1. The Theory of Plate Tectonics

2. The Theory of Plate Tectonics
Pieces of Earth’s lithosphere (plates) are in constant, slow motion, driven by convection currents in the mantle.

3. The Theory of Plate Tectonics
Combines what geologists knew about sea-floor spreading, Earth’s plates, and continental drift into a single theory. +

4. Key Points
The lithosphere is broken into separate sections called plates.

5. Key Points The plates float on top of the asthenosphere. CRUST
Rigid Mantle

6. Key Points
Movement of convection currents cause plates to move.

7. Read, “How Plates Move” on page 159

8. The Mosh Pit we call Earth’s Surface
No plate can budge without affecting the other plates surrounding it.
As the plates move, they collide, pull apart, or grind past each other.
Causes changes in Earth’s surface (volcanoes, mountain ranges, deep-sea trenches)

9. Speaking of Mosh Pit Analogies…
You can think of plate movements like crowd surfing.
where are the convection currents…and where is the lithospheric plate?

10. Plate Boundaries Are where the edges of different plates meet.
3 Types of plate boundaries:

11. Sliding Boundaries
Where two plates slip past each other, moving in opposite directions.
Produces: earthquakes
Example – The San Andreas Fault

12. Read, “Sliding boundary” on page 161

13. Spreading Boundaries Where two plates move apart.
Produces: eruptions of molten material, new crust + earthquakes
Examples – mid-ocean ridge & the Great Rift Valley in East Africa

14. Read, “Spreading Boundary” on page 160

15. Colliding Boundaries Where two plates come together.
Produces: volcanoes or mountain ranges, + earthquakes
Examples – Himalayas (India) & Aleutian Islands (Alaska)

16. Colliding Boundaries
Density determines which plate will come out on top.

17. Read, “Colliding Boundary” on page 161

18. Draw a picture & write examples
Tree Map
Plate Boundaries
Write Type of boundary
Write definition
Draw a picture & write examples