barchan उदाहरण वाक्य

It has barchan dunes as well as " 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, which can take hundreds of thousands of years to form; mesoscale dunes ( including the stardunes ), which form on the mega dunes; and yet smaller ones which migrate over the bigger ones.