Science Olympiad Dynamic Planet Glaciers 2014

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carrieross
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269859
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Science Olympiad Dynamic Planet Glaciers 2014
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2014-04-13 15:31:17
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science olympiad glaciers glaciation Dynamic planet
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Review of SciOly.org's Dynamic Planet page.
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  1. First year glacial snow is known as _____.
    neve
  2. Accumulated snow that has survived one melt season is known as _____.
    firn
  3. What are the 3 mechanisms affect how glaciers are able to flow?
    • The first is the slope of the bedrock surface
    • The second mechanism of flow is internal deformation
    • The third is the amount of basal meltwater
  4. How does the slope of the bedrock surface affect how glaciers are able to flow?
    The steeper the surface is the easier it is for a glacier to flow. Until a glacier is greater than 60m thick it is unable to flow on level ground or uphill.
  5. How thick must a glacier be to flow on level ground or uphill?
    60m
  6. How does internal deformation affect glacier flow?
    Ice crystals inside the glacier can be flattened into sheets due to the immense pressure. This can allow ice crystals above them to slide on the flattened sheets in a form of plastic flow.
  7. What is plastic flow?
    Ice crystals inside the glacier can be flattened into sheets due to the immense pressure. This can allow ice crystals above them to slide on the flattened sheets in a form of plastic flow.
  8. How does basal meltwater affect glacial flow?
    Basal meltwater helps to lubricate the glacier allowing it to flow more easily. Basal meltwater can also lead to glacial surges, when the glacier moves very quickly (up to cms or ms more movement per day) due to this lubrication.
  9. What is basal meltwater?
    Basal meltwater is water that accumulates at the base of the glacier either due to surface meltwater that has percolated through the glacier or due to the pressure melting effect at the base of the glacier.
  10. What are glacial surges and what is one major factor that can influence them?
    Glacial surges are when the glacier moves very quickly (up to cms or ms more movement per day) and are due to the lubrication from basal meltwater.
  11. What are the 2 types of basal meltwater?
    Surface meltwater that has percolated through the glacier or water due to the pressure melting effect at the base of the glacier.
  12. What is downwasting?
    Downwasting occurs when melting is greater than the glaciers rate of flow.
  13. Can glaciers move/flow backward?
    Glaciers can only flow forward, not backward.
  14. Define a glacier's mass balance?
    A glacier's mass balance is defined as the difference between accumulation levels and ablation
  15. What are the 3 parameters of the earth's orbit that cause glacial fluctuations which Milutin Milankovitch proposed in 1930?
    • 1. Orbital eccentricity
    • 2. Obliquity
    • 3. Precession
  16. What are glacial fluctuations?
    Glacial fluctuations result from changes in the mass balance of glaciers; if snow accumulation at the source outweighs glacier ablation, glacier thickening and the forward advance of the glacier snout occurs.
  17. What happens if the rate of ablation exceeds snow accumulation?
    If the rate of ablation exceeds snow accumulation, the glacier thins and recedes.
  18. What are 3 factors of climatic conditions which might correspond to specific mass balance fluctuations?
    • Temperature
    • Precipitation (snowfall)
    • Wind speed
  19. How do you derive a record of glacial front movements?
    A record of glacial front movements is generally derived from moraines.
  20. Why is radiocarbon dating not an effective method in dating glacial movements?
    Radiocarbon dates on organic material in soils which have developed on moraines provide only a minimum age for glacial advance, since a considerable time lag may exist between moraine deposition and soil formation.
  21. What are 2 other methods that may be used in the dating of glacial events?
    Lichenometry (lichens) and tephrochronology (lava flows) may sometimes be used to assist the dating of glacial events.
  22. What does a Stage 5 problem refer to?
    Stage 5 problem refers to the timing of the penultimate interglacial that appears to have begun 10k years in advance of the solar forcing hypothesized to have caused it.
