Which rock type forms when existing rock is transformed by heat and pressure?

Which rock type forms when existing rock is transformed by heat and pressure?

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

Answer: (C)

Rocks change form under heat and pressure to become metamorphic rocks. In metamorphism, the rock remains solid while the minerals recrystallize and the texture reorients, often producing foliation or new mineral assemblages. This happens deep inside Earth where temperatures and pressures rise, or when heat from nearby magma alters the rock. Examples show the idea: limestone can become marble, shale can become slate, and sandstone can become quartzite. Quartz is a mineral, not a rock, so it isn’t the type formed by this process.

Rocks change form under heat and pressure to become metamorphic rocks. In metamorphism, the rock remains solid while the minerals recrystallize and the texture reorients, often producing foliation or new mineral assemblages. This happens deep inside Earth where temperatures and pressures rise, or when heat from nearby magma alters the rock. Examples show the idea: limestone can become marble, shale can become slate, and sandstone can become quartzite. Quartz is a mineral, not a rock, so it isn’t the type formed by this process.