Which rock type is formed from existing rocks transformed by heat and pressure?

• A. Igneous
• B. Sedimentary
• C. Metamorphic
• D. Fossil

Answer: (C)

Metamorphism is the process by which existing rocks are transformed by heat and pressure. This happens while the rock remains mostly solid, but the added heat speeds chemical reactions so minerals can recrystallize into new forms, and the pressure from deep burial or tectonic forces can squeeze and realign minerals, often creating a layered texture called foliation. Any starting rock type—igneous, sedimentary, or even another metamorphic rock—can become metamorphic if it experiences these conditions, which is why we call the resulting rocks metamorphic. For example, slate forms from shale, marble from limestone, and schist or gneiss from other rocks under increasing temperature and pressure. This differs from igneous rocks, which form when molten material cools and solidifies, and from sedimentary rocks, which form from compacted and cemented sediments. Fossils aren’t a rock type themselves; they are remains that can be found within rocks, most commonly sedimentary ones.