What is the special feauture of the upper mantle?

The upper mantle is characterized by its semi-solid state, which allows for the movement of tectonic plates above it. It contains a layer known as the asthenosphere, where convection currents occur, driving plate tectonics. Additionally, the upper mantle is composed predominantly of peridotite, a dense rock rich in magnesium and iron, which contributes to its unique physical and chemical properties. This layer plays a crucial role in the Earth's geology and the dynamics of the crust above.