Grand Erg Oriental

Across the northern Sahara, the dunes of the Great Eastern Erg reach into southern Tunisia. Long ridges and high mounds of sand stand beside wind-scoured gravel flats, their shapes made by winds blowing across the desert. To the east the sand gives way to the rocky country approaching Ghadames, while oases provide scattered green islands at the margins of the erg. Beneath the arid surface lie deep stores of groundwater, accumulated in much wetter ages.