Process that takes place at mid-ocean ridges?

Sea-floor Spreading. The formation of new areas of oceanic crust, which occurs through the up welling of magma at mid ocean ridges and its subsequent outward movement on either side.

Explanation:

A mid-ocean ridge or mid-oceanic ridge is 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.