedo, decreasing reflectivity and accelerating further warming(AMPLIFICATION OF CHANGE).

Question 29

What does a negative feedback system do?

Answer 29

A negative feedback system decrease is the warming or cooling rates. Increasing global warming leads to more evaporation and, overtime, pollution from industrialisation adds to global cloud cover. Increasingly cloudy skies could reflect more solar energy back to space and diminish the effect of warming – so called ‘global warming’ may be less intense because of this global dimming. Ice sheet dynamics can disrupt the thermohaline circulation(THC). Warming water in the Artic disrupts ocean currents; less warm water from the gulf stream is drawn north, which could lead to global cooling in northern Europe.

Question 30

What are the two short-term causes of climate change?

Answer 30

Sunspot activity and volcanic emissions.

Question 31

What are sunspots and how do they cause climate change?

Answer 31

Sunspots are caused by magnetic activity in the Sun’s interior. An increase in the number of sunspots fans that the Sun is more active and giving off more energy, so sunspot numbers indicate levels of solar output, and they vary over an 11-year cycle. The climate has fluctuated during the Holocene epoch, with cooler temperatures occurring between 1300 and 1870, a time known as the Little Ice Age.

Question 32

Give the case study that gives evidence to variations in solar output being responsible for climate change?

Answer 32

Observations of the sun during the latter part of the Little Ice Age(1650-1750) indicate that very little sunspot activity was occurring on the Sun’s surface(period known as Maunder Minimum) and during this time Europe and North America experienced colder than average temperatures.

Question 33

What is the most significant volcanic impact on the climate?

Answer 33

The injection into the atmosphere of large quantities of sulphur dioxide gas, which remains in the atmosphere for as long as three years. Sulphate aerosols are formed, which increase the reflection of radiation from the sun back into space, cooling the Earth’s lower atmosphere.

Question 34

Give the case study that gives evidence to volcanic emissions being responsible for climate change?

Answer 34

In April 1815 the Indonesian Mount Tambora produced one of the most powerful volcanic eruptions in recorded history. Accounts of very cold weather were documented in the year following this eruption in a number of regions across the planet.

Question 35

Why wasn’t ash emitted from volcanic eruptions responsible for solar radiation and therefore climate change?

Answer 35

The ash emitted was cleared within months and therefore could not be constituted as solar radiation blocking.

Question 36

What was the cause of the Loch Lomond Stadial?

Answer 36

The huge proglacial Lake Agassiz was drained which disrupted the Thermohaline Circulation(THC), which cut off the poleward heat transport from the Gulf Stream.

Question 37

What were the characteristics of the Loch Lomond Stadial?

Answer 37

The Loch Lomond Stadial began retreating 18,000 years ago, with rapid deglaciation by 15,000 year ago(late glacial interstadial). However, around 12,500 years ago the temperatures plunged downwards and by 11,500 years ago glacial conditions occurred with temperatures around 6-7˚C lower; many glaciers re-advanced including the formation of the ice caps in the Scottish highlands and cirque glaciers in the lake district and North Wales. Greenland ice core data showed that the temperature change was 7˚C and therefore the milankovitch cycles, sunspot variation and volcanic eruptions are not responsible.

Question 38

What was the cause of the little ice age?

Answer 38

It has not been scientifically agreed upon; however, the short term causes of climate change seem to be responsible for causing the little ice age. These are a lack of sunspot activity and volcanic emissions that saw the temperature change of 1-2˚C.

Question 39

What are some of the characteristics of the little ice age?

Answer 39

The Little Ice Age brought colder winters. Rivers and Canals in the British isles and the Netherlands were often frozen and so deep deep that they would have ice skating competitions on the ice.

Farms and Villages in the Swiss Alps were destroyed as glaciers advanced. The Mer de glace(sea of ice) in France extended to the floor of the Valle de Chamonix.

Iceland’s cereak crops failed, and its people were forced to change from a grain-based diet.

Greenland was largely cut off by ice from 1410 until the 1720’s.

Crop practices across Europe had to change to adapt to a shorter growing season- and there were many years of famine.

Question 40

What is the cryosphere?

Answer 40

The cryosphere consists of ice sheets and glaciers, together with sea ice, lake ice, ground ice(permafrost) and snow cover. Mass and energy are constantly exchanged between the cryosphere and other major components of Earth systems; the hydrosphere, lithosphere, atmosphere and biosphere.

