Topic 2 - EQ1 - Glaciation (Mr W)

Question 1

What state has the earth been in for 90% of its existence?

Answer 1

Greenhouse state (no ice on earth whatsoever)

Question 2

How old is the Earth?

Answer 2

4.5 billion years old

Question 3

What state is the earth currently in?

Answer 3

It’s icehouse state (we have ice on earth)

Question 4

What happens in the icehouse state?

Answer 4

The climate fluctuates between cooler glacial periods of ice advance and warmer interglacial periods of ice retreat (we are in the warmer interglacial period)

Question 5

What was the name of the last glacial period?

Answer 5

Pleistocene epoch (it lasted until approx. 11,500 years ago)

Question 6

What is the name of the current epoch we are in?

Answer 6

The Holocene epoch (interglacial epoch which began approx. 10,000 years ago)

Question 7

What was the Devensian?

Answer 7

The last glacial maximum which occurred approx. 18,000 years ago

Question 8

What are stadials?

Answer 8

Relatively short lived pulses of ice

Question 9

What was the Loch Lomond Stadial?

Answer 9

The last glacial advance (glacial advance up to Loch Lomond) and marked the end of the Pleistocene epoch.

Question 10

When did the quaternary period start?

Answer 10

2.6 million years ago

Question 11

What caused the quaternary period to start?

Answer 11

The collision of S and N America which redirected the Gulf Stream warming the Western European shores

Question 12

What are the three orbital variation cycles known as the Milankovitch cycles?

Answer 12

Axial tilt, eccentricity (the shape of the Earth’s orbit can vary from circular to more oval shaped) and precession (wobble)

Question 13

Do the Milankovitch cycles have an impact individually?

Answer 13

Individually they have a very limited impact on Earth’s weather

Question 14

How often do the Milankovitch cycles combine? What’s the impact?

Answer 14

Every 100,000 years. This combination of oscillations causes major temperature changes leading to dramatic variations in global ice volumes.

Question 15

How much is the Earth’s temperature actually changed by the Milankovitch cycles alone?

Answer 15

The actual impact of combines orbital changes on solar radiation amount and distribution is small and probably only enough to change global temperatures between 0.5°C to 1°C.

Question 16

What is the positive feedback of the Milankovitch cycles coinciding?

Answer 16

The change of 0.5°-1°C leads to small increases in snow and ice levels which increases surface albedo (reflectivity) so more solar energy is reflected back into space leading to further cooling and more snow and ice and more reflectivity. This positive feedback can cause temperature drops of up to 5°C because of the Milankovitch cycles.

Question 17

What are two major short term causes of climate change?

Answer 17

Sun spot activity and Volcanic activity

Question 18

How does volcanic activity affect climate change?

Answer 18

• Ash is released in large quantities causing blocking of the suns radiation to the surface of the Earth but the ash settles within months
• Sulphur dioxide is emitted in large quantities by large eruptions, Sulphur dioxide forms sulphate aerosols and these aerosols increase the reflection of the Sun’s radiation back into space which cools Earth’s lower atmosphere. The aerosols remain in the atmosphere for as long as 3 years.

Example is: Mount Tambora in the 19th C

Question 19

How do sunspots cause climate change?

Answer 19

Sunspots are caused by intense magnetic activity in the Sun’s interior and an increase in sunspots means the Sun is giving off more energy so the climate is warmed. A lack of sunspot activity then leads to cooler periods, one of the theories for the cause of the little ice age.

Question 20

What is the cause of the Loch Lomond Stadial?

Answer 20

-Drainage of a huge Canadian proglacial lake, disrupting the Thermo-Haline Circulation which could have cut off the heat transport of the Gulf Stream causing major cooling

Question 21

What were the characteristics of the Loch Lomond stadial?

Answer 21

6-7°C lower average temperatures and glaciers re-advanced and ice caps formed in the Scottish highlands

Question 22

What was the cause of the Little Ice Age?

Answer 22

One potential cause is volcanic activity causing cooling. The most likely cause is a lack of sunspot activity causing lower levels of solar radiation

Question 23

What were the characteristics of the Little Ice Age?

Answer 23

Period between approx 1350 and 1850 of 1-2°C cooler temperatures. Colder winters led to the freezing of British and Dutch rivers allowing for ice skating. Swiss alpine farms were destroyed by farms, many upland Scandinavian farms had to be abandoned, Iceland’s cereal crop failed so switched from a grain based diet, Iceland and Greenland were cut off by ice for centuries, positive net mass of glacial mass.

Question 24

Where are high latitude ice sheets distributed?

Answer 24

Within the Arctic and Antarctic circle exclusively. Greenland and Antarctica are notable examples.

