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
Arabic nouns and adjectives to ones ending in , with the masculine and feminine ' being used as adjectival forms of the concept-noun (e.g. ) depending on agreement. Thus the feminine ' of ' "partnership, cooperation, participation (definite)", ' is the Arabic word for "socialism," and the word "socialist" (both as an adjective and as the term for one who believes in socialism) is ' in the masculine and "" in the feminine. The Arabic has given rise to English adjectives of nationality for Arabic countries: Iraq"i" (from ), Kuwait"i" (from ), etc. Every verb has associated active and passive participles, as well as