Erg (landform) when liquid methane rained and eroded the ice bedrock, possibly in the form of flash floods. Alternatively, the sand could also have come from organic solids produced by photochemical reactions in Titan's atmosphere. 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
Erg of Bilma Erg of Bilma The Erg of Bilma is a dune sea (Arabic: "erg") in the Ténéré desert region of the south central Sahara Desert. The Erg of Bilma stretches southwest from Fachi and the Tibesti Mountains. On the west it is bounded by the Aïr Mountains in north central Niger, and to the east it passes Bilma, continuing on to the Chadian border. It surrounds on three sides the oasis of Bilma, southernmost of a north–south string of oasies of the Kaouar rise. The Erg covers an area of approximately . At its southernmost edge, some of the dunes have