Exfoliation is a type of physical weathering process that occurs when large, curved plates or slabs of rock are stripped away from the outer surface of a rock mass. It is also known as sheeting or unloading.
Exfoliation is caused by the release of confining pressure on a rock mass, which can occur due to a variety of factors, including uplift and erosion, thermal expansion and contraction, and the removal of overlying rock by erosion or mining activities. As the pressure on the rock is reduced, the outermost layers of the rock begin to expand and separate from the underlying layers, creating fractures that gradually propagate inward. Over time, these fractures can develop into large, curved sheets or slabs of rock that peel away from the surface of the rock mass.
Exfoliation is particularly common in areas with large, rounded rock formations, such as granite domes and inselbergs. These features are often the result of differential weathering, where the outermost layers of the rock are more susceptible to exfoliation than the underlying layers due to differences in chemical composition or structure.
Exfoliation can have important practical implications, as it can cause rockfalls and landslides that pose a hazard to people and infrastructure in the vicinity of exposed rock formations. However, it can also create unique and visually striking geological features, such as the distinctive domes and cliffs found in many national parks and other natural areas around the world.
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