noun. the lower layer of the crust.
- natural object
Example sentences of the word asthenosphere
1. Noun, singular or mass
The lithosphere encompasses the very top of the mantle above the asthenosphere as well as the overlying crust.
The bottoms of the tectonic plates are at the boundary between asthenosphere and lithosphere, not the bottom of the crust, and it is the plastic nature of the asthenosphere that allows the tectonic plates to move.
Before digging into the asthenosphere and lithosphere, let's break down the basic anatomy of the planet.