Grand Erg Oriental follow the wind's direction. There are other types of dunes, as well as "complex" dunes. Saharan winds are also known to clear an area of sand altogether, leaving bare rock (hamada) or gravel (reg). The "Grand Erg Oriental" is accessible overland by an Algerian road, which goes south from Constantine. It passes through the Aurès mountains, then salt lakes by the city of Biskra. Next the road skirts the western edge of the erg. After about 500 km. in all, it reaches the ancient oasis of Ourgla [Wargla]. Since late antiquity Wargla was a stop for the Saharan trade, being
Erg Ferradj Erg Ferradj Erg Ferradj () is a town and commune in Abadla District, Béchar Province, in western Algeria. According to the 2008 census its population is 4,406, down from 4,670 in 1998, and an annual population growth rate of -0.6%, the second lowest in the province. The commune covers an area of . Erg Ferradj lies at an elevation of to the west of an extensive palm plantation covering 3000 hectares lying along the western side of the Oued Guir. The rocky hills of the hamada are found on both sides of the river, but are more dramatic on the