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 they recommended using the prefix ""C.G.S. unit of ..."" and requested that the word "erg" or "ergon" be strictly limited to refer to the "C.G.S. unit of energy". In 1922, chemist William Draper Harkins proposed the name micri-erg as a convenient unit to measure the surface energy of molecules in surface chemistry. It would equate to 10 erg, the equivalent to 10 joule. The erg has not been a valid unit since 1 January 1978 when the EEC ratified a directive of 1971 which implemented the International System (SI) as agreed by the General Conference of Weights and Measures. It