What is the name of the boundary between Earth's liquid outer core and solid inner core?

The Lehmann discontinuity is the boundary between Earth’s liquid outer core and solid inner core.

Danish seismologist Inge Lehmann proposed the existence of Earth’s solid inner core in 1936 after studying how earthquake waves travel through the planet. The inner core begins at the Lehmann discontinuity, roughly 5,150 kilometers below the surface, and extends to Earth’s center at about 6,371 kilometers depth.

The outer core is mostly liquid iron and nickel, while the inner core is solid because immense pressure raises the melting point of its material. Convection in the electrically conducting outer core helps generate Earth’s magnetic field. Seismic waves reveal these layers because their speeds and paths change when they encounter different materials.

This boundary is distinct from the Gutenberg discontinuity, which marks the mantle–outer-core boundary at about 2,900 kilometers depth. Naming these boundaries correctly helps separate Earth’s major internal transitions.