In some case, lake pH levels exceed 10. They include sodium chloride, sodium sulphate, calcium sulphate and magnesium sulphate. Salt crystal growth occurs when salts are no longer able to remain in solution due to evaporation or temperature changes. Solutes filling pores and fractures in rocks will start to precipitate the mineral salts, with the resultant volume increase causing rock breakdown. This may occur progressively over a long time period due to daily fluctuations in temperatures, which influence the mineral solubilities.
Hydration is also important.
Certain mineral salts may hydrate, i.e. absorb water, and change to their hydrated form. In doing so, the volume of crystalline material increases - sometimes up to 300 per cent. If a hydrating mineral is positioned within a rock pore or fracture, large pore pressures will result which can physically break down rock. Finally, salt crystals can thermally expand and contract. If the thermal expansion properties of salts are greater than that of the host rock, then rock breakdown may occur in response to the physical stresses.