Destructive Plate Margins
This is a plate margin where two plates are moving towards each other resulting in one plate sinking beneath the other.
Convection currents in the mantle cause the plates to move together. If one plate is made from oceanic crust and the other from continental crust, the denser oceanic crust sinks under the lighter continental crust. This is called subduction.
If two continental plates meet each other, they collide rather than one sinking beneath the other. This collision boundary is a different type of destructive margin.
Constructive plate margins
- A plate margin where two plates are moving apart.
- When plates move apart they cause a constructive plate boundary to form.
- This type of plate boundary normally occurs in oceans
- As the oceanic plates pull away from each other, cracks and fractures form.
- Magma forces its way into the cracks and eventually forms volcanoes.
- In this way new land is formed as the plates gradually pull apart.
Conservative plate margins
- A plate margin where two plates are sliding alongside each other.
- The plates are moving in a similar (not the same) direction, at slightly different angles and speeds.
- As one plate is moving faster than the other and in a slightly different direction, they tend to get stuck.
- As there is a build up of pressure it causes an earthquake
- At a conservative margin, crust is neither being destroyed or made.