GLG Ch 3

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Arizona State University, Tempe *

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GLG 101

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Geology

Date

Apr 3, 2024

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docx

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Uploaded by MasterMetalLyrebird39

CHAPTER 3: PLATE TECTONICS 1. The surface of Earth is notable for many geologic features including intricate coastlines , undersea trenches , dramatic mountains , and beautiful valleys . 2. There are 7 continents on Earth. 3. The puzzle-like fit of the continents, similarity of rock types across continents, and glacial evidence all were pieces of evidence supporting Wegener's hypothesis of continental drift. What was another piece of supporting evidence? ○ Similar fossils are distributed across multiple continents 4. Gondwana is the name given to the combination of southern continents proposed by Wegener in his hypothesis of continental drift. 5. Land bridges were originally proposed to explain fossil evidence as provided by the presence of Mesosaurus and Glossopteris on continents separated by large oceans. One supercontinent that split apart by continental drift better explains this evidence. 6. Earth's surface is notable for many geologic features such as beautiful valleys, intricate coastlines, and deep ocean trenches. 7. Glacial evidence in Southern continents that are too warm for glaciers in their current position is evidence of continental drift. 8. Using the figure, where are earthquakes most likely to occur? ○ Along continent edges and mid-ocean ridges 9. Which pieces of evidence supported Wegener's hypothesis of continental drift? ○ Southern continental landmasses seem to fit together like puzzle pieces. ○ Fossils of animals and plants that existed more than 150 million years ago are present on several continents that are now divided by an ocean. ○ Similar rocks and geologic structures exist in South America, Africa, and Antarctica. ○ Glacial evidence exists in places that are now close to the equator, and the direction of glacial movement indicates the continents were once joined. 10. Geologists fit together the southern continents into the supercontinent Gondwana . 11. Which of the following statements are accurate about volcano distributions on Earth? ○ Volcanism occurs along mid-ocean ridges. ○ Many volcanoes along the edge of the Pacific Ocean are associated with earthquakes. ○ There is a large volcanic belt along the west coasts of North and South America. 12. Scratch marks made on rocks in the southern continents by ancient glaciers show that the continents were once connected around the South Pole and then moved apart by continental drift.

13. Using the map (yellow circles represent earthquake locations and orange triangles represent volcano locations), which one of these is a better guide to plate boundaries on Earth? ○ Earthquakes 14. Earthquakes are more common along the edges of continents and mid-ocean(ic) ridges 15. ○ A → Divergent ○ B → Convergent ○ C → Transform 16. Gondwana is the name given to the combination of southern continents proposed by Wegener in his hypothesis of continental drift. 17. ○ Yellow → Divergent ○ Red → Convergent ○ Green → Transform 18. Volcanoes and earthquakes often occur in the same areas on Earth's surface. 19. Which of the following is not a characteristic of a mid-ocean divergent boundary? ○ As the plates move apart, solid lithosphere moves upward into the asthenosphere. ○ Characteristics: A rift runs along the axis of mid-ocean ridges because of movement as the plates diverge from each other; Submarine lava flows form new ocean crust; Mid-ocean ridges are elevated above the surrounding seafloor 20. The location of earthquakes is a better guide to plate boundaries than the locations of volcanoes. 21. When divergent boundaries occur on continents, the process is called continental rifting.

22. What two plate boundary types work together to define mid-ocean ridges? ○ Divergent ○ Transform 23. When two plates move toward each other, convergent boundaries are formed. 24. Match the phrases to describe a mid-ocean ridge. ○ A rift is → located in the middle; it is a down-dropped area. ○ Magma is → created when rising asthenosphere melts due to decompression. ○ New ocean crust is → made from lava flows and solidification at depth. 25. Along the boundary of an oceanic-continental convergence, the oceanic plate subducts beneath the continental plate . Oceanic plates subduct beneath continental plates because oceanic plates are dense and continental plates are buoyant . 26. Volcanoes that extend from the southwestern Pacific Ocean, through the Philippine Islands, Japan, and Alaska, then down the western coasts of the Americas form the Pacific Ring of Fire. 27. A divergent boundary can form within a continent. If it does it is called a continental rift . 28. The convergence of two continental masses is known as a continental collision . 29. Convergent boundaries are formed when two plates move toward each other . 30. The type of plate movement that occurs at transform faults is horizontal . 31. Convergence of two ocean plates forms an ocean-ocean convergent boundary . 32. A fault that accommodates the horizontal movement of one tectonic plate past another is a(n) transform/strike-slip fault. 33. The Pacific Ring of Fire is formed by a string of volcanoes . 34. When two continental masses converge, we refer to it as a continental collision . 35. A triple junction is a place where three plate boundaries meet . 36. Select the statement that best describes how the process of plate tectonics circulates materials between the asthenosphere and the lithosphere. ○ Some asthenosphere becomes lithosphere at mid-ocean spreading centers and reenters the asthenosphere at subduction zones. 37. For a plate to move, the driving forces must exceed the resisting/opposite/opposing forces. 38. Plates move 1 to 15 cm per year. 39. Which tools do we use to directly measure plate motion? ○ Lasers ○ GPS satellites

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