Which of the following statements with reference to Salt Weathering is/are correct?

1. Salt crystallisation is the most effective of all the salt weathering processes.

2. Salt crystal growth is more effective over sedimentary rocks as compared to igneous rocks.

Select the answer using the code given below:

The correct answer is Both 1 and 2.

Key Points

• Salt crystallisation is indeed the most effective of all salt weathering processes due to its ability to exert high pressure on rock surfaces during crystal growth.
• Salt weathering is more pronounced in sedimentary rocks compared to igneous rocks because sedimentary rocks are often porous, allowing salts to penetrate and crystallize.
• Salt crystal growth typically occurs when saline water evaporates, leaving behind salts that expand during crystallization, causing rock disintegration.
• This process is common in arid and semi-arid regions, where evaporation rates are high, and saline groundwater or coastal environments contribute to salt deposition.
• Examples of salts involved include halite (NaCl), gypsum (CaSO₄·2H₂O), and anhydrite (CaSO₄), which play a significant role in this weathering phenomenon.

Additional Information

• Salt Weathering Terminology:
  • Salt weathering refers to the breakdown of rocks due to the growth and expansion of salt crystals.
  • It is also known as haloclasty.
• Impact on Different Rock Types:
  • Porous rocks like sandstone are more susceptible to salt weathering due to higher permeability.
  • Igneous rocks like granite are less affected because of their dense structure and lower porosity.
• Environmental Factors:
  • Salt weathering is influenced by factors like temperature fluctuations, humidity, and the availability of saline water.
  • Frequent wetting and drying cycles accelerate the crystallization process.
• Real-world Examples:
  • This process contributes to the formation of tafoni (hollowed rock features) and honeycomb structures seen in coastal and desert landscapes.
  • It is a significant factor in the degradation of historical buildings and monuments made from porous stones.