Erg Chebbi Erg Chebbi Erg Chebbi () is one of Morocco's several ergs – large seas of dunes formed by wind-blown sand. There are several other ergs such as Erg Chigaga near M'hamid. Technically all these ergs are within an area of semi-arid Pre-Saharan Steppes and not part of the Sahara desert which lies some distance to the south. In places, the dunes of Erg Chebbi rise up to 150 meters from the surrounding hamada (rocky desert) and altogether it spans an area of 28 kilometers from north to south and up to 5–7 kilometers from east to west lining the Algerian
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