Which rock type forms when existing rocks are subjected to high heat and pressure, causing changes?

Which rock type forms when existing rocks are subjected to high heat and pressure, causing changes?

• A. Sedimentary Rock
• B. Igneous Rock
• C. Metamorphic Rock
• D. Limestone

Answer: (C)

When rocks are altered by high heat and pressure deep in the Earth, they undergo metamorphism and become metamorphic rocks. This process rearranges minerals and often changes texture without melting, producing rocks that may have a layered (foliated) appearance or a more uniform texture. That’s exactly the scenario described—existing rocks changing form under heat and pressure. Shale can become slate, limestone can become marble, and granite can become gneiss, illustrating how the same original material can transform into different metamorphic forms under these conditions. Sedimentary rocks form from sediments that settle and are cemented together, so they aren’t defined by heat and pressure changing existing rocks. Igneous rocks form from molten rock that cools and solidifies, a different process altogether. Limestone is an example of a sedimentary rock (made largely of calcium carbonate), though it can become marble if subjected to metamorphism.

When rocks are altered by high heat and pressure deep in the Earth, they undergo metamorphism and become metamorphic rocks. This process rearranges minerals and often changes texture without melting, producing rocks that may have a layered (foliated) appearance or a more uniform texture. That’s exactly the scenario described—existing rocks changing form under heat and pressure. Shale can become slate, limestone can become marble, and granite can become gneiss, illustrating how the same original material can transform into different metamorphic forms under these conditions.

Sedimentary rocks form from sediments that settle and are cemented together, so they aren’t defined by heat and pressure changing existing rocks. Igneous rocks form from molten rock that cools and solidifies, a different process altogether. Limestone is an example of a sedimentary rock (made largely of calcium carbonate), though it can become marble if subjected to metamorphism.