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.
Erg (tug) of Canada, which kept records of the activity in the harbour, advised that from 1940 to 1943, there were at least 12 vessels involved in accidents within Halifax Harbour. Vessels such as "Camperdown", "Claire Lilley" and "Nueva Indalucia" ran aground, whereas others such as "Otter", and "Trongate" caught fire and sank (or, in the case of "Trongate", was made to sink as the flames were completely out of control). In 1940, "Herbidean" was sunk by the British ship "Esmond"; a forerunner to the fate of "Erg". On June 6, 1943, "Erg" was carrying workers and equipment (air compressors and electric