General Oceanography Online 1 Midterm Exam Geology 20: General Oceanography Dr. Christopher DiLeonardo Spring Quarter 2016 Earth & Space Sciences Program Online Midterm Exam Part A 200 pts. (4 pts. each) Basic Knowledge & General Understanding Use this copy of the exam to prepare your answers for the midterm exam. The Midterm is available for you to answer online by the middle of this week. In the midterm work on the answers to the questions and record them below. You are encouraged to work together…. However you cannot simply post answers in the forum. You may discuss answers if you like but that is different. Science and the Scientific Method Questions 1 through 5: Multiple Choice “Mental Warm Up” 1. Two fellow students in a humanities class on campus notice that their professor glares every time he sees the young woman in the front row texting beneath her desk. Taking notice of the professor’s response to the young woman’s behavior would be an example of a(n): a. experiment b. theory c. hypothesis d. observation e. scientific law or principle 2. The same young woman sits in the front row of a history class, which is also attended by your two friends. They notice in this class as well her history professor seems upset with her when she uses her cell phone beneath her desk to text. Noticing that other people in the back row are texting as well, they conclude that the professors just have it “out for this student.” Your friends’ conclusion would be an example of a(n): a. experiment b. theory c. hypothesis d. observation e. scientific law or principle 3. Your friends decide to test their conclusion by looking at the young woman’s test scores from these two classes. As a control, they decided to ask the other students in the front rows about their grades as well. This test of their conclusion is a(n): a. experiment b. theory c. hypothesis d. observation e. scientific law or principle 4. The data showed that every single person sitting in the front row of each of these classes received an “A” on the first test. The young woman was given an “F” by both instructors. Your friends felt vindicated as the results of their work supports their conclusion that the two professors are “out to get this young woman.” The method employed to consider whether or not the two professors were biased against this student: a. is an example of thinking by imitation. b. is based on faith. c. is an example of scientific methodology. d. is an example of argumentative reasoning. 5. Hint to question 4 above, does scientific methodology guarantee a correct answer? a. YES b. NO General Oceanography Online 2 Midterm Exam The Science of the Ocean Floor Questions 6 through 10: True/False Note: on Scantron® form mark T(a) and F(b) for true and false respectively. 6. The Vine-Matthew-Morley hypothesis is supported by the correlation of magnetic data across various mid-ocean ridges and rises with Cox’s magnetic stratigraphy of the Earth. 7. Radiometric dating of ocean crust around the world supports the Vine, Matthew and Morley Hypothesis (Seafloor Spreading). 8. People studying Earth’s magnetic field have found that it periodically “flips” polarity over short periods of geologic time. 9. Wegner’s early work on Continental Drift was widely accepted by the scientific community of his time. 10. One of Alfred Wegner’s lines of evidence supporting the movement of continental landmasses was the pattern of magnetic lineations on the seafloor. Features of the Seafloor Questions 11 through 20: Multiple Choice: Choose the BEST answer from the choices given. 11. An active continental margin: a. is characterized by earthquakes. b. sheds more sediment than [passive] margins. c. is typically volcanically active d. all of the above (choices a, b, c) e. none of the above is correct. 12. Abyssal plains are: a. deeper than mid-ocean ridges. b. are typically less rugged than mid-ocean ridges. c. are typically less rugged than mid-ocean rises. d. all of the above (choices a, b, c) e. none of the above statements are correct. 13. Which of the following statements regarding volcanic arcs is (are) FALSE: a. Volcanic arcs are associated with active continental margins. b. Volcanic arcs are found above suduction zones at convergent margins. c. Volcanic arcs are only found circling the Pacific Ocean basin (Ring of Fire). d. None of the above statements are false. e. All of the above statements are false. 