What is the term for the layer of Earth that is liquid and primarily composed of iron and nickel?

The layer of Earth that is liquid and primarily composed of iron and nickel is known as the outer core. This region lies beneath the solid mantle and above the inner core. The outer core is critical to our understanding of Earth's structure because it is responsible for generating the planet's magnetic field through the movement of these molten metals.

In terms of composition, the outer core is liquid due to the extremely high temperatures that exist at these depths, which are sufficient to keep iron and nickel in a molten state. This liquidity contrasts significantly with the solid inner core, which, despite being even hotter, remains solid due to the immense pressure that exists there.

Understanding the outer core is essential for comprehending various geological and geophysical phenomena, including convection currents that occur in this layer, which in turn drive the tectonic activity of the plates above it.