What Is an Exfoliation Weathering? Causes Of Exfoliation Weathering
What Is an Exfoliation Weathering?
Exfoliation is a type of weathering that occurs when thin, curved layers of rock peel off from the surface of a rock mass. This can create dome-like hills and rounded boulders.
Exfoliation typically occurs along lines called joints, which are located at or near the surface of the rock and are curved and somewhat parallel to it.
These joints are usually a few inches apart at the surface but can be several feet apart at deeper levels. As each layer peels off, the rock becomes more rounded or dome-shaped.
Some people believe that exfoliation is caused by a decrease in pressure at the earth’s surface, which allows the rock to expand and become unstable.
Exfoliation domes are a type of weathering that commonly occurs in granitic rock, where the outer layers of rock peel off in thin, concentric shells, much like the layers of an onion. This process is called spheroidal weathering, and it is caused by the expansion of certain minerals such as feldspar when they are chemically weathered and transformed into a new product with a larger volume.
This type of weathering is most common in igneous rocks which are particularly prone to mechanical weathering due to their composition and structure.
Causes Of Exfoliation Weathering
Exfoliation is a process that can be caused by several factors. It can occur when stress is released in a rock causing expansion joints.
This can happen when rocks that were previously buried are exposed due to erosion or when ice sheets melt.
It can also occur as a result of physical and chemical weathering where the outer surface of the rock experiences a breakdown of minerals, especially in the presence of water. This type of weathering is common in igneous rocks, such as granite, as certain minerals like micas, amphiboles and pyroxenes break down into clay.
The expansion and contraction of the clay caused by alternating wetting and drying can lead to the disintegration and exfoliation of the rock. Exfoliation can also be caused by the expansion of water trapped in the grains or fractures of a rock during freezing or by temperature changes in the rock.
It can also be induced by humans by heating rock and then pouring water on its surface, which can create thin, sharp shards.
Exfoliation is a process in which the surface layers of rock weaken and separate due to chemical weathering, thermal weathering, or the release of pressure caused by erosion. This can occur when certain minerals in the rock such as biotite and feldspar, break down and cause the rock to expand.
Temperature changes and the removal of the overlying layers of rock can also contribute to exfoliation by causing the rock to fracture and release internal stress. Some geologists dispute the role of temperature changes in exfoliation, however.
Characteristics Of Exfoliation Weathering
Exfoliation weathering is a form of mechanical weathering that occurs in regions where large differences in temperature can be found. It is caused by the thermal expansion and contraction of large, flat rock surfaces, leading to the formation of parallel layers.
This type of weathering can be seen in granite rock formations all over the world, often forming interesting patterns on mountainsides.
The most prominent characteristics of exfoliation weathering include an increase in surface area, depressions in the rock surface, and curved lines tracing along the rocks’ edges.
Additionally, many times these features will exhibit a domed shape as there are often more fractures at the center than at the edges.
In conclusion, exfoliation weathering is a mechanical process of breakdown caused by the expansion and contraction of rocks due to variation in temperature and pressure.
It is much faster than chemical weathering and creates unique land forms such as rounded domes and concentric rings.
Exfoliation weathering helps to break down large rocks into smaller ones, making them easier to transport away from their source. As a result, this weathering process plays an important role in shaping the Earth’s landscape over time.