The transition zone from the outer core to the mantle is uneven and is known as the Gutenberg discontinuity.
Step-by-step explanation:
Gutenberg discontinuity is present in the interior of the earth at about 2900kms below the surface. In this area, there is an sudden change in the seismic waves that travel through the earth. This zone marks the boundary between the two sections of earth's interior which are mantle and the outer core.