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,
What Is a Nation? Anderson also points out that the reason many French citizens of Renan's time knew anything of these massacres was because they learned of them in state-run schools. Thus, the state itself preserved the knowledge which needed to be forgotten for national identity. In a 1995 book, "For Love of Country: an essay on patriotism and nationalism", Maurizio Viroli called Renan's essay "the most influential late nineteenth-century interpretation of the meaning of nation", because of its focus on the "spiritual principle" as opposed to race, religion or geography. Other authors, like Joxe Azurmendi, consider that really there is no such opposition