Erg (landform) Erg (landform) An erg (also sand sea or dune sea, or sand sheet if it lacks dunes) is a broad, flat area of desert covered with wind-swept sand with little or no vegetative cover. The term takes its name from the Arabic word "ʿarq" (), meaning "dune field". Strictly speaking, an erg is defined as a desert area that contains more than of aeolian or wind-blown sand and where sand covers more than 20% of the surface. Smaller areas are known as "dune fields". The largest hot desert in the world, the Sahara, covers and contains several ergs, such as
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