Multiple choice What is the name given to the imaginary line separating Earth's mantle from its crust? Gutenberg Weichert Discontinuity Mohorovicic Discontinuity Asthenosphere Mesopause Reveal answer Fill a bubble to check yourself B Correct answer Explanation The Gutenberg Discontinuity is the boundary, as detected by changes in seismic waves, between the Earth's lower mantle and the outer core about 1800 miles below the surface.