Here's why:
* Confining Pressure: The weight of overlying rocks creates a force pushing down on the rocks below. This is called confining pressure and is a significant factor in metamorphic processes.
* Differential Stress: Sometimes, pressure is not evenly distributed. This can happen when tectonic plates collide, creating areas of intense compression or stretching. This type of pressure, known as differential stress, can cause rocks to deform and change their mineral composition.
Both confining pressure and differential stress contribute to the formation of metamorphic rocks.
