Earthquakes and volcanoes occur along the edges of the plates. ... When plates move apart, they produce new ocean floor as magma from the mantle rises up through volcanoes and deposits new rock along the plate boundaries. In some areas plates slide alongside each other, neither creating nor destroying land.
Volcanoes form when magma from earth's mantle makes its way to the surface where it erupts lava (which is magma exposed to air). Over time the the ash and hardned lava deposits will start forming the mountainous shape of a volcano.
Earthquakes is when two blocks of earth suddenly break along a fault and slip past one another. As the plates moves againsit one another, it causes seismic waves which shake the earth causing it to "quake".
