There are 2 types of plate...
•Continental plates tend to be larger than oceanic plates. Continental plates tend to less dense.
•Oceanic plates are thinner and denser than continental plates.
This is important because this affects the way the plate behave at plate boundaries
•Oceanic plates are thinner and denser than continental plates.
This is important because this affects the way the plate behave at plate boundaries
Destructive/Convergent Plate Boundary
•A destructive plate margin is found where a continental (land) plate meets an oceanic plate and they are forced together by convection currents.
•The oceanic plate goes under the continental plate because it is denser and it sinks due to gravity; this is called subduction. •Some of the oceanic plate melts due to friction and is destroyed, forming magma. •This new magma rises and erupts through a crack in the crust. •Earthquakes also occur as the plates move together and then slip, releasing energy. •An example is where the Nazca plate is subducted beneath the South American plate. •Seawater evaporating at the plate boundary adds steam to the eruption which makes the lava thicker and more explosive than at a constructive margin. |
Constructive/Divergent Plate Boundary
•At a constructive plate margin, two plates move apart due to convection currents moving in opposite directions.
•As the two plates move apart with the help of gravity, cracks appear in the crust, magma rises up due to the intense pressure in the mantle to fill these cracks, creating new land. •This causes volcanoes. However, since the magma can escape easily at the surface the volcano does not erupt with much force creating a shield volcano. •Earthquakes are also found at constructive boundaries which are caused by the magma rising. •An example of a constructive margin is the Mid-Atlantic Ridge. |
Conservative/Transform Plate Boundary
•Conservative plate margins exist where two plates slide past each other.
•This can be because the plates move in opposite directions or the same, at different speeds. •Friction builds up and eventually the jagged plates lock together, this causes an increase in pressure. •This then leads to a jolt which causes the plates to move, leading to a release of energy. • No volcanoes are found along these plate boundaries, but earthquakes do occur. •An example of such a boundary is the San Andreas Fault in California where the Pacific plate slides past the North American plate. |