GEOLOGY 161 Study guide for unit 2 - Physical Oceanography and Paleoceanography
Questions to direct your studying:
1. What is the nature of the general circulation pattern in the atmosphere and how does it lead to the pattern of prevailing winds we see?
2. What happens to the solar radiation that reaches earth? Do all points on earth receive the same amount of energy from the sun?
3. When oceanographers say that the oceans are stably stratified, what do they mean? List two effects of stable stratification in the oceans.
4. Explain the general pattern of surface current gyre circulation in the oceans. What factors cause this pattern?
5. How do western boundary currents differ from eastern boundary currents?
6. How do ocean currents act to produce net movement of heat from low to high latitudes?
7. Explain Ekman flow. What effects does Ekman flow have on surface currents?
8. How do surface circulation patterns cause changes in sea surface elevation? Explain using the concept of geostrophic flow.
9. What is the origin of equatorial countercurrents and undercurrents?
10. How does Ekman flow generate upwelling or downwelling along coasts? along the equator? Explain how the patterns vary between the northern and southern hemispheres.
11. How do cyclonic and anticyclonic winds interact with Ekman flow to generate upwelling or downwelling in areas of low and/or high atmospheric pressure?
12. What is thermohaline circulation, and what causes it? What is the difference in the driving force behind surface current circulation versus thermohaline circulation?
13. What are ocean waves, and what forces cause them? How do ocean waves (which are orbital waves) differ from other types of waves we have considered?
14. What is the difference between deep water waves and shallow water waves? What factors control the wave speed of these two types of waves?
15. Based on the above question, explain:
- how waves will disperse in deep water. Explain one effect of wave dispersion.
- how waves will refract in shallow water. Explain one effect of wave refraction.
16. What causes waves to break?
17. Explain how interference among two or more waves in an area can either increase or diminish local wave height.
18. Storm waves, tsunami and rogue waves are three large and potentially destructive types of waves. What are the different forces that generate these waves?
19. Explain some of the effects of wave processes:
- on rocky shorelines.
- on sandy shorelines.
20. Why will waves "straighten out" shorelines over time? Why will normal swell waves cause beaches to build up over time?
21. Give some examples of how longshore drift affects human use of coastlines.
22. How does the equilibrium theory explain the origin of the tides?
23. What effects do the earth's obliquity, the moon's elliptical orbit and the sun have on the tides?
24. How does treating the tidal bulges as shallow water waves give us a better understanding of the tides?
25. Use the concepts of standing waves and resonance to explain how tidal ranges and types of tides can vary among coastal areas.
26. Use the concept of an amphidromic system to explain why tidal ranges and the timing of high and low tides can vary among coastal areas.
27. Outline how the different types of tidal waves (e.g. progressive waves, standing waves, Kelvin waves) affect the nature of the tidal currents observed in an area; that is, explain why some coasts have reversing tidal currents while others have rotary tidal currents.
Study Questions: Paleoceanography
1. How long have the oceans been on earth? Where did the water probably come from? Discuss evidence.
2. What is the Wilson Cycle? Give examples from the present world of ocean basins in various stages of the Wilson Cycle.
3. What geologic evidence can indicate the presence of a now-extinct ocean basin?
4. How do we know that eustatic sea level changes have occurred? How has eustatic sea level varied though geologic time?
5. How do glacio-eustatic sea level changes occur? What is the significance of polar ice caps for atmospheric and oceanic circulation?
6. How do tectono-eustatic sea level changes occur?
7. How and why do sea level changes track broad patterns of continental assembly and breakup through geologic time?
8. Why is sea level lower today than it has been for most of the geologic past? What type of marine environment was common in the past that is not common on the earth today?
9. What major paleoceanographic events characterize the Paleozoic era? The Mesozoic era? The Cenozoic era?
10. In what ways did the Cretaceous oceans differ from the modern oceans? (Think about circulation patterns, oxygenation, global geography and sea level). What evidence suggests that rates of plate tectonic movement where high for much of the Cretaceous?
11. What is the evidence for the Messinian Event? Why did it occur? Could it occur again?
12. What are greenhouse gases, and why do they produce the greenhouse effect? What are the major greenhouse gases?
13. How does evidence from the geologic past help us put present CO2 increases into perspective?
14. According to Al Fischer there have been two major climatic cycles over the last 1 billion years.
What are the driving forces behind these two cycles?