What lies beneath the lithosphere around 200 km thick?

Beneath the lithosphere, which consists of the Earth's crust and the uppermost part of the mantle, lies the asthenosphere. This layer extends to about 700 kilometers below the surface and is characterized by partially molten rock that allows for the slow flow of material. The asthenosphere plays a crucial role in tectonic processes, facilitating the movement of tectonic plates above it. This dynamic layer is essential for understanding phenomena such as earthquakes and volcanic activity.