Question 41

Name a visible and sensitive barometer of climate change? and why?

Answer 41

Glaciers,because they constantly grow/advance and shrink/retreat in reponse to changes in temperature and precipitation.

Question 42

Are glaciers the main store within the hydrological cycle?

Answer 42

No, they are no where near the main store but still a store.

Question 43

How do the components of the cryosphere play a role in the Earth’s climate?

Answer 43

Snow and ice reflect heat from the sun- called the albedo affect- which helps to regulate temperatues on Earth. Polar regions are among the most sensitive to temperature change, so the cryosphere is an important focus for climate change.

Question 44

Why is the cryosphere important?

Answer 44

Snow and ice reflect heat from the sun- called the albedo affect- which helps to regulate temperature on Earth.

The cryosphere acts as a store for the global hydrological cycle.

Question 45

What is the cryosphere;s role in global systems?

Answer 45

Mass and energy are exchanged betweened the cryosphere and many other major components of Earth’s systems: hydrosphere, lithosphere, atmopshere and biosphere.

Question 46

Describe the ice mass “ice sheet”, give the average size, give the degree of constraint and give an example?

Answer 46

A mass of ice and snow of considerable thickness.
Average size: 50,000km^2
Degree of constraint: Unconstrained
Example: East antartic ice sheet

Question 47

Describe the ice mass “ice sheet”, give the average size, give the degree of constraint and give an example?

Answer 47

An ice cap is a dome-shaped mass of glacier ice, usually in a highland area.
Average size: 50,000km^2
Degree of constraint: Unconstrained
Example: Northern antartic peninsula.

Question 48

Describe the ice mass “ice field”, give the average size, give the degree of constraint and give an example?

Answer 48

An ice field is similar to ice caps, typically smaller, icefield topography is determined by the shape of the surrounding land.
Average size: 10-10,000km
Degree of constraint:Constrained
Example: Patagonia(Chile)

Question 49

Describe the ice mass “ice field”, give the average size, give the degree of constraint and give an example?

Answer 49

An ice field is similar to ice caps, typically smaller, icefield topography is determined by the shape of the surrounding land.
Average size: 10-10,000km
Degree of constraint:Constrained
Example: Patagonia(Chile)

Question 50

Describe the ice mass “Valley glacier”, give the average size, give the degree of constraint and give an example?

Answer 50

A valley glacier is bounded by the walls of a valley, and descending from high mountains, from ice cap on a plateau, or from an ice sheet.
Average size: 3-15,0000km^2
Degree of constraint: Constrained
Example: Aletshgletscher, longest glacier in the alps.

Question 51

Describe the ice mass “piedmont glacier”, give the average size, give the degree of constraint and give an example?

Answer 51

A piedmont glacier is a glacier that spreads out as a wide lake as it leaves a narrow mountain valley to enter a wide vallye or a plain.
Average size:1-1,000km^2
Degree of constraint: Constrained
Example: Southern Axel Heiberg island(Canadian arctic)

Question 52

Describe the ice mass “Cirque glacier”, give the average size, give the degree of constraint and give an example?

Answer 52

A Cirque glacier is a glacier occupying a cirque(armchair shaped hollow-steep).
Average size:0.5-8km^2
Degree of constraint: Constrained
Example: Teton glacier in Grand tetons national park, Wyoming,USA.

Question 53

Describe the ice mass “ice shelf”, give the average size, give the degree of constraint and give an example?

Answer 53

An ice shelf is a large slab of ice floating ont he sea, but remainin attached to and largely fed by land-derived ice.
Average size: 10-100,000km^2
Degree of constraint: Unconstrained
Example: East Antartica, Princess Elizabeth Land

Question 54

Does a warm based(temperate) glacier occur in high or low altitude?

Answer 54

They occur in high altitude areas outside the polar region(Alps&sub-arctic areas)

Question 55

Does a cold based(polar) glacier occur in high or low latitudes?

Answer 55

A cold based glacier occurs in high latitudes- particularly in Antartica and Greenland.

Question 56

What makes a temperate glacier a temperate glacier and what conditions are put upon it to make and keep it warm-based?

