We learned some new terminology while at Coral Sand Dunes and thus I will share with you as we saw several of these and other Hummocks on this hike too: Plants can cause the formation of hummocks - clumps of plants that accumulate a mound of sand around them. Once a plant starts to grow, it will act as a small wind block and "catch" the sand. In order to survive, the plant must grown faster than the mound of sand accumulating around it.