Which clay minerals cause the greatest drying shrinkage on playas?

On playas, the amount of volume change that occurs during drying depends on the specific clay minerals present in the muds. Smectite clays experience the greatest shrinkage upon drying.1

This effect is often enhanced by the presence of salts, as the deposition and crystallization of these salts within drying cracks can create a polygonal network of salt wedges. In some instances, these conditions lead to the formation of giant desiccation polygons, which can reach up to 90 metres across.1