exfoliation

Type of physical weathering in which the outer layers of a rock surface peel off in flakes and shells. It is caused by the rapid expansion and contraction of the rock surface when subjected to extreme changes of temperature. Exfoliation occurs particularly in hot dry desert climates, and on sheets of rock that are jointed parallel to the surface, such as granite. The process is encouraged by the effects of chemical weathering on the inner edges of the joints. Exfoliation contributes to the rock cycle, the formation, change, and reformation of the Earth's outer layers.

The combination of exfoliation and chemical weathering produces rounded inselbergs (prominent steep-sided hills) in arid regions, such as Ayers Rock in central Australia.