EQ1- How Has Climate Change Influenced The Formation Of Glaciated Landscapes Over Time Flashcards
Approximately how old is the earth
4.6 billion years old
What are the two dominant states of the earth which fluctuate
Icehouse state - there is ice and snow on earth
Greenhouse state - there is no ice/snow on earth
What state and period is the earth in currently
The earth is in an icehouse state as there is ice on earth
We are currently in an interglacial period
What is the Quaternary
The most recent ice age that we are currently in.
It is one of 5 glacial periods in the cenzoic era
What are the two epochs in the Quaternary age
The Pleistocene- lasted until 10,000 years ago
The Holocene - Began 10,000 years ago till present day
What is the Pleistocene
An epoch in The Quaternary ice age
Is known as an ice age as it has had over 50 glacial- interglacial periods
What are the 3 characteristics of the Pleistocene epoch
It was not just a single ice age, there was a number of ice advances and retreats
The extent to each ice advance during each glacial was different
There are many fluctuations
What are stadials
Short lived pulses of ice advance
What are interstadials
The warmer periods of retreat
What is Devensian
Was the last known glacial maximum , which occurred 18000 years ago
What is Loch Lomand Stadial
Marked the end of the Pleistocene epoch, 12,000 years ago
Explain the long term factors that lead to climate change (milankovitch cycle)
Individually, the orbital variations of precession, eccentricity and obliquity have little impact on the 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
What is the Milankovitch cycle
A cyclical movement related to the earths orbit around the sun.
There are three of them : precession, eccentricity and obliquity
Define positive feedback
How did it lead to climate change
Positive feedback is amplification
To explain the large temperature changes for expanses of ice to form or melt positive feedback is involved.
This happens when a small increase of snow/ice increases the surface albedo, more energy is reflected back into space, leading to further snowfall.
This continues to amplify bringing drastic temperature change
Define negative feedback
Trying to restore dynamic equilibrium
Explain the short term causes of climate change (volcanic eruption)
Volcanic eruptions emit ash and more importantly sulfur dioxide gas in large quantities
Sulphate aerosols are formed and they stay in the atmosphere for years
They cause an increase in the reflection of radiation from the sun back into space , cooling the earths atmosphere
Explain the short term causes of climate change (solar output variations)
Sunspots are dark patches on the face of the sun caused by intense magnetic activity in the interior
An increase in sunspots means that the sun is more active and gives off more energy, heating the earths atmosphere
Explain the short term causes of climate change (feedback mechanisms)
Neither solar output variations or volcanic activity can cause climate change
Feedback mechanisms are needed to amplify change associated with short term stadial and interstadial fluctuations
Describe the cause of the Loch Lomand Stadial (pleistocene)
One possibility was that it was triggered by the drainage basin of the lake agassiz which disrupted the thermal haline current, cutting off the transfer of heat from the gulf stream ocean current
Describe the characteristics of the Loch Lomand Stadial
Ice began to readvance as temperatures lowered by 6-7 degrees
Describe the cause of the little ice age (holocene)
A possibility is that four big volcanic eruptions led to global cooling due to the huge amount of sulphate aerosols in the atmosphere
Another possibility was solar output variations
Describe the characteristics of the little ice age
Brought cold winters, frozen rivers and lakes
Sea ice extended in Iceland
Artic sea ice spread down south
Define the Cryosphere
Places on earth where water is permanently frozen there and stored as snow or ice
What are the three main roles of the cryosphere
Constantly exchange mass and energy with other components
Help regulate temperatures on earth
Sensitive barometers of climate change
Explain one approach to classifying ice masses (warm based glaciers)
Seen in high altitude locations like the Alps and Subarctic areas
Warmer due to the friction from the glacier moving and geothermal energy from the ground
At the base of the glacier it has reached pressure melting point
Cause glacial meltwater to form which acts as a lubricant
Glacial meltwater causes erosion as the glacier moves
It picks up debris and causes further erosion of the land
Explain one approach to classifying ice masses (cold based)
Seen in high altitude locations like the Antarctic and Greenland
Average temperature is below 0 degrees and the ground does not generate geothermal energy
Means no melting of the base or glacial meltwater
Glacier is frozen in place meaning there is an absence of erosion
Explain one approach to classifying ice masses (hybrid polythermal glaciers)
