mid-ocean ridge An underwater mountain range, formed by plate tectonics. This uplifting of the ocean floor occurs when convection currents rise in the mantle beneath the oceanic crust and create magma where two tectonic plates meet at a divergent boundary. The mid-ocean ridges of the world are connected and form a single global mid-oceanic ridge system that is part of every ocean. ENVO ENVO:00000406 EcoLexicon:oceanic_ridge OceanRidge TGN:23151 Wikipedia:Mid-ocean_ridge undersea ridge range of seamounts marine pelagic feature