  23. What does the 100,000 year problem refer to?
    The 100,000 year Problem eccentricity variations have a significantly smaller impact on solar forcing than precession or obliquity and may be expected to produce the weakest effects. The greatest observed response is at the 100k year timescale. During the last 1 million years, the strongest climate signal is the 100k year cycle.
  24. What does the 400,000 year problem (aka stage 11 problem) refer to?
    The 400,000 year Problem (aka stage 11 problem) eccentricity variations have a strong 400k year cycle. That cycle is only clearly present in climate records older than the last million years.
  25. What glaciation events does Milankovitch pacing best explain?
    Milankovitch pacing seems to best explain glaciation events with periodicity of 100k, 40k, and 20k years. This pattern seems to fit the info on climate change found in oxygen isotope cores
  26. What are the 3 stable isotopes of oxygen and why are they one of the most significant keys to deciphering past climates.?
    The 3 stable isotopes of oxygen are 16O, 17O, and 18O. The ratio of heavy & light varieties (isotopes) of oxygen in H2O changes with the climate. By determining how the ratio of heavy and light oxygen in ice cores is different from a universally accepted standard, scientists can learn something about climate changes that have occurred in the past.
  27. Cold oceans are richer in which oxygen isotope?
    Cold oceans are richer in 18O
  28. What are the two important parts to glacial geology?
    There are two important parts to glacial geology: erosion and deposition.
  29. Many essential erosional landforms occur as a result of ______ glaciation, rather than ______ glaciation.
    There are many essential erosional landforms to know, many of them occurring as a result of alpine glaciation, rather than continental glaciation.
  30. Glaciers are mainly classified based on size. What is the smallest?
    Cirque glacier is the smallest and forms in a small bowl shaped depression in the mountains. These will be a few square kilometers in size.
  31. What are Cirque glaciers also known as?
    Cirque glaciers are also known an Alpine glaciers.
  32. What are the next largest glaciers after cirque glaciers and where do they flow through?
    Valley glaciers are the next largest glaciers, which flow through valleys in the mountains, and sometimes are cirque glaciers that have escaped their depression.
  33. What is a Valley Glacier that flows out onto an adjacent plain?
    Piedmont Glaciers occur if valley glaciers flow out onto an adjacent plain
  34. Which are larger - ice fields or ice sheets?
    Ice fields are hundreds of square miles of glaciation, while ice sheets can cover thousands of square miles.
  35. Why are ice streams an important part of glacial systems?
    Ice streams are important parts of glacial systems due to the fact that they discharge a majority of ice and sediment.
  36. In what glacial zone does snow melt in the Summer and in what zone does it last all year? What line separates the 2 zones?
    Glaciers have a zone of ablation, where snow melts in the summer, and a zone of accumulation, where it lasts all year. These two zones are separated by the snow line, which moves during the summer.
  37. What is basal ice freezing?
    Basal ice freezing is thought to be to be made by glaciohydraulic supercooling, though some studies show that even where physical conditions allow it to occur, the process may not be responsible for observed sequences of basal ice.
  38. Plucking is the process which involves the glacier freezing onto the valley sides and subsequent ice movement pulling away masses of rock. Since bedrock is greater in strength than the glacier how does plucking pull away masses of rock?
    Only previously loosened material can be removed. It can be loosened by local pressure and temperature, water and pressure release of the rock itself.
  39. How are supraglacial and subglacial debris different?
    Supraglacial debris is carried on the surface of the glacier as lateral and medial moraines. Subglacial debris is moved along the floor of the valley either by the ice as ground moraine or by meltwater streams formed by pressure melting.
  40. What do terminal and recessional moraines consist of?
    Terminal and recessional moraines consist of till.
  41. Glacial periods are times in the Earth's history where average global temperatures were approximately 6°C lower and glaciers covered much of the planets surface. What are the 6 main factors that contribute to global climate and can cause glacial periods?
    • 1. solar variability
    • 2. insulation
    • 3. dust
    • 4. atmospheric composition
    • 5. sea ice
    • 6. ocean current circulation and *atmospheric circulation
    • *All of these are natural processes and the only one that is affected by humans is atmospheric composition.
