Glaciation Flashcards
Define stadial and interstadial
Stadial: Short-lived colder periods within a major glacial, associated with ice advance.
Interstadial: Short-lived warmer periods within a major glacial, associated with ice retreat.
What is a key factor in determining whether we enter a glacial period?
The amount of solar radiation received during the summer months as this will determine whether ice built up over the winter will stay or melt.
What is an example of an unconstrained ice mass?
Ice sheets, ice caps, ice streams.
Where are periglacial landscapes found?
At the edge of permanent ice.
What are the processes operating in periglacial landscapes?
nivation, frost heave, freeze-thaw weathering, solifluction, ground contraction, high wind, meltwater erosion, groundwater freezing.
What is dynamic equilibrium?
Rates of accumulation match rates of ablation.
What is the difference between pressure melting points of temperate and polar glaciers?
-PMP in temperate glaciers are more consistent with depth, whereas PMP in polar glaciers increases with depth.
-PMP is higher in temperate glaciers than in polar glaciers.
What is one example of a meso-scale landform?
Roche moutenées, crag and tail, drumlins, meltwater channels, eskers, moraines.
describe the process of plucking.
plucking occurs when basal meltwater freezes around part of the bedrock at the base of the glacier. Any loosened rock fragments are plucked away as the glacier moves forward.
Where does medial moraine form?
At the intersection of two joining glaciers.
periglacial processes-nivation
a combination of processes weakens and erodes the ground beneath a snow patch including freeze-thaw weathering, solifluction and meltwater erosion.
periglacial processes-frost heave
the freezing and expansion of soil water creates pore ice or ice needles. this causes the upward dislocation of soil and rocks. As the ground freezes, large stones become chilled more rapidly than the soil. water below these stones freezes and expands, pushing these stones upwards
periglacial processes-freeze-thaw weathering
when water freezes in the cracks and joints of rocks, it expands. this exerts stresses within the rock, enlarging cracks and pores. eventually large chunks of rock break away.
periglacial processes-solifluction
the downslope movement of the saturated active layer under the influence of gravity
periglacial processes-ground contraction
when dry areas of the active layer refreeze, the ground contracts and cracks. meltwater enters the cracks during the summer and will then freeze in the winter
periglacial processes-high wind
a lack of vegetation cover means the wind is able to pick up large amounts of material and redeposit it far away.
periglacial processes-meltwater erosion
during the summer, thawing creates meltwater which erodes stream or river channels. refreezing in winter causes sediment deposition in the channel
periglacial processes-groundwater freezing
when 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.
periglacial landforms-patterned ground
repeated freezing and thawing of moist, frost-susceptible soil forming circles, polygons, irregular nets and stripes.
periglacial landforms-ice wedges
vertical masses of ice that penetrate down to 10 metres from the surface in some cases. formed as a result of meltwater entering a ground crack in the summer and freezing when the temperature drops. causes an expansion which fractures the surrounding material and makes the wedge deeper and wider. during the intense cold of winter, the surrounding soil contracts which creates a gap between the developing ice wedge and adjacent soil where more water can infill. this process will continue over time and the ice wedge will continue to widen and deepen
periglacial landforms-blockfields
extensive areas of angular rock that have been created by regular freeze-thaw activity. the material is left strewn across the level ground with blocks representing more homogenous lithology and the gaps where the bedrock had more weaknesses and/or joints. large areas of these rocks are called felsenmeer- where this occurs on rock faces on a gradient, scree will be left at the bottom of the slope where talus accumulates.
periglacial landforms- pingos
hills with an ice core. they are between 3 to 70 metres in height and circular in shape. the ice in the centre accumulates because of hydrostatic pressure or groundwater flow
periglacial landforms-solifluction lobes
created the the saturated layer of soil is thawed, usually in summer months. gradient of the ground is important as they only form on slopes. winter freeze-thaw weathering loosens material while summer thaw melts the ice content and then it will flow down the hill. when the gradient changes and flattens out, the material flow slows and is deposited in a tongue shape.
terminal moraine
material eroded by the glacier and left as the glacier retreated. this marks the furthest extent of the glacier and is therefore called terminal moraine
erratic
glacier-transported rock which differs from the local geology, left behind as the glacier melted
talus
accumulation of loose rock at the base of a steep slope, eroded by the glacier
hummocky drift
let down by the glacier as it melted
periglacial
areas at the edge of permanent ice characterised by permanently frozen ground.
