Glaciers and the Cryosphere: The Dynamic Earth

1. Snow has a density that is approximately ___ times that of liquid water.
2. Ice has a density that is approximately ___ times that of liquid water.
3. The two areas that have continental ice sheets today are ___ and ___.
4. The kind of glacier encountered in high mountain areas is an ___ glacier.
5. Glaciers can reach a maximum thickness of approximately ___ km, beyond which the pressure at the base causes the base to melt.
6. Glaciers flow from the part of the glacier that is ___ toward the edge or terminus of the glacier.
7. All particles of ice in a flowing glacier are moving ___ (toward/away from) the terminus.
8. The upper ___ m of the glacier has ice that is brittle and that fractures and faults.
9. Below the brittle zone, the glacier ___ rather than breaks, like silly putty.
10. The zone of ___ is the part of the glacier where more snow and ice collects each year than is melted off.
11. The zone of ___ is the part of the glacier where less snow and ice collects each year than is melted off.
12. The ___ ___ is the dividing line between the two zones mentioned in the previous questions.
13. A ___ is a crack in the upper surface of a glacier.
14. In an advancing glacier, the terminus moves ___ (upflow, downflow).
15. In a retreating glacier, the terminus moves ___ (upflow, downflow).
16. In a retreating glacier, the ice in the glacier moves ___ (upflow, downflow).
17. In a traverse across the upper surface of an alpine glacier (from side to side), the fastest ice is closer to the ___ (middle, sides)
18. Going from the top of the glacier to its base in a vertical borehole, the fastest ice is ___ (on the top, in the middle, at the base)
19. Approximately ___% of the ice in an iceberg lies under the water surface.
20. ___ moraines are found along the sides of alpine glaciers.
21. Glaciers excavate ___-shaped valleys, while streams erode ___-shaped valleys.
22. The moraine that is most distant from the source of a glacier is called the ___ moraine.
23. Moraines deposited inside of the most distant moraine, but which are roughly parallel to that most distant moraine, are called ___ moraines because they form as the glacier is melting back.
24. A ___ moraine forms through the coalescence of two lateral moraines in an alpine glacier.
25. Layers known as ___ are formed in a glacial lake by seasonal variations in sedimentation of clays and silts, and carbon deposition from dead plant/animal matter.
26. A ___ is a bowl-shape depression on the side of a mountain that has been sculpted by an alpine glacier. It is the source area of the glacier.
27. It is thought that mean global temperatures must decrease by an average of approximately ___ degrees centigrade over a period of a few decades to trigger another ice age.
28. Sea level was approximately ___ m lower during the recent glacial maximum than it is today.
29. Ice retreated from the northern part of the continental US approximately ___ years ago.
30. The most recent glacial maximum in the northern part of the continental US was about ___ years ago.
31. The various advances and retreats of the Quaternary ice age began about ___ years ago.

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