Physical Geography: Unit 3

1. Physical Geography: Unit 3 • Some things we will learn about • Earth’s Interior • Geological eras • Continental Drift • Plate Tectonics • Rocks! • Natural disasters- earthquakes, volcanoes, tsunamis • Glaciers • Ecozones in Canada • Weather and climate • Soils

2. Layers of the Earth and Continental Drift

3. The Layers of the Earth • As we learned In “The Core”…. The Earth is made up of different layers!

4. The Four Layers The Earth is composed of four different layers. The crust is the layer that you live on, and it is the most widely studied and understood. The mantle is much hotter and has the ability to flow. The outer core and inner core are even hotter with pressures so great you would be squeezed into a ball smaller than a marble if you were able to go to the center of the Earth!

5. The Crust The Earth's Crust is like the skin of an apple. It is very thin in comparison to the other three layers. The crust is only about 8 kilometres thick under the oceans (oceanic crust) and about 32 kilometres thick under the continents (continental crust).

6. The Lithosphere The crust and the upper layer of the mantle together make up a zone of rigid, brittle rock called the Lithosphere.

7. The Crust The crust is composed of two rocks. The continental crust is mostly granite. The oceanic crust is basalt. Basalt is much denser than the granite. Because of this the less dense continents ride on the denser oceanic plates.

8. The Mantle The Mantle is the largest layer of the Earth. -composed of very hot dense rock

9. The Lithospheric Plates The crust of the Earth is broken into many pieces called plates. The plates "float" on the soft, semi-rigid asthenosphere.

10. The Asthenosphere The asthenosphere is the semi-rigid part of the middle mantle -movement of the asthenosphere is the reason that the crustal plates of the Earth move

11. The Outer Core The outer core is so hot that the metals in it are all in the liquid state. -composed of nickel and iron.

12. The Inner Core The inner core of the Earth has temperatures and pressures so great that metals are squeezed together and are not able to move about like a liquid, but are forced to vibrate in place like a solid.

13. Earth’s Interior: More for your notes… Crust - 8-64 km thick - cold - Granite and Basalt Mantle - 1800 km thick - hot, liquid rock - Magnesium and Silicon Outer Core - 2000 km thick - 3 - 4000°C - liquid Nickel and Iron Inner Core - 1400 km thick - 5 - 6000°C - solid Nickel and Iron

16. Continental Drift • This is VERY IMPORTANT to know and understand for the unit test and the final exam

17. Agenda: Friday • Opening Activity • P/T Interviews?? • Continental drift- notes • Colliding Continents

19. Theory of Continental Drift • Alfred Wegener, in 1915, came up with the idea of Continental Drift. • He said that the continents of the Earth slowly moved. He said they used to be one supercontinent called Pangaea (meaning “all lands”) but split apart and moved to where they are today. • Pangaea was intact until about 200 million years ago, then began to break up

20. Alfred Wegener • Wegener was a German meteorologist who also was an explorer in Greenland. • He died there in his tent while travelling to relieve a group of scientists who were without enough food.

21. Plate Tectonics - Continental Drift

22. Continental Drift

23. http://eesc.ldeo.columbia.edu/courses/w4947/images/plate_motions.gifhttp://eesc.ldeo.columbia.edu/courses/w4947/images/plate_motions.gif

24. Plate Tectonics - Continental Drift THE CONTINENTS TODAY Antarctica

25. Wegener’s Proof 3 pieces of evidence for his theory were: • 1. The jigsaw fit of the continents, especially South America and Africa

26. 2nd piece of evidence… • Fossils that were the same on both sides of the Atlantic. • At a certain point, the fossils begin to show different evolution on the different continents, suggesting they were geographically separated.

27. Plate Tectonics - Continental Drift PROOF!

28. 3rd piece of evidence… • Geologic evidence: mountains of the same age and similar structure found on both sides of Atlantic

29. http://www.youtube.com/watch?v=uGcDed4xVD4

30. But… • Wegener's hypothesis of continental drift lacked a geological mechanism to explain how the continents could drift across the earth's surface. • It wasn’t until the 1960s that the theory of plate tectonics was advanced to explain how the continents could separate. A Canadian by the name of Tuzo Wilson played an important part in the development of this theory…

31. Theory of Plate Tectonics • This theory (idea) was made by J. Tuzo Wilson in 1968. • He said that the Earth’s crust is made up of many lithospheric plates and that these plates move on top of the mantle. The movement of the plates causes changes to the Earth’s surface.

32. The plates float on the interior of the earth, like crackers on a bowl of hot soup

33. Plate Tectonics cntd. • The Earth’s crust is divided into 12 major plates. • Heat from deep inside the earth causes plates to move • Earth’s continents sit on plates, so when the plates move, the continents move with them • The movement of these plates is called PLATE TECTONICS

34. On average, the plates move about as fast as fingernails grow…an inch or so every year

35. Agenda: Monday • Opening Activity: Mental Monday • Finish continental drift PPT • Geologic Eras • Finish Colliding Continents video?

36. The Plates Plates are pieces of the Earth’s crust. • The plates that move are both continental and ocean plates.

37. More about the Internal structure of the Earth • The crust of the earth is divided into two layers: • A lower layer of oceanic crust is made of denser basalticrock that is continuous (extends) all over the earth. • A lighter and discontinuous continental crust, made of less dense granitic rock, “floats” on the oceanic crust.

38. Plate Tectonics Cntd. • Plates move constantly, and when they move different things happen… • They can collide, pull apart, or scrape against each other. • Each type of movement causes changes on Earth’s surface… structures or “tectonic” features (ex. Mountains, volcanoes). • The word, tectonic, refers to the distorting of the crust as result of plate interaction.

39. Plate Tectonics Map

40. Convection Currents • Plates move because of Convection Currents • The mantle is made of much denser, thicker material, because of this the plates "float" on it like oil floats on water.

41. Convection Currents The middle mantle "flows" because of convection currents. Convection currents are caused by the very hot material at the deepest part of the mantle rising, then cooling and sinking again --repeating this cycle over and over.

42. Convection Currents

43. Convection Current Diagram for your notes!

44. Convection Currents The next time you heat anything like soup or water in a pan you can watch the convection currents move in the liquid. When the convection currents flow in the asthenosphere they also move the crust. The crust gets a free ride with these currents, like the cork in this illustration.

45. Convection Currents • http://www.youtube.com/watch?v=Kpoko_l34ZE

46. Ice Age Trailer • https://www.youtube.com/watch?v=bdeb7qGSnP4