Plate Tectonics Origins of Plate Tectonic Theory: From early ideas to mapping the ocean floor by Anne E. Egger, Ph.D. Reading Quiz Teach with this 1. The contraction theory implied that Earth's features formed through the process of continental drift. magma upwelling. cooling and contracting. seafloor spreading. 2. What data did Wegener use to prove that the continents had once been joined together? paleoclimate data magnetic stripes seafloor topography magma 3. Although Wegener proposed his continental drift theory in 1915, it was not widely accepted until the 1960s. Why not? Continental drift still did not explain the presence of marine fossils in the Himalayas. Wegener's book was not read outside of Germany. Wegener had not proposed a driving force for the movement of the continents. Wegener had looked only at South America and Africa. 4. Who proposed the theory of seafloor spreading based on maps of the ocean floor? Vine and Matthews Alfred Wegener a British geologist Harry Hess 5. Why was the mapping of the ocean floor such an important step in the development of plate tectonic theory? The features mapped on the ocean floor disproved continental drift. Most plate boundaries are under the ocean. The ocean floor had tracks from the continents Nobody had known how deep the oceans were. 6. Earth's magnetic field is constant. true false 7. Which feature on the ocean floor caused Hess to suggest the presence of subduction zones? flat plains magnetic stripes mid-ocean ridges deep trenches 8. When did the Pangaean supercontinent begin to break up? billions of years ago 200 million years ago 1915 in the 1960s 9. Vine and Matthews are considered to have discovered the final proof for seafloor spreading. What were they able to show based on magnetic bands? Mid-ocean ridges and subduction zones are plate boundaries. Seafloor rocks contain magnetite. Earth's magnetic field had reversed in the past. New crust is being generated at mid-ocean ridges. 10. Plate tectonic theory fundamentally altered how geologists view the earth. The biggest difference in the new theory was that Earth is contracting. is dynamic, constantly changing. has numerous features on the ocean floor. has a magnetic field that fluctuates. Score Quiz
