The correct option is Exfoliation.
Explanation
Weathering is the disintegration and decomposition of rocks in situ. It is classified into physical (mechanical), chemical, and biological weathering. The specific process described involves the physical separation of rock layers due to changes in pressure or temperature.
Option Analysis
- Carbonation Carbonation: Incorrect. Carbonation is a type of chemical weathering involving the reaction of carbonate and bicarbonate ions with minerals. It is most effective in limestone regions and does not typically result in the flaking of curved sheets.
- Exfoliation Exfoliation: Correct. Exfoliation is a physical weathering process in which curved sheets or shells of rock flake off from the main rock body, similar to peeling layers off an onion. This occurs primarily due to the release of confining pressure (unloading) when overlying material is removed by erosion, or due to thermal expansion and contraction. It results in smooth, rounded surfaces often forming exfoliation domes.
- Hydration Hydration: Incorrect. Hydration is a chemical weathering process where minerals absorb water and expand. While this expansion causes stress within the rock, the specific term for the flaking of curved sheets is exfoliation.
- Oxidation Oxidation: Incorrect. Oxidation is a chemical weathering process where minerals react with oxygen, commonly observed as rusting in iron-rich rocks. It leads to decomposition rather than the mechanical flaking of sheets.
Key Takeaway
Exfoliation is the mechanical weathering process where rock layers peel off in curved sheets, often caused by unloading (pressure release) or thermal expansion, creating rounded landforms known as exfoliation domes.