Plate Tectonics

1. Plate Tectonics

2. Looking at the world map, what do you notice about the shape of the continents?

3. The thing is…the world didn’t always look like this! It used to look like this:

4. How is this possible?!?!?

6. Plate Tectonics Theory • The earth is divided into a number of large and small plates and the plates are floating on the mantle

10. Can you see the direction of movement?

11. What about the tectonic map, see anything sneaky? What major physical features does this map show?

12. Plate Boundaries In some places of the world, plates move away from each other. This is because magma from the mantle spreads open the ocean floor.

13. Divergent boundary:

15. This is an area of Iceland where two pieces of land are getting further from each other.

16. Some plates are moving toward each other and are colliding

17. When Ocean Plates collide with Contintental Plates • Can Create near coast volcanoes • Can create earthquakes

19. When a continental plate collides with another continental plate • Mountainranges are created (example: Himalayan Mountains)

22. Himalayan Mountains

23. Sometimes plates are neither moving toward nor away from each other, they are moving past one another.

24. Transform Fault Boundary • The plates may move in opposite directions or in the same directions but at different rates and frequent earthquakes are created (example: San Andreas Fault)

25. San Andreas Fault

26. So is the Earth getting bigger? • No • Plates are destroyed as fast as they are created (2 ways) • Plates may be subducted and melted or may push be pushed upward to form mountains

28. What causes this? Convection currents within the mantle

30. Speed of Spreading • Atlantic Ocean – 2-3 cm/year • South Pacific Ocean – 15-18 cm/year

31. Continental Drift Theory The continents have shifted their position over geologic time

32. At one time all land masses were connected into one piece called Pangaea