What term describes the layer of Earth that includes the crust and upper mantle?

The term that describes the layer of Earth that includes the crust and upper mantle is the lithosphere. This layer is comprised of the solid, outermost part of the Earth, which encompasses both the lithospheric mantle and the overlying crust. The lithosphere is characterized by its rigidity and is important in the study of plate tectonics, where the tectonic plates exist.

This layer is distinct from the underlying asthenosphere, which is part of the upper mantle but is semi-fluid and allows for the movement of the lithospheric plates above it. Understanding the structure of the lithosphere helps explain many geological processes, including the formation of mountains, earthquakes, and volcanic activity. The core refers to the innermost layer of the Earth, the mesosphere relates to deeper layers of the mantle, and the asthenosphere is not included in the definition of the lithosphere, as it lies beneath it.