Plates

Plate boundaries are found at the edge of the lithospheric plates and are of three types, convergent, divergent and conservative. Wide zones of deformation are usually characteristic of plate boundaries because of the interaction between two plates. The three boundaries are characterized by their distinct motions.

The first sort of plate boundary is called a divergent boundary, or spreading center. At these boundaries, two plates move away from one another. As the two move apart, mid-ocean ridges are created as magma from the mantle upwells through a crack in the oceanic crust and cools. This, in turn, causes the growth of oceanic crust on either side of the vents. As the plates continue to move, and more crust is formed, the ocean basin expands and a ridge system is created. Divergent boundaries are responsible in part for driving the motion of the plates.