1. The Earth

2. The Layers of the Earth!

3. Earth Layers The Earth is divided into four main layers. *Inner Core *Outer Core *Mantle *Crust

4. The Crust * The Earth’s crust is like the skin of an apple. It is very thin compared to the other three layers. *The crust makes up 1% of the Earth. (approx 35km thick) * The crust of the Earth is broken into many pieces called plates.

5. The Mantle The mantle is the layer below the crust. The mantle is the largest layer of the Earth.(approx 2850km thick) The mantle is divided into two regions: the upper and lower sections.

6. Outer Core * The core of the Earth is like a ball of very hot metals. The outer core is made up of liquid iron and nickel. It is very dense and is the second largest layer- approx 2270km thick

7. Inner Core The inner core of the Earth has temperatures and pressures so great that the metals are squeezed together and are not able to move. Size- 1216 km thick * The inner core is a solid.

8. CONTINENTAL DRIFT

10. There are many theories about how the earth has come to take the shape that it is now.

11. Theory #1- Continental Drift Alfred Wergener- about 100 years ago noticed a pattern and believed that the continents had once been joined. He had 4 main pieces of evidence to support his Continental Drift Theory

12. 1. Jigsaw effect-the continents fit together like a jigsaw puzzle, especially South America and Africa Making Connections: Canada’s Geography. Clark & Wallace. Prentice Hall Ginn, 1999.

13. 2. Fossils- fossils form the same animal/ dinosaur were found on both sides of the Atlantic Ocean

14. 3. Geologic evidence: mountains have the same age and structure on both sides of Atlantic Making Connections: Canada’s Geography. Clark & Wallace. Prentice Hall Ginn, 1999.

15. 4. Ice Sheets- evidence of ice sheets have been found in very hot places (like India and the Southern part of Africa)

16. PLATE TECTONICS

17. In the early 1960’s the theory of Plate Tectonics emerged. So what was the difference? Wegener could not explain how the plates moved and Plate Tectonics did

18. The Difference It was discovered that the plates are floating on the mantle (magma) and different convection currents moves the plates around (think boiling water moving the lid...)

20. Continents and Plate Tectonics

21. So, what’s happening? The outer surface of the Earth is a thin crust of fragile rock, fractured like the cracked shell of an egg. The pieces of the crust are Earth's tectonic plates -- there are 12 major ones -- and they float along on vast convection currents in the upper layer of the mantle called the asthenosphere. http://www.eas.purdue.edu/~braile/edumod/journey/journey_files/image006.jpg 21

22. The Major Plates

23. Remember, there are two types of crust: Oceanic crust, which extends all over the earth and is broken into the 12 large and many smaller plates; and, Continental crust, which “rides around” on top of the oceanic crustal plates 23

24. Mantle Asthenosphere Oceanic Crust Continental Crust Sea level 24

25. Types of Plate Movement

26. There are three basic plate movements or boundaries. 1. Divergent: where the plates move apart new magma wells up to the surface forming new crust (a ridge) the Mid-Atlantic ridge is a prime example. 26

27. http://www.geo.lsa.umich.edu/~crlb/COURSES/117/Lec19/div.j peg 27 Divergent Boundary: Plates move away from each other

28. 2. Convergent: two plates come together one plate subducts (goes under) the other plate, creating a subduction zone the crust at the leading edge of the subducting plate melts back into the mantle the Pacific Rim of Fire is a good example of this 3 different types of convergent boundaries (ask your teacher if you need to know them) 28

29. Plate Tectonics Colliding

30. A. Mid Ocean Convergence Zone: Oceanic Crust to Oceanic Crust. 30

31. B. Convergence Zone: Oceanic Crust and Continental Crust 31

32. C. Convergence Zone: Continental Crust to Continental Crust 32

33. Less dense material that has accumulated on the surface of the crust melts as it goes down into the mantle. Because it is less dense, it rises back up as liquid rock, and creates volcanoes and volcanic islands beside the trench. Japan is a good example of this. 33

34. The Pacific Ring of Fire Mt St Helen’s 34

35. http://en.wikipedia.org/wiki/Image:Sthelens3.jp g 35

36. http://en.wikipedia.org/wiki/Mount_St._Hel ens 36

37. 3. Transform Boundaries: two plates slide past each other this can create tremendous friction, which may be eventually released in the form of violent earthquakes Example : the San Andreas Fault is a transform boundary http://observe.arc.nasa.gov/nasa/earth/tectonics/graphics/Imag e43.jpg 37

38. Transform plate margins: where two plates slip past one another. 38

39. The San Andreas Fault, California 39

40. Plate Tectonics Sliding

41. The main types of plate boundaries. 41

42. Indian Plate collides with Eurasian Plate 42

43. The result: the Himalayas and Mt. Everest 43

44. earthquake.usgs.gov/ faq/plates.html Click here to see a web animation of plate movement to this position.here 44

45. http://sts.gsc.nrcan.gc.ca/page1/geoh/quake/figures.htm Tectonic setting of western British Columbia and Washington state. The oceanic Juan de Fuca plate is moving beneath the continental North America plate at a rate of about 4 cm/year. Earthquakes occur along parts of the boundary between the two plates. 45

46. http://www.pbs.org/wnet/savageearth/hellscrust/index.html This map, which shows 20th-century earthquakes in red, illustrates how they cluster on the edges of the major tectonic plates (outlined in yellow). 46

47. Volcanoes forming Land Bill Nye