1. Plate Tectonics Shake, Rattle, & Roll!

2. Plate Tectonics
a scientific theory that describes the large scale motions of the Earth's plates which make up the lithosphere. These plates rest on the asthenosphere.

3. Layers of the Earth

4. Plate Movement
It is believed that tectonic plates are moved by several different forces:
Rotation of the earth
Tidal forces of sun & moon
Gravitational pull
Convection cell
Plates move at a rate about 2 to 5 centimeters per year. (About the same speed that your finger nail grow) WOW!

5. Alfred Wegener (VAY guh nuhr)
Developed the theory of Pangea & Continental Drift.

6. Continental Drift Theory
First proposed by…
Alfred Wegener
Continental Drift Theory says…
The continents were all once connected and have since…
Drifted apart!

7. Pangea

8. Plate Tectonics Since the earth’s tectonic plates are moving…
And they are so close together…
They must be colliding, grinding past, and pulling away from each other.

9. Types of Plate Motion Convergent Divergent Transform
Under the Earth & Beyond – Plate Tectonic Motion

10. Convergent Plate Boundaries
To converge means to…
Collide!
When plates collide, what do you think happens to the land?

11. Continent-Continent Convergent
When two continents collide the result is a highly crumpled area of mountains.
The Himalaya mountains of Asia are an example.
India has “slammed” into southern Asia at a relatively fast speed.

12. Continental Continental
Tectonic Plate Motion

13. Subduction
When two plates collide, sometimes one is driven down beneath the other.
It’s usually the denser plate that “subducts” beneath the other.

14. Ocean-Ocean Convergent
One oceanic plate usually subducts beneath another.
The result is that the subducting plate melts when it reaches the mantle.
These molten pockets of magma rise by convection to the surface, melting their way through the rock.
The landform that results is an island arc like Japan, the Philipines, or New Zealand.
There is also a deep sea trench formed, like the Marianas Trench in the Pacific Ocean.

15. Oceanic Oceanic
Tectonic Plate Motion

16. Continent-Ocean Convergent
Oceanic crust is more dense than continental crust so which is the subducting plate?
The oceanic crust!
What results is a volcanic mountain range on the continent, with a deep ocean trench off shore.
The Cascade Mountains on the Western US is an example.

17. Oceanic Continental
Tectonic Plate Motion

18. Divergent Plate Boundaries
If converge means to collide. What does diverge mean?
To move away!
What do you think happens when the plates slide away? What is under the plates?

19. Continent-Continent Divergent
Beneath the earth’s crust of course is molten rock.
So when two plates diverge, the hot molten rock is forced up through the resulting opening.
A rift valley, such as in Eastern Africa, forms eventually filling with water.
Fissures or cracks leak lava onto the surface, which spreads out and flattens.

20. Continental Rift
Tectonic Plate Motion

21. Ocean-Ocean Divergent
The same thing that happens at continent- continent divergent boundaries, happens at ocean-ocean divergent boundaries.
The lava cools very quickly and builds up to form seamounts – underwater mountains.
Iceland is an example.

22. Mid Ocean Ridges
Ocean-Ocean Divergent boundaries also form mid ocean ridges.
This is where sea mounts form all along a long ocean-ocean divergent boundary.
The Mid Atlantic Ridge is an example

23. Sea Floor Spreading
Tectonic Plate Motion

24. Transform Plate Boundaries
Sometimes the direction two plates are moving are neither toward nor away from one another.
When two plates slide sideways past each other we call this a transform plate boundary.
This usually results in a slightly crumpled landscape with many faults where earthquakes occur.
The San Andreas Fault is an example.

25. Transform Boundary
Tectonic Plate Motion

26. Transform Boundary Arial photo of the San Andreas Fault
Border of the Pacific & North American plate, 810 miles long.
Arial photo of the
San Andreas Fault

27. Recap 1. What are the 3 types of plate boundaries?
2. Why does one plate subduct beneath another?

28. It’s ACTING!
In groups of 4, I want you to work out a way to ACT OUT the type of plate boundary I give your group.
You may use any props that you can quickly scrounge up.
You will perform your creations for the class.

29. Exit Ticket
On a separate sheet of paper, identify the three types of plate boundaries. Use arrows to identify the direction of movement.