The Wadi al-Hayat is one of three wadis (dry rivers where the underground water is near enough to the surface to support vegetation and to be accessed through wells) in the modern region of the Fezzan, situated in south-west Libya. The wadis run east-west across this region, with the surrounding environment dominated by extensive sand seas and rocky plateaus. The Wadi al-Hayat is defined to the north by the Ubari sand sea and to the south by a barren, stony plateau called the Murzuq hamada. The landscape of the wadi is defined and dominated by the escarpment of this plateau, which rises abruptly in a steep, rocky cliff for 100-200 m above the floor of the wadi. Along the southern edge of the wadi the escarpment juts out in a series of dramatic, narrow promontories and isolated, rocky islands. For much of its length, the escarpment presents an impenetrable barrier with few natural routes across it. One of the main ways into and out of the wadi is through the Maknusa Pass, a wide, sandy valley which runs away to the south. Today, there is no surface water in the wadi. It is irrigated by numerous wells which pump underground water to the crops, businesses and homes, producing a pleasant, vegetated environment capable of sustaining a sizeable population. Until about 3 000 years ago, the wadi was supplied with seasonal or perennial springs issuing from the escarpment and streams running off it which, at certain times of the year, may have fed pools of surface water. Small, shallow lakes also persisted intermittently in parts of the wadi during the last 12 000 years.