Plate Tectonics Review Answers
- 1. Plate Tectonics Review Questions 1. What is plate tectonics in your own words? The Earth’s crust is broken into pieces called “Lithospheric Plates” that “float” over top the asthenosphere. These plates move relative to one another as magma circulates underneath. As the plates move, they affect one another by placing stress along the boundaries. Plates exhibit 3 types of motion; they can divide, collide, or slide past each other. 2. What are the three types of plate boundaries? a. Divergent b. Convergent c. Transform 3. What kind of motion would be expected at a convergent plate boundary? The plates move together – squeezing the rock and/or making the rock sink back down into the mantle. 4. Generally, how fast is the motion of the plates? 2-3 cm per year or 1 inch per year 5. What kind of motion would be expected at a transform fault boundary? The plates slide past and along each other horizontally. 6. What drives the motion of the plates? Heat from the core of Earth is being transferred to the colder surface. As this material circulates inside the asthenosphere (hotter material moves toward the crust and colder material moves toward the core), the solid lithosphere moves along with the convection currents. 7. What is the name of the process that occurs at the mid ocean ridge? Sea – Floor Spreading (SFS) 8. What kind of motion would be expected at a divergent boundary? The plates are dividing and moving apart from one another 9. Describe what may become of the East African Rift Valley in millions of years. The rift valley is caused by tension along a divergent boundary. Over time, the valley will continue to widen and separate eventually forming a new ocean with a mid-ocean ridge at the center. 10. What is happening to Iceland? Iceland was built along the mid-Atlantic ridge and is separating about 1 inch per year. The island is being built from an east to west direction. 11. What is going on in the middle of the Atlantic Ocean? Sea-Floor Spreading is creating a mid-ocean ridge widening the Atlantic Ocean. 12. On average, in ten years, how much bigger will the Atlantic Ocean be? About 10 inches 13. How could two plates moving in the same direction cause a transform fault? A fracture zone along a mid-ocean ridge has different rates of spreading. The area between two spreading areas could be moving horizontally opposite to each other as a result.
- 2. Plate Tectonics Review Questions 14. What is the situation at the San Andreas Fault? San Andreas Fault is Located in California where the North American and Pacific Plate interact. The Pacific Plate is moving faster to Northwest sliding past the North American Plate. This causes earthquakes in California. 15. What are the three possible types of convergences that can occur when two tectonics plate collide with one another? a. Oceanic-Oceanic b. Oceanic-Continental c. Continental-Continental 16. Complete the following chart… Boundary Type of Crust Resulting Feature Examples Divergent Oceanic-Oceanic Mid-Ocean Ridge Mid Atlantic Ridge East Pacific Ridge Continental-Continental Rift Valley Iceland East African Rift Convergent Oceanic-Continental Ocean Trench Volcanic Mountains Peru-Chile Trench Andes Mt. Oceanic-Oceanic Ocean Trench Volcanic Island Arc. Marianas Trench Japan Caribbean Islands Continental-Continental Mountain Range Appalachian Mt. Himalayan Mt. Transform Continental-Continental Strike Slip Fault San Andreas Fault Oceanic-Oceanic Fracture Zone Mid – Atlantic Ridge Fracture Zone 17. How would the behavior of two plates that are said to be along a convergent boundary best be described? The plates are colliding and moving together, if one plate is more dense than the other subduction will also occur allowing one plate to slip underneath of another. 18. During Oceanic-continental convergence, which plate sinks into the mantle? Why does it do this? The oceanic plate will sink into the mantle because ocean crust is more dense than continental crust. 19. Define the word “Subduction.” Subduction refers to the movement of one plate below another due to differences in density. The more dense plate will sink into the mantle and the less dense plate will float overtop. 20. Explain how oceanic-oceanic convergence differs from oceanic-continental convergence. Both convergences produce similar features, however, each will produce a different type of volcano. The oceanic to oceanic produce volcanic island arcs, while the oceanic-continental will produce volcanic mountain ranges each with a different type of magma.