Which layer of the Earth is composed primarily of liquid iron and nickel?

The outer core is composed primarily of liquid iron and nickel, making it a crucial layer of the Earth's structure. This layer lies beneath the mantle and above the inner core. Unlike the solid inner core, the outer core is in a molten state, which is vital for the generation of the Earth's magnetic field. The movement of the liquid iron and nickel creates electric currents, which in turn produce magnetic fields—a phenomenon known as the geodynamo.

The distinction between the outer core and the other layers of the Earth is significant. The crust is the thin, solid outer layer of the Earth, primarily made up of silicate rocks. The mantle, located beneath the crust, is composed of solid rock that behaves plastically over geological time, allowing for convection currents that drive plate tectonics. The inner core, which is solid despite its high temperature, is made largely of iron and nickel but remains in solid form due to immense pressure. Understanding the composition and properties of the outer core is fundamental in geology, particularly in discussions around the Earth's magnetic field and its implications for geodynamics and tectonic activity.