Chapter 17. Glaciers and Climate. 
After reading the chapter and attending all lectures and viewing the films, you should be able to:
1. appreciate that while they are not now here, our local are was profoundly affected by glaciation.
2. give a general sketch of the extent of glaciation in PA; in your home state. 
3. cite several examples of glacial features in this area, or near your home. Cite several examples of US or global features which were shaped by glaciation. How close are you now to the nearest glacier? 
4. define 'glacier'.
5. distinguish between a continental (=ice sheet), valley (alpine), and piedmont glacier. 
6. distinguish between an ice sheet and ice cap.
7. delineate the factors involved in calculating an area's snow budget: accumulation=ablation. Discuss the roles of precipitation, sublimation, melting, and calving.
8. determine under what conditions might a glacier form in this area? advance? retreat
9. explain the structural changes which occur as newly fallen snow is changed to firn and finally glacial ice
10. compare Greenland and Antarctica as the two great continental glaciers extant today.
11. sketch a side view of the anatomy of a glacier. Indicate the snow line, zone of fracture, crevasses, zone of plastic flow, and the terminus
12. use the conveyor belt analogy to describe the movement of ice in a glacier and the deposition of transported materials.
13. recap what was learned by positioning stakes in/on a glacier and observing them through time.
14. indicate the processes that make glaciers one of the most important erosional agents: plucking and abrasion; explain how these processes can cause glacial striations and form roche moutonnées.
15. compare "before and after" sketches of an alpine glacier to identify the features produced:  cirque, arête, horn, trough, hanging valley, tarns, paternoster lakes, and fjord.
16. distinguish between the two major categories of glacial deposits (drift): stratified drift and till.
17. define a moraine. Indicate the position of a lateral, median, terminal, ground, and recessional moraine on sketch of the anatomy of a glacier.
18. explain the occurrence of other glacial deposits such as erratics and drumlins.
19. characterize glacial landforms found in stratified drift: outwash plain, esker, kame, kettle.
20. determine the economic value of glacial features and deposits. For instance, why might an economic geologist investigate a medial moraine?
21. discuss how glacial action shaped and formed many lakes and features, such as the Great Salt Lake, the Great Lakes, and Niagara Falls.
22. explain the information which may be obtained from varves, sedimentary deposits in glacial lakes.
23. demonstrate the cyclic nature glaciation by listing the of advances and retreats of ice ages for the past two million years. With each glacial and interglacial period, give its estimated length.
24. explain, in general terms, how glaciologists have been able to piece together this time line.
25. evaluate the different hypotheses which attempt to explain the cause of ice ages: the effect of plate tectonics, the Milankovitch hypothesis, and variations in atmospheric CO2 and dust levels. 

Critical Thinking Questions and Activities: 
1. Calculate the pressure exerted by a continental ice sheet. The Antarctic ice sheet is as much as 5 km thick; the Greenland ice sheet is almost 1.5 km thick. It is possible to find the pressure at the base of the ice by multiplying the density of the ice by the thickness of the ice, and by acceleration of gravity. 
2. A 5 C increase in global temperature would probably raise ocean level by 65 meters. A 5 C decrease in global temperature would probably lower ocean level significantly. While we are far enough inland to not be terribly effected by a change in ocean water levels (but what about the advancing ice sheet?), investigate the effects of changing sea level on New York City (or the coastal area of your choice). Plot on a map how your selected area is effected. 
3. Compare the conversion of snow to glacial ice to that of a sediment being converted to a metamorphic rock.
4. Do you think that we are in an extended interglacial period, or is this just a pause in Pleistocene glaciation? What evidence would you like to see before making this decision?
5. Assume that sometime in the future, all the world's glaciers will have melted. If you were living at that time, what evidence preserved on land would suggest that ice sheets had once existed?
6. The earth receives nearly the same amount of heat throughout the Milankovitch cycle, yet the cycle has been suggested as a cause of glacial advances and retreats. How could this be?
7. Explain how cores of glacial ice have been used to chart variations in the Earth's climate over the past 160,000 years. How do these variations correlate with variations in the carbon dioxide content in the cores?
8. What mechanism related to atmospheric carbon dioxide regulates the Earth's climate? Name at least three other factors that may be involved in climate regulation?
9. During the Pleistocene glaciation, a large fraction of the earth's land surface may have been covered by ice. Assume that 10% of the 149 million square kilometers was covered by ice averaging 1 kilometer thick. How much would sea level have been depressed over the 361 million square kilometers of oceans? You may find it interesting to examine a bathymetric (depth) chart of the oceans to see how much new land this would have exposed.

1 Ausubel, J. H. 1991. A second look at the impacts of climate change. American Scientist 79: (May-June): 210-221.
2. Berner, R. and A. Lasaga. 1989. Modeling the geochemical carbon cycle. Scientific American 260 (March): 74-81.
3. Carozzi, A. 1984. Glaciology and the Ice Age. Journal of Geological Education 32: 158-170.
Glacial Deposits of Pennsylvania (Map 59). Pennsylvania Topographic and Geologic Survey, Harrisburg, PA.
4. Houghton, R. and G. Woodwell. 1989. Global climate change. Scientific American 260 (April): 36-44.