The Earth's interior is composed of several distinct layers. The boundaries between these layers are known as discontinuities, which are identified by abrupt changes in the velocity of seismic waves. These changes are due to differences in the density and composition of the rock on either side of the boundary.
Step 1: Understanding the Question:
The question asks to name the specific discontinuity that marks the boundary between the Earth's crust and the underlying mantle.
Step 2: Detailed Explanation:
Let's analyze the discontinuities given in the options:
Gutenberg Discontinuity: This separates the mantle from the outer core.
Mohorovičić Discontinuity (Moho): This is the boundary between the crust and the mantle. It is characterized by a sharp increase in the velocity of seismic P-waves.
Lehmann Discontinuity: This separates the liquid outer core from the solid inner core.
Conrad Discontinuity: This is a less distinct boundary found within the continental crust, separating the upper (felsic) crust from the lower (mafic) crust.
The boundary between the crust and the mantle is correctly identified as the Mohorovičić Discontinuity.
Step 3: Final Answer:
Therefore, the Mohorovičić Discontinuity is the correct answer.