What creates a rift valley?

Rift valleys are formed when tectonic plates move away from each other, causing the land in between to sink and form a valley. This happens when the plates move apart due to the convection currents in the Earth's mantle. The mantle is the layer of the Earth that is located between the crust and the outer core. When the mantle moves, it causes the tectonic plates to move along with it. If the plates move apart, the land in between sinks and forms a rift valley.