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 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