Which one of the following is not an example of chemical weathering?

The correct answer is  Salt Crystal Growth.

Key PointsChemical Weathering

• Chemical weathering involves the breakdown of rocks through chemical changes, altering the minerals within the rocks.
• Acid action: This process involves the reaction of rock minerals with acidic solutions, such as carbonic acid formed when CO₂ dissolves in water. This can lead to the dissolution of minerals.
• Hydrolysis: This is a chemical reaction between minerals and water, leading to the formation of new minerals and the breakdown of the original rock. For example, feldspar can be converted into clay minerals.
• Oxidation: This chemical process involves the reaction of rock minerals with oxygen, often leading to the formation of oxides. For instance, iron in rocks can react with oxygen to form iron oxide (rust).
• Salt Crystal Growth is primarily a physical weathering process. It involves the growth of salt crystals in rock cracks and pores, which can cause the rock to break apart mechanically due to the expansion of the crystals.

Additional Information

• Physical weathering involves the breakdown of rocks through physical processes without changing the rock's mineral composition.
• Examples of physical weathering include freeze-thaw cycles, thermal expansion, and salt crystal growth.
• Freeze-thaw cycles: Water enters cracks in rocks, freezes, and expands, causing the rock to break apart.
• Thermal expansion: Temperature changes cause rock to expand and contract, leading to mechanical breakdown.
• Salt crystal growth: Salt crystals form in rock pores and cracks from evaporating saline water, exerting pressure and causing the rock to disintegrate.
• Understanding the difference between chemical and physical weathering is crucial for fields such as geology, geography, and environmental science.