Exfoliation
Also called: Onion-skin weathering · Topic: Geomorphic Processes: Weathering, Mass Movement, Erosion and Soil Formation · NCERT: Class 11, Ch 5 "Geomorphic Processes"
Meaning
Exfoliation is the peeling off of curved sheets or shells of rock from its surface. It leaves smooth, rounded forms, a little like peeling an onion. Exfoliation is a result, not a process. It can be caused by unloading (pressure release), by thermal expansion and contraction, and by salt weathering. Large-scale exfoliation through unloading creates exfoliation domes. Smaller-scale peeling rounds off boulders.
Example
Granite boulders and hills on the Karnataka plateau show thin curved shells of rock peeling away. This leaves them smooth and rounded.
Don't confuse with
- Unloading: it is a process (rock expanding after the weight above is removed). Exfoliation is one of the results it produces.