the shallow region of the ocean that occurs above the continental shelf
Continental shelf The continental shelf is an underwater landmass which extends from a continent, resulting in an area of relatively shallow water known as a shelf sea. Much of the shelves were exposed during glacial periods and interglacial periods.
Mid-ocean ridge A mid-ocean ridge (MOR) is an underwater mountain system formed by plate tectonics.[1] It consists of various mountains linked in chains, typically having a valley known as a rift running along its spine. This type of oceanic mountain ridge is characteristic of what is known as an 'oceanic spreading center', which is responsible for seafloor spreading.[2] The production of new seafloor results from mantle upwelling in response to plate spreading; this isentropic upwelling solid mantle material eventually exceeds the solidus and melts. The buoyant melt rises as magma at a linear weakness in the oceanic crust, and emerges as lava, creating new crust upon cooling. A mid-ocean ridge demarcates the boundary between two tectonic plates, and consequently is termed a divergent plate boundary.