Plates come together and one is recycled back into the mantle.
A. Ocean - Ocean Convergence
- Two plates are oceanic --> one descends beneath the other in a process called subduction
- The oceanic lithosphere of subducting plate sinks into asthenosphere and, replaced by mantle convection system
- This downward buckling produces a long, narrow deep-sea trench (ex. Marianas Trench of the western Pacific)
B. Ocean - Continent Convergence
- If one plate has a continental edge, it overrides the oceanic plate b/c the continental crust is lighter and less easily subducted than oceanic crust
- The continental ledge crumples and is uplifted into a mountain chain (ex. the Andes)
- The enormous forces of collision and subducton produces great earthquakes
C. Continent - Continent Convergence
- Two continental plates collide --> crust crumples and thickens, creating high mountains and a wide plateau (ex. Himalaya and Tibetan Plateau)
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