The process by which rocks are transformed by heat and pressure is:

• A. Weathering
• B. Metamorphism
• C. Erosion
• D. Sedimentation

Answer: (B)

Heat and pressure inside the Earth rearrange minerals in a rock and push it toward new stable forms without melting. This solid-state transformation changes both the mineralogy and the texture, often producing larger grains and, under directed pressure, a layered or banded (foliated) appearance. Fluids can also drive chemical reactions that create new minerals, so the rock ends up with a different composition and structure than before. Examples include limestone turning into marble, shale into slate, and granite into gneiss, depending on the specific temperature, pressure, and fluid conditions.

Weathering is the breakdown of rocks at or near the surface through climate and chemical or physical processes; erosion is the removal and transport of the resulting materials; sedimentation is the deposition and lithification of those sediments into sedimentary rocks.