Question

Which of the following statements about lithosphere and asthenosphere is true?

a. Lithosphere consists of the crust and the upper mantle and behaves like a rigid layer that breaks or bends rather than flowing like the asthenosphere.
b. Lithosphere is more mafic than asthenosphere.
c. Lithosphere and asthenosphere have the same physical properties; they are both rigid.
d. Asthenosphere is defined as mantle material that is cooler than 1,280°C, whereas lithosphere is warmer than 1,280°C.

Answer 1

The lithosphere is rigid and consists of the crust and upper mantle, capable of breaking, unlike the plastic and flowing asthenosphere.

Step-by-step explanation:

The lithosphere consists of the crust and the upper mantle and behaves like a rigid layer that breaks or bends rather than flows like the asthenosphere. The lithosphere is a rigid, brittle layer made up of the crust and the uppermost part of the mantle. This layer can break under stress, causing earthquakes. In contrast, the asthenosphere lies beneath the lithosphere and is characterized by its ability to flow, owing to its semi-molten state. It behaves plastically, which allows for the movement of tectonic plates. The asthenosphere is crucial for plate tectonics since it is the layer on which the lithospheric plates can move due to mantle convection.

Additionally, the composition of the lithosphere may vary, with the oceanic lithosphere being more mafic but overall, the lithosphere is not defined by its mafic content when compared to the asthenosphere. Meanwhile, temperature distinctions between these layers are not the primary characteristic used to differentiate them, instead, they are defined by their mechanical, not thermal, properties.