What is the fourth layer of Earth called?

The fourth layer of Earth is called the outer core. It is a liquid layer composed primarily of iron and nickel, located beneath the mantle and above the inner core. The movement of the molten metal in the outer core is responsible for generating Earth's magnetic field. This layer extends from about 2,900 kilometers (1,800 miles) deep to approximately 5,150 kilometers (3,200 miles) deep.