OCN 201 First Reading Discussion Questions

Plate Tectonics and the Ocean Floor

Trujillo and Thurman - Chapter 2

Read pp. 35-50 to better understand the following sections

2.3 What Features Occur at Plate Boundaries? (p. 50)

1. List the three plate boundary types and give the relative motion for each type. (Also see fig. 2.14 and table 2.1)

2. State whether sea floor is created, destroyed, or neither at divergent, convergent, and transform plate boundaries. (See table 2.1)

Divergent Boundary Features

3. Explain why a rift valley forms at the mid-ocean ridge's (MOR's) summit. (Also see figs. 2.15, 2.16, and 2.17)

4. Explain how sea floor is created at the MOR. (Also see figs. 2.15 and 2.17)

5. Explain how spreading rates affect an MOR's shape.

6. Describe the East Pacific Rise's trend (pattern/location), and give its spreading rate in cm/yr. (See fig. 2.13)

7. Describe the Mid-Atlantic Ridge's trend (pattern/location), and give its spreading rate in cm/yr. (See fig. 2.13)

Convergent Boundary Features

8. Which major feature is associated with a convergent plate boundary? (Also see fig 2.20 a and b, and fig. 2.21)

9. Describe a deep-ocean trench.

10. Describe a volcanic arc. (Also see fig. 2.20)

11. Explain the formation of a volcanic arc.

12. Explain why an oceanic plate subducts when it collides with a continental plate. (Also see fig. 2.20 a)

13. Explain why continental arc eruptions are explosive. (Also see fig. 2.21 c)

14. Which plate subducts during oceanic-oceanic convergence?

15. Explain why island arc eruptions are explosive.

16. Explain why neither plate subducts during continental-continental convergence. (Also see figs. 2.20 and 2.22)

17. Explain why deep earthquakes are associated with subduction zones.

Transform Boundaries

18. Draw and label a MOR section and include the relative motion at the divergent and transform boundaries. (See fig. 2.23)

19. Name the longest and most famous transform fault. (See fig. 2.23)

20. Give the spreading rate along the San Andreas Fault.

2.4 Testing the Model: What Are Some Applications of Plate Tectonics?

Hot Spots and Mantle Plumes

21. Explain the formation of the Hawaiian Islands and Emperor Seamount Chain. (Also see fig. 2.25)

Seamounts and Tablemounts

22. Explain the formation of a guyot. (Also see fig. 2.26)

Coral Reef Development

23. Explain Darwin's theory of atoll formation using fig. 2.27.

2.5. How Has Earth changed in the Past, and How Will It Look in the Future?

24. Explain why the Pacific Ocean is surrounded by subduction zones, yet the Atlantic Ocean has almost none. (Also use figs. 2.24 and 2.30 to answer this critical thinking question)

2.6 Plate Tectonics...To Be Continued

25. Give an example of a region in the embryonic stage of the Wilson Cycle. (See fig. 2.33)

26. Give an example of a region in the juvenile stage of the Wilson Cycle. (See fig. 2.33)

27. Give an example of a region in the mature stage of the Wilson Cycle. (See fig. 2.33)

28. Give an example of a region in the declining stage of the Wilson Cycle. (See fig. 2.33)

29. Give an example of a region in the terminal stage of the Wilson Cycle. (See fig. 2.33)

30. Give an example of a region in the suturing stage of the Wilson Cycle. (See fig. 2.33)