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
What Is a Nation? Language, by contrast, "invites us but does not force us, to unite". Countries which share the Spanish or English language don't merge with one another, while the people of Switzerland speak several languages. Modern nationhood also cannot be based on religion, which Renan observes, is currently practiced according to individual belief. "You can be French, English, German, yet Catholic, Protestant, Jewish, or practicing no religion". Mutuality of interests is fine for corporations and their affiliates, but nationality is based on sentiment. Geography merely leads us astray, and often to violence: "Mountains don't know how to carve out countries". Renan concludes