Granular exfoliation describes which process?

• A. Sheet of concentric plates spall off due to release of overburden pressures
• B. Formation of rounded grains by wind
• C. Crystallization of minerals
• D. Erosion by water

Answer: (A)

Unloading of overburden causes outer rock layers to crack and peel off in concentric slabs, a process known as exfoliation. When the pressure from the overlying material is released, the outer layers can expand and relieve tensile stresses parallel to the surface, causing slabs to spall off like onion skins. This description—sheets of concentric plates peeling away as the overburden is removed—matches granular exfoliation precisely.

The other processes involve different mechanisms: wind shapes grains by abrasion leading to rounded grains, crystallization of minerals is mineral precipitation, and erosion by water removes material rather than peeling it off in orderly, concentric sheets.