EQ1: How has climate change influenced the formation of glaciated landscapes over time?

Question 1

What does current geological evidence suggest about the age of the Earth?

Answer 1

Current geological evidence suggests that the Earth is 4.6 billion years old and that throughout its history the planet’s climate has been fluctuating.

Question 2

What are the different states that Earth’s climate fluctuates between?

Answer 2

DOMINANT STATES:

• Greenhouse Earth = This occurs when there are no continental glaciers as a result of warming processes (e.g. higher levels of greenhouse gases or volcanic activity).
• Ice-house Earth = A global ice age, where large ice sheets are present on the Earth.

ICE PERIODS (Advances and Retreats):

• Glacials = Cooler periods when ice advances, ice-house periods within the Pleistocene.
• Interglacials = Warmer periods when the ice retreats, similar to the present (greenhouse periods).
• In the last 1 million years, there may have been as many as ten glacial periods, separated by interglacials.

Question 3

What are the 5 known ice ages in Earth’s history from the most recent?

Answer 3

CENOZOIC ERA

1. Quaternary Period (2.6 million years ago)
   a) . Holocene Epoch (present-day to 10,000 years ago).
   b) . Pleistocene Epoch (11,500 - 12,000 years ago).
2. Tertiary Period
   a) . Pliocene Epoch.
   b. Miocene Epoch.
   c) . Oligocene Epoch.
   d) . Eocene Epoch.
   e) . Palaeocene Epoch.

MESOZOIC ERA

3. Cretaceous Period (66 million years ago).
4. Jurassic Period (144 million years ago).
5. Triassic Period (206 million years ago).

Question 4

How many advances and retreats were present in the Pleistocene Epoch?

Answer 4

PLEISTOCENE EPOCH

• Pleistocene = the Ice Age (colloquially).
• 50 glacial-interglacial periods, during which glaciers reached their maximum extent.

Question 5

What were the last known glacial advances?

Answer 5

• The last glacial advance in the UK was known as the Loch Lomond Stadial (occurring between 12,000 and 10,000 years ago).
  Large fluctuations.
• The last glacial maximum is known as the Devensian, occurring 18,000 years ago.

Question 6

What are the 3 main characteristics of the Pleistocene Epoch (Ice Age)?

Answer 6

PLEISTOCENE EPOCH

1. It wasn’t just a singular ice age. Over the 2 million or so years during which it lasted, temperatures fluctuated enough to allow a number of ice advances and retreats.
2. The extent to which the ice advance during each glacial was different.
   - 50 glacial-interglacial periods, during which glaciers reached their maximum extent.
3. There are fluctuations within each major glacial. These relatively short-lived pulses of ice advance are known as stadials and warmer periods of retreat known as interstadials.

Question 7

What are short-lived pulses of ice advances in glacials known as?

Answer 7

GLACIAL PULSES

• Stadial = Short term fluctuation within ice-house-greenhouse conditions of short-lived pulses of ice advance.
• Interstadial = Short term fluctuation within ice-house-greenhouse conditions of short-lived warmer periods of ice retreat.

Question 8

What are the long-term factors leading to climate change?

Answer 8

LONG TERM FACTORS

1. The hanging position of the continents (Tectonics).
2. Milankovitch cycles (Astronomical theory/Orbital changes).
3. Feedback mechanism

Question 9

How has Tectonics led to climate change?

Answer 9

THE HANGING POSITIONS OF THE CONTINENTS

a) . Start of Quaternary Ice Age linked to the continental drift.
b) . Around 3 million years ago, North and South American plates collided, creating the Panama Isthmus.
c) . This reroutes ocean currents so that the warm Caribbean waters were forced Northwest towards Europe (creating the Gulf Stream).
d) . This transported extra moisture into the Arctic atmosphere which fell as snow in that colder climate, triggering the build-up of the Greenland Ice Sheet, which may have kick-started the Ice Age/Pleistocene.

Question 10

How has Astronomics led to climate change?

Answer 10

MILANKOVITCH CYCLES
- By geophysicist in 1920. Long-term changes in the Earth’s orbit around the Sun are currently seen as the primary cause of the oscillations between glacial and interglacial conditions caused by variations in the amount of solar radiation received and forces the climate to change in response.

1. Eccentricity -
   a) . The shape of the earth’s orbit changes from circular to elliptical over 100,000 years.
   b. ) Variation in solar radiation in the elliptical orbit.
   c) . Furthest away from the Sun at Aphelion.
2. Obliquity/Axial tilt -
   a) . The tilt of the axis from shifts between 21.5-24.5 (currently at 23.5) over a timescale of 41,000 years.
   b) . This changes the intensity of sunlight received at the poles and therefore changes the severity of seasons.
3. Precession of the equinoxes/Wobble -
   a) . Earth wobbles as it spins on its axis, changing the point in the year at which the Earth is closest to the Sun over 21,000 years.
   b) . The season during which the Earth is nearest to the sun changes along Earth’s orbital path.

Question 11

What is the evidence for Astronomics leading to climate change?

Answer 11

ASTRONOMICAL THEORY

• Individually, the orbital variations of axial tilt, eccentricity, and wobble have a limited impact on Earth’s weather.
• But over a 100,000-year cycle, these oscillations combine to cause major temperature changes leading to dramatic variations in global ice volumes.
• In support of Milankovitch’s theory is the fact that glacials seem to have occurred at regular intervals of approximately 100,000 years.
• However the actual impact of combined orbital changes on solar radiation amount and distribution is small, probably only enough to change global temperatures by between 0.5 and 1C.
• Coral reefs in Barbados prove a correlation between interglacial periods of the last 160,000 years and eccentricity cycles.
• To explain the larger temperature changes of up to 5C that were required for the vast expanses of ice to form, or alternatively melt, we have to look at climate feedback mechanisms.

