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,
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