Question 25

Where is the high latitude tundra distributed?

Answer 25

All located within the North of the Northern hemisphere. Stretches through northern Russia, Finland, Sweden and Norway. On the other side of the Atlantic the tundra stretches across Northern Canada to Alaska.

Question 26

Where are the high altitude glaciers located?

Answer 26

Mountainous regions of high altitude, e.g. Rocky Mountains, Himalayas, European Alps. Nothing to do with latitude.

Question 27

Compare present day and Pleistocene high latitude ice sheet extension?

Answer 27

• Pleistocene maximum ice cover was 3x today
• Ice coverage was similar in Greenland and Antarctica, Pleistocene slightly greater
• Pleistocene era saw ice sheets in North America and Scandinavian continents/subcontinent

Question 28

What is the cryosphere.

Answer 28

The frozen part of the Earth’s hydrological system, e.g. ice sheets and glaciers

Question 29

Why is the cryosphere important?

Answer 29

• The cryosphere is a very visible barometer of climate change
• Snow and ice help to regulate the Earth’s temperature through the albedo effect
• Mass and energy are constantly exchanged between the cryosphere and other major components of Earth’s systems

Question 30

How are ice masses classified?

Answer 30

By scale and location, also sometimes by their thermal characteristics

Question 31

What is the size progression of glaciers?

Answer 31

Niche -> Cirque -> Valley -> Piedmont

Question 32

What is the size order of ice masses (not including glaciers)?

Answer 32

Ice fields -> Ice caps -> Ice shelfs (ice masses that extend over water) -> Ice sheets (only 2, Greenland and Antarctica)

Question 33

What are warm based glaciers?

Answer 33

Glaciers which occur at high altitudes outside the polar region. The effects of pressure, geothermal energy and percolation of meltwater (caused by temperatures fluctuating above and below zero) all contribute to prevent the glacier freezing to its bed. Warm based glaciers have a debris rich meltwater basal layer. The meltwater layer acts as a lubricant making it easier for the glacier to move downhill with the collection of debris and erode the surface beneath.

Question 34

What are cold based glaciers?

Answer 34

Glaciers which occur in high latitudes and because of the extremely low surface temperatures the temperature at the base of the glacier does not rise to 0°C and so the glacier is permanently frozen to its base. The glacier has no debris rich basal layer. The only meltwater occurs during the cool polar summers but there is very little percolation to affect the glacier. Thus, they have little erosion.

Question 35

What are constrained ice masses?

Answer 35

Ice masses that are constrained to the shape of the land that they exist in. E.g. Ice fields and all glaciers

Question 36

What are unconstrained ice masses?

Answer 36

Ice masses that are not limited to the shape of the environment they exist in (e.g. ice shelves, ice caps, ice sheets)

Question 37

What are the main types of cold environments?

Answer 37

• Polar (high latitude) regions of permanent ice (effectively just the ice sheets of Greenland and Antarctica)
• Periglacial (tundra) regions characterised by permanently frozen ground
• High altitude (alpine) regions
• Glacial environments

Question 38

What latitude is continuous permafrost most commonly found at? How deep is this permafrost?

Answer 38

65°N to 75°N. Permafrost here is can be up to 800m deep and has an active layer no deeper than 1m (usually).

Question 39

What latitude is discontinuous permafrost most commonly found at? How deep is this permafrost?

Answer 39

60°N to 65°N. Permafrost only about 45m deep at most, active layer is 1.5 to 1m deep.

Question 40

What is the name of the unfrozen ground between bands of discontinuous permafrost?

Answer 40

Talik

Question 41

How is latitude, temperature, depth of permafrost and depth of active layer linked?

Answer 41

Higher latitudes = Lower temperatures = Greater Depth of Permafrost = Thinner Active layer

Question 42

How does climate control the distribution and character of permafrost?

Answer 42

Temperature and amount of moisture available determines the presence or absence of permafrost and the depth/extent of permafrost

Question 43

What are the local factors affecting permafrost coverage?

Answer 43

• Position of water bodies like lakes (water insulates ground below so no permafrost beneath water bodies like lakes)
• Slope orientation (Northern slopes more likely to have more permafrost as they receive less sunlight during the day so are colder than Southern slopes)
• Character of ground surface (bare, dark ground absorbs the sun’s radiation so more fragmented and shallower permafrost beneath)
• Vegetation cover (coniferous trees shed needles onto the forest floor and these needles accumulate creating a layer of insulation meaning more fragmented and shallower permafrost)
• Snow cover (Albedo effect so sun’s radiation is reflected and the ground beneath snow is cooler and more likely to be continuously and much deeper frozen)
• Proximity to oceans (warm ocean currents may result in less permafrost)

Question 44

How much does water expand by when it freezes during freeze thaw weathering?

