EARTH’S INTERNAL PROCESSES

1. EARTH’S INTERNAL PROCESSES Chapter 25

2. THE PLATE TECTONICS THEORY – 25.1 A. Continental Drift 1. Please Define Continental Drift: Two hundred million years ago the supercontinent, called Pangaea, separated into pieces that drifted over the surface of the Earth like rafts on water.

3. Who first proposed Continental Drift? Alfred Wegener first proposed Continental Drift.

4. When was Continental Drift first proposed? In 1915, about 100 years ago.

5. What was the first and large supercontinent called? Pangaea

6. Evidence for continental drift a. Coastlines 1. Alfred Wegener observed that the eastern coastline of South America fit together with the western coastline of Africa.

7. Fossils 1. What large land animal and plant supported Continental Drift? a.) Cynognathus

8. b.) Lystrosaurus

9. c.) Mesosaurus

10. d.) Glossopteris

11. Rocks and mountains 1. Examples are: a.) Cape Fold Belt

12. b.) Appalachians mountains

13. The controversy Wegener, however, could not explain how the continents drifted. He suggested that Earth’s rotation, the gravitational pull of the Sun and the Moon, and the centrifugal force moved the continents. Physicists quickly concluded that these forces were unable to explain continental drift.

14. Seafloor Spreading Hypothesis 1. Please Define Mid-Ocean Ridge: A system of mountain ranges with a rift valley between them that extends around Earth on the seafloor; formed where oceanic plates spread apart due to magma rising from Earth’s mantle.

15. Please Define Rift Valley: Long narrow depression formed in between the peaks along the mid-oceanic ridge.

16. Rocks and sediments on the seafloor a. Where are the oldest rocks found on Planet Earth? The oldest rocks are on the Continents and the youngest rocks on the Seafloor. The difference in age can only be explained if rocks on the Seafloor are continually being created at a mid-ocean ridge.

17. Where are the youngest rocks found on Planet Earth? The youngest rocks are found on the ocean seafloor which are being created at a mid-ocean ridge.

18. Magnetic polarity of rocks a. Rocks equal distances from either side of the Mid Oceanic Ridge have the same magnetic polarity.

19. The Plate Tectonics Theory 1. Please Define Continental Plate: The Earth’s surface is made of separate slabs of rigid rock called plates that move slowly over Earth’s upper mantle.

20. Convergent plate boundaries a. Please Define Convergent Plate Boundary: Boundary where two plates collide, and produces either subduction zones or continental collisions.

21. Subduction zones 1.) Please Define Subduction: The movement of a dense oceanic plate under a buoyant continental plate.

22. 2.) Example of a Continental-Oceanic Convergent Plate Boundary. The Andes Mountains in South America are an example of a continental- oceanic convergent plate boundary.

23. 3.) Example of an Oceanic-Oceanic Convergent Plate Boundary. Japan is an example of an oceanic-oceanic convergent plate boundary.

24. c. Continental collision 1.) Example of Continental-Continental Convergent Plate Boundary. Along some convergent plate boundaries, two continental plates of equal density collide and do not subduct. Because no subduction occurs, the plates collide and buckle upward to form a high range of folded mountains. Volcanic activity is absent and there is no deep-sea trench. The Himalaya Mountains in Asia are an example of a continental-continental convergent plate boundary.

25. c. Continental collision 1). Example of Continental-Continental Convergent Plate Boundary.

26. Continental collision Indian plate collides with the Asian plate to make the Himalaya Mountains in Asia.

27. Divergent plate boundaries a. Please Define Divergent Plate Boundary: The boundary between two plates that are moving apart. The magma rises between the plates, erupts from a rift valley as lava, and then cools to form new crust.

28. 3. Divergent plate boundaries A mid-ocean ridge is one example of a divergent plate boundary. In some places, such as the East African Rift, divergent plate boundaries create intraplate rift valleys that form in the middle of a continent.

29. 4. Transform plate boundaries a. Please Define Transform Plate Boundary: Tectonic plate boundary in which plates slide horizontally past each other in opposite directions.

30. 4. Example of Transform plate Boundary: The San Andreas Fault in California is an example of a transform plate boundary. Earthquakes are common along transform plate boundaries.

31. D. Plates in Motion 1. Convection a. Please Define Convection: Transfer of thermal energy in a fluid by the movement of warmer and cooler fluid from one place to another.

32. 2. Slab pull, ridge push, and friction a. Please Define Slab Pull: When subduction occurs along a convergent plate boundary, a force called slab pull helps to move the plates.

33. Please Define Ridge Push: In contrast to slab pull, ridge push moves plates along a mid-ocean ridge.

34. c. Please Define Friction as it pertains to Plate Motion: Friction between a plate and the mantle also has an affect on plate motion. For example, plates that drag continental material along with them are slower than those that drag oceanic material.

35. EARTHQUAKES – 25.2 A. Earthquake Distribution 1. Please Define Earthquake: Sudden movement or vibration of ground that occurs when rocks slip and slide along enormous cracks in Earth’s crust.

36. 2. Where do Earthquakes occur? Earthquakes occur at tectonic plate boundaries.

37. Earthquakes depth a. Where are Earthquakes shallow? Earthquakes that occur along divergent and transform plate boundaries tend to be shallow, typically less than 70 km depth.

38. b. Where are Earthquakes deep? However, earthquakes that occur along convergent plate boundaries commonly occur at depths greater than 70 km.

39. Causes of Earthquakes 1. Deformation a. Please Define Deformation: A force applied to an object can cause the object to change its shape, or be deformed.

40. b. What are the four main types of stress that causes Earthquakes? 1.) Compression stress, in which an object is squeezed or shortened.

41. 2.) Tension stress, in which an object is stretched or lengthened.

42. 3.) Shear stress, in which different parts of an object are moved in opposite directions along a plane.

43. 4.) Torsion stress, in which an object is twisted.

44. Types of deformation 1. What are the different types of Deformation? a.) Elastic deformation occurs when a material, such as rock, deforms as stress is applied but snaps back into its original shape when the stress is removed.

45. b.) Plastic deformation occurs when a material changes shape as a stress is applied and remains in the new shape when the stress is removed.

46. Energy release a. Please Define Fault: Crack in Earth’s crust along which rock has moved.

47. Please Define Elastic Rebound: The sudden release of strain energy from rock as it moves along a fault.

48. Seismic Waves 1. Please Define Focus: Point of origin for an earthquake, the point from which seismic waves originate.

49. Please Define Epicenter: The point of Earth’s surface directly above the focus of an earthquake.

50. Primary waves a. Please Define Primary wave: Primary waves are also called P-waves are similar to waves that travel along a coiled spring. Primary waves cause particles inside the Earth to move back and forth in the same direction that the wave is traveling. P-waves are faster seismic waves and can travel through Earth’s interior with speeds between 5 km/s and 7 km/s. P-waves travel through both solids and liquids.