Which feature of the earth system is caused by the movement of ions in earths core

Magnetic Field

Explanation:

The outer core of the Earth possesses molten iron. This core gives rise to convectional currents. The movement of the convectional currents gives rise to the electric currents which make up the magnetic field of the Earth. The magnetic field of the Earth is also known as the Earth's magnetosphere. This is the area which comprises of the magnetic field of the Earth caused due to the movement of ions inside the core of the Earth.