14. Deep ocean trenches are: a. always associated with subduction of oceanic lithosphere. b. usually but not always associated with subduction of oceanic lithosphere. 15. Deep-ocean trenches are: a. are associated with divergence. b. are associated with subduction zones. c. are formed by turbidity currents. d. both b. and c. are correct. e. both a. and c. are correct. 16. Submarine canyons are: a. are associated with divergence. b. are associated with subduction zones. c. are formed by turbidity currents. d. both b. and c. are correct. e. both a. and c. are correct. General Oceanography Online 3 Midterm Exam 17. Submarine canyons: a. are found cutting the abyssal plains. b. are found cutting the mid-ocean ridge systems forming large fracture zones. c. are found cutting across continental shelves and slopes. d. all of the above. 18. Mid-ocean ridges are steeper and less broad than rises because: a. the rocks of the mid-ocean ridges are composed of more dense mineral than the rises. b. the rocks of the mid-ocean ridges are composed of less dense mineral than the rises. c. The seafloor spreading rate of ridges are faster than rises causing the oceanic crust to subside closer to the ridge axis. d. The seafloor spreading rate of ridges are slower than rises causing the oceanic crust to subside closer to the ridge axis. e. Every ridge is composed of continental crust. 19. Fracture zones (not oceanic transform boundaries) are: a. seismically active (have earthquakes). b. are aseismic (no earthquakes). 20. A passive continental margin: a. is characterized by earthquakes. b. sheds more sediment than [active] margins. c. is typically volcanically active d. all of the above (choices a, b, c) e. none of the above is correct. Plate Boundaries & the Ocean Floor Question 21: Match the best answer for each described tectonic setting. Note: an answer may be used more than once. 21.1 Plate boundary associated with volcanic arcs. a. Divergent Margin 21.2 Pillow basalts form to create new ocean floor. b. Continental Collision (Convergent Margin) 21.3 Margin where oceanic crust is consumed. c. Transform Margin 21.4 Hydrothermal vent activity. d. Subduction Zone 21.5 Most powerful earthquakes. (Convergent Margin) 21.6 Deep focus earthquakes. e. Fracture Zone (beyond oceanic transform) 21.7 Most explosive volcanic eruptions. 21.8 Closing of an ocean basin. 21.9 Aseismic (no earthquakes). 21.10 Accretionary wedge. 21.11 Deep ocean trench. 21.12 Plates sliding laterally past each other. 21.13 Plates moving away from each other. 21.14 Continental rifting, such as the East-African rift zone. 21.15 Continental mountain belts associated with wide zones of seismicity. General Oceanography Online 4 Midterm Exam Plate Boundary Processes Questions 22 through 26: Multiple Choice: Choose the BEST answer from the choices given. 22. At a _____________ new oceanic crust forms along midocean ridges. a. convergent margins (subduction zone setting) b. convergent margins (continent/continent collision setting) c. divergent margins d. transform margins e. fracture zones 23. At which type of plate boundary would you expect to find the strongest earthquakes? a. convergent margins (subduction zone setting) b. convergent margins (continent/continent collision setting) c. divergent margins d. transform margins e. fracture zones 24. At which type of plate boundary would you expect to find the most explosive volcanism? a. convergent margins (subduction zone setting) b. convergent margins (continent/continent collision setting) c. divergent margins d. transform margins e. fracture zones 25. Which type of tectonic boundary is associated with the deepest earthquakes? a. convergent margins (subduction zone setting) b. convergent margins (continental collision setting) c. divergent margins d. transform margins 1. fracture zones 26. At a _____________oceanic crust is consumed back into the asthenosphere. a. convergent margins (subduction zone setting) b. convergent margins (continent/continent collision setting) c. divergent margins d. transform margins e. fracture zones Marine Sediments Question 27: Matching: For each of the following statements indicate the matching sediment. 