The theory of plate tectonics as it relates to vents The earth's surface is broken up into several large and a few smaller plates . These plates include the crust and the top portion of the mantle . Together these two layers make up the lithosphere , therefore the plates are referred to as lithospheric plate s. The plates can consist of ocean crust or continental crust , or more often, a combination of the two. Places where plates meet are called plate boundaries or plate margins.
Convergent boundaries are places where plates come together.
Divergent boundaries are places where plates pull apart. Magma rises up from the mantle and adds new sea floor to the separating plates. Fractures develop as the plates are pulled apart. The superheated water is forced back up to the sea floor carrying dissolved minerals leached from the basalt ocean plate. A vent forms when the jet of water shoots through the sea floor and its dissolved minerals begin to precipitate out.