Which term describes the mechanical action of roots prying rocks apart?

• A. Frost action
• B. Glaciers
• C. Root pry
• D. Rain (chemical)

Answer: (C)

Biological activity that physically breaks rocks is a form of mechanical weathering. Plant roots grow into cracks and push against the rock as they lengthen and thicken. That outward pressure wedges the rock apart, gradually widening the cracks and splitting the rock without changing its chemical makeup. This specific action is described as root pry (root wedging).

Frost action also causes mechanical weathering by ice expanding in cracks, but it’s driven by freezing water rather than plant growth. Glaciers wear and break rocks through movement and abrasion, another physical process. Rain that’s labeled chemical indicates chemical weathering, where minerals are dissolved or altered chemically rather than physically pried apart by roots.