Answer 56

The temperature of the surface layer fluctuates above and below melting point, depending on the season, whereas the temperature of the rest of the ice down to the base is close to melting point. Because of the increased pressure of overlying ice, water exists as a liquid at temperatures below 0˚C, causing the basal ice to melt continiously. The effects of pressure, geothermal energy and percolation of meltwater all contribute to prevent the glacier freezing to its bed.

Question 57

What does a ‘warm-based’ glacier have at its base?

Answer 57

It has lots of debris in its basal layers, and significant subglacial depositional features.

Question 58

What makes a cold-based glacier a polar glacier and what conditions are put upon it to make and keep it cold-based?

Answer 58

The average temperature of the ice is below 0˚C, as a result of the extreme surface temperature(-20˚- -30˚C). The accumulation of heat from geothermal sources is not great enough to raise the temperature a the base of the glacier beyond 0˚C, even though the ice may be up to 500m thick. The glacier is permanently frozen to its bed, so there is no debris rich basal layer.

Question 59

Give one difference between a warm-based and cold-based glacier.

Answer 59

A warm based glacier has basal ice that melts continiously whereas a cold-based glacier is frozen to its bed.

The warm-based glacier has a debris rich bed whereas the cold-based glacier has no debris at its base.

Question 60

What is a hybrid polythermal glacier?

Answer 60

The underneath of the glacier is warm(wet) based and the margin is cold-based.

Many large glaciers are cold based in their upper regions and warm based lower down, when they extend into warmer climate zones.

Question 61

What is a hybrid polythermal glacier?

Answer 61

The underneath of the glacier is warm(wet) based and the margin is cold-based.

Many large glaciers are cold based in their upper regions and warm based lower down, when they extend into warmer climate zones.

Question 62

Give the case study that hybrid polythermal glaciers are common?

Answer 62

Svalbard, Norway.

Question 63

SAM: Explain one approach to classifying ice masses(6 marks)

Answer 63

In warm based glaciers(e.g the Alps which is a higher altitude region outside the polar region), the base is warmer than the melting point of the ice. It’s warmer because of the heat from friction caused by the glacier moving or because of geothermal heat from the Earth. Because of increased pressure of overlying ice, water exists at a liquid at temperatures below 0˚C, cauing the basal ice to melt continiously. The ice at the bottom of the glacier melts, and the meltwater acts as a lubricant, making it easier for the glacier to move downhill. Ice at the surface also melts if the temperature reaches 0˚C, and the meltwater moves down through the glacier, lubricating it even more. Lots of movement means that there will be lots of erosion.

In cold-based glaciers(e.g Antartica and Greenland which are in very high altitudes) the base is so cold that there is very little melting. The ice is frozen to the base of the valley, so there’s very little movement. There’s hardly any melting at the surface either, even in the summer. This means that cold-based glaciers don’t cause very much erosion at all.

In polythermal glaciers(e.g Svalbard, Norway) the underneath is warm(wet) based and the margin is cold-based. Many large glaciers are also cold-based in their upper regions and warm-based lower down, when they need to extend into warmer climate zones.

Question 64

SAM: Explain the role of Milankovitch cycles in causing variations in the relative global ice volume.

Question 64

SAM: Explain the role of Milankovitch cycles in causing variations in the relative global ice volume. (6 marks)

Answer 64

The Milankovitch cycles play an important long-term role in the relative global ice volume. The three individual variations that have a limited impact on the Earth’s weather are: orbital variations of axial tilt, eccentricity, and wobble. However, over a 100,000-year cycle, these oscillations combine to cause major temperature change leading to dramatic variations in global ice volumes which is known as Milankovitch cycles. The impact of combined orbital changes on solar radiation amount and distribution is small, only enough to change global temperatures by between 0.5˚ and 1˚C.

To achieve the larger temperature changes of up to 5˚C that were required for vast expanses of ice to form and then melt we look at the climate feedback system. In the positive feedback, there is an amplification of change in the amount of snow and ice cover because the snow reflects sunlight it leads to further cooling and further snow coverage and repeats. The snow eventually melts due to the release of CO2(which accelerates warming).

Question 65

What are the four main types of cold environment?

Answer 65

Polar (high latitude) regions
Periglacial (tundra) regions
Alpine/mountain (high altitude) regions
Glacial environments

Question 66

Define polar(high latitude) regions

Answer 66

Areas of permanent ice (essentially the vast ice sheets of Antartica and Central Greenland) inside the 66.7˚ latitude of the Arctic and Antarctic circles.

