1. The Earth’s Internal Properties

2. I. Seismic Waves A. = Earthquake-generated waves traveling through the Earth’s interior B. Give us clues to the composition of the Earth

3. C. Types of Seismic Waves 1. Surface waves – travel on the Earth’s surface 2. Body waves – travel through the Earth’s interior

4. Body waves  P-waves (primary waves) Compress and expand rock Compress and expand rock Are the fastest of all seismic waves Are the fastest of all seismic waves First waves to register on seismograph First waves to register on seismograph

5. Body waves b. S-waves (secondary waves)  Vibrate up and down  Second waves to register on a seismograph

6. Seismograph = Device which measures seismic waves

7. II. Earth’s internal layers Geologists did research with seismic waves Geologists did research with seismic waves Concluded that the Earth’s Concluded that the Earth’s interior is layered.

8. Earth’s internal layers

9. A. The Core- 1. Composed mostly of iron and nickel 1. Composed mostly of iron and nickel 2. Inner Core 2. Inner Core very hot very hot solid Fe & Ni due to high pressure of the Earth solid Fe & Ni due to high pressure of the Earth

10. The Core (continued) 3.Outer Core 3.Outer Core  less pressure from the earth  liquid Fe & Ni  Flow in the outer core generates an electric current that powers the Earth’s magnetic field.

11. B. The Mantle Rocky layer Rocky layer About 3000km thick About 3000km thick

12. 1. Two parts of mantle a. Lower mantle b. Upper mantle – two sections two sections

13. b. Upper mantle  Asthenosphere - behaves in a semi-fluid manner

14. b. Upper mantle ii. Lithosphere- rigid and brittle

15. C. The Crust  Uppermost portion of the lithosphere  Two types of crust a. Oceanic crust - about 10 km thick a. Oceanic crust - about 10 km thick

16. C. The Crust b. Continental crust – b. Continental crust – about 20-60 km thick

17. III. Theory of Continental Drift A. Belief that the earth is a dynamic planet with the continents in constant motion (i.e. continents are moving)

18. III. Theory of Continental Drift B. All continents once joined together into supercontinent called Pangea (meaning = all land) (meaning = all land) C. Theory formulated by Alfred Wegener

19. III. Theory of Continental Drift D. Evidence that supports theory = 1. Geologic (rock) 2. Biologic (life) 3. Climatological (past weather) 4. Continental Shelves fit together very well well

20. Tectonic Plates = moving sections of the lithosphere on which continents lie on which continents lie

21. IV. Faults  fault = a fracture along which visible displacement can be detected on one side relative to the other.  Types of faults 1. Footwall-Fig 23.17 1. Footwall-Fig 23.17 (“one on bottom”)

22. Footwall

23. B. Types of faults 2. Hanging wall- Fig 23.17 (“one on top”)

24. V. Vertical movement along a fault 1. Reverse Fault- Fig 23.18- Footwall down Examples: Examples: Rocky Mountains Rocky Mountains Canadian Rockies Canadian Rockies Appalachian Mts. Appalachian Mts.

25. V. Vertical movement along a fault 2. Normal Fault- Fig 23.19- Footwall up

26. VI. Horizontal movement along a fault boundary (Fig. 23.22)  Transform-fault boundary – plates are sliding past one another plates are sliding past one another (Figs. 23.27 & 28) (Figs. 23.27 & 28) E.g. San Andreas fault in California California ★ Earthquakes caused by sheering forces

27. B. Divergent Boundaries 1. two plates are moving apart (Fig. 23.23)  Plate A Plate B  (Fig. 23.23)  Plate A Plate B  2. Creates rift valleys – 2. Creates rift valleys – large spreading valleys large spreading valleys at fault line at fault line 3. Creates sea floor spreading- 3. Creates sea floor spreading- a rift valley on sea floor a rift valley on sea floor 4. Caused by tensional forces 4. Caused by tensional forces

28. B. Divergent Boundaries

29. C. Convergent Boundaries 1. Two plates move towards each other (Fig 23.24) Plate A   Plate B Plate A   Plate B 2. Leads to subduction- one plate (usually oceanic crust) (usually oceanic crust) goes beneath the other goes beneath the other (continental crust). (continental crust).  Caused by compressional forces

30. C. Convergent Boundaries

31. E. g. Andes Mountains in S. America (Still growing because of subduction) (Still growing because of subduction) 3. ★ Common place to find volcanoes E.g. Cascade Range (Mt. St. Helens, Mt. Rainier…)

32. Tectonic Plate Movement

33. Major Tectonic Plates