Question 12

What role do Feedback Mechanisms play in climate change and regulation?

Answer 12

POSITIVE FEEDBACK (Amplify a small change and make it larger) =

a) . Snow and ice cover.
- Small increases in snow or ice raise surface albedo (reflective coefficient of a surface) so more solar energy is reflected back into space, leading to further cooling which could lead to further snowfall and ice cover.
b) . The melting of snow/ice cover by carbon dioxide emissions decreases albedo.
- Methane is emitted as permafrost melts, and warming seas lead to the calving of ice sheets (breaking up of chunks of ice at the glacier snout or ice sheet to form icebergs as the glacier reaches a lake or ocean).
- This all leads to a loss of snow/ice cover and of surface albedo, decreasing reflectiveness and accelerating further warming.

NEGATIVE FEEDBACK (Diminish the change and make it smaller) =

a) . Increasing global warming leads to more evaporation and pollution from industrialisation adding to global cloud cover.
- Increasing cloudy skies could reflect more solar energy back to space and diminish the effect of warming, or maybe less intense due to global dimming.
b) . Ice sheets dynamics can disrupt the Thermohaline Circulation (THC Ocean Conveyor = A global system of surface and deep-water ocean current driven by differences in temperature (thermo) and salinity (haline) between areas of the oceans).
- Warming water in the arctic disrupts ocean currents; less warm water from the Gulf Stream is drawn North, which could lead to global cooling in Northern Europe.

Question 13

What are the short-term factors leading to climate change?

Answer 13

SHORT-TERM FACTORS

1. Volcanic Emissions.
2. Variations in Solar Output.
3. Short Term Feedback Mechanisms.

Question 14

How do Volcanic Emissions influence climate change?

Answer 14

VOLCANIC EMISSIONS

a) . In the case of a volcanic eruption, large fluxes of Ash is thrown into the atmosphere, affecting the climate in the short term causing widespread cooling, by partially blocking the transmission of solar radiation, yet most ash returns to Earth within months.
b) . Yet, the injection of large quantities of sulphur dioxide gas (remains in the atmosphere for three years) can be detrimental to global warming.
c) . Sulphate (volcanic) aerosols are also formed, which increase the reflection of radiation from the Sun, cooling the atmosphere.
d) . In 1815, Tambora in Indonesia ejected 200 million tonnes of Sulphur Dioxide into the atmosphere, with the average temperatures 2/3 years later being 0.4-0.7C lower.

Question 15

How do Variations in Solar Output influence climate change?

Answer 15

VARIATIONS IN SOLAR OUTPUT

a) . Sunspots (dark spots) on the sun are caused by intense magnetic activity in the Sun’s interior.
b) . They Indicate levels of solar output.
c) . So an increase in sunspots means more active and more energy. They appear to vary over an 11-year cycle.
d) . Climate has fluctuated with cooler temperatures in 1550-1750, known as The Little Ice Age, with observations of the Sun during the latter part of The Little Ice Age indicating that very little sunspot activity was occurring on the Sun’s surface (known as a Maunder Minimum).

Question 16

How do Short Term Feedback Mechanisms influence climate change?

Answer 16

SHORT TERM FEEDBACK MECHANISM
a). Attributing causal relationships in science can be very problematic, especially as both of the possible causes discussed could not by themselves explain the size of the temperature changes associated with short-term stadial and interstadial fluctuations, so yet again feedback mechanisms would be needed to amplify the change.

Question 17

What are two examples of shorter-term climate events?

Answer 17

1. Loch Lomond Stadial (Pleistocene).

2. The Little Ice Age (Holocene).

Question 18

What are the characteristics of The Loch Lomond Stadial?

Answer 18

1. LOCH LOMOND STADIAL (PLEISTOCENE)
   a) . UK’s last max glacial advance. A rapid drop in average temps during the Pleistocene triggered the Devensian period.
   b) . Ice sheets began retreating 18,000 years ago with rapid deglaciation by 15,000 years ago (late glacial interstadial).
   c) . 12,500 year ago, temperatures plummeted at 6-7⁰C lower, allowing glaciers to re-advance (Cirque and Valley glaciers flowed outwards.
   d) . Perhaps triggered when drainage of the huge proglacial Lake Agassiz disrupted the Thermohaline Circulation, thus cutting off the poleward heat transport from the gulf stream.
   e) . Yet inconsistent with orbital forcing, as neither solar forcing nor volcanic eruptions could lead to the fluctuation of such magnitude.
   f) . The Loch Lomond stadial shows how ice accumulates and spreads in response to climatic conditions. Icecap developed over the Western Uplands in Scotland and elsewhere.

Question 19

What are the characteristics of The Little Ice Age?

