1. Do First Actions: Turn in yesterday’s lab Questions:
Why does an oceanic plate slide under a continental plate when they converge?
What is the above process called?

2. Agenda Plate Interaction Notes
Why Plates Move the Way they Do Video Review

3. What are Plates? Lithosphere is broken in parts called plates.
The Earth’s crust and upper mantle=lithosphere

4. Types of Plates Oceanic plates - plates below the oceans
Continental plates - plates below the continents
Which type of plate is more dense?

5. Plate Tectonics
Plate tectonics refers to the movement of plates on top of the asthenosphere (putty layer), which is a part of the mantle.
There are 12 plates moving in various directions very slowly (2-5 cm a year)
The interactions of these plates create structures or “tectonic features”

6. Plate Tectonics

7. Why Plates Move Convection Currents 2. Gravity
Hot magma in the Earth moves toward the surface, cools, then sinks again
Causes the asthenosphere to move which forces the plates on top of them to move like an object on a treadmill
The individual currents are known as convection cells
2. Gravity
Pushes down on the plates
Forces the denser plates to sink

8. Why Plates Move
tinyurl.com/k8jaj7p

9. Plate Boundaries ↑↓     1. Divergent
Plate boundaries are where plates touch
There are three types of movements at plate boundaries:
1. Divergent
 
2. Convergent
 
3. Transform ↑↓

10. Three Basic Types of Plate Boundaries
Using hands to show relative motion
Divergent
Transform
Convergent
Video: Plate Boundaries— Plates can have three kinds of motion across boundaries: [note video lecture on next slide]
They can move away from each other like at a divergent boundary (= spreading ocean ridge or a rift zone). Or use parallel hands like the transform beginning hands and move them apart allowing the magma (thumbs) to come up.
2. They can move toward each other to make a convergent boundary.
3. They can slide past each other horizontally at a transform boundary.
When two plates carrying continents converge, a continental collision occurs where continental crust piles up. Continental crust is lower density than mantle rocks, so continental rocks cannot be “subducted” into the mantle. If continental rocks are pushed into the mantle, they will soon pop up again. This is like trying to push a piece of styrofoam into a swimming pool. You can push the styrofoam into the water (with some force) but, when you let it go, it pops back to the surface because it is much less dense than the water on which it floats.
ACTIVITY: Teaching about Plate Tectonics Using Foam Models: Download FoamFaultModel_Activity.pdf from Animations Page:
Graphics from “This Dynamic Planet, World Map of Volcanoes, Earthquakes, Impact Craters, and Plate Tectonics.” A Smithsonian, USGS, US Naval Research lab publication.
You can find this at .ﾊCopyright protected: The content may only be used for personal, educational or noncommercial purposes;
USGS Graphics

11. Divergent Boundaries  
What’s happening?
Boundary between two plates that are moving apart or rifting
RIFTING causes SEAFLOOR SPREADING
What features are formed?
Mid-ocean ridges (ocean)
rift valleys (continent)
fissure volcanoes

15. East African Rift Valley

16. Convergent Boundaries  
What’s happening?
Boundaries between two plates that are colliding
There are three types:
Oceanic – Continental
Oceanic – Oceanic
Continental - Continental

17. Type 1: Oceanic - Continental
What’s happening?
Oceanic plate colliding with a less dense continental plate
What features are formed?
Subduction Zone: where the denser plate slides under the less dense plate forming a trench
Where plates are recycled into the mantle
VOLCANOES occur at subduction zones

19. Andes Mountains, South America

20. Type 2: Oceanic - Oceanic
What’s happening?
Oceanic plate colliding with another oceanic plate
What features are formed?
Subduction Zone or Trench
Volcanos

22. Aleutian Islands, Alaska

23. Type 3: Continental – Continental
What’s happening?
A continental plate colliding with another continental plate
What features are formed?
Mountains

26. Transform Fault Boundaries
What’s happening?
Boundary between two plates that are sliding past each other
What features are formed?
Earthquakes

28. San Andreas Fault, CA

29. Three Basic Types of Plate Boundaries
Divergent
Transform
Convergent
Animations: Divergent and Convergent Plate Boundaries
Video lecture by Dr. Robert Butler:Types of Boundaries.mov on the site
Plates can have three kinds of motion across boundaries [more details on next slides]: 1. They can move away from each other like at a divergent boundary (= spreading ocean ridge or a rift zone);
2. They can move toward each other to make a convergent boundary.
3. They can slide past each other horizontally at a transform boundary.
Graphics from “This Dynamic Planet, World Map of Volcanoes, Earthquakes, Impact Craters, and Plate Tectonics.” A Smithsonian, USGS, US Naval Research lab publication.
You can find this at .ﾊCopyright protected: The content may only be used for personal, educational or noncommercial purposes;
USGS Graphics

30. Video Watch the short video to understand why and how plates move

31. DYL What are the 3 types of plate interactions?
What type of interaction is shown in the picture below?

32. Resources http://pnsn.org/outreach/about-earthquakes/plate-tectonics
planet/plate_boundaries/en/index3.html?width=570&height=475&p opup=true