Question

which layers of the earth are common to both the compositional and mechanical descriptions?
a. crust and mantle
b. lithosphere and mesosphere
c. inner and outer core
d. crust and lithosphere
please select the best answer from the choices provided

Explanation:

• Compositional Layers:
• The Earth's compositional layers are based on chemical composition. The main compositional layers are crust (silicate rocks), mantle (silicate minerals rich in iron and magnesium), and core (iron - nickel alloy).
• Mechanical Layers:
• The mechanical layers are based on physical properties (e.g., rigidity, ability to flow). The main mechanical layers are lithosphere (rigid outer layer, includes crust and upper - mantle), asthenosphere (weak, ductile layer), mesosphere (more rigid part of the mantle below the asthenosphere), outer core (liquid), and inner core (solid).
• Analysis of Options:
• Option a: The crust (compositional) and mantle (compositional) - The mantle in the mechanical description is divided into lithosphere (part of the upper mantle), asthenosphere, and mesosphere. So, just saying mantle (compositional) is not the same as in the mechanical description.
• Option b: Lithosphere (mechanical) and mesosphere (mechanical) - These are only mechanical layers.
• Option c: Inner and outer core - The core (compositional) is also present in the mechanical description (outer core is liquid, inner core is solid in the mechanical description based on physical state).
• Option d: Crust (compositional) and lithosphere (mechanical) - The lithosphere is a mechanical layer that includes the crust and part of the upper mantle.

Answer:

C. inner and outer core