Sand pillars develop when there is uneven moisture in a beach or dune surface and the wind erodes the drier sand, leaving the wetter sand behind. Moisture in the sand holds the grains together (beachgoers use this principle to build sand castles) and makes the sand more resistant to wind erosion. As the pillars dry out, they will erode until there is nothing left.

One activity that may cause uneven moisture in a beach/dune surface is water draining into the sand unevenly after a heavy precipitation event. The preferred pathways for water drainage become the wettest, and these pathways turn into the pillars when wind removes the drier surrounding sand.