18. Plate Boundary Notes
- 2. Proposed by Alfred Wegener in 1912; the hypothesis that state that the continents once formed a single landmass (Pangea), broke up, and drifted to their current location
- 4. a) Shape of the continents b) Fossil evidence on both sides of the Atlantic c) Rock formations on both sides of the Atlantic d) Climatic evidence (i.e. evidence of glaciers in Southern Africa)
- 6. He could not come up with the mechanisms or process that caused the continents to move
- 7. a) Mid-Ocean Ridges – a long undersea mountain chain that has a steep, narrow valley at its center, that forms as magma rises from the mantle, and that creates new ocean floor as the tectonic plates move apart
- 8. b) Sea Floor Spreading – the process by which new oceanic crust forms as magma rises to Earth’s surface and solidifies at a mid-ocean ridge, symmetry of rock layers show oldest layers are farther from the ridge
- 9. c) Paleomagnetism – • As magma solidifies, iron particles line up with the Earth’s magnetic field • Rocks show reversals in the Earth’s Magnetism • Rocks show symmetrical patterns on both side of the ridges, thus both plates formed at the same time
- 11. The theory that explains how large pieces of the crust, called plates, move and change shape
- 12. Lithosphere – solid, outer layer of the Earth that consists of the crust and the rigid upper part of the mantle Asthenosphere – the solid, plastic layer of the mantle that flows slowly
- 13. 15 Major Plates Identified:
- 14. Convection – the movement of hot, less dense material up and cold, more dense material down
- 15. • Interior of the Earth heats the mantle which rises to the surface at the Mid- Ocean Ridges • Cools into rock and eventually sinks back into the mantle where it is melted and sinks • This movement of the mantle drags the plates with it
- 17. The boundary between tectonic plates that are moving away from each other. Results in: magma rises to surface, forms mid-ocean ridges and rift valleys
- 18. The boundary between tectonic plates that are moving towards each other
- 19. One plate subducts under the other, forming a trench and melting the plate causing an island arc
- 20. The oceanic plate subducts under the less dense continental plate, the oceanic plate melts, causing volcanoes above
- 21. Neither plate is dense enough to subduct, thus mountains are built up
- 22. The boundary between two tectonic plates that are sliding past one another, like the San Andreas fault