Issaouane Erg confined to basins. Sand in the Issaouane Erg, below the level of the sand dunes, has accumulated to a depth of 20 to 30 meters. It has barchan dunes as well as star dunes of 300 to 430 meters high. The presence of both barchan dunes (which form due to unidirectional winds) and star dunes (which form when winds from various directions deposit sand) "suggests that wind regimes have changed over time". NASA's "Earth Observatory" notes all three types of erg dunes are present in the photos of the Issaouane Erg taken from the International Space Station: stationary mega dunes,
Geography of French Guiana 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 Ocean, between Brazil and Suriname. South America. Total: 91,000 km².<br> Land: 89,150 km².<br> Water: 1,850 km². Total: 1,183 km.<br> Border countries: Brazil 673 km, Suriname 510 km (disputed).<br> Coastline: 378 km. Exclusive economic zone: territorial sea: . Tropical; hot. Low-lying coastal plains rising to hills and small mountains, see Guiana Shield. Bauxite, timber, gold