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,
Arabic nouns and adjectives to ones ending in , with the masculine and feminine ' being used as adjectival forms of the concept-noun (e.g. ) depending on agreement. Thus the feminine ' of ' "partnership, cooperation, participation (definite)", ' is the Arabic word for "socialism," and the word "socialist" (both as an adjective and as the term for one who believes in socialism) is ' in the masculine and "" in the feminine. The Arabic has given rise to English adjectives of nationality for Arabic countries: Iraq"i" (from ), Kuwait"i" (from ), etc. Every verb has associated active and passive participles, as well as