  42. What are the two main processes used to determine ablation or accumulation?
    The two main processes used to determine ablation or accumulation are probing and crevasse stratigraphy
  43. What is probing?
    Probing: researchers will place poles in the icepack at various points, at the beginning of the melt period or accumulation period. After a few months the researchers will return and look at the changes in levels of ice, by looking at the height of the ice along the pole.
  44. What is crevasse stratigraphy?
    Crevasse stratigraphy: researchers will find crevasses, then observe the number of layers that formed. Based on the layers the researchers will be able to determine how much snow accumulated. The layers are almost like rings in a tree trunk.
  45. What is an interglacial period and what period are we currently in?
    Glacial periods are characterized with large ice sheets and are normally known as ice ages. The periods between these are known as interglacial periods and currently we are in the Holocene interglacial period.
  46. What causes interglacial periods and what causes the Earth to shift from a glacial to interglacial period?
    Interglacial periods are caused by shifts in the Earth's orbit and this causes a change in the amount of solar radiation that hits the Earth. When the amount of solar radiation increases, this is when the Earth shifts from a glacial to interglacial period.
  47. Why is Antarctica a great indicator if Earth is in a glacial or interglacial period?
    Antarctica is a great indicator if Earth is in a glacial or interglacial period because the amount of ice and snow on it indicates the amount of solar radiation that is hitting the Earth as well as the average temperature of the Earth.
  48. Why is CO2 also an indicator of the changing from a glacial to interglacial period or vice versa?
    As the CO2 levels increase the Earth's average temperature will increase and it will move into an interglacial period whereas if the CO2 levels were to fall, the average temperature would fall and the Earth would change to a glacial period.
  49. What characterizes glacial periods and what is another name for a glacial period?
    Glacial periods are characterized with large ice sheets and are normally known as ice ages
  50. When was the last glacial period and during what Epoch did it occur?
    The last glacial period was between 120,000 to 11,500 years ago and was during the Pleistocene Epoch.
  51. What is the name of the current System we are in and when did it begin? What System was before it?
    The Quaternary System has lasted from the present to approximately 2.588 million years ago with the Neogene System before the Quaternary.
  52. What 2 series does the Quaternary contain and which one are we in presently?
    The Quaternary System contains 2 series: the Holocene and the Pleistocene with the Holocene being the present
  53. What side of the drumlin points in the direction in which the ice flowed?
    The steeper side of the drumlin points in the direction in which the ice flowed.
  54. What is Glaciohydraulic supercooling?
    Glaciohydraulic supercooling is a process that allows water at the base of a glacier to remain liquid at a temperature below its freezing point in response to the geometry of water flow and subglacial pressure.
  55. What are the 6 types of moraines?
    • Terminal Moraine: deposited at terminus (end) of glacier, marking its furthest advance
    • Recessional moraines: ridges that are behind the terminal moraine - mark other spots where glacier stopped in the past
    • Lateral moraines: material pushed off to the side of glaciers
    • Medial moraines: form when two glaciers converge
    • Ground moraine: the layer of till and other sediments underneath a glacier
    • Supraglacial moraines: accumulations of debris on top of the glacial ice
  56. How are glaciers classified?
    Glaciers are mainly classified based on size
  57. How do ice fields and ice sheets form?
    Sometimes, a large number of glaciers are able to collect and join together, when this happens ice fields and ice sheets form.
  58. The top end of a glacier is known as its ____, and the downhill end is known as the________.
    The top end of a glacier is known as its head, and the downhill end is known as the terminus.
  59. Glacial Erosion or Glacial Deposition:
    Arete                    Moraine
    Drumlin                 Cirque
    Hanging Valley       Kame
    Horn                     Roche Moutonnée
    Esker                    Kettle
    • GLACIAL EROSION GLACIAL DEPOSITION
    • Arete                      Moraine
    • Cirque                     Drumlin
    • Hanging Valley         Kame
    • Horn                       Esker
    • Roche Moutonnée     Kettle

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