1. Plate Tectonics and Continental Drift

2. Tectonic plates
large, solid pieces of the Earth’s lithosphere that are continuously moving in different directions atop the asthenosphere

3. Did you know?
All of the Earth’s crust – even the bottom of the oceans – are sitting on tectonic plates.

4. Did you know?
There are about seven major tectonic plates, and several minor plates.
We are on the North American plate.

5. Pangaea
A large, ancient supercontinent, composed of all continents joined together

6. Did you know?
Pangaea broke up in stages, first breaking into smaller supercontinents including:
Laurasia
Gondwanaland

7. Convergent boundary
boundary between two tectonic plates that are moving toward each other

8. Did you know? Volcanoes are common along convergent boundaries.
A circle of volcanic zones called the Ring of Fire surrounds the Pacific Plate on converging boundaries.

9. Did you know?
Convergent boundaries are DESTRUCTIVE because old crust at plate edges is destroyed and recycled as they come together.

10. Divergent boundary
boundary between two tectonic plates that are moving away from each other

11. Did you know?
Divergent boundaries are CONSTRUCTIVE because this is where we find Earth’s youngest crust.

12. Did you know?
There is a HUGE divergent boundary running down he middle of the ocean floor in the Atlantic Ocean.

13. Transform boundary
boundary where two tectonic plates slide past each other horizontally

14. Did you know?
Transform boundaries are commonly active earthquake zones.
Southern California has about 10,000 earthquakes each year (most too small to feel).

15. Theory
A possible explanation that is supported by a large amount of evidence ?

16. Did you know?
The Theory of Continental Drift proposed by Alfred Wegner only dates back to about 1912.

17. Did you know?
Fossils of the same species of plants and animals can be found on different continents.

18. Convection currents
circular movement of heating, rising, cooling, and sinking molten material in Earth's mantle transfers heat that results in the movement of tectonic plates

19. Did you know? You can also find convection currents in The air
The oceans
Lava lamps

20. Subduction zone
A convergent boundary where one tectonic plate slides under another tectonic plate

21. Did you know?
Subduction zones often produce volcano chains offshore or along the coast of a continent.
Example: Ring of Fire around the Pacific Ocean - including the west coast of the US

22. Sea Floor Spreading
Hess's theory that new seafloor is formed when magma is forced upward toward the surface at a mid-ocean ridge

23. Did you know?
Sea floor spreading happens at ocean floor divergent boundaries.

24. Did you know?
Sea floor spreading happens at a rate of about 5 cm each year.

25. Continental Drift
Wegner's hypothesis that all continents were once connected in a large, single landmass that broke apart about 200 million years ago and drifted slowly to their current positions

26. Did you know? Earth’s Future Supercontinent???
In the future, another supercontinent may form as continents run into each other again.
(millions of years from now)
Earth’s Future
Supercontinent???