Glacier can become so big that its a hybrid polythermal glacier
Cold based in the upper regions and warm based when it extends into warmer climate zones
Scale and location - Ice sheet
Give a description, size, degree of constraint and example
A mass of snow/ice with considerable thickeness
50,000 sq/km
Unconstraint
The edge of the east Antarctic
What does constraint mean
What does unconstraint mean
Where the ice mass shapes the landscape
Where the ice mass runs over the landscape
Scale and location - Ice cap
Give a description, size, degree of constraint and example
Dome shaped mass of glacier ice , found in highland areas
50,000 sq/km
Unconstraint
Northern antarctic peninsula
Scale and location - ice field
Give a description, size, degree of constraint and example
Small and determined by the shape of the surrounding land
Less than 50,000 sq/km
Constraint
Scale and location - Valley glacier
Give a description, size, degree of constraint and example
A glacier bounded by the walls of a valley and descending mountains
Constraint
In the Alps
Scale and Location - Piedmont Glacier
Give a description, size, degree of constraint and example
A glacier which spreads out as a wide lobe as it leaves the narrow mountain valley
Constraint
Southern Axel Heiberg Island
Scale and location - Cirque Glacier
Give a description, size, degree of constraint and example
A glacier occupying a cirque ( a hollow formed from glacial erosion)
Small in size
Constraint
Teton Glacier in USA
Scale and location - Ice Shelf
Give a description, size, degree of constraint and example
A large slab of ice floating on the sea but remaining attached to land derived ice
Big in size
Unconstraint
Tubular ice bergs in East Antartica
What are the 4 parts of the distribution of cold environments
Polar(high latitude) regions : areas of permanent ice
Periglacial (tundra) regions : layer of permanently frozen ground (permafrost)
Alpine/mountain (high altitude) regions : where glaciers are found
Glacial environments : found at edges of ice sheets in mountainous regions
What are the different types of evidence for the Pleistocene ice sheet which covered the majority of the UK
Depositional evidence : drumlins and moraines formed
Erosional evidence : includes corries , arêtes and glacial troughs found in Snowdonia and the Lake district
Meltwater evidence: Meltwater channels, glacial tills and eskers were formed
Describe the distribution of :
i. High latitude polar ice sheets
ii. High altitude alpine glaciers
Mainly found in Antartica and Greenland
Found in mountainous areas around the world like: North America, Chile, Europe and Asia (Himalayas)
Define permafrost
Is soil and rock which remains frozen as long as temperatures do not exceed 0 degrees Celsius
Define :
i. Continuous Permafrost
ii. Discontinuous Permafrost
iii. Sporadic Permafrost
Forms in the coldest areas in the world where it can exceed downwards hundreds of metres
More fragmented and thinner
Occurs in periglacial environments and is very fragmented
What is the active layer
The top layer of soil in permafrost environments that thaws during the summer and freezes during the winter
Explain the periglacial process of Nivation and the effect it has on the landscape
When a combination of freeze thaw weathering, chemical weathering and solifluction causes nivation hollows to form and increase in size.
Eventually the nivation hollow gets so big that glacial ice forms and it forms a corrie
Explain the periglacial process of frost heave and the effect it has on the landscape
Is a process which forms patterned ground
Happens due to the freezing and expansion of soil water causing the upward movement of soil and rock.
Stones are heaved upwards and cause stone polygons or strips to form on the surface.
Explain the periglacial process of solifluction and the effect it has on the landscape
Solifluction forms solifluction lobes
This happens when the active layer becomes over saturated and water cannot percolate as its on top of permafrost.
The active layer moves downwards,due to gravity, and forms a solifluction lobe
Explain the periglacial process of ground contraction and the effect it has on landscapes
Is a process which forms ice wedge polygons.
This happens when extremely low temperatures cause the ground beneath the active layer to crack.
Glacial meltwater enters the crack and expands due to freeze thaw weathering
Ice wedges form in the cracks and cause rock and sediment to be lifted upwards forming patterned ground
Explain aeolian action (loess)
Wind is able to pick up and transport dry sediment from the grounds surface, due to limited vegetation cover
Extensive accumulations of wind deposits are called loess
Explain meltwater erosion (braiding)
Where meltwater is created by thawing in the summer. It erodes the river channel causing high discharge.
The drainage pattern near the margins of glaciers is braided as high amounts of debris is carried.
What is groundwater freezing
Where water is able to filter into the upper layer of the ground and freeze causing an ice cored dome to form, called a pingo
