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 Chigaga Erg Chigaga Erg Chegaga (or Chigaga) is one of two major Saharan ergs of the Sahara in Morocco, the other being the Erg Chebbi near Merzouga. This dunes are located in the Drâa-Tafilalet area about 50 km west of the rural town of M'Hamid El Ghizlane, itself located about 98 km south of the town of Zagora. With a length of approximately 40 km to 15 km width, some dunes are around 60m high (significantly less than the dunes at Erg Chebbi with up to 150m), it is the largest and wildest of Morocco. Because it is relatively difficult to