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 French Guiana (widely scattered), cinnabar, kaolin, fish, [shrimp], rice, bananas. Arable land: 0%.<br> Permanent crops: 0%.<br> Permanent pastures: 0%.<br> Forests and woodland: 0%.<br> Other: 10% (1996 est.).<br> Irrigated land: 20 km² (1993 est.).<br> Natural hazards: high frequency of heavy showers and severe thunderstorms; flooding.<br> Environment - current issues: NA.<br> Geography - note: mostly an unsettled wilderness. Geography of French Guiana French Guiana is an overseas region of France, located on the northern coast of South America between Suriname and Brazil. See also the article on the geography of Suriname. Northern South America and part of Caribbean South America, bordering the North Atlantic