Plate Boundaries


Plate Boundaries are where two plates meet.


There are three types of plate boundaries:

1) Convergent Boundaries:  Convergent means come together.  At this boundary the plates are moving toward each other. It is also called a destructive boundary because the older more dense plate melts into the mantle.

2)  Divergent Boundaries:  Divergent means move apart.  At this boundary the plates are moving away from each other.  This is also called a constructive boundary because new ocean floor is formed.  Ocean Floor Spreading occurs here.



The diagram above shows what occurs at a divergent boundary.  Notice the magma explodes from the mantle (volcanic activity).  This pushes the plates apart.  We end up with a mid-ocean ridge with a rift valley between the ridges.  New ocean floor is formed at the bottom of the rift valley.  The oldest rock is farthest from the center.




 3) Strike-Slip Boundary (Transform Fault):  The movement at a strike-slip boundary, also called a transform fault, is sideways.  The plates move past each other. These occur at faults or cracks in the crust and are caused by                                earthquakes.