The Physics of Blown Sand and Desert Dunes (1941) is a science book, written by Ralph A. Bagnold. The book laid the foundations of the scientific investigation of the transport of sand by wind. It also discusses the formation and movement of sanddunes in the Libyan Desert. During his expeditions into the Libyan Desert, Bagnold had been fascinated by the shapes of the sand dunes, and after returning to England he built a wind tunnel and conducted the experiments which are the basis of the book. The book is still a main reference in the field, and was, for instance, used by NASA for studying sand dunes on Mars. It was recently reissued by Dover.