Assignment
Part I: General Questions (you will need to perform a web search for some of these questions)
1. What was the name of Wegener's proposed supercontinent?
Click Pangaea.JPG to see a diagram of the continents.
2. What are three pieces of evidence that support the hypothesis of Continental Drift?
Click RockProof.jpg to see an example.
3. The supposition that the continents could be "fit" (that's a hint) back together was not originally widely accepted. What was wrong (when it was presented) with this piece of evidence? What was discovered in 1960 to provide better evidence for the fit?
4. What are three pieces of evidence for Plate Tectonics?
Part II: Figure Analysis
Define the following physiographic features associated with plate boundaries.
1. Rift Valley
2. Oceanic Ridge
3. Deep Ocean Trench
4. Volcanic Island Arc
5. Continental Volcanic Arc
Click Boundaries.JPG to see the diagram for questions 6-10.
6. Is diagram A a convergent, divergent, or transform boundary? Briefly describe what is happening. Is material being destroyed or created?
7. Which of the above features (1-5) is created at this boundary?
8. Is diagram B a convergent, divergent, or transform boundary? Briefly describe what is happening. Is material being destroyed or created?
9. Which of the above features (1-5) is created at this boundary?
10. Is diagram C a convergent, divergent, or transform boundary? Briefly describe what is happening.
Refer to page 100 in your text to see a world map of plate margins.
11. The Mid-Atlantic Ridge lies between which two plates?
12. Geographically (locations on a map - don't give plate names) identify a convergent boundary - which edges of which plates are involved?
Click SubductionZone.jpg to see the diagram for questions 13-15.
Click OceanFloor.jpg to see a diagram of the ocean floor.
13. What ocean floor feature is created just offshore at a subduction zone?
14. As the subducting plate dives deeper into Earth the leading edge melts. What causes the melting?
15. What ocean floor feature is created in the mid-ocean where the plates are diverging?
16. The plates diverge through a process named Sea Floor Spreading. Describe that process and what happens.
17. What northern country is the result of sea floor spreading in the Atlantic Ocean?
18. What type of landform makes up most of that country?
19. How does this country make use of the ridge system for its energy source?
20. What continental features are created by the melting of the leading edge of the plate in the subduction zone?
Click HotSpot.jpg to see the diagram for questions 21 - 24
21. What is the name of the oldest Hawaiian island?
22. What is the name of the youngest Hawaiian island?
23. What is the direction of plate movement?
24. How long ago was Oahu sitting over the Hot Spot?
25. What is the name of the new underwater island now forming?
Click ReversalColumn.jpg to see the diagram for questions 26 - 31. These questions deal with the reversal of polarities Earth has experienced. Read pages 114-116 in your text.
26. During the last 4 million years, how many times has Earth changed polarity (from normal to reversed and vice versa)? Colors are normal polarity, white is reversed.
27. Approximately how long ago did the current normal polarity begin?
28. Which direction, north or south, would a compass needle have pointed 1.5 million years ago? (1 pt)
29. How long ago did the period of normal polarity C begin?
30. During the last 4 million years, each period of reverse polarity has lasted more or less than 1 million years? (1 pt)
31. Based on the information in the diagram, are we due for a polarity reversal in the near future? (1 pt)
32 When the polarity reversals occur, Earth loses its magnetic field. What effect would that have on the human body? (2 pts)
Click FloorReversal.jpg to see the diagram for questions 33 - 35.
33. Which type of plate boundary do these diagrams represent?
34. In the South Atlantic Ocean diagram, what is the age of section a-c? (refer to the reversal column link above)
35. Calculate the rate of spreading for the South Atlantic Ocean in cm/yr. Show your work.