EXFOLIATION

Aptly called 'onion weathering', exfoliation is a process of physical weathering in which the outer layers of a rock split off into thin sheets or scales. It has been suggested that it is caused by the alternate expansion and contraction resulting from a wide diurnal range of temperature in arid regions, which would lead to stresses in the rock. However, it is now thought that the presence of water may be important. in the process. Screes are mounds of angular rock particles weathered from the rocky masses and which collect round their bases. Exfoliation domes are to be seen in Khasi Hills, Meghalaya. The large domal hill in Tiruchirapalli, too, is an example of exfoliation effect