Chapter 10 ii
- 1. Chapter 10 – Section I
- 2. The continental drift hypothesis – continents have moved slowly to their current locations
- 3. All continents were once connected as one large landmass now called Pangaea
- 4. The land mass broke apart, and the continents drifted to their present positions.
- 5. Evidence for continental drift
- 6. Puzzle-like fit of the continents
- 7. Similar fossils have been found on different continents
- 8. Remains of warm-weather plants in Arctic areas and glacial deposits in tropical areas suggest that continents have moved
- 9. Similar rock structures are found on different continents.
- 10. At first, continental drift was not accepted because no one could explain how or why continents had moved
- 11. Chapter 10 Section II Seafloor Spreading
- 12. Using sound waves, scientists discovered a system of underwater mountain ranges called the mid-ocean ridges in many oceans.
- 13. In the 1960s, Harry Hess suggested the theory of seafloor spreading to explain the ridges
- 14. 1) Hot, less dense material below Earth’s crust rises towards the surface at the mid-ocean ridges.
- 15. 2) Then, it flows sideways, carrying the seafloor away from the ridge.
- 16. 3) As the seafloor spreads apart, magma moves up and flows from the cracks, cools, and forms new seafloor
- 18. Evidence for seafloor spreading Youngest rocks are located at mid-ocean ridges. Reversals of Earth’s magnetic field are recorded by rocks in strips parallel to ridges.
- 19. Section III – Theory of Plate Tectonics Plate movements
- 20. 1) Earth’s crust and upper mantle are broken into sections
- 21. 2). The sections, called plates, move on a plasticlike layer of the mantle
- 22. 3) The plates and upper mantle form the lithosphere.
- 23. 4. The plasticlike layer below the lithosphere is called the asthenosphere
- 24. Plate Boundaries 1. Plates moving apart – divergent boundaries
- 25. Movie
- 26. 2. Plates moving together – convergent boundaries
- 27. Denser plates sink under less dense plates.
- 28. Newly formed hot magma forced upward forms volcanic mountains.
- 30. Plates Collide Plates crumple up to form mountain ranges
- 32. Plates slide past – called transform boundaries, sudden movement can cause earthquakes.
- 34. Convection inside Earth – The cycle of heating, rising, cooling, and sinking of material inside Earth is thought to be the force behind plate tectonics.
- 35. Features caused by plate tectonics 1) Fault and rift valleys.
- 36. 2) Mountains and Volcanoes
- 37. Strike-slip faults – cause of earthquakes
- 38. Testing for plate tectonics – scientists can measure movements as little as 1 cm per year