The outermost part of Earth's structure is known as the lithosphere. The lithosphere consists of the crust and small portion of the upper mantle. The lithosphere is divided into a num… See more

The edges of Earth's lithospheric plates have boundaries which are both well defined and poorly defined. Well-defined boundaries include mid-ocean ridges and ocean tren… See more

Mid-ocean ridges are divergent boundaries where convection currents in the mantle lift the ocean floor and produce a rift in the lithosphere that follows the crest of the ridge. New … See more

Ocean trenches form where a plate with a leading edge of oceanic lithosphere collides with another plate. In these situations, an oceanic plate normally subducts into the mantle, for… See more