How does pressure affect metamorphic rock formation?

Pressure plays a crucial role in metamorphic rock formation by causing existing rocks to undergo physical and chemical changes. As rocks are subjected to increased pressure, typically from tectonic forces, their minerals can recrystallize, leading to the formation of denser, more stable structures. This process often results in foliation, where minerals align in response to directional stress, creating distinct layering. Overall, pressure, along with temperature and fluid activity, contributes significantly to the transformation of sedimentary or igneous rocks into metamorphic rocks.