What is physical weathering?

• A. Erosion
• B. Chemical breakdown
• C. Mechanical breakdown of rock
• D. Transport of sediment

Answer: (C)

Physical weathering is the mechanical breakdown of rocks into smaller pieces without changing their mineral composition. It happens when rocks are stressed by temperature changes that cause expansion and contraction, water and ice that crack and pry rocks apart (frost wedging), unloading that causes slabs to peel, and biological actions like plant roots growing into cracks and widening them. The result is more surface area for future weathering and soil formation, but the minerals themselves aren’t chemically altered in this process. By contrast, erosion involves moving those fragments away, and chemical weathering involves minerals changing through chemical reactions.