1. Plate Tectonics
Continental Drift

2. The Earth’s crust (lithosphere) is made up of plates that float on a flexible/plastic layer of hot magma.
These plates are not fixed. In fact, although the continents seem stable, they are always moving.
The way they move is predictable.
Their movements guide the way our earth is formed.
Plate Tectonics

3. Crustal Plate Boundaries

4. Plate Boundaries

5. Long ago the continents were in completely different places.
Over the billions of years the Earth‘s changes have moved the continents in and out of their current locations.
This is called continental drift.
It is governed by the massive heat energy coming from the center of the Earth.
Continental Drift

6. Pangaea

7. Laurasia and Gondwanaland

8. Continental Drift

9. Plate Types There are two kinds of plates:
Continental plates are the plates that are made up of land masses. These are simply the big masses of rock that form the continents.
These plates are lighter. They “float” higher.
Oceanic plates are the plates that sit under the oceans. They are the big masses of rock that like a bowl, hold the oceans.
These plates are denser. They “sink” lower.
Plate Types

10. The oceans and continents all sit on different tectonic plates
The oceans and continents all sit on different tectonic plates. Like all territories, these plates have edges that we call boundaries.
How the edges, or boundaries, behave determines what we call them.
There are three kinds of plate boundaries:
Convergent
Divergent
Transform
Plate Boundaries

11. Plate Boundaries

12. Convergent Boundaries
To converge means to come together.
A convergent plate boundary is where two plates meet and smash up against one another.
Sometimes this makes mountains as when two continental plates come together.
Sometimes this makes volcanoes, as when a continental and an oceanic plate come together.
When this happens, one plate goes under the other. We call that a subduction zone.
Convergent Boundaries

13. Mountain Making Convergence

14. Subduction Zone

15. Subduction Zone

16. Oceanic Convergence

17. Ring of Fire Subduction Zones are where volcanoes appear
There is a huge area of the Earth where most subducting activity is created.
There are volcanoes all around it.
For this reason we call it the Ring of Fire.
Ring of Fire

18. Ring of Fire

19. Divergent Boundaries To diverge means to separate.
A divergent plate boundary is where two plates are pulling apart from one another.
There are two kinds:
One kind is an oceanic spreading ridge. There is one going down the whole of the Atlantic ocean. Where it spreads apart new crust is formed where the magma comes up from the earth and cools.
It is made of two oceanic plates spreading apart.
The other kind is a rift zone. This is where the continental plates are tearing apart.
It is made of two continental plates spreading apart.
Divergent Boundaries

20. Divergent Boundaries

21. Mid Atlantic Ridge

22. Mid Atlantic Ridge

23. Rift Zone

24. Iceland Rift

25. Iceland Rift

26. Iceland Rift

27. Hawaii Rift

28. A transform boundary is where two plates are sliding past one another.
They are on continental and oceanic plates.
They make a lot of earthquakes.
We have a HUGE one – the San Andreas Fault. It is the cause of most of our earthquakes in California.
Transform Boundaries

29. Transform Fault

30. Oceanic Transform Fault

31. San Andreas Fault

32. Transform Boundary Damage

33. Transform Boundary Damage