EQ1- Glaciation

Question 1

What state is the Earth currently in?

Answer 1

Earth is an icehouse because glaciers haven’t completely melted, and large sheets of ice are still present.
A greenhouse earth occurs when there are no continental glaciers on the planet as a result of warming processes, such as high levels of greenhouse gases in atmosphere may be due to volcanic activity.

Question 2

What does glacial and interglacial mean?

Answer 2

cold period (glacial)- ice advances
warm period (interglacial)- ice retreats
We are in an interglacial period.

Question 3

What is the name of the ice age the earth is currently in?

Answer 3

Quaternary which started 2.6 million years ago.

Question 4

What two epochs is the quaternary ice age divided into?

Answer 4

Pleistocene- lasted approx 11,500-12,000 years ago.
Holocene- began 10,000 years ago and continues today.

Question 5

What are the three main characteristics of the pleistocene?

Answer 5

1. wasnt just a single ice age. Lasted 2 million years, temps fluctuated enough to allow advances and also retreates.
2. The extent to the ice advance during each glacial was different.
   3.There are fluctuations within each major glacial.

Question 6

What is the difference between stadials and interstadials?

Answer 6

They are stages dividing the quaternary period.
-Stadials are periods of colder climates.
-interstadials are periods of warmer climates.

Question 7

What are the long- term factors of climate change? (Milankovitch cycles)

Answer 7

1. Eccentricity cycle (ORBIT) - the shape of the Earth’s orbit varies from circular to elliptical over 100,000 year cycles. This means that the amount of solar radiation received in summer and winter equinoxes changes causing an increase in the magnitude of seasonal changes. Temperatures at high latitudes in northern hemisphere decrease increasing ice volume. This sets up a positive feedback loop where increased ice in northern hemisphere increases albedo further reducing temps and increases in ice volume.

2.Obliquity cycle:(TILT) the tilt of the Earth’s axis varies between 21.5 degrees and 24.5 degrees over 41,000- year cycles. When the tilt is less, there are warmer winters but cooler summers and so glaciers do not melt in the summer and so advance. This reflects more of incoming solar radiation further cooling the planet and causing variations in ice volume.

3.Precession of equinoxes- the earth wobbles as it spins on its axis. This changes the point in the year at which the Earth is closest to the sun (axial precession) over a 22,000 year time cycle.

These three orbital cycles can combine together to minimise the amount of solar energy reaching the northern hemisphere during summer (leading to cooler summers overall). The impact of combined orbital changes on solar radiation amount is small, to explain larger temp changes we have to look at climate feedback mechanisms.

Question 8

What is the positive climate feedback mechanism? increasing the warming or cooling rates

Answer 8

-Small increases in ice raise surface albedo (reflectivity) so more solar energy is reflected back into space, leading to further cooling- could lead to further snowfall and ice cover due to cooling
.
-the melting of snow/ ice cover by co2 emissions decreases albedo, and methane is emitted as permafrost melts, and warming seas lead to calcing of ice sheets, leading to loss of snow/ ice cover and of surface albedo accelerating further warming.

Question 9

What is the negative feedback: decreasing the warming or cooling rates

Answer 9

• increasing global warming leads to more evaporation and, over time, pollution adds to global cloud cover. Increasingly cloudy skies could reflect more solar energy back to space and diminish the effect of warming.
• ice sheet dynamics can distrupt the thermohaline circulation (THC). Warming water in the arctic disrupts ocean currents; less warm water from the gulf stream is drawn north, leading to global cooling in norther europe.

Question 10

Explain two short- term causes of climate change (6 marks)

Answer 10

1) VARIATIONS IN SOLAR OUTPUT
- Sunspots are caused by intense magnetic activity in the sun’s interior.
- An increase in the number of sunspots means that the sun is more active and giving off more energy, so sunspot numbers indicate levels of solar output.
- They appear to vary over an 11 year cycle.
- The climate has fluctuated during the holocene epoch with cooler temperatures between 1330 and 1830 ( the little ice age)
- Evidence that the little ice age cooling was triggered by variations in solar output.
- during 1650-1750 indicates that very little sunspot activity was occurring and during this time Europe and North America experienced colder temperatures.

2) VOLCANIC EMISSIONS
- IN April 1815 Mount Tambora (Indonesia) produced one of most powerful volcanic eruptions recorded in history.
- Very cold weather the year after the eruption.
- Initially, scientists thought that the ash emitted into the atmosphere from large volcanic eruptions was responsible for cooling by partially blocking the transmission of solar radiation.
- However, it was discovered that most of the ash thrown into the atmosphere during volcanic eruptions returns to the earths surface within months.
- The most significant volcanic impact is the injection into the atmosphere of large quantities of sulphur dioxide gas, which remains in atmosphere for three years.
- Sulphate aerosol are formed, which increases the reflection of radiation from the sun back into space, cooling the earth.

Feedback mechanisms would be needed to amplify change

Question 11

Describe the causes of the loch lomond stadial

Answer 11

The loch lomond stadial was triggered when drainage of the huge proglacial lake Agassiz disrupted the THC, thus cutting off the poleward heat transport from the gulf stream.