Answer 19

2. THE LITTLE ICE AGE (HOLOCENE)
   a) . Was a period of cooling following the Medieval Warm Period and lasted from 1550-1750. Bringing colder winters with many rivers and canals freezing over.
   b) . Different causes suggested:
   i) . Volcanic activity - although this can’t be the sole cause as it is on a scale of centuries and climates increased 1-2⁰C.
   ii) . Low levels of solar radiation - very little sunspot activity.
   iii) . The argument that this could’ve been developed into a new stadial, but that this was prevented by the onset of the industrial revolution, fired by coal. The release of Carbon Dioxide triggered climate warming, which dramatically halted the cold period
   c) . A number of effects:
   i) . Greenland largely cut off for 300 years due to ice, farms and villages in the Swiss Alps destroyed as glaciers advanced.
   ii) For many years of famine in Europe as crop practices had to adapt, Sea ice extended out from Iceland for miles in every direction, polar bears being seen Northern Europe (Iceland), rivers in the UK froze over.

Question 20

What is the Cryosphere?

Answer 20

• CRYOSPHERE = The frozen park of the Earth’s hydrological system, in the form of ice on land surfaces and oceanic sheets (sea ice, lake ice, river ice, snow cover, glaciers, ice caps, ice sheets and permafrost) all acting as stores within the cycle. From the Greek word for cold (Kryos).

Question 21

Why is the Cryosphere important?

Answer 21

CRYOSPHERE

1. Play a vital role in the Earth’s climate.
   - Snow and ice reflect heat from the Sun (Albedo effect) which helps to regulate temperatures on Earth.
2. Mass and energy are constantly exchanged between the cryosphere and other components of Earth’s systems
   - The hydrosphere, lithosphere, atmosphere and biosphere.
3. Polar regions are among the most sensitive and visible barometer to temperature change/climate change.
   - They retreat and grow in response to different adapting climate.
   - It is, therefore, a valuable focus for climate scientists researching global climate change.

Question 22

What are the 2 different morphologies of glaciers?

Answer 22

MORPHOLOGY OF THE GLACIER

1. Unconstrained
   - Larger glacial forms (such as ice sheets and ice caps).
   - These are so thick and extensive that they submerge the landscape.
   - They are drained by outflowing ice streams and outlet glaciers.
2. Constrained
   - Glaciers pathway and extent is predetermined by enclosed topography or landscape (valleys).
   - Normally smaller and gravity forces the glacier into a constrained landscape.
   - Valley glaciers can sometimes only escape across pre-existing cols by the process of diffluence (flowing away) as their snouts become ‘trapped’.

Question 23

What are the 2 different ways of identifying ice masses?

Answer 23

1. Classification of Ice Masses by scale and location.

2. Classification of Ice Masses by Polar and Temperate Environments.

Question 24

In what ways can you identify ice masses by scale and location?

Answer 24

CLASSIFICATION OF ICE MASSES BY SCALE AND LOCATION

1. Ice Sheet
   a) . The largest mass of ice and snow of considerable thickness in-depth, completely submergence of regional topography (bury the landscape, except the highest mountain summits - known as Nunataks); forming a gently sloping dome of ice more than 50,000 square KM.
   i) . 50,000 - 100,000 square KM.
   ii) . Not constrained.
   iii) . EXAMPLE. Greenland, Antarctica (14 million KM² - stores 90% of Earths Freshwater).
2. Ice Cap
   a) . A dome-shaped mass of glacier ice, usually situated in an upland area, outlet glaciers and ice sheets drain both ice sheets and caps. This is generally defined as covering up to 50,000 Square KM.
   i) . 3 - 50,000 square KM.
   ii) . Not constrained.
   iii) . EXAMPLE. James Ross Island, Northern Antarctic Peninsular
3. Ice Shelf
   a) . A large slab of ice floating on the marine but mainly, attached to and largely fed by land derived ice sheets. These may calve to form detached floating ice masses (icebergs).
   i) . 10 - 100,000 square KM.
   ii) Not constrained.
   iii) . EXAMPLE. Princess Elizabeth Land, East Antarctic.
4. Ice Field
   a) . Similar to ice caps, but are typically smaller, the ice field topography is determined by the shape of the surrounding land, with ice not being thick enough to bury topography (Nunataks), it’s normally less than 50,000 Square KM.
   i) . 10 -10,000 square KM.
   ii) . Not constrained.
   iii) . EXAMPLE. Patagonia (Chile).
5. Valley Glacier
   a) . A glacier confined by the walls of a valley and descending from high mountains, terminating in a narrow tongue or into the sea as a tidewater glacier: forms from ice caps/sheets or cirques from an ice cap on a Plateau or from an Ice Sheet.
   i) . 3 - 15,000 square KM.
   ii) . Constrained.
   iii) . Mer De Glace or the Aletsch Glacier, Alps.
6. Piedmont Glacier
   a) . A valley glacier that spreads out as a wide lobe as it leaves a narrow mountain valley to enter a wider valley or a flat plain.
   i) . 3 - 1,000 square KM.
   ii) . Constrained.
   iii) . Piedmont Glaciers, Axel Heiberg Island.
7. Cirque Glacier
   a) . A smaller glacier calving a cirque/corrie/tarn with an air shaped hollow on the North Facing mountainside (in the Northern Hemisphere) with a steep side and back walls (armchair shaped) - a smaller version is known as a niche.
   i) . 0.5 - 8 square KM.
   ii) . Constrained.
   iii) . Grand Teton National Park, Wyoming, USA.

Question 25

In what ways can you identify ice masses by Polar and Temperate Environments?

