What does the lithosphere consist of?

The lithosphere consists of a rigid layer that includes both the upper mantle and the crust. This definition is crucial because the lithosphere encompasses the solid and outermost shell of the Earth, which is involved in various geological processes. The upper mantle, while it may technically still have some plasticity at greater depths, is primarily rigid in terms of the interactions it has with the overlying crust.

The lithosphere is important in environmental science and geology as it is the layer where tectonic plates are located, playing a key role in processes such as earthquakes, volcanic activity, and continental drift. This rigid layer is distinct from other layers of the Earth, such as the asthenosphere, which sits below the lithosphere and is semi-fluid, allowing for the movement of tectonic plates. Understanding the composition and function of the lithosphere is essential for grasping the dynamics of the Earth's surface and geological events.