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Q42 (NDA-II/2022) Geography › World Physical Geography › Earth interior structure

Which one of the following ‘discontinuities’ separates the Earth’s crust from the mantle?

Result
Your answer: —  ·  Correct: B
Explanation

The Earth's interior is divided into distinct layers separated by seismic discontinuities where wave velocities change abruptly due to physical or chemical shifts [2]. The Mohorovicic Discontinuity, commonly known as the 'Moho', is the boundary that separates the Earth's crust from the underlying mantle [1][2]. Discovered by Andrija Mohorovicic in 1909, it marks a transition from silica-rich crustal rocks to denser, ultramafic mantle rocks, resulting in a sharp increase in P-wave velocity. In contrast, the Conrad discontinuity separates the upper and lower crust [2], while the Repetti discontinuity divides the upper mantle from the lower mantle [2]. The Gutenberg discontinuity is located much deeper, at approximately 2,900 km, serving as the boundary between the mantle and the liquid outer core [2].

Sources

  1. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 4: Earths Interior > Seismic Discontinuities > p. 56
  2. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 4: Earths Interior > The Mohorovicic (Moho) Discontinuity > p. 53
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