Grand Erg Occidental Grand Erg Occidental The Grand Erg Occidental (, al-ʿIrq al-Gharbī al-Kabīr), (also known as the Western Sand Sea) is the second largest erg in northern Algeria after the Grand Erg Oriental. It covers an area of approximately . The sand dunes in the erg are formed by the wind, and can be up to high. Certain crescent-shaped dunes, known as barchans, are actually mobile; the wind can push these dunes as much as 20 to 30 m (65-100 ft) in one year. It is a desert natural region that receives less than 50 mm (1,96 in) of rainfall per year.
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