1. Plate Tectonics The Theory of

2. What are tectonic plates?

3. lithosphere- the crust and rigid upper layer of the mantle, broken up into blocks called tectonic plates 3 types of tectonic plates (a.k.a. crust) 1) Continental crust = low-density silicate rock (granite) 2) Oceanic crust = dense, Iron/Mg rich rock (basalt) 3) A combination of continental and oceanic

4. Where are tectonic plates found? The plates are Earth’s shell; but unlike an eggshell, these pieces are always being created, destroyed, or moved

5. How is plate movement explained? The theory of plate tectonics- How t The theory of plate tectonics- How t ectonic plates move around on a plastic layer of the mantle called the asthenosphere “Plastic”- like nacho cheese, pudding, or syrup

6. Where is plate movement happening?

7. Where one plate ends and another plate begins; cracks in the lithosphere mark plate boundaries

8. What are the 3 plate boundaries? What are the 3 plate boundaries? There are 3 kinds of boundaries: Divergent   = spreading boundaries Convergent   = colliding boundaries   Transform   = sliding boundaries

9. What are mid-ocean ridges?

10. Divergent = spreading boundaries   Mid-ocean ridge- An undersea mountain range with a rift valley running through the center of it   Hot magma rises to the surface, cools as rock, and the new crust spreads out 60 foot-wide boundary of the N. American and Eurasian plates

11. Mid-ocean ridges = rift zones Rift- cracks in the center of a ridge where magma, which is less dense than rock, flows upward

12. Mid-ocean ridges = rift zones Rifting causes new crust to push the older crust aside; they are divergent, or spreading, boundaries Rifting causes new crust to push the older crust aside; they are divergent, or spreading, boundaries

13. What is paleomagnetism? Iron inside the Earth makes Earth a giant magnet When hot magma cools off, the bits of iron in the crust will point to the poles like a compass needle

15. Paleomagnetism = Earth’s magnetic memory Iron in new crust pushes the older crust aside; they record their polar-charge for thousands of years Iron in new crust pushes the older crust aside; they record their polar-charge for thousands of years

16. The magnetic poles have reversed in the past, and the rocks on the sea-floor show this change

17. Proof for the Theory of Plate Tectonics: Recording movement at plate boundaries (earthquakes) Recording movement at plate boundaries (earthquakes) Studying how magma forms new crust at rift valleys and mid-ocean ridges (rifting) Studying how magma forms new crust at rift valleys and mid-ocean ridges (rifting) Observing that many volcanoes are occurring near plate boundaries, such as, the Ring of Fire Observing that many volcanoes are occurring near plate boundaries, such as, the Ring of Fire

18. What is the Ring of Fire?

19. A zone of active volcanoes and earthquakes that marks the Pacific Plate boundary Deep- point that goes very far down into the crust Trench- steep, narrow valley where a plate ends

21. For your summary answer… What are tectonic plates made of? What are tectonic plates made of? What are the 3 types of boundaries? What are the 3 types of boundaries? What is paleomagnetism? What is paleomagnetism?

22. Resources Wikipedia Wikipedia http://images.google.com/imgres?imgurl=http://mens a- barbie.com/bloggerimages/MB_Leif_luck_bridge_tect on%2520copy.JPG&imgrefurl=http://mensa- barbie.blogspot.com/2007_03_01_archive.html&usg=_ _AjtDMB4aNJNetWXC- b0hnRWFnrM=&h=272&w=425&sz=33&hl=en&star t=3&um=1&itbs=1&tbnid=Gm8U8eb0aJOB- M:&tbnh=81&tbnw=126&prev=/images%3Fq%3DBr idge%2Bacross%2Bthe%2B%25C3%2581lfagj%25C3 %25A1%2Brift%2Bvalley%26um%3D1%26hl%3Den %26sa%3DN%26rlz%3D1R2GWYE_en%26tbs%3Di sch:1 http://images.google.com/imgres?imgurl=http://mens a- barbie.com/bloggerimages/MB_Leif_luck_bridge_tect on%2520copy.JPG&imgrefurl=http://mensa- barbie.blogspot.com/2007_03_01_archive.html&usg=_ _AjtDMB4aNJNetWXC- b0hnRWFnrM=&h=272&w=425&sz=33&hl=en&star t=3&um=1&itbs=1&tbnid=Gm8U8eb0aJOB- M:&tbnh=81&tbnw=126&prev=/images%3Fq%3DBr idge%2Bacross%2Bthe%2B%25C3%2581lfagj%25C3 %25A1%2Brift%2Bvalley%26um%3D1%26hl%3Den %26sa%3DN%26rlz%3D1R2GWYE_en%26tbs%3Di sch:1tbs%3Di sch:1tbs%3Di sch:1

23. What is the Ring of Fire? A zone of active volcanoes and earthquakes that marks the Pacific Plate boundary Deep- point that goes very far down into the crust Trench- steep, narrow valley where a plate ends

24. Warm up 1) Describe one part of this figure or, describe a part that you do not understand. 2) What do you think is a good title for this figure? 3) How many plate boundaries do you see?