Rift- Valleys can be formed when plate motion starts to stretch the lithosphere, at the same time plums of hot rock rise from the mantle. The rising plums bend the crust upward, weakening and fracturing it. . The fractures allow magma to the surface, resulting in the new floor called a rift valley.
Mid-Ocean ridges are created when convection currents rices in the mantle beneath and and create magma where they meet.
Mid-Ocean ridges are created when convection currents rices in the mantle beneath and and create magma where they meet.