What type of rocks are formed when sedimentary and igneous rocks are subjected to heat or pressure?

Metamorphic rocks are formed from existing sedimentary or igneous rocks through processes that involve intense heat and pressure. This transformation alters the mineral composition and structure of the original rock, resulting in a new type of rock that often has distinct characteristics compared to its parent material. For example, granite, an igneous rock, can transform into gneiss under high temperature and pressure, while limestone, a sedimentary rock, may become marble.

Understanding the processes that lead to the formation of metamorphic rocks is crucial in geology, as it helps in studying Earth's history and the dynamic changes within the Earth's crust. This process of metamorphism explains how rocks can evolve and change over geological time scales, illustrating the interconnectedness of the different rock types in the rock cycle.