Pangaea At one time in geologic history the continents were joined together in one large landmass that was called Pangaea. Plates move at a very slow rate 1 to 10 cm per year. Motion of Lithospheric Plates Plates float on the upper part of the Mantle. What causes plates to move? Convection currents can cause the asthenosphere (mantle) to flow slowly carrying with it the plates. https://www.youtube.com/watch?v=ryrXAGY1dmE Convection currents in the mantle is the reason why plates move. This movement of plates changes the sizes, shapes, and positions of Earth's continents and oceans. As plates move they can do one of the following: 1. Bump into each other. 2. Pull away from each other. 3. Slide past each other. These 3 things create plate boundaries. 3 types of plate boundaries: 1. Divergent Boundaries 2. Convergent Boundaries 3. Transform Boundaries Divergent Boundaries: where 2 plates are moving apart. New crust forms when magma pushes up and hardens between separating plates. Most divergent boundaries occur at the mid ocean ridge. (Sea Floor Spreading) Mid Ocean Ridge Convergent Boundaries: where 2 plates come together and collide. Crust gets destroyed at a convergent boundary(subduction) or it can build a mountain when two continental plates meet. Types of convergent boundaries: 1. If an ocean plate collides with a continental plate, the ocean plate slides under the continental plate. 2. If a continental plate collides with another continental plate, both plates push upward and mountains form. Subduction Zone: When ocean plates collide with continental plates the ocean plates slides under the continental plate. Part of the ocean plate goes back into the mantle and some crust gets destroyed. Subd Subduction Zone Transform Boundary: Where 2 plates slide past each other. Earthquakes occur frequently along this boundary. Crust is neither created nor destroyed. Number your paper 1. Earth was once one large landmass called _________. A. The great continent. B. Pangaea C. Boundaries D. The Great plates 2. What is the rate at which lithospheric plates move? A. 1 to 10 miles per year. B. 20 km per year. C. 1 to 10 centimeters per year. D. Plates do not move. 3. What layer of the Earth do lithospheric plates float on? A. Crust B. Inner Core C. Outer Core D. Mantle 4. What causes lithospheric plates to move? A. Convection Currents in the mantle. B. Convection Currents in the core. C. Earth's magnetic field. D. Solar winds A. Divergent B. ConvergentC. Transform 5. When two plates come together and collide. 6. When two plates are moving apart. 7. When two plates slide past each other. A B C 10. Where do most divergent boundaries occur? A. Where mountains form. B. At the mid ocean ridge. C. At subduction zones D. Near plates that push together. Mid Ocean Ridge 11. At what plate boundary do Earthquakes occur most frequently? A. Convergent B. Divergent C. Transform 12. What happens when 2 continental plates collide? A. One plate goes under the other. B. Mountains form 13. What happens when an ocean plate collides with a continental plate? A. Mountains form B. Ocean plate goes under the continental plate. C. The continental plate goes under the ocean plate. 14. What happens at the subduction zone? A. Some crust gets destroyed. B. Mountains form. C. Some crust gets created. 1. What is Pangaea? 2. What causes plates to move? 3. What is a convergent boundary? 4. What is a divergent boundary? 5. What is a transform boundary? 6. Where do earthquakes occur most often? 7. How fast do plates move? 8. Where do most divergent boundaries occur? 9. What happens at the mid-ocean ridge? 10. What happens at the subduction zone? 11. Why does ocean crust sink when it collides with continental crust? 12. What forms as a result of two continental plates colliding? 13. What layer of the Earth do plates float on? 14. What causes plates to move? Pangaea Convection Currents Convergent Divergent Transform Subduction Zone Mid Ocean Ridge For each vocabulary word, provide a definition and draw a picture. Evidence that supports plate movement: 1. Fossils 2. Landform Shape and Features 3. Rock Structures 4. Climate Change Landform shape and features. Landmass changes can occur at hotspots: Hotspots are stationary. As the plate moves, new land gets formed. Hawaii was created by a hotspot. Earth's landmasses will continue to move and change during the geologic time of the future.