Here's why:
* Metamorphism is the process of transforming existing rocks (igneous, sedimentary, or even other metamorphic rocks) through intense heat and pressure.
* The weight of overlying rocks contributes significantly to this pressure, which causes changes in the rock's mineral composition, texture, and sometimes even its chemical composition.
For example, limestone (a sedimentary rock) can be transformed into marble (a metamorphic rock) under intense pressure from overlying rocks.
