Conrad Discontinuity: Transition zone between SIAL and SIMA, Mohorovicic Discontinuity: Transition zone between the Crust and Mantle, Repiti Discontinuity: Transition zone between Outer mantle and Inner mantle, Gutenberg Discontinuity: Transition zone between Mantle and Core, Lehman Discontinuity: Transition zone between Outer core and Inner core.