These unusual geological features called 'sand strips' were first identified by French physicist Phillip Claudine as an initial stage of dune development. As thousands of sand grains move across a smooth surface, one grain may stop, acting as an anchor for another to stop, eventually causing the formation of these shallow ridges. They form perpendicular to the wind direction, and the resulting wavelength may be related to instability patterns created by the wind.

At Great Sand Dunes, sand strips are often visible after a rain as the dunes begin to dry out. Coarser sand dries first, because it has less surface area than a finer sand. Coarse sand here is lighter colored, originating in the nearby Sangre de Cristo Mountains, while the darker sand originates in the distant San Juan Mountains. Once the coarser grains are dry and begin to move, they accumulate into strips. Once the entire dune surface is dry, all sand on the surface moves with the wind and the sand strips are reworked into the normal dune surface.