There are several major discontinuities:
* Mohorovičić discontinuity (Moho): The boundary between the Earth's crust and the mantle.
* Gutenberg discontinuity: The boundary between the Earth's mantle and the outer core.
* Lehmann discontinuity: The boundary between the Earth's outer core and the inner core.
These discontinuities are identified through seismic waves, which change speed and direction as they pass through different layers of the Earth.
