1. Plate Boundary Notes

2. 3 Forces that Move the Plates
Convection currents in the asthenosphere
create 3 forces that move the lithospheric
plates around.
Tension
Compression
Shearing

3. Tension – pulls plates away from each other.
Divergent Boundary – when 2 plates
are pulled apart. Causes rift valleys
& mid-ocean ridges.

4. Compression –pushes plates towards each other.
Convergent Boundary – when 2 plates
are pushed together.

5. Oceanic-Continental Convergence
When oceanic crust & continental crust converge, the oceanic plate subducts under the continental plate & melts, creating a trench & a volcanic arc. Ex: the Andes

6. Subduction - When 1 plate is pushed under another plate & back into the mantle, forming trenches & volcanoes.

7. Trench
Oceanic Crust
Continental Crust

8. Oceanic-Oceanic Convergence
When both edges of two plates that are converging are made of oceanic crust, the older, denser plate subducts under the younger oceanic plate, forming a trench & a volcanic island arc. Ex: The Marianas Trench & Mariana Islands

9. Trench
Oceanic Crust
Oceanic Crust

10. Volcanoes

11. Continental-Continental Convergence
When 2 continents meet head-on, the crust buckles & is pushed upward.
Ex: The Himalayan mountain range

12. Continental Crust
Continental Crust

13. Shearing –pushes plates past each other in opposite directions.
Transform Boundary – when 2 plates are pushed past each other in opposite directions. Produces earthquakes (San Andreas Fault).

14. Earthquakes

15. Hot Spots
A large, stationary plume of super hot magma that breaks through the tectonic plate moving over it, causing continual volcanic activity.