Erg (landform) and western Asia, and Central Australia. In South America, ergs are limited by the Andes Mountains, but they do contain extremely large dunes in coastal Peru and northwestern Argentina. They are also found in several parts of the northeast coast of Brazil. The only active erg in North America is in the Gran Desierto de Altar () that extends from the Sonoran Desert in the northwestern Mexican state of Sonora to the Yuma Desert of Arizona and the Algodones Dunes of southeastern California. An erg that has been fixed by vegetation forms the Nebraska Sandhills (). Sand seas and dune
Erg of Bilma Erg of Bilma The Erg of Bilma is a dune sea (Arabic: "erg") in the Ténéré desert region of the south central Sahara Desert. The Erg of Bilma stretches southwest from Fachi and the Tibesti Mountains. On the west it is bounded by the Aïr Mountains in north central Niger, and to the east it passes Bilma, continuing on to the Chadian border. It surrounds on three sides the oasis of Bilma, southernmost of a north–south string of oasies of the Kaouar rise. The Erg covers an area of approximately . At its southernmost edge, some of the dunes have