Which of the following seismic discontinuities marks the boundary between the Earth's lower mantle and the outer core?

💡 Solution & Explanation

The Gutenberg discontinuity marks the boundary layer between the Earth's lower mantle and the outer core, situated at a depth of approximately 2,900 kilometers beneath the surface. Seismic waves change behavior drastically here, as primary waves slow down and secondary waves disappear entirely due to the liquid nature of the outer core. In contrast, the Mohorovicic discontinuity separates the crust from the mantle. This internal zoning of the Earth is established primarily through seismic wave velocity studies.