Answer 25

CLASSIFICATION OF ICE MASSES BY POLAR AND TEMPERATE ENVIRONMENTS

1. Temperate (Warm/Wet) Based
   a) . Formed at:
   i) . High altitudes areas outside of the polar regions (Alps).
   ii) . Small scale ice masses - valley glacier.
   b) . The temperature of the surface layer fluctuates above and below the melting point, depending on seasonality.
   i) . Whereas the temperature of the rest of the ice, extending downwards, is close to the pressure melting point.
   ii) . This is because of increased pressure of overlying ice, water exists as a liquid at temperatures below 0٥C.
   iii) . This causes the basal ice to melt continuously.
   c) . The effects of effective normal pressure, geothermal energy and percolation of meltwater, all contribute to preventing the glacier freezing to its bed.
   i) . The glacier had lots of debris in its basal layers, with significant subglacial depositional features as a result of the basal meltwater acting as a lubricant for the glacier, leading to greater momentum and alternatively a greater erosive power to abrase away the debris on the base of the glacier.
2. Polar (Cold) Based
   a) . Formed at:
   i) . High latitudes (Antarctica, Greenland).
   ii) . Large scale ice masses - ice sheets, ice caps.
   b) . The average temperature of the ice is usually well below 0٥C, as a result of the extreme surface temperature (as low as -20٥C to - 30٥C).
   i) . The glacier is permanently frozen to its bed so there is no debris-rich basal layer.
   ii) . The accumulation of heat from geothermal sources is not great enough to raise the temperature at the base of the glacier to 0٥C, even if the ice may be 500m thick.
   c) . There is relatively little surface melt in the short-lived polar summer.
   i) . So meltwater percolates downwards and refreezes to the bedrock below.
3. (Hybrid) Polythermal Glacier
   a) . Further subdivision whereby the underneath is warm (wet) based and the margins (snout) is cold-based and therefore frozen to the bedrock.
   i) . Many large glaciers are cold-based in their upper regions and warm based lower down when they extend into warmer climate zones (Svalbard, Norway).
   b) . Surging glaciers or ice streams may occur within warm based, cold-based or polythermal glaciers.
   i) . This may have rates of flow up to 100m per day (Greenland outlet glaciers average 30m a day) with huge amounts of calving (ice breaking off at the edges).

Question 26

What are glaciers and how are they formed?

Answer 26

GLACIERS

• Glaciers are large bodies of ice that flow downhill under the influence of gravity.
• They form in areas where temperatures are sufficiently low to allow snow to persist from year to year, enabling thick layers of snow to accumulate and be slowly compressed to form glacier ice.
• Snowflakes have an open feathery structure that traps the air as they accumulate on the ground (Alimentation), with this process continuing the lower snowflakes are compressed and gradually lose their edges, meltwater seeping into the gaps, expelling any air which then refreezes.
• Further accumulation increases pressure results in a mass of tightly packed, randomly orientated ice crystals separated by tiny air passages (firn or névé).

Question 27

What is the thermal regime?

Answer 27

THERMAL REGIME

- This has a major impact on glacier movement, the operation of glacial processes and subsequent landforms produced.

Question 28

What is the pressure melting point?

Answer 28

PRESSURE MELTING POINT
- The temperature at which ice is on the verge of melting as a result of the pressure exerted from the overlying ice lowering the temperature at which ice melts.

Question 29

What are the 4 different types of cold environments and their characteristics?

Answer 29

DIFFERENT COLD ENVIRONMENTS

1. Polar
   - Glacial environments found at high latitudes (66.7) of the Arctic/Greenland and Antarctica.
   - They are characterised by extremely cold temperatures and low levels of precipitation with permanent ice.
2. Alpine
   - Glacial environments are found at high altitudes in mountain ranges and mid to low latitudes (European Alps).
   - They are characterised by high levels of precipitation and a wide temperature range with frequent freeze-thaw cycles.
3. Glaciers
   - Slow-moving bodies of ice in valleys.
   - This shapes the landscapes in both polar and alpine environments.
4. Periglacial
   - No glaciers but are found next to glacial areas (edges).
   - They are characterised by permafrost.
   - Occurring at high latitude or high altitude areas where temperatures are above and below freezing point.
   - Extensive periglacial environments are found across Siberia.
   - Replacing glacial environments as ice retreats.

Question 30

What is the present-day distribution of high latitude ice sheets?

Answer 30

PRESENT-DAY DISTRIBUTION OF HIGH LATITUDE ICE SHEETS

1. Polar Ice Masses
   a) . Due to limited solar insolation as the Sun’s rays hit the ground at a lower angle so the solar energy received has to heat a larger area.
   b) . Around 85% of all glacial ice is contained in Antarctica.
   i) . The Greenland Ice Sheet is the second-largest accumulation of glacial ice with near 11% of the Earth’s total ice cover.
   ii) . Remaining ice cover is distributed among Icecaps.

Question 31

What evidence is there for Pleistocene Ice Sheet Extent?

Answer 31

PLEISTOCENE ICE SHEET EXTENT EVIDENCE

1. Ice cover in the Pleistocene maximum was more than three times greater than the present-day at 15.78 Square KM from 45.31 Square KM.
   a) . The Antarctic and Greenland ice sheets only covered a slightly greater area than they do today.
   b) . Glacial ice changes during the glacial-interglacial cycles of Pleistocene.
   i) . As the ice advanced and retreated in response to climate change.
   ii) . Periglacial environments existed at the margins of ice and shifted with ice movement, replacing glacial environments as the ice retreated.
   b) . Major extensions were two ice sheets in North America (Laurentide and Cordilleran) and the Scandanavian Ice Sheet in Europe.
   i) . With the North American sheets seeing the greatest retreats.
   ii) . Yet all growing to a thickness of 3000 - 4000m and transforming the landscapes.
   iii) . Other extensions include Southern South America, New Zealand’s South Island, Siberia and the Himalayas.

