How does rock salt form from evaporating seawater?

Rock salt, known mineralogically as halite, forms through the evaporation of seawater in environments where water loss exceeds replenishment from rainfall or inflow.12

The process typically occurs in restricted or "barred" marine basins. As seawater evaporates, its volume decreases, causing dissolved minerals to precipitate in an orderly sequence based on their solubility. Initially, less soluble components like gypsum and anhydrite form. Once the volume of the remaining brine is reduced to approximately one-tenth of the original seawater, more soluble minerals, including halite, begin to crystallize.132

For thick, extensive rock salt deposits to accumulate, these basins must be partially isolated from the open ocean by a seafloor barrier, which prevents concentrated brines from escaping. Periodic replenishment of the basin with fresh seawater, often caused by sea-level changes or crustal movement, allows for the buildup of massive, layered evaporite sequences over geologic time. In arid regions, these deposits may remain near the surface, while in other areas, pressure can force the salt upward to form salt domes.24