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 number of te… See more

The edges of Earth's lithospheric plates have boundaries which are both well defined and poorly defined… 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, f… 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 lithosphere is created by volcanic activit… See more