1. Plate tectonics What you need to know

2. Earth’s 3 Layers Earth can be divided into three layers based on chemical composition: the crust, the mantle, and the core.

3. Lithosphere The outer part of the earth is the lithosphere The lithosphere is broken into sections called tectonic plates

4. The Crust The outer layer of the lithosphere is the crust

5. Tectonic plates

6. Asthenosphere Beneath the tectonic plates is a layer of the earth known as the Asthenosphere. This layer is made up of the mantle, which has the slow moving rock that moves the plates.

7. Moving Plates Because the plates sit on top of melted rock they are constantly in motion.

8. Evidence of Plate Tectonics In the late 1800s, Alfred Wegener proposed his hypothesis of continental drift. According to this hypothesis, the continents once formed a single landmass, broke up, and drifted.

9. Pangaea Today, scientists accept that the continents were once joined. About 245 million years ago, the continents were joined in a single large landmass called Pangaea. Over millions of years, Pangaea broke into fragments that drifted and collided with each other.

10. PANGEAPANGEA

11. Tectonic plate boundaries There are three types of plate boundaries: – Convergent boundaries – Divergent boundaries – Transform boundaries Each type of boundary is associated with characteristic landforms.

12. Convergent boundaries form where two plates collide. Remember having a conversation with someone. Creates mountains and trenches

13. Mountains Where two continental plates collide the formation of mountains occur

14. At a divergent boundary, two plates move away from each other, and magma forms new lithosphere or land. This is happening at mid-ocean ridges.

15. A boundary at which two plates move past each other horizontally is called a transform boundary. At transform boundaries, the motion of the two plates often produces earthquakes.

16. EARTHQUAKES Earthquake – the shaking of earth’s surface, caused by the quick release of stored pressure in rocks. The pressure is caused by plates: 1.Pressing against each other 2.Sliding by one another 3.Stretching and pulling from each other.

17. Earthquakes Fault – The break or crack, in Earth’s surface along which movement has occurred. Earthquakes are also associated with folding. Folding is when rock layers bend without breaking.

18. Subduction If two plates collide, subduction can happen. Subduction is one plate sinks and melts back into the mantle A deep canyon or trench forms where the plates meet. Volcanic mountains can also form at subduction zones

20. Oceanic/Continental Subduction This also occurs with oceanic and continental plates. The denser oceanic plate sinks (SUBDUCTS) below the continental plate, forming volcanoes.

21. Magma and Lava Magma – is molten rock that has not reached the surface Lava - is molten rock that has reached the surface.

22. Hot Spots An area of volcanic activity in the middle of a tectonic plate is known as a hot spot. Hot spots will always be located in the same area. The Hawaiian Islands are examples of a hot spot.

23. The Ring of Fire The area that forms the outer edge of the Pacific Ocean is also called the ring of fire. More than 75% of volcanoes and earthquakes take place in this region.