Question 32

What is the present-day distribution of high altitude glaciated landscapes and aspect?

Answer 32

PRESENT-DAY DISTRIBUTION OF HIGH ALTITUDE GLACIATED LANDSCAPES AND ASPECTS

1. Altitude (Alpine Glaciers)
   a) . High altitudes are impacted by the environmental lapse rate (ELR).
   i) . This is when the temperature declines by 1٥C for every 100m ascended.
   ii) . Upland glacial environments are found in the highest mountainous region.
   iii) . Such as glaciers above 4000m in Ecuador in the High Andes, Mount Kilimanjaro in Tanzania, The Himalayas and Southern Andes.
2. Aspect (Locally significant factors)
   a) . Determine the amount of snow falling and settling.
   b) . Relief in mountainous areas affects the distribution of cirque glaciers.
   c) . North-East facing slopes in the Northern Hemisphere are both more sheltered and shadier, and thus more conducive to snow accumulation.
   d) . Prexisting snow cover.
   i) . Glacial ice covers over 10% of the Earth’s land area.
   - 75% of the World’s freshwater is locked in this ice cover.
   - About 1.8% of all the water.

Question 33

What is the Environmental Lapse Rate?

Answer 33

ENVIRONMENTAL LAPSE RATE

• The rate of atmospheric temperature decreases with altitude at a given time and location.
• When the temperature declines by 1٥C for every 100m ascended.

Question 34

What are some examples of evidence of relict landscapes from the Pleistocene?

Answer 34

EVIDENCE OF RELICT LANDSCAPES FROM THE PLEISTOCENE

1. Relict glacial environment (as found in Britain)
   a) . It no longer experiences active glacial processes.
   b) . But it does display geomorphological evidence of the Pleistocene glaciation.
2. Erosional Evidence
   a) . Found in the Cairngorms (Scotland), Snowdonia (Wales) and the Lake District (England).
   b) . It includes Corries, Arêtes and Glacial Troughs.
   i) . Other landforms such as Rosh Moutonées, Crag and Tail and Knock and Lochan landscapes.
3. Depositional Evidence
   a) . Drumlins (Vale of Eden, Cumbria), Erratics (Bowder Stone in the Lake District), Moraine (Cairngorms).
4. Meltwater Evidence
   a) . Meltwater channels (Newtondale, North Yorkshire), Glacial Till (Holderness Coast), Eskers (Blakeney, Norfolk).

Question 35

What is a Periglacial Landscape?

Answer 35

PERIGLACIAL

• Climate conditions characterised by permanently frozen ground near the margins of glacial ice where subsoil temperatures remain below 0٥C for at least 2 consecutive years.
• The distribution of permafrost gives a good indication of the main periglacial regions (with permafrost being concentrated to high latitudes, but also in lower latitudes at higher altitudes).

Question 36

What are the characteristics of a Periglacial Landscape?

Answer 36

PERIGLACIAL CHARACTERISTICS

a) . Although they do not have a permanent covering of ice, they include:
i) . All non-glacial extreme cold climates with dry conditions (low precipitation - usually under 600mm per year).
ii) . This results in no tree growth/small shrubs (as growth is hindered by mean annual temperatures resulting in a short-lived growing season).
iii) . These low-growing plants are adapting to reduced water loss caused by exposure to strong winds in winter and thin soils becoming waterlogged (poorly drained land and thawing) in summer.
iv) . This barren tundra landscape is underlain by permafrost, with frequent free-thaw cycles causing interstitial ice (ice with cracks) to melt and permafrost.
v) . Mean temperature of less than 0٥C, minimum temperatures of -50٥C (high latitudes and high altitude environments which may or may not contain glaciers).
vi) . These climate conditions give variety in processes to produce distinctive landforms native to periglacial landscapes.
b) . Intense frosts during Winter and snow-free ground in Summer (-4 to 1٥C).
i) . Temperatures fluctuating through frequent cycles of freezing and thawing to cause interstitial ice (ice within cracks) to melt.
ii) . Thaw lakes are common as they form is Summer when any laying snow melts (together with the thin active later of thawed topsoil). As water retains heat from solar radiation, it increases the depth of thawing of the underlying permafrost (forming unfrozen zones known as Taliks).

Question 37

Where was the past distribution of periglacial landscapes?

Answer 37

PAST PERIGLACIAL LANDSCAPES

1. The distribution of periglacial environments in the Pleistocene glacial periods was widespread.
   a) . 33% of the world supposedly experienced these conditions (even at lower latitudes).
   b) . Even places as far south as the Mediterranean.
   c) . Relict landform evidence shows that Southern Britain was not covered by Ice, but instead experienced periglacial conditions.
2. During Pleistocene glacials, large areas of the present temperate mid-latitudes experienced periglacial conditions because of their proximity to ice sheets.
   a) . An additional 20-25% of the Earth’s land surface would have experienced permafrost or intense frost action during the Pleistocene glacials.

Question 38

Where is the present distribution of periglacial landscapes?

Answer 38

PRESENT PERIGLACIAL LANDSCAPES

1. 20% of the Earth’s land surface experiences periglacial conditions.
   a) . This is largely concentrated in the Northern Hemisphere at high altitudes and latitudes (Siberia, Canada, Scandinavia).

