How do salts help create polygon-shaped cracks in playa surfaces?

On a playa, the formation of polygon-shaped cracks is primarily driven by the drying and shrinking of clay sediments, particularly those containing smectite minerals.

The presence of salt significantly enhances this process. As the surface dries, the deposition and subsequent crystallization of salts within the developing cracks create salt wedges. These wedges act to expand and define the polygonal network, resulting in the characteristic geometric patterns observed on the surface of the playa.1