asthenosphere

The asthenosphere is a semi-fluid layer located beneath the Earth's rigid outer shell, the lithosphere. It extends about 100 to 700 kilometers beneath the surface and is composed of partially melted, ductile rock. This layer allows the rigid plates of the Earth's crust to move slowly over it, causing phenomena like earthquakes and plate tectonics. The asthenosphere's semi-fluid nature results from high pressure and temperature, enabling the rock to deform and flow, which is essential for the dynamic processes shaping our planet's surface.