What happens when two tectonic plates come together?
AKS 17b2

Deformation
• The process by which a rock changes shape.
The forces are called stress.

Three ways it can change
1 – compression is the stress when an object is squeezed
2- tension is the stress that occurs when an object is stretched
3 - shearing is the stress when objects push past each other.

Boundary
• A place where tectonic plates touch. Stress occurs here
• Three types of boundaries–
Divergent – pulls apart
Convergent – pushes together
Transform – slides beside

Using your hands demo
Divergent – move hands apart
Convergent – move hands together
Transform – move hands back and forth

Practice plate boundaries!

Practice

Practice

1 = convergent, 2 = divergent, 3 = transform a. Which happens when two boundaries slide past each other.
b. What happens when two boundaries come together.
c. What happens when two boundaries push apart.

Divergent boundaries
- Where tectonic plates are pulling apart
- Always oceanic plate and oceanic plate
- Magna rises toward surface and pushes plates apart
- Makes new crust
- Causes seafloor spreading
- produces the mid-oceanic ridge

Watch this!
http://geology.com/nsta/divergent-boundarycontinental.gif

IN YOUR OWN WORDS, DESCRIBE WHAT IS HAPPENING HERE.

Transform boundary where plates push past each other.
Can be continental or oceanic plates.
Ex: San Andreas fault in California

In your own words, what is happening here?

Watch this!
http://geology.com/nsta/transform-boundary.gif

1 = divergent, 2 = transform a. Magma comes close to the surface b. Happens only with oceanic plates c. Happens when tectonic plates push apart d. Happen with any kind of tectonic plate e. Happens when tectonic plates slide past each other f. Results in sea-floor spreading and mid-ocean ridges

Convergent boundary
Where boundaries push together.
Can be continental and continental
Can be oceanic and continental
Can be oceanic and oceanic

Continental and continental convergent boundary
Results in plates being pushed up and creates mountains

Watch this!
http://geology.com/nsta/convergentboundary.gif

Oceanic vs. continental
Results in the most dense (oceanic) layer being subducted. This creates a subduction zone, an area where one layer is pushed under the other and is remelted and recycled. May result in volcanoes

Watch this!
http://geology.com/nsta/convergent-boundaryoceanic-continental.gif

Oceanic and oceanic convergent plates
- results in a subduction zone
- May result in volcanoes and volcanic islands.

Watch this!
• http://geology.com/nsta/convergentboundary-oceanic-oceanic.gif

1= divergent, 2= convergent, 3 = transform a. Results in seafloor spreading b. Results in mountains c. Happens when tectonic plates slide past each other d. Happens when tectonic plates push together e. Happens when tectonic plates pull apart f. Creates the mid-oceanic ridge

A
Identify the boundary
B
C