The Gutenberg discontinuity occurs within Earth's interior at a depth of about 2,900 km (1,800 mi) below the surface, where there is an abrupt change in the seismic waves (generated by earthquakes or explosions) that travel through Earth.
This distinct change marks the boundary between two sections of the earth's interior, known as the lower mantle (which is considered solid) and the underlying outer core (believed to be molten).
The molten section of the outer core is thought to be about 700 °C (1,292 °F) hotter than the overlying mantle.
These undulations are affected by the heat-driven convection activity within the overlying mantle, which may be the driving force of plate tectonics-motion of sections of Earth's brittle exterior.
These undulations in the core–mantle boundary are also affected by the underlying eddies and currents within the outer core's iron-rich fluids, which are ultimately responsible for Earth's magnetic field.