27.1 Found below the carbonate compensation depth (CCD) a. Siliceous Ooze in an area of high productivity and low sediment influx. b. Carbonate Ooze 27.2 Found above the carbonate compensation depth (CCD) in an area of high productivity and low sediment influx. c. Pelagic (Abyssal) clay (mud) 27.3 Found as a deposit in a deep-sea fan. d. Turbidite Deposit 27.4 Found in a sediment-starved area of the ocean floor. e. Manganese Nodule 27.5 Found in an area of high sediment influx and low biologic productivity. General Oceanography Online 5 Midterm Exam Questions 28 through 32: Multiple Choice: Choose the BEST answer from the choices given. 28. In regions of the seafloor below the Carbonate (Calcite) Compensation Depth (CCD) and without an influx of lithogenous sediment, you would expect to find: a. Carbonate (calcareous) ooze deposition. b. Pelagic (abyssal) clay (mud) deposition. c. Manganese nodules. d. Siliceous ooze deposition. 29. In regions of the seafloor above the Carbonate (Calcite) Compensation Depth (CCD) and without an influx of lithogenous sediment, you would expect to find: a. Carbonate (calcareous) ooze deposition. b. Pelagic (abyssal) clay (mud) deposition. c. Manganese nodules. d. Siliceous ooze deposition. 30. Beneath the carbonate (calcite) compensation depth (CCD) there will be no: a. Carbonate (calcareous) ooze deposition. b. Pelagic (abyssal) clay (mud) deposition. c. Manganese nodules. d. Siliceous ooze deposition. 31. Turbidite deposits are: a. normally graded. b. Composed of lithogenous sediment. c. Found in deep-sea fans. d. All of the above. e. None of the above. 32. In regions of the seafloor below the Carbonate (Calcite) Compensation Depth (CCD) and with high sediment influx from windblown dust you would expect to find: a. Carbonate (calcareous) ooze deposition. b. Pelagic (abyssal) clay (mud) deposition. c. Manganese nodules. d. Siliceous ooze deposition. Part B 50 pts. (5 pts. each) Application and Deeper Understanding Seafloor Spreading & the Ocean Floor For questions 51 through 55 please refer to the map and cross-section of the North Atlantic Ocean basin (Figure 1, below). Note: ignore the age scale across the top of the figure. Question 1: Matching For each of the following statements indicate the lineation pattern that best matches. 1.1 Ridge with fastest rate of seafloor spreading. A. South Atlantic 1.2 Ridge with slowest rate of seafloor spreading. B. North Pacific 1.3 Ridge with moderate rate of seafloor spreading. C. Pacific Antarctic 1.4 Magnetic record showing largest amount of seafloor. 1.5 Magnetic record showing least amount of seafloor. General Oceanography Online 6 Midterm Exam Figure 1. Record of magnetic lineations extending from the center of three oceanic ridge/rise systems outward onto the deep-ocean floor. The Age column is only tied to each of the magnetic records at the ridge axis which is 0. The three magnetic records each have their own scales. Sedimentary Deposits Question 2: Matching: Match each of the descriptions of marine sediments to the correct sampling location. Note: A sample may be used more than once or not at all. You have been hired as a summer intern to work for Dr. Dave at his sand laboratory in Pasadena. He has collected samples from various parts of the world and its your job to catalog the sediments. But you mix up the samples and have to quickly place the proper label back on the right sediment sample, before Dr. Dave comes to inspect your work. Hurry, you have only minutes before he makes it into the lab. A. Fine-grained sand deposit. Grains of sand are very-well-rounded and “frosted.” The composition of the sand is dominated by quartz and minor amounts of feldspars. B. Medium to fine-grained sand deposit composed of angular sand grains of rock fragments, feldspars, quartz and some mafic minerals. C. Very coarse (large grains) sand deposit mixed with gravel. Composed of rounded quartz and feldspar grains with some rock fragments. D. Sand deposit composed of mostly dark, mafic minerals and basaltic rock fragments. E. Sand-sized particles of carbonate shell fragments. 2.1 Beach deposit from coastal California (active margin setting). 2.2 Beach deposit from the southeastern coast of the Big Island of Hawaii. 2.3 Sand dune deposit (wind-blown sand) from the Saudi Peninsula. 2.4 Stream deposit collected high in the Sierra Nevada of California. 2.5 Beach deposit from the coast of Aruba in the Caribbean.