The World’s Biggest Sand Dunes

The Sahara is best known for its massive sand dunes. These sand dunes cover about one-quarter of the Sahara, the tallest, most complex, most extensive dune fields in the world. These dunes are the result of powerful, constant, continental winds moving sand left over from a time when the Sahara had lakes, streams, and floods, all of which have left their silts and sands lying in the depressions with barely a root to hold them down. Some pyramid-shaped dunes in the Sahara tower 500 feet (167 m) tall. Some of the mountainous sand ridges that cross the desert reach heights of 1,000 feet (330 m), made almost entirely of fine-grained sand. As seen in the color insert on page C-7, those shifting fields of dunes dwarf similar features in other deserts, like the red dunes of Monument Valley in the Great Basin Desert or the smaller dune fields near Yuma in the Mojave Desert.