71) Glaciation can take about ________ years, whereas deglaciation requires about ________
years.
A) 1000; 100
B) 100; 1000
C) 100,000; 10,000
D) 10,000; 90,000
72) The 10°C (50°F) isotherm for July is used as the environmental criteria to define
A) the Arctic region.
B) the Antarctic convergence.
C) the Antarctic region.
D) the extent of Pleistocene glaciation.
73) Which of the following is not true?
A) The Antarctic is generally colder than the Arctic.
B) Antarctica can be thought of as a continent covered by a single enormous glacier.
C) The Arctic is a large landmass surrounded by a cold ocean.
D) About half of the Arctic sea-ice volume has disappeared since 1970.
74) Which of the following has not been sited as a possible cause of ice sheet darkening?
A) ice melt has exposed darker land surface, water, and vegetation
B) black carbon accumulation from wildfires
C) sunspot activity
D) snow metamorphism
75) Which of the following is evidence of recent changes in polar regions?
A) decrease in Arctic sea-ice volume
B) ice sheet darkening
C) increase in meltponds
D) the breakup of ice shelves
E) decrease in sea ice volume, ice sheet darkening, increased meltponds, and ice shelves calving
are all evidence of recent changes in polar regions
76) In which year did surface melt on the Greenland ice sheet reach its greatest extent?
A) 2002
B) 2006
C) 2012
D) 2013
77) Which of the following has been sited as a positive feedback loop involving the thawing of
permafrost?
A) Thawing of permafrost will increase albedo, leading to more warming.
B) Thawing of permafrost will release vast amounts of carbon to the atmosphere, accelerating
warming.
C) Thawing of permafrost will contribute to sea level rise, which will further reduce overall
global albedo values.
D) Thawing of permafrost will inhibit frost wedging action on large boulders, altering absorption
ability.
17.2 True/False Questions
1) Many western states rely heavily on snowmelt for their municipal water supplies.
2) All snowflakes have six sides and show a remarkable degree of similarity to one another.
3) The snowline is at a higher elevation on equatorial mountains than on midlatitude mountains.
4) Firn has a higher density than glacial ice.
5) Glacial ice can form during the duration of a single winter season in most glacial areas.
6) Combined, alpine glaciers and ice sheets cover about 10% of the Earth’s land surface.
7) Worldwide, alpine glaciers are presently increasing in size and number.
8) A valley glacier is a form of alpine glacier.
9) Calving leads to the formation of icebergs.
10) Approximately, 81% of Greenland and 90% of Antarctica are covered with ice sheets.
11) The ice sheets of Greenland and Antarctica have an average thickness of about 2 km (1.24
mi).
12) An ice cap is the most extensive form of continental glacier.
13) Surprisingly, there are no ice caps in Iceland.
14) Glacial ice forms more quickly in polar environments than in midlatitude, alpine
environments.
15) A glacier is an open system with inputs of snow and outputs of ice, meltwater, and water
vapor.
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16) Melting at the surface, internally, and the base, deflation, calving, and sublimation are all
examples of ablation.
17) Over 25% of the measured sea level rise has been attributed to alpine glacier wastage.
18) A glacier behaves more like a plastic than a rigid body.
19) Most glaciers are stationary, moving at no more than several millimeters per year.
20) Ice regelation incorporates rock debris into a glacier.
21) Crevasses in alpine glaciers result from friction, tension, or compression.
22) If a glacier does not have debris embedded in its base, it is not a very effective agent of
abrasion.
23) During a surge, a glacier moves up to 2 km/hr.
24) The presence of meltwater at the bottom of a glacier can increase its rate of movement.
25) Glacial erosion and deposition produce landforms similar to fluvial processes and are,
therefore, difficult to ascertain their origins.
26) Alpine glaciers eroding parallel valleys may produce thin, sharp ridge forms known as arête.
27) Drumlins and kettles are examples of alpine glacial landforms.
28) The Matterhorn in the Swiss Alps is an example of a nunatak.
29) Unlike V-shaped stream-cut valleys, glacial cut valleys are U-shaped.
30) A paternoster lake is a singular lake filling a small cirque basin behind risers of rock
material.
31) A fjord is a glacial landform that occurs in areas in which a glacier encounters the ocean and
subsequently retreats.
32) The general term for glacially deposited sediments is alluvium.
33) Materials transported directly by glaciers tend to be unsorted when deposited. However,
those carried by meltwater are sorted.
34) If two glaciers with lateral moraines join, a medial moraine may form.
35) Cirques, horns, cols, and arête are example of depositional landforms from ice sheets.
36) The Great Lakes of the United States resulted from repeated glacial advances and retreats
which enlarged and deepened stream valleys to form the basins of the future lakes.
37) Most periglacial environments at high latitudes are seasonally snow-free.
38) Permafrost requires soil, sediment, or rock temperatures to remain below freezing for at least
2 years.
39) Permafrost describes those portions of the ocean that are constantly covered by floating ice.
40) Approximately 80% of Alaska has permafrost beneath its surface.
41) The thickness of the active layer increases toward the poles.
42) A talik connects the surface to groundwater in discontinuous permafrost.
43) patterned ground results from repeated freeze/thaw cycles and self-organization whereby
stones are attracted towards stone domains and soil towards soil domains.
44) Solifluction is the downslope movement of soil particles resulting from freeze/thaw cycles.
45) The Pleistocene ice age began 18,000 years ago.
46) During the Pleistocene up to 11% of Earth was covered with ice.
47) During the height of the Pleistocene ice age, the glaciers extended as far south as the Ohio
and Missouri river systems.
48) During the Pleistocene, there was as many as 18 glacial advances and retreats.
49) During the Pleistocene ice age, many areas of the southwestern United States were covered
by large pluvial lakes.
50) The Arctic region is defined based on the July 10°C (50°F) isotherm whereas the Antarctic
region is defined based on the February 10°C (50°F) isotherm.
51) Overall, the Arctic is much cooler than Antarctic.
52) About half of Arctic sea-ice volume has disappeared since 1970 due to warming throughout
the region.
53) The albedo of the Greenland Ice Sheet has decreased over the past decade due to ice sheet
darkening.
54) There is no evidence of recent Antarctic ice sheet breakup.
55) Disappearance of Mount Kilimanjaro’s glaciers have been attributed solely to climate
change.
56) Thawing of permafrost could create a positive feedback loop as vast amounts of carbon are
released into the atmosphere, further amplifying warming.
17.3 Essay Questions
1) Describe the process by which snow becomes glacial ice.
2) Differentiate between alpine and continental glaciers, ice caps and ice fields.
3) Describe the process of glacial movement.
4) Discuss the process of glacial erosion.
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5) List several distinct landforms created by alpine glaciers and ice sheets, describing the manner
in which they formed.
6) Describe the importance of periglacial processes.
7) What is the importance of the Pleistocene ice age epoch to the modern day?
8) Summarize the recent changes in the Arctic and Antarctic regions as a result of climate
change.
9) Discuss several issues glacial and periglacial environments may face during the 21st Century.