Study Guide: Plate Tectonics Test Cheng/6th Grade Earth Science To prepare for the test, please review your notes, graphic organizers, homework worksheets, and look over PowerPoint lectures on Continental Drift, Plate Tectonics Theory, Sea Floor Spreading, Plate Boundaries. 1. Wegener’s Continental Drift Theory was based on the idea that the continents had once been joined together in a single landmass called Pangaea, and over tens of millions of years, drifted apart to their present day locations. 2. Wegener’s Continental Drift Theory was supported by the following evidence: a. Landforms: When Wegener looked at maps of Africa and South America, a mountain range running from east to west in South Africa lined up with a range in Argentina. European coal fields matched up with similar coal fields in North America. b. Fossil Evidence: Fossils of the plant Glossopteris have been found in Africa, South America, Australia, India and Antarctica. The fact that these are found on separated continents support the idea that the continents were once joined. Fossils of a reptile called a Mesosaurus, a fresh water dwelling animal, were found in only two regions, southern Africa and the southern part of South America. These two regions are far from each other and separated by the Atlantic Ocean, further supporting that the continents were once joined. c. Climate Evidence: An island in the Arctic Ocean contain fossils of tropical plants, indicating that the island was once located close to the Equator. Scratches on rocks made by glaciers show that places with mild climates were once cold enough for glaciers to form. 3. Why was Wegener’s Theory of Continental Drift not accepted by the scientific community? 4. The Theory of Plate Tectonics is the geological theory that grew out of Wegener’s Continental Drift Hypothesis. Plate Tectonics states that pieces of Earth’s lithosphere are in constant, slow motion, driven by Convection Currents in the Mantle (Asthenosphere). 5. The Theory of Plate Tectonics developed in the 1950’s and 1960s through scientific investigation of the sea floor. The evidence discovered which supported Plate Tectonics was: a. Mid Ocean Ridges-huge underwater mountain ranges that circled the Earth’s Ocean floors b. Evidence of Sea Floor Spreading c. Evidence of rock samples and age of sea floor d. Ocean Trenches e. Evidence from magnetic stripes. 6. The process, which begins at the mid-ocean ridge where molten material rises from the mantle, erupts, spreads out pushing older material to both sides of the ridge is called Sea Floor Spreading. 7. What happens to the old oceanic crust as new molten material rises from the mantle? The new molten material splits apart the strip of solid rock (oceanic crust) at the ridge, older crust is pushed aside down into deep ocean trenches, where Subduction occurs. Gravity helps pull the dense ocean crust down into these trenches to the Mantle, where it is melted again, and recycled in the convection current process. 8. What proof do scientist have that Sea Floor Spreading happens? a. “Pillow Lava,” rock found on the ocean floor, in the rift zones of the mid ocean ridges. A Rift zone is the valley between the two ridges where the sea floor spreads apart and magma from the mantle is forming new ocean floor. b. Drilling samples from the ocean floor showed that the rock closed to the mid ocean ridges is younger than rock found further away from the ridges. c. Magnetic Stripes -Rock on the ocean floor show that the Earth’s magnetic polarity has reversed directions many times in the past. The pattern of matching stripes on either side of the mid ocean ridges form as iron particles in the new ocean floor take on the orientation of Earth’s magnetic field poles at the time the rock material hardens. 9. Be able to look at a diagram, like the one on the Sea Floor Spreading Worksheet, and identify the features that are formed, and the processes that are occurring. Examples: What features form as a result of Sea Floor Spreading? What process occurs at Deep Ocean Trenches, describe what happens here? 10. What are the three main types of Plate Boundaries? Be able to recognize visually. 11. What features and processes occur at each type of Plate Boundary? Example: at Divergent Plate Boundaries, the process of Sea Floor Spreading occurs, Rift Valleys and mid ocean ridges (mountain ridges) form. 12. Be able to label the seven major plates, and identify from a tectonic plate map with a key, each of the three types of plate boundaries are located. 5 The place where two plates come together or converge is called: a. divergent boundaries b. transform boundaries c. convergent boundaries d. subduction boundaries 6. The process which occurs during the convergence of two oceanic plates, or an oceanic-continental plate resulting in old oceanic plate (old sea floor) being recycled back down into the mantle is called: a. sea floor spreading b. convection c. subduction d. elimination 7. The result of two oceanic-oceanic plates converging would be: a. folded mountains b. rift valley c. mid-ocean ridge, or sea floor spreading d. volcanic mountains, volcanic island arcs, deep ocean trenches. 8. Subduction zones occurs at the following type of boundary: a. convergent boundaries, of oceanic-oceanic, or oceanic-continental plates b. transform boundaries c. divergent boundaries d. convergent continental plates 9. Divergent boundaries between two oceanic plates would most likely create: a. folded mountains b. coastal mountain ranges c. mid-ocean ridge, new sea floor d. volcanic island arcs 10. Two continental plates converging would create which of the following: a. volcanic arcs b. coastal mountain ranges c. folded mountain ranges d. mid-ocean ridges 11. Which of the following would result when a continental plate collides with a oceanic? a. subduction zone b. deep ocean trench c. coastal mountains d. all of the above 12. Plate boundaries where no new crust is created or destroyed are: a. b. c. d. transform convergent divergent subduction Name: _________________________ Period: _________________________ Continental Drift/Plate Tectonics Quiz Part B Mrs. Cheng/6th Grade Earth Science Use the words in the word bank to fill in the blanks: Asthenosphere Convection currents lithosphere plates plate tectonics ocean trenches convergent boundaries 13. The Theory of ___________________ states that the Earth’s crust and upper mantle are broken into sections. 14. These sections called _______________ are composed of the crust and a part of the upper mantle. 15. The crust and the upper mantle are called the _____________________. 16. The plastic-like layer upon which the plates float are called the ______________. 17. The driving force behind the movement of the Asthenosphere are ____________ in the mantle. 18. At deep _____________ subduction allows part of the ocean floor to sink back down into the mantle. 1. What is the Theory of Plate Tectonics? 2. What was Harry Hess’s radical idea of Sea Floor Spreading? 3. What evidence supported Hess’s Theory of Sea Floor Spreading? There are three evidences. (See Power Point Notes, and Harry Hess Article).