1. Plate Tectonics

2. What is Plate Tectonics
The Earth’s crust and upper mantle are broken into sections called plates
These plates move around on top of the asthenosphere like rafts

4. Lithosphere The crust and part of the upper mantle = lithosphere
Less dense than the material below it so it “floats”

5. Asthenosphere The “plastic” layer below the lithosphere
The plates of the lithosphere float on the asthenosphere

7. 2 Types of Plates
Ocean plates - plates below the oceans
Continental plates - plates below the continents

8. Plate Boundaries

9. Divergent Boundaries
Boundary between two plates that are moving apart or rifting
 

10. Examples of Divergent Boundaries
Mid-ocean ridges
rift valleys

13. Convergent Boundaries
Boundaries between two plates that are colliding
 
There are 3 types…

14. Type 1 Ocean plate colliding with a less dense continental plate
Subduction : occurs where the more dense plate slides under the less dense plate

15. Subduction Zones occur here
Deep ocean trenches may occur here
Mountains and volcanoes may occur

17. Andes Mountains, South America

18. Type 2 Ocean plate colliding with another ocean plate
The more dense plate slides under the less dense plate creating a subduction zone called a TRENCH

20. Aleutian Islands, Alaska

21. Type 3 A continental plate colliding with another continental plate
a place where folded and thrust faulted mountains form.

23. Transform Fault Boundaries
Boundary between two plates that are sliding past each other
EARTHQUAKES along faults

25. San Andreas Fault, CA

26. Questions... What are the three types of boundaries?
What direction do plates go for each?
Which boundary has a subduction zone…what occurs at a subduction zone?

27. Causes of Plate Tectonics

28. Convection Currents
Hot magma in the Earth moves toward the surface, cools, then sinks again.
Creates convection currents beneath the plates that cause the plates to move.

30. Questions... What causes plates to move?
How is a convection current formed?

31. New sea-floor is produced at what type of boundary?
A. convergent
B. divergent
C. transform
D. I don’t know

32. Mt. Everest was produced by this type of plate boundary.
A. convergent
B. divergent
C. transform
D. I Don’t Know

33. This type of boundary, found near San Francisco CA, is the result of shear force.
A. convergent
B. divergent
C. transform
D. I Don’t Know