Question

Why the upper mantle called the asthenosphere

Answer 1

Because it is made up of rocks and fluid which can move.

Answer 2

Answer:

because The upper mantle is not uniform throughout. Below the lithosphere is a layer of upper mantle called the asthenosphere. This is made up rock that is fluid and can move.It is this fluidity that powers the movement of the tectonic plates of the Earth's crust.