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 is still widely used in astrophysics and sometimes in mechanics. Erg The erg is a unit of energy and work equal to 10 joules. It originated in the centimetre–gram–second (CGS) system of units. It has the symbol "erg". The erg is not an SI unit. Its name is derived from "ergon" (ἔργον), a Greek word meaning "work" or "task". An erg is the amount of work done by a force of one dyne exerted for a distance of one centimeter. In the CGS base units, it is equal to one gram centimeter-squared per second-squared (g·cm/s). It is thus equal to