Which process accelerates soil formation by mineral breakdown and clay formation?

• A. Physical weathering
• B. Chemical weathering
• C. Biological weathering
• D. Metamorphism

Answer: (B)

Chemical weathering is the process that breaks down minerals through chemical reactions driven by water and acids, transforming primary minerals into secondary minerals like clays. In soils, this chemical alteration is how minerals are altered and reshaped into clay minerals such as kaolinite and illite; dissolution and hydrolysis release ions and nutrients, and oxidation changes minerals like iron oxides. This chemical change is what accelerates soil formation by turning solid rock into clay-rich materials that help build soil structure and fertility.

Physical weathering, on the other hand, breaks rocks into smaller pieces without changing their mineral composition, so it speeds fragmentation but not clay formation. Metamorphism involves mineral changes under high temperature and pressure deep in the crust, not a surface-weathering process tied to soil development. Biological weathering can assist chemical processes through acids from organisms, but the dominant mechanism for mineral breakdown into clays is chemical weathering.