1. Increased Temperature: The most obvious cause of rock melting is simply increasing the temperature. Deep within the Earth, the heat from the planet's core and mantle can melt rock. This is the primary way that magma forms in areas of active volcanism.
2. Decreased Pressure: Rocks melt at lower temperatures when the pressure on them is reduced. This is why rocks can melt at the base of mountains or along fault zones where the overlying rock has been removed, even though the temperature may not be extremely high.
3. Addition of Water: Water acts as a flux, lowering the melting point of rocks. Water can be added to the rock through various processes, such as the subduction of ocean plates, where water trapped in the oceanic crust is released into the mantle. This water-rich environment lowers the melting point of the surrounding rock, allowing it to melt and form magma.
