GEOLOGY

Detailed explanation-1: -Upwelling is a process in which currents bring deep, cold water to the surface of the ocean. Upwelling is a result of winds and the rotation of the Earth.

Detailed explanation-2: -In contrast to wind-driven surface currents, deep-ocean currents are caused by differences in water density. The process that creates deep currents is called thermohaline circulation-“thermo” referring to temperature and “haline” to saltiness.

Detailed explanation-3: -Deep currents are caused by differences in the density of ocean water. Currents move water from the equator to the poles. As water temperatures begin to decrease and salinity increase, the water becomes denser and sinks. Then, the cold water flows back along the ocean floor as a deep current.