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
Geography of Algeria Geography of Algeria Algeria comprises 2,381,741 square kilometers of land, more than four-fifths of which is desert, in northern Africa, between Morocco and Tunisia. It is the largest country in Africa. Its Arabic name, Al Jazair (the islands), derives from the name of the capital Algiers ("Al Jazair" in Arabic), after the small islands formerly found in its harbor. It has a long Mediterranean coastline, most of which is more properly termed the Alboran Sea, which is the westernmost element of the Mediterranean Sea. The northern portion, an area of mountains, valleys, and plateaus between the Mediterranean Sea and the