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 Iguidi Erg Iguidi The Erg Iguidi (), is a large erg in the area of Tindouf in southwestern Algeria extending into northern Mali and Mauritania. The Erg Iguidi is a sandy desert with a clear pattern of narrow linear dunes stretching for a length of 400 km. Part of the greater Sahara, it is located in its northwestern region and is characterized by Harmattan withering winds. The highest point is 540 m. Compared to the neighboring Erg Chech to the south, this erg is relatively humid. Groundwater is especially abundant towards the north-eastern edge of the Erg Iguidi. There are patches