Plate Boundaries Review Concepts
Convergent Boundaries
Plates are moving towards each other
Oceanic - Continental
● Plates collide and the more dense oceanic plate subducts
● Volcanic Mountains form on continental side.
● Trench forms on oceanic side
● Oceanic crust is destroyed as it subducts
Continental - Continental
● Plates collide but neither one is dense enough to subduct into the
mantle.
● Mountains form as a result of continental crust folding from
compression.
Oceanic - Oceanic
● Plates collide and the most dense oceanic plate subducts.
● Volcanic island arcs form on less dense oceanic plate.
○ Called Archipelago
● Trench forms on subducting side
● Oceanic crust is destroyed as it subducts
Transform Boundaries
Plates are moving past each other
● Occur when plates are sliding past one another
● Earthquakes are very common
● Crust is neither created nor destroyed
Divergent Boundaries
Plates are moving away from each other
Continental - Continental
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Plates break as they are spreading apart.
Crust is thinning.
Over time water fills in low spots and an ocean eventually forms.
Some volcanic activity can occur.
Oceanic - Oceanic
● Plates are spreading apart at mid ocean ridges.
● Ocean expands over time.
● New crust is formed.