accumulation
a net gain of ice over the course of a year. inputs exceed outputs
ablation
a net loss of ice during a year. outputs exceed inputs
avalanching
rapid flow of snow down a slope
sublimation
the change from the solid state to gas with no immediate liquid stage
hoar forst
occurs when a sub-zero surface comes into contact with moist air. water vapour in the air turns directly into ice by deposition
plucking
meltwater freezes around bedrock at base of glacier. as glacier moves, it pulls out pieces of this rock
abrasion
sandpapering effect of ice as it scours away at the landscape
debris
loose pieces of rock
basal melt
melting at the base of the glacier
moraines
material eroded by the glacier and left as the glacier retreats
subaerial melt
melting on the surface of the glacier
calving
the breaking of ice chunks from the edge of the glacier
subaqueous frontal melt
underwater melting
polar glaciers
glaciers in cold, polar environments (Greenland, Antarctica). the glaciers are frozen onto the bedrock beneath so melting is limited during the short summer season. move more slowly than temperate glaciers
temperate glaciers
occur in alpine glacial environments (Alps, Norway, New Zealand). temperature of ice is often close to zero and mild summer temperatures cause melting. move faster than polar glaciers.
pressure melting point
temperature where ice is on the verge of melting. as pressure increases, freezing point falls below 0 degrees.
supraglacial
mainly weathered material carried on top of the ice
englacial
formally supra glacial material, but now buried by fresh snowfall carried within the ice
subglacial
material carried below the ice, which is dragged and pulverised by the overlying glacier.
meltwater erosion
a large volume of water produced by basal melting causes fluvial erosion (hydraulic action, attrition, abrasion) which will erode at the base of the glacier overtime.
Arctic-polar tourism
increase in tourism in Svalbard- tourists travel up the Norwegian Coast with North Cape receiving 1 million tourists every year
there has been a huge increase in landing sites (almost 200) which increases the amount of damage to uninhabited areas.
increasing number of ships- more restrictions of tourist activities- “current environmental regulations are not sufficient to protect Svalbard’s endangered nature and cultural heritage”-Ellen Hambro (director)
however, this creates economic issues- these areas rely on tourism for economy which means that they will have to focus on different, suitable activities like guided tours (similar to that in the Galápagos Islands) with strict visitor regimes but this could still limit the economic reach.
Antarctic Treaty
1st December 1959, Australia became the first among 12 to sign the Antarctic treaty.
54 nations have now signed the treaty that bans mining and militarisation of the continent.
in 2048, it could be argued that the area can open up for mineral resource activity
provisions:
Antarctica shall be used for peaceful purposes only, freedom of scientific investigation shall continue, scientific observations and results from Antarctica shall be exchanged and made freely available
all members have to inform each other of their activities in Antarctica and facilitate inspections by other parties
74,000 visitors per season
Alpine Convention
sustainable life in the alps- first international treaty aimed at sustainable development of an entire mountain range
2 degrees temp increase in the alps since 19th century
alpine convention was entered into force in 1996
parties only consist of 8 alpine countries (Austria, Germany, France, Italy, Liechtenstein, Monaco, Slovenia and Switzerland) and the EU
17 goals to establish sustainable development
however, some goals are unachievable or difficult to achieve e.g. the climate action goal is achievable on a local scale, but will take more than the 8 countries and EU to combat climate change and its impacts solely in the Alpine region. similarly with sustainable consumption and production of energy will be near impossible/ ineffective on this scale
Svalbard Environmental Protection Act
disembarkation of tourist businesses in the protected area on Svalbard
protection of polar bears- 500 metre distance
ships sailing in protected areas- max 200 passengers
motor traffic ban on sea ice- ban on selected fjords for visitors and permanent residents
however this act has been heavily criticised as it completely limits the tourist industry in Svalbard, the regulations on permanent residents has caused reactions as it limited their freedom of movement.
yamal peninsula
threats: infrastructure constructed for the exploitation of gas is destroying pasture, causing overgrazing by reindeers that has led to the disruption of migration routes
gas exploitation has led to cultural and environmental concerns. projects have led to eviction of over 160 reindeer herds
infrastructure projects have created concerns surrounding the Nenets and their ability to maintain their culture whilst being forced to live a modern lifestyle- however these projects will benefit local community through hospitals and schools
climate change-permafrost stores high volumes of carbon and methane. releasing them could create a positive feedback loop of melting permafrost, released greenhouse gases and rising temperatures.
lake district
relict landscape- current threats include congestion, increased house prices, environmental damage and footpath erosion. However, there have been positive impacts to the Lake District as a result of tourism which includes improvements to public transportation, job opportunities for locals, bringing in around £1.48 million a year.
Management: Fix the Fells- management strategy which involves a volunteer project in which the paths of the landscape are repaired- 400 miles of path are repaired each year.
on top of restoring paths, over 70 volunteers have been conserving the park through litter picks
Paris agreement
legally binding treaty on climate change that was adopted by 196 parties at COP21 on December 12th 2015 and was entered into force on 4th November 2016.
overarching goal is to limit the temperature increase from 2 degrees to 1.5 degrees above pre-industrial levels
it works on a five year cycle of increasingly ambitious climate action
long term strategies include submitting long-term low greenhouse gas emission development strategies
since its entry, low-carbon solutions and new markets have been established and more and more countries, regions, cities and companies are establishing carbon neutrality targets.
however, it could be argued that this is unachievable by 2030 despite continued efforts by countries and regions
