Here's how it works:
* The Asthenosphere: This layer of the Earth's mantle is located beneath the lithosphere and is characterized by its semi-solid, partially molten state.
* Pressure and Melting Point: The melting point of rock is influenced by pressure. As pressure increases, the melting point also increases.
* Pressure Release: As hot, solid rock from the deeper mantle rises towards the surface, the pressure on it decreases. This decrease in pressure lowers the melting point of the rock, causing it to partially melt.
This process, known as decompression melting, is a major factor in the formation of magma at mid-ocean ridges and volcanic hot spots.