Question 39

What are the different types of Permafrost?

Answer 39

DIFFERENT TYPES OF PERMAFROST

1. Continuous Permafrost
   - Found at the highest latitudes when mean annual air temperatures are below -6٥C, and virtually all the ground is permanently frozen an there is very little, if any, surface melting. It may extend to depths of several 100 meters.
2. Discontinuous Permafrost
   - Shallower and the permanently frozen ground is fragmented and thinner by patches of unfrozen ground (Talik) with an open, through or closed talik.
   - The surface layer of the ground melts during the summer months to form Thaw Lakes.
3. Sporadic Permafrost
   - Occurs where the mean annual temperature is only just below freezing and permafrost cover amounts to less than 50% of the landscape, at the margins of periglacial environments.
   - Often occurs on shady hillsides or beneath peat.
4. Isolated Permafrost
   - Occurs when less than 10% of an area is affected by permafrost.

Question 40

What is the active layer?

Answer 40

THE ACTIVE LAYER

• The upper layer of the soil in permafrost environments that regularly thaws during the summer months.
• Unlike the permafrost below, it is highly mobile as a result of frequent freeze-thaw cycles and meltwater saturation, caused by the impermeable nature of the permafrost.
• This energy balance is positive, causing overlying snow and ice to melt away.
• On slopes, the saturated active layer will move downslope under the influence of gravity, slowly shaping landforms and landscape.
• Varies from a few cm’s to as deep as 3m.

Question 41

What factors influence the distribution and character of permafrost? -

Answer 41

FACTORS THAT INFLUENCE THE DISTRIBUTION AND CHARACTER OF PERMAFROST

1. Climate
   a) . Main control as temperature and the amount of moisture available determines the presence or absence, depth and extent of permafrost.
2. Proximity to water
   a) . Local-scale, as lakes are relatively warm and remain unfrozen throughout the year with a deep active layer by insolating the ground.
   b) . Thaw Lakes - Form in summer, when any laying snow melts (with the thin active layer of thawed topsoil). Water retains heat, and its relatively dark surface absorbs radiation from the sun.
   i) . This warmth increases the depth of thawing of the underlying permafrost - forming unfrozen zones called Taliks.
3. Slope Orientation
   a) . Influences the amount of solar radiation, and therefore melting, freeze-thawing and wind.
   b) . South facing = Less permafrost.
4. The character of the ground surface
   a) . (Different rock and soil types) this can determine the degree and depth of permafrost.
   b) . Albedo effect: Dark compacted rocks absorb a greater amount of solar radiation.
5. Vegetation Cover
   a) . This can insulate the ground from temperature extremes.
6. Snow Cover
   a) . This can slow the freezing process in winter and, in Spring, delay the thaw and development of the active layer.
7. Energy Balance
   a) . At the surface, the thermal characteristics of subsurface material, and geothermal heat flow from below.

Question 42

What are geomorphological processes?

Answer 42

GEOMORPHOLOGICAL PROCESSES

• Those that result in the modification of landforms on the Earth’s surface.
• These processes are most active at the margins of cold environments - where precipitation amounts are higher, liquid water is readily available, and temperatures hover above and below freezing.
• These processes actively shape the landscape by weathering and mass movement.
• Yet out of these processes, only frost shattering occurs outside periglacial areas; contraction and cracking of rapidly freezing soils, mitigation of subsurface water and mass movement of the active layer downslope are associated with permafrost and melting and movements within the active layer.

Question 43

What is weathering?

Answer 43

WEATHERING

- The breakdown or disintegration of rock in the situ, at or just below the ground surface.

Question 44

What are the different periglacial processes?

Answer 44

PERIGLACIAL PROCESSES

1. Nivation
   a) . A combination of processes associated with the accumulation of snow which weakens and erodes the ground beneath a snow patch.
   i) . Nivation Hollow (Berkshire Downs).
2. Frost Heave
   a) . The freezing and expansion of soil water causing the upward dislocation of soil and rocks. As the ground freezes, large stones become chilled more rapidly than the soil. Water below such stones freezes and expands, pushing the stones upwards and forming small domes on the ground surface.
   i) . Stone polygons on flat surfaces.
   ii) . Stone stripes or rock avalanches on slopes (Tinto Hills, Scot).
3. Freeze-Thaw Weathering
   a) . When water freezes in the cracks and joints of rock (commonly affecting bare rocky outcrops on a mountainside), it expands by up to 9% of its volume, exerting stress within the rock - enlarging cracks and pores, repeatedly weakening the rock and causing disintegration through this repeated cycle until chunks of rock break off and pile up as scree at the base of the slope (also known as frost action or frost shattering).
   i) . Blockfields (Cairngorms).
   ii) . Tors.
   iii) . Scree or Talus Slopes (Wastwater, Lake District).
   iv) . Pro Talus Ramparts.
   v) . Rock Glaciers.
4. Solifluction (Mass Movement)
   a) . This is the gradual downslope movement of the saturated active layer down a slope over a permanently frozen soil in tundra regions under the influence of gravity (known as gelifluction when it occurs over impermeable permafrost).
   i) . Solifluction lobe (College Valley, Northumberland).
5. High Winds (Aeolian Action)
   a) . Due to limited vegetation cover, the wind is able to pick up and transport the fine, dry sediment from the ground surface.
   i) . Loess as a windblown deposit of fine-grained silt or clay in glacial conditions (Parts of East Anglia).
6. Meltwater Erosion
   a) . During the short summer, thawing creates meltwater, which erodes stream or river channels. Refreezing at the onset of winter causes a reduction in discharge and sediment deposition in the channel.
   i) . Braided streams.
   ii) . Dry Valley (Devils Dyke).
7. Groundwater Freezing
   a) . Where water is able to filter down into the upper layers of the ground and then freeze, the expansion of the ice causes the overlying sediments to heave upwards into a dome, which may rise as high as 50m.
   i) . Pingo (North York Moors)
8. Ground Contraction
   a) . When dry areas of the active layer refreeze, the ground contracts and cracks. Ice wedges will form when meltwater enters the crack during the summer and refreezes at the start of winter. Repeated thawing and refreezing of the ice widens and deepens the crack, enlarging the ice wedges.
   i) . Ice-wedge polygons (Banks of the River Till).

