Question

Choose the correct statement(s) regarding discontinuities within the Earth:

1. The Gutenberg Discontinuity lies between the crust and mantle.

2. The Repetti Discontinuity divides the upper and lower mantle.

• A. 1 only
• B. 2 only
• C. Both 1 and 2
• D. Neither 1 nor 2

Answer 1

Answer:

B. 2 only

• Correct Answer: Option B) 2 only

• To understand the discontinuities within the Earth, we need to examine each statement carefully:

• Statement 1: The Gutenberg Discontinuity lies between the crust and mantle.This statement is Incorrect. The Gutenberg Discontinuity (also known as the Core-Mantle Boundary) lies between the mantle and the outer core, not between the crust and mantle. The boundary between the crust and mantle is called the Mohorovičić Discontinuity (or Moho).

• Statement 2: The Repetti Discontinuity divides the upper and lower mantle.This statement is Correct. The Repetti Discontinuity is located at approximately 700 km depth and marks the boundary between the upper mantle and lower mantle. It represents a significant change in the physical and chemical properties of mantle materials.

• Key Earth Discontinuities to Remember:

• Mohorovičić Discontinuity (Moho): Crust-Mantle boundary

• Conrad Discontinuity: Within the continental crust (separates upper and lower crust)

• Repetti Discontinuity: Upper Mantle-Lower Mantle boundary (~700 km depth)

• Gutenberg Discontinuity: Mantle-Outer Core boundary (~2900 km depth)

• Lehmann Discontinuity: Outer Core-Inner Core boundary (~5150 km depth)