These world-famous landscapes are unique in North America. This 260km2 plain covered with salt, in a layer up to almost 2m thick, comes from the evaporation of the former Lake Bonneville, which took place after the last Ice Age. The thin layer of water that covers the plain in winter disappears in spring and summer, and the wind smoothes a flat surface, causing it to become rock-hard and thereby preventing any the growth of ant plants.