Question 45

How are there periglacial landforms?

Answer 45

• Periglacial environments contain some unique landforms and some that are found more widely.
• It is the assembly of these landforms within a tundra slope catena, and tundra ecosystems and soils which create the distinctive periglacial characteristics.
• Periglacial features can appear in the relict form when the climate warms in periglacial conditions (a thermo-karst landscape can occur following the thawing of permafrost).

Question 46

What periglacial landforms does ‘Nivation’ form?

Answer 46

1. NIVIATION HOLLOW
   a) . The localised process of nivation occurs when both weathering and erosion takes place around and beneath a patch of accumulated snow (which can initiate the formation of cirques).
   i) . Fluctuating temperatures and the presence of meltwater promote frost shattering downwards under the force of gravity (weathering).
   ii) . Summer meltwater erosion will carry away any weathered rock debris, to reveal an ever-enlarging nivation hollow.
   iii) . As well as slumping in summer as saturated debris collapses due to the force of gravity (Solifluction).
   b) . As long as the freshly weathered material is removed by meltwater (or mass movement), the rounded nivation hollows will continue to be enlarged and eventually be occupied by glacial ice (corrie) in upland areas.

Question 47

What periglacial landforms does ‘Frost Heave’ form?

Answer 47

1. PATTERNED GROUND (STONE POLYGONS)
   a) . The freezing/expansion of soil water causing the upward dislocation of soil and rocks.
   i) . As the ground freezes, large stones become chilled more rapidly than the soil.
   ii) . Water below such stones freezes and expands up to 9% (ice lenses), frost push propels the stones upwards and while frost heave causes the stones to migrate outwards forming small up-doming on the ground surface.
   iii) . The up doming of the circle created by heave means that larger stones roll outwards as a result of gravity, finer sediments remain central (however smaller particles may then be removed by wind or meltwater).
   b) . As a result of mass movement, stone polygons are elongated into stone nets and stripes, with a clear relationship between slope angle and the type of patterned ground.
   i) . Sloping can distort the polygons, stone stripes form at steeper gradients.
   ii) . Stone polygons are found at gradient <6°.
   iii) . Stone stripes are found at gradient >6°.
   iv) . Once slope gradients go beyond 30°, patterned ground features no longer form and rock avalanches may occur.

Question 48

What periglacial landforms does ‘Frost Shattering (Freeze-Thaw Weathering)’ form?

Answer 48

1. BLOCKFIELDS (FELSENMEER)
   a) . Water freezes in the cracks and joints of rock.
   i) . It expands by up to 9% of its volume, exerting stress within the rock - enlarging cracks and pores.
   ii) . This weakens the rock and causing disintegration through this repeated cycle until chunks of rock break off and pile up as scree at the base of the slope (also known as frost action or frost shattering).
   b) . This accumulation of angular, frost shattered rock, which piles up on flat plateau surfaces, they form in situ, created by frost heaving of jointed bedrock and freeze-thaw weathering.
2. TORS
   a) . These which ‘crown’ hilltops, stand out from block fields as they form where more resistant areas of rock occur (less well-jointed rock).
3. SCREE OR TALUS SLOPES
   a) . Formed when rock fragments fall and accumulate on the lower slopes or base of cliffs.
   i) . The larger the material that makes up the slopes, the steeper its angle of rest tends to be.
   ii) . The slope is more a reflection of the rock type, length of slope and fragment shape, with shale/slates ‘packing’ together.
4. PRO-TALUS RAMPARTS
   a) . Created if a patch of snow has settled at the base of a cliff.
   i) . When rocks fall, as they are shattered by frost action, the snow patch acts as a buffer.
   ii) . The rocks settle at the base of the snow patch, leaving a rampart of boulders when the snow melts.
5. ROCK GLACIERS
   a) . When large amounts of frost shattered rock mixes with ice.
   i) . On the surface, rock glaciers look like streams/fans or angular rocks, but they are conjoined with interstitial ice below and move slowly like glaciers (up to 1m a year).

Question 49

What periglacial landforms does ‘Solifluction (Mass Movement)’ form?

