Plate Boundaries

There are three different types of plate boundaries, divergent plate boundaries, convergent plate boundaries (subduction and collision), and transform plate boundaries. Convergent plate boundaries form when two plates are moving towards one another. Colliding plates happen when two plates of equal densities collide. For instance, two continental plates would collide and when they touch their crusts are so thick that they get pushed upwards and mountains form. Subduction happens when one plate goes underneath another plate. This occurs when a coninental plate collides with an oceanic plate. Becuase the oceanic plate has a greater density it will subduct under the continental plate. This forms a trench. And it will loften form a vocano on land becuase there the oceanic crusts enters the earth, magma begins to bubble up and has to be released out of the volcano. Subduction can also occur when two oceanic crusts collide. This will form volcanic islands. Divergent plate boundaries happen when two plates are moving away from one another. This will form a ridge beucase as the plates move apart magma comes up and solidifies, creating a ridge (such as the Mid-Atlantic Ridge, which is in the picture). Transform plate boundaries happen when two plates are grinding against each other (San Andreas Fault), this often results in earthquakes.