1. Plate Tectonics

2. The Theory of Plate Tectonics
The Earth’s surface is made of large slow moving pieces of the Earth’s crust called tectonic plates.
Tectonic plates move by floating on a layer of partly melted rock (the asthenosphere)
The places where the tectonic plates interact are called plate boundaries.

3. Types of Plate Boundaries
Boundary
What Happens
Diagram
Transform
Plates move by each other
Convergent
Plates move toward each other
Divergent
Plates move apart

4. Transform Boundary It’s a type of fault; a break in the Earth’s crust
Earthquakes happen when huge areas of rock suddenly move or break
The San Andreas fault in California is a transform boundary (pg. 391, textbook)
**add pictures of normal and reverse faults

5. Convergent Boundary A boundary between two continental plates
Mountains form when 2 continental plates push together (add two continental plates colliding)
A boundary between two oceanic plates
A trench forms when one oceanic plate is subducted or pushed under the other plate
As the subducted plate sinks into the mantle, some rock will melt into magma

6. A boundary between an oceanic plate and a continental plate (add picture of continental plate and oceanic plate colliding)
When they collide, the oceanic plate will slide under the continental plate.
Volcanic mountains can form on the edge of the continental plate

7. Divergent Boundary Plates move apart
A crack called a rift forms between the plates
As magma rises up through the rift, new crust forms
When this process happens on the ocean floor it is called sea-floor spreading
** add picture of two oceanic plates pulling apart

8. The Ring of Fire A zone of frequent earthquakes and volcanic activity
More than 75% of Earth’s volcanoes are located in this area
Add picture of ring of fire and out line the ring of fire (textbook pg. 463).

9. A Hot Spot
An area of volcanic activity that is not near a plate boundary
The hot spot stays in one place and the plate slowly moves over it
The Hawaiian Islands were formed this way
** add hot spot picture