Question 67

Define periglacial(tundra) regions

Answer 67

The ‘edge of permanent ice. These are characterised by permanently frozen ground(permafrost), and include large tracts of northern Canada, Alaska, Scandinavia and Russia. These regions vary between areas that are permanently frozen and those that thaw in summer.

Question 68

Define Apine/mountain (high altitude) regions

Answer 68

For example, the European Alps, Himilayas, northern rockies and andes- where high altitudes result in cold conditions. It’s in these high altitudes that glaciers and glaciated landscapes are found.

Question 69

Define glacial environments areas

Answer 69

Found at the edges of the ice sheets and, in particular, in the highest mountainous regions,e.g, the Himalayas and southern Andes.

Question 70

Describe the global distribution of high latitude(polar) ice sheets (3 marks)

Answer 70

The high latitude polar ice sheets are all located in Northern canada and Northern Russia as well as in the Nordic countries.

Question 71

Describe the global distribution of high altitude(alpine) glaciers. (3 marks)

Answer 71

The high altitude alpine glaciers are located in Canada, South America near Chile, Eastern Europe and Southeast Asia.

Question 72

Compare the present-day distribution of high latitude ice shees and Pleistocene ice sheet extent.

Answer 72

Ice cover at the pleistocene maximum was more than three times greater than the present day.

The Antartica and Greenland ice sheets only covered a slightly greater area than they do today.

The major extensions were two ice sheets in North America (Laurentide and Cordilleran) and the Scandinavian ice sheet in Europe respectively.

Other significant extensions included all of southern South America, South island New Zealand, Siberia and the Himalayas.

Question 73

What are the three different forms of evidence for glaciated landscapes in the UK.

Answer 73

Erosional evidence
Depositional evidence
Meltwater evidence

Question 74

What is the erosional evidence for the glaciated landscapes in the UK?

Answer 74

Found in the Cairnogorms(scotland), Snowdonia(Wales), and the Lake District(England). It includes: corries, aretes and glacial troughs, along with rough moutonees, crag and tail, and knock and lochan landscapes.

Question 75

What is the depositional evidence for relict glaciated landscapes in the UK?

Answer 75

Drumlins(e.g in the Vale of Eden, Cumbria), erratics(e.g the Bowder Stone in the lake district), moraine (in the Cairngorms).

Question 76

What is the meltwater evidence for relict glaciated landscapes in the UK?

Answer 76

Meltwater channels(e.g Newtondale, North Yorkshire), glacial till(e.g the Holderness coast), and eskers(e.g Blakeney, Norfolk).

Question 77

Define permafrost

Answer 77

Permafrost is permanently frozen ground. Soil and rock remains frozen as long as temperatures do not exceed 0˚C in the summer months for at least two consecutive years.

Question 78

What is continuous permafrost?

Answer 78

Continuous permafrost forms in the coldest areas of the world where mean annual air temperatures are below -6˚C. It can extend downwards for hundreds of meters.

Question 79

What is the difference between continuous and discontinuous permafrost?

Answer 79

Discontinuous permafrost is more fragmented and thinner than continuous permafrost.

Question 80

What is the active layer in relation to permafrost?

Answer 80

The top layer of soil in permafrost environments that thaws during summer and freezes during winter. This layer varies from a few centimeters to as deep as 3m.

Question 81

Describe the distribution of permafrost in the Northern Hemisphere.

Answer 81

Continuous permafrost is situated in very high latitudes at around 70˚ latitudes in Greenland and the most northern parts of Russia.

Discontinuous permafrost is situated in quite high latitudes around 60˚ latitude in North America and some more southern parts of Russia in comparison to continuous permafrost.

Sporadic permafrost is found at 50˚ latitude and is more common than any other type of permafrost. It can be found in southern parts of Greenland, central Russia middle of north America in states such as Denver.

Question 82

What is the main factor that affects the distribution and character of permafrost?

Answer 82

Climate is the main control, as temperature and the amount of moisture available determine the presence or absence, depth, and extent of permafrost.

Question 83

What are the 5 factors excluding climate that influences the distribution and character of permafrost on a local scale?

Answer 83

1. Proximity to water(e.g lakes)
2. Slope orientation
3. Character of the ground surface
4. Vegetation cover
5. Snow cover