What type of rock is formed from existing rocks that have been subjected to heat and pressure?

The formation of metamorphic rocks occurs through the process of metamorphism, wherein existing rocks are subjected to high temperatures and pressures, leading to changes in their mineral composition and texture. This process can occur deep within the Earth's crust, where the conditions are conducive to altering the structure of the original rock without melting it. Instead of becoming molten, the minerals within the rock can recrystallize, resulting in a new, more stable form that is often quite different in appearance and physical properties from the original rock.

Igneous rocks originate from the cooling and solidification of molten material called magma or lava. Sedimentary rocks are formed through the accumulation and compaction of sediments. Weathered rocks are simply the result of the breakdown of existing rocks due to weathering processes, not changes caused by heat and pressure. Hence, the correct identification of metamorphic rocks is crucial in understanding the rock cycle and the geological processes that shape our planet.