How is a bolson related to a playa or salt pan?

A bolson is a semiarid, flat-floored desert valley or basin that is entirely surrounded by hills or mountains. It is fundamentally related to a playa or salt pan because the bolson is typically centered on these features, which serve as the terminal point for the valley's interior drainage.12

In this geological context, the bolson acts as the broader landscape unit, while the playa represents the flat-bottomed, central depression within that basin. Because bolsons are enclosed, water from precipitation flows toward the lowest point—the playa—where it eventually evaporates, leaving behind deposits of salt, sand, and mud. This relationship is characteristic of basin-and-range terrain, particularly in regions such as the southwestern United States and northern Mexico.13