Salt-Crystal growth is a specific type of physical weathering that occurs when the growth of salt crystals causes rocks to break apart. This process is commonly observed in desert environments where there is abundant salt and limited rainfall. As water evaporates from the rocks, it leaves behind salt deposits that can grow and exert pressure on the surrounding rock, leading to its fragmentation.

Explanation:

Physical weathering is the process of breaking down rocks into smaller fragments without changing their chemical composition. One of the mechanisms of physical weathering is salt-crystal growth.

- Salt-Crystal growth occurs in arid or semi-arid regions where there is limited rainfall. In these environments, the rate of evaporation is higher than the rate of precipitation, leading to the concentration of dissolved minerals, including salt, in the remaining water.
- When water containing dissolved salt seeps into the cracks and pores of rocks, it can evaporate due to high temperatures and low humidity. As the water evaporates, the concentration of salt increases, eventually reaching a point where the salt begins to precipitate out of the water.
- As the salt crystals form, they occupy more space than the original dissolved salt, exerting pressure on the surrounding rock. This pressure can cause the rock to crack and fragment.
- Over time, the repeated cycles of salt crystal growth and evaporation can lead to the progressive disintegration of the rock.
- In desert environments, salt-crystal growth is a prominent form of physical weathering as it contributes to the formation of features such as honeycomb weathering, tafoni, and salt pans.

In conclusion, salt-crystal growth is an example of physical weathering that occurs when the growth of salt crystals exerts pressure on rocks, leading to their fragmentation. This process is commonly observed in arid or semi-arid regions where there is abundant salt and limited rainfall.