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Glaciation > EQ1 > Flashcards

EQ1 Flashcards

1
Q

What is a glacial period?

A

cold, ice-house in the pleistocene

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2
Q

What is an interglacial?

A

the warm period when glaciers generally retreat, similar to now

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3
Q

What is the Pleistocene?

A

Geological epoch before holocene, from 2.5 million years to 11.5 thousand years, (often referred to as the ice age).

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4
Q

What are stadials and interstadials?

A

short-term fluctuations within ice-house-greenhouse conditions, stadials are colder periods leading to ice re-advances.

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5
Q

what is orbital/astronomic forcing?

A

mechanism that alters global energy balance and forces climate to change

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6
Q

What is eccentricity and what does it do (Milankovich)?

A

Orbit changes from elliptical to circular over a period of around 100,000 years. Changes amount of radiation from sun.

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7
Q

What does axial tilt do (Milankovich)?

A

Changes intensity of sunlight received at the poles, which impacts the difference between summer and winter.

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8
Q

What is axial precession and what does it do (Milankovich)?

A

Earth wobbles on its axis, changing the point in the year that Earth is closest to the Sun over a period of 21,000 years. Causes long term changes to Earth’s orbital path.

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9
Q

How can volcanic eruptions affect climate?

A

Can eject large amounts of gases eg sulphur dioxide, which can block out solar radiation and cool the planet.

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10
Q

What was the Loch Lomond Stadial?

A

a period of glacial readvance during the overall shrinking of the British-Irish Ice Sheet.

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11
Q

What were impacts of the Little Ice Age?

A
  • many glaciers in Europe re-advanced down valleys
  • Arctic sea ice spread further south
  • Rivers in UK + NY froze over
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12
Q

What is the cryosphere?

A

The Earth’s ice, snow and permafrost.

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13
Q

What is a cirque glacier?

A

Small glacier occupying a hollow on the mountain side - carves out a corrie

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14
Q

What is a valley glacier?

A

a long, narrow glacier in a mountain valley.

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15
Q

What is a warm based glacier?

A

fast-moving, ‘temperate’, ‘alpine’ glaciers - basal meltwater lubricates the glacier, reducing friction. High altitude areas away from polar.

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16
Q

What is a cold based glacier?

A

slow moving, ‘polar’ glaciers- glaciers are frozen to their beds, and little meltwater is available. High latitude areas.

17
Q

What is the present day distribution of ice cover?

A

about 85% is contained in Antarctica. impacted by latitude and altitude

18
Q

How does the present day distribution of ice cover compare to the Pleistocene?

A

Ice cover in the Pleistocene was over 3x greater than now. Antarctica + Greenland ice sheets only covered a bit more than they do now.

19
Q

What are three characteristics of periglacial environments?

A
  • temps rarely rise above 18c, even in summer
  • low precipitation
  • temps fluctuate through frequent cycles of freeze/thaw
20
Q

What is continuous permafrost?

A

found in coldest regions ( -6 degrees) can extend down hundreds of metres

21
Q

What is discontinuous permafrost?

A

fragmented, thinner than continuous

22
Q

What is sporadic permafrost?

A

occurs at the margins of periglacial environments and is usually very fragmented. Only a few metres thick.

23
Q

What are 3 factors influencing distribution + character of permafrost?

A
  • climate (temp + moisture)
  • vegetation cover
  • character of ground surface
24
Q

What is the active layer?

A

the top layer of the permafrost which thaws in summer and freezes in winter

25
Q

What is nivation?

A

a combination of freeze-thaw action, solifluction, and chemical weathering

26
Q

What is frost heave?

A

the freezing and expansion of soil water causes the upward dislocation of soil and rocks

27
Q

What is solifluction?

A

gradual movement of wet soil or other material down a slope, especially where frozen subsoil acts as a barrier to the percolation of water.

28
Q

What is meltwater erosion?

A

during the summer, thawing creates meltwater which erodes streams or river channels

29
Q

How are ice wedge polygons formed?

A

Frost cracking. When the active layer thaws, water can get in and then when it refreezes it contracts.

30
Q

How is patterned ground formed?

A

Frost heave pushes rocks up and creates domes due to expansion of ice. This pushes rocks to the edges due to gravity.
Larger stones move further downslope and polygons become elongated.

31
Q

How are pingos formed?

A

Ice cores force up overlying sediments, causing dilation cracks. Once ice cores are exposed at the surface they melt, making a crater

32
Q

What is loess?

A

Wind blown deposit of fine-grained silt/clay

Glaciation (4 decks)

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