Question 12

Describe the characteristics of the loch lomond stadial

Answer 12

• Around 12,500 years ago the temperatures plunged downwards and by 11,500 years ago, glacial conditions occurred with 6-7 degrees lower.
• Caused glaciers to re-advance in many parts of the world including the formation of ice caps in Scotland.
• After the event, rapid rise of 7 degrees with a rapid rise in sea level.

Question 13

Describe the cause of the little ice age

Answer 13

• Period of cooling which occurred after the medieval warm period.
• Lasted from about 1550-1850
• volcanic activity caused it (although can’t be solely explained by volcanoes) and also low levels of solar radiation due to lack of sunspot.

Question 14

Describe the characteristics of the little ice age

Answer 14

• colder by 1-2 degrees.
  Many impacts such as:
• arctic sea ice spread further south with polar bears seen in iceland
• rivers in UK and lowland Europe froze over.
• Many glaciers in europe re-advanced
• icelands cereal crops also failed.
• Greenland largely cut off by ice.

Question 15

Why was the little ice age developing into a new stadial prevented?

Answer 15

• the industrial revolution and coal.
• release of co2 triggered climate warming, halting the cold period.

Question 16

What is the cryosphere?

Answer 16

• The frozen part of the earth’s hydrological system.
• Consists of ice sheets, and glaciers together with sea ice, lake ice, permafrost and snow cover.

Question 17

Why is the cryosphere important?

Answer 17

• acts as stores within the hydrological cycle.
• snow and ice reflect heat from the sun- albedo effect- helps to regulate temperatures on earth.

Question 18

How are ice masses classified by scale and location?

Answer 18

by scale:
- ice sheets- largest masses of ice ( >50000km 2)
- ice caps - Dome-shaped masses that cover mountain peaks <50,000km 2
- ice fields- cover upland areas but ice isn’t thick enough to bury topography. 10-10,000km 2
- valley glacier- glacier confined to a valley- 3-1000km 2
- cirque glacier- forms in hollow on mountain side
0.5-3km 2

by location:
warm based glaciers- high altitude areas where it warm enough to melt the base of the glacier.

cold based glaciers- polar glaciers occur in high latitudes. Low temperatures mean the glacier is permanently frozen to its bed.

Question 19

Explain one approach to classifying ice masses (6 marks)

Answer 19

• In warm- based glaciers, e.g- In the Alps and sub- arctic areas, the base is warmer than the melting point of ice.
• It’s warmer because of heat from friction caused by the glacier moving, or because of geothermal heat from the earth.
• The ice at the bottom of the glacier melts, and the meltwater acts as a lubricant, making it easier for the glacier to move downgill.
• ice at the surface also melts if the temperature reaches 0 degrees celsius, and meltwater moves down through the glacier, lubricating it even more.
• In cold based glaciers e.g- Antarctica, the base is cold so there is very little melting.
• The ice is frozen to the base of the valley, so there is very little movement.
• There’s hardly any melting at the surface, even in the summer.
• This means cold- based glaciers don’t cause very much erosion at all.

Question 20

The four main types of cold environment?

Answer 20

polar- high latitude, areas of permanent ice.
periglacial (tundra)- permanently frozen ground (permafrost).
alpine/ mountain- high altitude- where glaciers and glaciated landscapes are found,
Glacial environments- found at the edges of the ice sheets, high mountainous areas.

Question 21

What evidence was found in UK landscapes that much of the country was covered by an ice sheet during the pleistocene

Answer 21

erosional evidence- found in Scotland and Wales and lake district. Corries, aretes, glacial troughs, roches moutonees, crag and tail and knock and lochan.

depositional evidence- drumlines, erratics moraine

meltwater evidence- meltwater channels.

Question 22

What is continuous permafrost?

Answer 22

Forms in the coldest areas of the world where mean annual air temperatures are below -6 degrees.

Question 23

What is discontinuous permafrost?

Answer 23

more fragmented and thinner

Question 24

What is sporadic permafrost?

Answer 24

occurs at the margins of periglacial environments and is usually very fragmented and only a few meters thick, often occurs on shady hillsides or beneath peat.

Question 25

What is the active layer?

Answer 25

The top layer of soil in permafrost environments that thaws during summer and freezes during winter.

Question 26

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

Answer 26

climate- as temperature and the amount of moisture available determine the presence or absence, depth or extent of permafrost.

Question 27

Other factors that influence the distribution and character of permafrost on a local scale? (finish)

Answer 27

• proximity to water-no permafrost under lakes, only talik.
• slope orientation- when facing away from the sun the bottom of the slope is colder, because the sun doesn’t reach it. NE facing- less sun.
  Vegetation cover- only highly adapted plants can survive in the cold weather with little rainfall. The temp leads to a slow nutrient cycle. Permafrost makes it hard for plants to grow as they cannot infiltrate the soil.
  character of ground surface- darker surface absorbs more sun.

Question 28

What is freeze thaw weathering?

