2 Plate Tectonics Study Guide GEOL101 PDF

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This is the study guide that we were given in the class for Exam 1. This guide only covers part of the material for Exam 1....

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GEOL101 Fall 2021

Study Questions for Lesson 2: Plate Tectonics

Use these questions to evaluate your knowledge of the material in order to better target concepts you should study further. They can provide a personalized road map of what concepts you need to focus on. The following questions will help you review the MAJOR concepts and relationships you should understand and may not comprehensively cover every question on the exam for this unit. Many of the questions require synthesis and integrate a number of concepts; they will take you some time to complete. Therefore, you work through these questions as we cover them in class to allow enough time for you to identify areas you need to study in more detail. Trying to complete this study guide hours before the exam will be overwhelming and is not the best approach for concept mastery. You do not have to submit this for a grade. In addition to these questions, you should review all Group Quizzes, assigned readings and videos, assignments, case studies, and handouts.

Plate Tectonics: Historical Context 1. Discuss Alfred Wegner’s contribution to the field of geology and how it laid the foundation for plate tectonics. Discuss 5 lines of evidence he used to support the existence of Pangaea. 2. Why did the scientific community largely reject Wegener’s ideas at the time? What paved the way for their later reexamination? 3. How does seafloor spreading and continental drift differ? 4. Based on plate tectonics, explain how continents move laterally over time. Define and incorporate the following terms correctly in your explanation: mid-ocean ridges, spreading centers, trenches, subduction zones. 5. Explain in detail how the following observations are explained by plate tectonics: a. The presence of mid-ocean ridges, trenches, and marine magnetic anomalies. Define each. b. Marine magnetic anomalies run parallel to and are symmetric about mid-oceanic ridges and alternate from normal to reverse polarities. c. Marine magnetic anomalies can be of varying thickness. c. Older rocks are farther away from mid-oceanic ridges, the youngest oceanic rocks are always at the axis of the mid-ocean ridges. d. Mid-ocean ridges have the highest heat flow and are elevated in relation to the surrounding ocean floor. e. Global earthquake distribution f. Hot spot tracks (volcanoes and seamounts) 6. How is Earth’s magnetic field formed? What specifically contributes to its generation and behavior? 7. Explain the process by which Earth’s magnetic field is recorded and preserved in the geologic record. 8. What is a magnetic reversal? Where will magnetic north be during periods of normal and reverse polarities? Earth’s Stratification 9. What are the two classification schemes used to partition Earth’s layers. 10. How do the properties of continental and oceanic crust affect isostacy? Explain how this is relevant to the distribution of ocean basins and the theory of plate tectonics. 11. Label the following on the figure below: continental crust, oceanic crust, asthenosphere, lithosphere, upper mantle, lower mantle, inner core, and outer core. Label their physical states (solid, liquid, a solid that deforms plastically).

12. Why are the asthenosphere and lithosphere important to plate tectonics? Plate Tectonic Boundaries 13. List the 3 main types of plate boundaries. Summarize the processes that occur at each. What features would you use to identify each? 14. Explain the processes taking place to create a divergent plate boundary. How do continental rift zones and spreading ridges differ? Describe the evolution of a continental rift zone to a spreading ridge. 15. Where do transform boundaries form? Why? What is an example of a transform plate boundary in the continental United States? 16. Label clearly on the following figure: spreading ridges, the direction each plate is moving, transform plate boundary, fracture zones.

17. What are 2 types of convergent plate boundaries? How are they different and why? List a present-day example of each. 18. Why does oceanic crust always subduct at a subduction zone? 19. Explain what happens when two continental plates converge. What is a present-day example of a continental/continental collision zone? Describe the evolution from a subduction zone to a collisional boundary. Plate Motion 20. What is the difference between relative and absolute plate motions? 21. Explain how we calculate current plate motions. Can this be used to determine past plate motions, why or why not. If not, describe how we determine the rate and direction plates have moved in the geologic past. 22. What is a hot spot? List two examples of hot spots in the United States. How do they differ in terms of geologic environment? 23. Determine the plate velocity (speed AND direction) in cm/year for sections A and B based the information on the map below. Note: 1 km = 1000 meters, 1 meter = 100 cm. What direction has this plate been moving through time and at what rate? Are these plate velocities reasonable compared with current plate velocities on Earth?

Practice Questions Multiple Choice: More than one answer can be correct. 1. Which of the following about marine magnetic anomalies is/are FALSE? A. Alfred Wegener used marine magnetic anomalies to support his idea of Pangaea. B. The thicker a marine magnetic anomaly, the faster the spreading rate and/or the longer the duration of that polarity. C. A record of a normal polarity means that Earth’s ancient magnetic field was parallel to Earth’s current magnetic field. D. Earth’s magnetic field is predictable and alternates on a regular basis, every 5 Ma (million years). E. Marine magnetic anomalies originate at trenches. 2. Earth’s can be divided into compositional layers, which are from the surface to the deepest interior: A. core, mantle, oceanic crust, continental crust B. mantle, core, oceanic crust, continental crust C. continental crust, oceanic crust, mantle, core D. continental crust, mantle, core oceanic crust E. None of the above as they’re all physical layers. 3. The ______ of oceanic lithosphere INCREASES with distance from the mid-ocean ridges. A. density B. age C. thickness D. velocity E. temperature 4. Which of the following could be likely characteristic(s) of a subduction zone? A. mountain ranges B. earthquakes C. where continental and oceanic lithosphere meet D. transform faults E. hot spots

True/False: If the statement is FALSE correct it so that it’s TRUE. 5. The plate depicted in Q16 above moved west and then changed to southwestly direction at ~2 Ma. 6. Earth’s magnetic field is currently in a normal polarity where magnetic north is in the Southern Hemisphere and coincides perfectly with geographic South Pole. 7. The mantle is part of the lithosphere and the asthenosphere, but is not a component of oceanic and continental crust. 8. A divergent boundary like a continental rift will occur when continental lithosphere collides with continental lithosphere.

Practice Question Answers 1. A, D, E 2. C 3. A, B 4. A, B, C 5. T 6. F 7. T 8. F...