Topic 2 - Glaciation: EQ1 Flashcards
What’s an icehouse state?
A global ice age when large ice sheets are present on the earth. During this time glaciers advance and retreats
What’s a greenhouse state?
When there is no continental glaciers on the planet as a result of warming processes such as high levels of greenhouse gases
What state is the earth at now?
Icehouse
When was the Pleistocene?
Lasted 2 million years and ended around 11,500-12,000 years ago
What’s the Holocene?
It began 10,000 years ago and continues today
When did the quaternary ice age start?
Started approximately 2.6 million years ago and extends up to an including the present day
What was the Loch Lomond Stadial?
This was the last glacier advance
What was Devensian?
last glacial period
What are the three main characteristics of the Pleistocene?
- it was just an ice age and it lasted 2 million years. The temperature fluctuated to allow ice advances and retreats.
- The extent the ice advanced during each glacial period was different
- They were short lived pulses of ice advances and warm pairs of retreat.
What are stadials and interstadials?
Stadials- where the ice advances
Interstadials- where the ice retreats
How have plate tectonics started the Pleistocene?
3 million years ago, the north and South American tectonic plate collided and this reroute ocean currents and were forced towards Europe and this created the Gulfstream and this transported extra moisture to the Arctic atmosphere and fell as snow and created ice sheets
Name a long-term cause of climate change
Long-term changes in the earths orbit around the Sun are currently seeing as a primary cause is the oscillations between glacial identical conditions
What is the Milankovitch theory?
It is changes in the orbital characteristics of a planet and controls how much sunlight different areas receive
Name the three main characteristics of the earths orbit
- Obliquity cycle
- Eccentricity cycle
- Procession of the equinoxes
What is a obliquity cycle?
The till of the Earth’s axis varies between 21.5° and 24.5° over 41,000 year cycles and this changes the severity of the seasons
What is eccentricity cycle?
The shape of the earths orbit varies from circular to elliptical over 100,000 year cycles. The earth receives less solar radiation in the elliptical orbit as it is further from the Sun.
What is the procession of the equinoxes?
The earth wobbles as it spins on its axis and this means that the season during which the Earth is nearest to the Sun varies. This varies over around 21,000 year cycles.
Evidence in support of the Milkankovitch cycles?
In support of the theory is the fact that glaciers have seen to occurred a regular intervals of approximately 100,000 years
What is the climate feedback?
Feedback effects are those that could either amplify a small change and make it larger which is positive or diminish the change and make it smaller which is negative
What is positive the feedback on the earth?
- Small increases of snow and ice raise surface albedo (reflectivity) so more solar energy is reflected back into space and lead to calling
- The melting of snow by carbon outside emissions decreases the albedo effect so more sun is absorbed which leads to warming
What is a negative feedback on the Earth?
- Increasing global warming means more more evaporation and this adds to global cloud cover and this means more solar energy energy is reflected back into space
- Warming waters in the Arctic disrupt ocean currents and this means less warm water from the Gulfstream goes north which could lead to global cooling
Name a short term cause of climate change
Variation in solar output
Volcanic emissions
Explain variations in solar output
Sun sports are caused by intense magnetic activity in the suns interior when they increase this means the sun is more active and giving off more energy and this means the number of sunspots indicate level of solar output. They vary over a 11 year cycle
Explain why volcanic emissions is a short-term cause of climate change
The most significant volcanic impact on climate is the injection into the atmosphere of large quantities of sulphur dioxide gas and this remains an atmosphere for as long as three years. Sulphate aerosols are formed which increased reflection of radiation from the Sun back into space, cooling the Earth.
Name some characteristics of the Loch Lomond stadial
Around 12,500 years ago, the temperature plunged downwards and glacial conditions occurred. Glaciers began to re advance in many parts of the world due to the temperature being 6 to 7°C lower.
It was triggered when drainage of the huge proglacial lake disrupted the THC and cutting off heat transport from the Gulfstream.
What was the little ice age and it’s affects?
It was the longest glacier oscillation in history
Affected farms in Iceland.
Many glaciers places in Europe re advanced down valleys
Rivers in UK and Europe froze over
What is the cryosphere?
Places that are so cold the water is permanently frozen and it’s stored as ice or snow
What is the cryosphere made of and why is it important?
Made of ice sheet and glacier and it is important as mass and energy a constant exchange between it and other components of the Earth systems
They also act to stores within the global hydrological cycle and plays a vital role in the earths climate
Name at least three types of ice masses
Ice sheets
Ice cap
Icefields
Valley glacier
Piedmont glacier
Cirque glacier
Ice shelf
What is the biggest type of ice mass?
Ice sheets which are over 50,000 km²
What does constraint mean?
