Gravel-size gypsum crystals in deserts move mainly because of wind and occasional water flow. Strong desert winds can push smaller crystals by bouncing them across the surface (saltation) or rolling them along the ground (creep). Even though gypsum is heavier than typical sand, open dry landscapes allow gusts to mobilize these grains. When rare desert rain arrives, flash floods and shallow sheet flow can also shift large amounts of gypsum, breaking apart bigger crystals and carrying the pieces over long distances.
Temperature changes and surface conditions help this movement happen more easily. Daily heating and cooling cause gypsum to expand and contract, loosening crystals from the ground, while freeze–thaw cycles can lift them upward so wind can grab them. Soil crusts cracking, animals disturbing the surface, and gentle slopes all contribute to gradual downhill movement known as dry ravel. Together, these natural forces continually reshape desert surfaces and redistribute gypsum across the landscape.