Answer 49

1. SOLIFLUCTION
   a) . Occurs in regions underlain by permafrost.
   i) . During the summer months, the active layer melts forming a mobile water-saturated layer.
   ii) . As the saturated soil slumps downhill, this results in the formation of either stone-banked or turf-banked solifluction lobes (Tongue shaped) on the base of slopes of 10°- 20°.
   iii) . Terraces or benches occur on more gentle slopes.
   iv) . The resulting deposits collect in the bottom of periglacial valleys and are known as head or coombe rock.
   v) . Clasts (The stones in them) shows downslope orientation and both angular and sub-angular shapes.
2. FROST CREEP
   a) . A very slow form of mass movement; material moves downslope by just a few centimetres per year, even on steeper slopes.
3. ASYMMETRIC VALLEYS
   a) . These occur in periglacial environments.
   i) . Differential rates of solifluction and frost creep lead to one side of the valley being significantly steeper than the other.
   ii) . This is such in the Northern Hemisphere, where South-Facing slopes are more exposed to the Sun (Insolation) and thaw more frequently, thus increasing soil moisture and promoting mass movement, leading to a less-steep slope.

Question 50

What is Mass Movement?

Answer 50

MASS MOVEMENT
- The downward movement of material under the influence of gravity. It includes a wide range of processes such as rockfalls, landslides, mudflows and also solifluction (soil flow).

Question 51

What periglacial landforms does ‘Aeolian Action (High Winds)’ form?

Answer 51

1. LOESS
   a) . The absence of vegetation and the plentiful supply of fine loose material provides abundant opportunities for wind action.
   i) . Extensive accumulation of windblown deposits of fine Silt-sized sediment = formed on the extensive outwash plains (Sandurs) were blown southwards and deposited as Loess over large areas.
   ii) . This formed soils of high agriculture potential.
   iii) . In some places, it can be 300m deep.
   b) . Similar processes occur in non-periglacial areas such as the Gobi Desert to the Loess plateau in Northern China.

Question 52

What periglacial landforms does ‘Meltwater Erosion’ form?

Answer 52

1. BRAIDED STREAMS
   a) . In summer when surface snow and ice and the active layer melt leading to short periods of very high meltwater stream discharge.
   b) . The drainage pattern near the margins of glaciers is typically braided (Anastomosing) because of the high amount of debris being carried by meltwater streams.
   i) . This is not a unique process as this type of drainage pattern us associated with any streams with variable discharge regimes, which carry large amounts of load.
   ii) . Similar to a River Delta.

Question 53

What is Catena?

Answer 53

CATENA

- A connected series of related features, such features formed by periglacial processes which change down a slope.

Question 54

What is a Paraglacial landscape?

Answer 54

PARAGLACIAL

- Rapidly changing landscapes which were once periglacial or glacial, but are now moving towards non-glacial conditions.

Question 55

What periglacial landforms does ‘Groundwater Freezing’ form?

Answer 55

1. PINGOS
   a) . Ice filled, either conical or elongated periglacial hill.
   i) . The growth of an ice core forces up the overlying sediment, causing dilation cracks.
   ii) . Once this ice core is exposed at the surface it ruptures and melts, causing the top of the Pingo to collapse (forming a crater - Ruptured Pingo) to be filled with meltwater or sediment.
   iii) . Palsas’ are similar and found in peat beds.
   b) . Open System Pingo (Hydraulic Pingos)
   i) . Where permafrost is thin or discontinuous or on valley floors.
   ii) . Freely available groundwater is forced up through the gaps between areas of permafrost (from unfrozen layers lower down).
   iii) . The water collects together and freezes.
   iv) . This leads to the expansion of ice within the soil.
   v) . Water is then drawn towards this expanding core which then pushes the ground above it upwards to form a dome-shaped hill less than 50m high and 500m across.
   vi) . Mainly found in sandier soils.
   c) . Closed System Pingo (Hydrostatic Pingo).
   i) . Associated in low-lying flat areas and only formed in zones of continuous permafrost.
   ii) . These form from the downward growth of permafrost.
   iii) . A lake insulates the ground and the area beneath it remains unfrozen.
   iv) . Often after a small lake is gradually enclosed with sediments or dries up, making the ground no longer insulated.
   v) . The loss of the insulating influence of the lake allows permafrost to advance inwards from the lakeside, trapping the body of water and putting it under hydrostatic pressure = ultimately freezing as a core of ice which pushes up the Earth above it.

Question 56

What periglacial landforms does ‘Ground Contraction’ form?

Answer 56

1. ICE WEDGE POLYGONS
   a) . In extremely low temperatures with the refreezing of the active layer during the winter, the process of frost cracking creates irregularities in the ground as it contracts and cracks develop.
   b) . During the summer, meltwater fills these cracks/pores and then freezes and contracts in the winter to form Ice Wedges (Ice Needles in soil and sediment).
   i) . As the meltwater contains sediment, this also begins to fill the cracks.
   ii) . These increase in size through repeated cycles of freezing and thawing.
   iii) . Usually tapering shape 1 to 2m wide and up to 10m deep, taking over 100 years to form.
   c) . These also affect the ground surface, by forming narrow surface ridges due to frost heave.
   i) . As ice wedges become more extensive, a polygonal pattern may be formed on the ground, with ice wedges marking the sides of the polygons - patterned ground.

Question 57

What is a located example of a Periglacial Landscape?

Answer 57

NORTHERN CANADA

• The largest island in the Arctic Archipelago is Canada’s Baffin Island.
• Baffin Island is a typical periglacial landscape and tundra.
• Baffin Island has a number of ice caps (Penny and Barnes ice caps being the largest).
• It has ponds fed by run-off streams.
• Winters are long, dark and cold, yet summers are short when the snow and soil layers melt.
• Waterlogged soils and 24-hour sunshine during the Summer period boosts rapid plant growth (densely packed low lying plants growing in the Tundra’s lower latitudes).