It is restricted to the shape of the area around it
How can ice masses be classified?
By scale, location and by their thermal characteristics
What is a warm based glacier?
They occur in high altitude areas such as the Alps. The temperature of the surface layer fluctuates above and below melting point. It moves rapidly due to meltwater
What is cold based glaciers?
They occur in high latitudes such as Greenland and they have very low temperatures and this means little surface melt water so it is permanently frozen to its bed
What is hybrid poly thermal glacier?
The underneath is warm based and the margin is cold based and this happens in places such as Norway
What are polar regions?
Areas of permanent ice
What are periglacial regions?
They are at the edge of permafrost ice and they are characterised by permanent frozen ground. These regions vary between areas that are permanently frozen and those that thaw in summer.
What are alpine/mountain regions?
High altitude result in cold conditions and there are glaciers and glaciated landscapes found here
What are glacial environments?
Found at the edges of the ice sheets and in particular the highest mountain regions
What is permafrost?
Permanently frozen ground
What is continuous permafrost?
Forms in the coldest areas of the world where the annual air temperature is below -6°C
What is discontinuous permafrost?
Is more fragmented and thinner
What is sporadic permafrost?
Occurs at the margins of Perry glacier environments and is usually very fragmented and only a few metres thick
What is the active layer?
The top layer of soil and permafrost environments that thaws during summer and freezes during winter
Name factors that might influence the distribution and character of permafrost
Proximity to water
Slope orientation
Character of ground service
Vegetation cover
Snow cover
What are Geomorphological processes?
The result in the modification of landforms in the Earth surface and the shape the Earth
What is freeze thaw weathering?
When water freezes in the cracks and joints of rock this expands to 10% of its volume and this weakens the rock and repeated freeze thaw cycles keeps making the crack bigger so more water can fall in and get frozen
What is block fields?
Are accumulation of frost shattered rock which pile up on flat surfaces. They formed in situ and are created by Frost heaving of joint bedrock and freeze thaw weathering
What are tors?
They stand out from Blackfield as they form where more resistant areas of rock occur. (Crown hill tops)
What is scree or talus?
Formed in rock fragments, fall and accumulate on the lower slopes or base of cliffs
What is pro-talus ramparts?
Are created of a patch of snow has settled at the base of a cliff and then rock falls and as they are shattered by frost action the snow patch act as a buffer. The rock settle at the base of the snow patch leaving boulders where the snow melts
What are rock glaciers?
Form when large amount of frost shattered rock mixes with ice. On the surface rock glaciers look like streams/fans or angular rocks. They move slowly like glaciers
What is nivation?
A combination of processes weakens and erodes the ground beneath a snow patch
What is frost Heave?
The freezing and expansion of soil water causes upward dislocation of soil and rocks. As the ground freezes large stones become chilled more rapidly than the soil and water below freezes and expands pushing the stones upwards.
How are stone polygons formed?
They are directly associated with ice wedges. Frost Heave causes the ground to expand and lift soil particles upwards. Smaller particles may then be removed by wind or melt water and this leaves a concentration of larger stones lying on top of the eye wedges and this makes a polygon pattern.
What leads to stone striping?
Sloping ground can distort the polygon as the stone gradually slides or rolls downslope and this leads to the formation of Stone stripes
What is ground contraction?
When dry areas of active layer refreeze the ground contracts and cracks. Ice wedges will form and then melt. Water enters the cracks during summer and freezes at the start of winter after it is repeated many times the ice edge widens and deepen the ice crack in the ice wedge
How do ice wedge polygons form?
When there are low temperatures the ground contracts and cracks develop. Meltwater fills these cracks and then freeze in summer (ice edges). These also affect the ground surface, by forming narrow surface rides due to frost heave. As ice wedges become more extensive a polygonal pattern may form on the ground
What is solifluction?
The downslope movement of the saturated active layer under the influence of gravity
How do solifluction lobes form?
Slow downhill flow of saturated soil. The active layer provides enough water to allow flow to occur. As the saturated soil slumps downhill during summer it forms solifluction lobes
What is mass movement?
The downward movement of material under the influence of gravity
What is Aeolian action?
Due to limited vegetation cover the wind is able to pick up and transport the fine, dry settlement from the ground surface
What is meltwater erosion?
During a short summer thawing create melt water which a erodes streams or river channels. Refreeze at the start of winter causes a reduction in the discharge and sediment deposition in the channel
What is the role of wind about water rivers in Periglacial areas?
Most of the water is frozen and not available for plant growth and this means the absence of vegetation provides opportunity for wind action
What is loess
Extensive accumulation of wind blown deposits
What is braiding (river)?
a type of river that form a network of many branches within a channel
