Glaciated Landscapes and Change Flashcards
What do periglacial processes include?
- Nivation, frost heave, freeze thaw weathering, solifluction, high winds, meltwater erosion
What are 4 unique periglacial landforms?
- Ice wedges 2. Patterned ground 3. Pingos 4. Loess
What are the three processes of accumulation?
- Direct snowfall 2. Avalanches 3. Wind depostion
What are the five processes of ablation?
- Melting 2. Sublimation 3. Calving 4. Evaporation 5. Avalanches
What are the three different processes that are important in the movement of glaciers?
- Basal slip 2. Regelation creep 3. Internal deformation
What are 5 factors that affect the rate of movement in glaciation?
- Altitude 2. Slope angle/gradient 3. Ice thickness 4. Bedrock permeability 5. Variations in mass balance (ice temp, rates of ablation and precip)
How and when were ice ages discovered?
In 1830s by Louis Agassiz in the Swiss Alps. Identified that they had occurred all over Europe, saw that certain areas had similar features
What is the theory of Uniformitarianism?
The assumption that the same natural laws and processes that operate in our present day scientific observations have always operated in the universe in the past and apply everywhere in the universe
What does glacial and interglacial periods mean?
Glacial - period of intense cold
Interglacial - period between glacial periods
How have ice cores helped determine past climates?
Bubbles trapped in the ice contain CO2 from the atmosphere
What epoch are we currently living in?
Quaternary epoch
What are epochs?
Periods of geological time. These relate to times of the past where geological strata were laid down. Epochs denote changes such as mass extinctions
What three epochs is the quaternary period divided into and explain them
- Pleistocene - covers the beginning of the quaternary period, this is the age we will study in detail 2. Holocene - interglacial period of man 3. Anthropocene - begins from when there was significant human impact on Earth until now, including such things as biodiversity loss and climate change
Does the Pleistocene epoch have multiple glacial and interglacial periods?
Yes, causes the landscape to remould and reshape each time, this makes it complex to reconstruct the past
How many years roughly is there a new glacial or interglacial period?
Every 100,000 years
Give another way glacial landscapes can be modified other than other glacial periods
Geomorphological processes
What are stadials and interstadials?
Stadials - smaller fluctuations and shorter periods of intense cold
Interstadials - shorter periods of relative warmth
Recent ice core analysis show these to be sometimes quite abrupt changes
Give the 5 types of glacial erosion
- Quarrying 2. Plucking 3. Abrasion 4. Crushing 5. Basal melting. These all combine with subaerial freeze thaw and mass movement
Give the 7 upland erosional features
- Cirques/corries 2. Aretes 3. Pyramidal peaks 4. Glacial troughs 5. Truncated spurs 6. Hanging valleys 7. Ribbon lakes
Give the 4 landforms due to ice sheet scouring
- Roches moutonnees 2. Whalebacks 3. Knock and lochan 4. Crag and tail
What is the pleistocene?
Covers the beginning of the quaternary period, glacial epoch. around 2,588,000 to about 11,700 years ago
What is precession?
A gradual change, or wobble, in the orientation of Earth’s axis affects the relationship between Earth’s tilt and eccentricity
When did the quaternary period start?
2.588 million years ago!!!!!!!! wow
How many years of climate can ice cores track back to?
800,000 years
What is the first milankovitch cycle theory and how often does this happen?
Eccentricity of orbit - happens every 100,000 years
How often does axial tilt happen?
41,000 years
How often does precession happen?
Every 21,000/22,000 years
Spell the volcano in Iceland that sir wants you to spell for some reason
Eyjafjallajokull
What are the three reasons for glacial deposition?
- When the velocity is reduced 2. They become overloaded with debris 3. When ablation increases
What are the six ice contact depositional features?
- Erratics 2. Medial moraines 3. Lateral moraines 4. Recessional moraines 5. Terminal moraines 6. Drumlins
What are the two types of till plains (lowland depositional features)?
- Lodgement till 2. Ablation till
Explain the eccentricity of orbit as a primary cause of climate change. 4 points
- Elliptical earth orbital cycle to circular every 100,000 years 2. Amount of solar radiation received in high eccentricity orbit varies greatly, increase in magnitude of seasonal changes 3. Low eccentricity leads to low seasonality - promotes glaciation 4. As a result, temps at high latitudes in northern hemisphere increase
Explain obliquity as a primary cause of climate change. 5 points
- Axial tilt varies from 21.8 degrees to 24.4 degrees, currently at 23.5 , 2. 41,000 year timescale 3. Impacts intensity of light received at poles - seasonality of Earth 4. Less tilt=warmer winters but cooler summers - glaciers do not melt in summer - advance, low obliquity=low seasonality 5. Glaciers will reflect more of incoming solar radiation further cooling planet
Give four different characteristics of glacial and fluvioglacial deposits
- Stratification 2. Sorting 3. Imbrication 4. Grading
Give three formations of fluvio-glacial ice contact features
- Kames 2. Eskers 3. Kame terraces
Give four fluvio-glacial proglacial features
- Sandurs 2. Pro-glacial lengths 3. Meltwater channels 4. Kettleholes
Explain precession as a primary cause of climate change in 5 points
- The earth wobbles on its axis changing the point in time the earth is nearest the sun (21,000/22,000 year cycle) 2. Means that the North Pole points both towards and away from the sun increasing the variation in the irradiation of the Northern Hemisphere 3. Causes variation in summer and winter temperatures and so causes variations in ice volume 4. Precession (tilt direction) works in conjunction with eccentricity to control the level of insolation at 65 degrees north 5. Glaciation is favoured when the direction of the tilt is such that N.hemisphere summers are at the largest earth-sun distance
How much do the Milankovitch cycles affect the temperature by?
1 to 1.5 degrees
How many degrees change does there need to be for ice to form?
5 degrees
Give an example of positive feedback
Small increases to snow and ice cover can raise surface albedo (the quantity of reflection of sunlight) - more solar radiation is reflected back into space - could lead to more snow and ice cover
Give two examples of negative feedback
- Increases global warming and industry leads to more evaporation which increases cloud cover - increased cloud cover reflects solar energy back into space - reducing the intensity of global warming 2. Ice sheet dynamics disrupt thermal heating circulation - warming waters in the Arctic disrupts ocean currents - less warm water from the gulf stream creating global cooling in N.Europe