Answer 44

9%

Question 45

How are tors and scree formed from freeze thaw weathering?

Answer 45

Tors are formed from more resistant rock that when the area was all rock this resistant rock was more resistant to freeze thaw weathering than the other rock. The other less resistant rock is broken away by freeze thaw weathering and this is the scree we see on slopes beneath the resistant tors.

Question 46

How does freeze thaw weathering form Felsenmeer/blockfields?

Answer 46

Felsenmeers are formed from freeze thaw weathering breaking up the top layer of rock revealing the underlying jagged boulder formations of more resistant rock. The block fields are formed of a combination of frost heave pushing up bedrock and the freeze thaw weathering.

Question 47

What is Nivation?

Answer 47

A combination of processes which weaken and erode the ground under a snow patch. These processes include freeze thaw weathering, meltwater erosion and solifluction.

Due to fluctuating temperatures in summer, the presence of meltwater from the snow promotes freeze thaw weathering. Meltwater also carries away any debris so that the hollow can be enlarged again.

Question 48

How often do the Milankovitch cycles coincide?

Answer 48

Every 100,000 years

Question 49

How do Milankovitch cycles cause glacials and a big increase in ice on earth?

Answer 49

The cycles coinciding effects on solar radiation amount and distribution is between 0.5° and 1°C. However, this small change leads to positive feedback, the small change leads to slightly more snow and ice cover which increase surface albedo cooling the earth more. Positive feedback of cycles causes the larger temperature changed of up to 5°C.

Question 50

What is solifluction?

Answer 50

The downslope movement of the unfrozen saturated active layer under the influence of gravity.

Question 51

What does solifluction result in?

Answer 51

Solifluction lobes forming on slopes

Question 52

What is loess?

Answer 52

The extensive accumulation of wind blown deposits of fine, dry sediment from the ground surface. Less vegetation enables easier movement.

Question 53

How is meltwater erosion significant in regards to the formation of braided streams?

Answer 53

Thawing in summer creates meltwater which erodes stream or river channels. Refreshing at the onset of winter causes a reduction in discharge and sediment deposition in the channel. Braided streams are formed with multiple channels separated by islands of deposited material.

Question 54

How is a closed system pingo formed?

Answer 54

These form in the continuous zone of permafrost. They form as a lake becomes infilled with sediment. The sediment then freezes over the lake. The lake then freezes (and expands) in the winter pushing the sediment above it up creating a mound. In the summer the lake melts and the mound collapses.

Question 55

How is an open system pingo formed?

Answer 55

These occur in the discontinuous zone of permafrost or valley floors. They are formed by the freezing of water in the upper layers of the soil leading to expansion of ice within the soil heaving up the overlying sediments creating a mound up to 50 metres high.

Question 56

What are pingos?

Answer 56

Ice core mounds 3-70m in height and 100m to 500m in diameter. They are formed from ice cores pushing up sediments or ground above them.

Question 57

What is frost heaving?

Answer 57

Frost heaving is when the ground freezes and the stones in the ground chill quicker than the soil and so the water below the stones freezes forming ice lenses, and this heaves up the stones creating a mound in the ground.

Question 58

What causes stone polygon and stone stripe formations?

Answer 58

The process of frost heaving and the upward movement of stones heaves stones up to the surface. When they reach the surface the shape of the stone is reflected on the ground of the mound, however, as the heaving creates mounds if the stone surfaces at a portion of land with a gradient >6 degrees then a striped pattern is left on the ground. Smaller particles are moved away by wind and meltwater and do not make a pattern.

Question 59

What is ground contraction? How does it lead to ice wedges?

Answer 59

When dry areas of the active layer refreeze, the ground contracts and cracks. Meltwater then fills the cracks and when winter comes the water freezes and expands by 9% widening the gap.

Question 60

How do ice wedges cause polygons to form on the ground?

Answer 60

After multiple winters the cracks in the ground get larger and some soil is pushed up to make tiny mounds in the ground either side of the original crack which has been filled with ice. These mounds are what create this polygon pattern on the ground similar to the polygons formed by frost heaving.

Question 61

What are two major causes of long term natural climate change?

Answer 61

• Milankovitch cycles
• Plate tectonics

Question 62

How have plate tectonics led to long term climate change?

Answer 62

Collision of N and S American plates 3 million years ago rerouted Gulf Stream, brought moisture to Arctic which led to increased snowfall in Greenland, causing the Greenland ice sheet which in turn triggered the last ice age.