What does the theory of plate tectonics suggest about the Earth's layers?

The theory of plate tectonics suggests that the Earth's layers are divided into both solid and liquid components. This framework describes how the Earth's outer shell, or lithosphere, is composed of rigid plates that float on the semi-fluid asthenosphere beneath them. The lithosphere includes the crust and the uppermost part of the mantle, both of which are solid.

Beneath the lithosphere lies the asthenosphere, which while technically still part of the mantle, behaves more like a viscous fluid over geological time scales. This allows the tectonic plates to move, causing geological phenomena like earthquakes, volcanic activity, and the formation of mountain ranges. Therefore, the representation of Earth's layers in the context of plate tectonics as consisting of both solid and liquid interactions is vital for understanding the dynamics that shape our planet.

It is important to recognize that the lithosphere and asthenosphere together illustrate the complexity of Earth's internal structure rather than a simplistic solely solid or exclusively liquid state.