Peter A. Kropotkin and John T. Bealby, 1911 Encyclopædia Britannica, Volume 15… (1911)
“ Barkhans, chiefly in the east, which are mounds of loose sand, 15 to 35 ft. high, hoof-shaped, having their gently sloping convex sides turned towards the prevailing winds, and a concave side, 30° to 40° steep, on the opposite slope. They are disposed in groups or chains, and the winds drive them at an average rate of 20 ft. annually towards the south and south-east. ”
