Gravity Forces, Salt, and Wind During certain seasons. gravity forces from the moon and the Earth's rotation create strong currents. The Moon pushes water away from the surface. This surface water is replaced with water that rises from deep down in the ocean. water at the bottom of the ocean has a lot of nutrients. When these currents rise from the ocean bottom to the surface, the process is called upwelling. The main benefit of upwelling is that fish and other marine life can easily be found on the surface.