Here, instead of finding chaos and disorder, the observer never fails to be amazed at a simplicity of form, an exactitude of repetition and a geometric order unknown in nature on a scale larger than that of crystalline structure. In places vast accumulations of sand weighing millions of tons move inexorably, in regular formation, over the surface of the country, growing, retaining their shape, even breeding, in a manner which, by its grotesque limitations of life, is vaguely disturbing to the imaginative mind.
The Physics of Blown Sand and Desert Dunes by Ralph Bagnold, Desert Explorer, founder of the Zerzura Club, used by Nasa to study dunes on Mars.
