Transcript Power Point 9.5

The Theory of Plate
Tectonics

Chapter 9, Section 5
• A geological theory stating that
pieces of Earth’s lithosphere are in
constant, slow motion.
• As plates move they crash
together, pull apart and grind past
each other.
 Each movement along a plate
boundary creates a different land
feature.
Plate Boundaries

Transform
Boundaries
• Two plates slip by
each other
• Crust is not created
or destroyed
• Earthquakes occur
often
What drives the plates?
Plate Boundaries

Divergent
Boundaries
• Plates move
away from each
other
• Found in the
oceanic and
continental crust
• Creates rift
valleys
• The mid-ocean
ridge is a D.B.
Plate Boundaries

Convergent Boundaries
•Plates come together, collide,
crash!
•3 things can happen depending
on the type of crust that is
colliding.
1 - Oceanic to Oceanic – the more
dense plate will subduct (go under
the other).
2 - Oceanic to Continental – the
more dense oceanic crust subducts
(goes under)
http://www.wwnorton.com/college/geo/egeo/animations/ch2.htm
3 - Continental to Continental
– builds mountains
Plate Boundaries

Demo• http://www.wwnorton.com/college/geo/
egeo/animations/ch2.htm
• Subduction http://oceanexplorer.noaa.gov/explorati
ons/03fire/logs/subduction_320.mov