Answer 28

The process begins when water seeps into cracks within a rock.
The temperature falls to 0 degrees or below, the water turns to ice and expands by 9%.
This exerts stresses within the rock- enlarging cracks and pores.
As the process of freezing and thawing is repeated, the cracks become larger until chunks of rock break away and pile up as scree at the foot of the slope.

Question 29

What features does free-thaw create?

Answer 29

Block fields \9felsenmeer) are accumulations of angular, frost shattered rock which pile up on flat surfaces. They are created by frost heaving of joined bedrock and freeze- thaw weathering.

Tors- “crown” hill tops, they form where more resistant areas of rock occur.

scree or talus slopes- formed when rock fragments fall and accumulate on the lower slopes or base of cliffs. The larger the material that makes up the slope, the steeper its angle of rest.

pro- talus ramparts- created if a patch of snow has settled at the base of a cliff. When rocks fall, as they are shattered by frost action, the snow patch acts as a buffer. The rocks settle at the base of the snow patch, leaving a rampart of boulders when the snow melts.

Rock glaciers- form when large amounts of frost- shattered rock mixes with ice.

Question 30

Explain the process of nivation and how it leads to nivation hollows ( 6 marks)

Answer 30

• Nivation takes place at high altitude on north and east facing slopes.
• When snow gets into a hollow in the ground, it increases the size of the hollow.
• The temperature fluctuates around 0 degrees, so freezing and thawing occurs. When temp is above 0 snow melts, below 0 refreezes as ice.

-Everytime ice refreezes/ melts, it expands and contracts and so freeze- thaw action operating under the snow causes underlying rock to disintegrate.

• As the snow melts in spring, the weathered rock debris is moved downslope by meltwater and solifluction.
• Over time, hollows enlarge and become wider and deeper- called nivation.

-hollows formed are known as nivation hollows.

Question 31

What is frost heave?
(patterned ground- stone polygons)

Answer 31

-The freezing and expansion of soil water causes the upward dislocation of soil and rocks.
- As the ground refreezes, large stones become chilled more rapidly than the soil.
- Water below such stones freezes and expands, pushing the stones upwards forming domes on ground surface.

On flat ground- stone polygons formed.
on slopes- stone stripes formed as stones move downhill.

Question 32

How does frost heave lead to patterned ground and stone polygons?

Answer 32

patterned ground-
- Frost push propels the stones upwards, frost heave causes the stones to migrate outwards to form circles (the basis for each pattern)
- This causes larger stones roll outwards as a result of gravity, while finer sediments remain central.
- As a result of mass movement, stone polygons are elongated into stripes.
- If the gradient is less than 6 degrees polygons form.
- if gradient is more than 6 degrees striping forms.
- if gradient is beyond 30 degrees- no longer form and rock avalanches may occur.
- sloping can distort polygons as the stones gradually slide down- leading to stone stripes.

Question 33

Explain how ground contraction leads to the formation of ice wedge polygons?

Answer 33

• Ice-wedges are downward- tapering bodies of ice. The refreezing of the active layer during the winter causes the soil to contract.

-Cracks open up on the surface. During melting the following summer, the cracks open up again and fill with meltwater.

-As the meltwater contains fine sediment, this also begins to fill the crack.

• The process occurs repeatedly through winter and summers widening and deepening the crack to form an ice wedge eventually. They can become 2-3m deep.

-The cracking produces a pattern on the surface, which is similar to the polygons produced by frost heaving.

• These are therefore known as ice- wedge polygons. When an ice wedge melts, it may fill with sediment to form an ice wedge cast.

Question 34

Explain how solifluction leads to solifluction lobes?

Answer 34

• The downslope movement of rock and soil material in response in response to gravity.
• The effect of the summer thaw on the active layer is to release lots of meltwater, this water is unable to percolate downwards, it saturates the soil, reducing internal friction between particles, making it highly mobile.
• The lack of substantial vegetation to fix the saturated soil means the soil begins to flow even on slopes of only a few degrees.
• This process is known as solifluction and the deposits it leaves behind are characterised as rounded, tongue like features.

-These solifluction lobes are stepped features that may be formed beneath turf of vegetation.

• When vegetation is sparse, stones heaved to the surface are pushed to the front of the advancing lobe and form a small stone bank at the front side of the lobe.

Question 35

How does wind create loess?

Answer 35

Due to limited vegetation cover, the wind is able to pick up and transport the fine, dry sediment from the ground surface and redeposit it far away from its source as loess. - extensive accumulations of wind- blown deposits.

Question 36

How does meltwater create braiding?

Answer 36

During the short summer, thawing creates meltwater which erodes streams or river channels. Refreezing at the onset of winter causes a reduction in discharge and sediment deposition in the channel. Leads to braided streams with multiple channels seperated by islands of deposited material.

Question 37

How does ground water refreezing lead to pingos? (associated with ice wedges, ground contraction)

Answer 37

The freezing of water in the upper layers of the soil, where permafrost is thin leads to an expansion of ice within the soil. This causes overlying sediments to heave upwards into dome-shaped feature known as a pingo.