What is the term for the in-place granular disintegration product of granite?

• A. Grus
• B. Laterite
• C. Shale
• D. Alluvium

Answer: (A)

Granite exposed at the surface weathers into a loose, gritty material called grus. This is the in-place granular disintegration product of granite—a coarse, sandy-granular mix of primarily quartz and feldspar grains that has been physically broken down and slightly chemically altered but not cemented back into a solid rock. It forms right where the rock sits, rather than being transported elsewhere.

This differs from the other terms: laterite develops in hot, tropical climates with intense chemical leaching and iron/aluminum accumulation, not just granite grains. Shale is a sedimentary rock formed from compacted mud, and alluvium consists of materials deposited by moving water, not the weathered, in-place product of granite.