Which rock cycle process involves the transformation of rocks from one type to another?

The process of metamorphism is integral to the rock cycle as it specifically involves the transformation of existing rocks into new types due to changes in temperature and pressure, as well as interactions with chemically active fluids. During this process, pre-existing rocks—be they sedimentary, igneous, or even other metamorphic rocks—undergo physical and chemical changes. This can result in the creation of new minerals or the reorganization of the rock's structure, ultimately leading to the formation of metamorphic rocks.

Metamorphism is essential for understanding how rocks not only change form but also how they contribute to the dynamic nature of the Earth's crust. This transformation reflects the interconnected processes of the rock cycle, highlighting the continuous nature of geological change over time.

In contrast, erosion refers to the process of transporting weathered materials, weathering involves the breakdown of rocks at the Earth's surface, and igneous formation pertains to the creation of rocks from molten material. While all these processes are important components of the rock cycle, they do not specifically denote the transformation from one rock type to another as metamorphism does.