Photos | Earth as art
Erg Iguidi, Algeria and Mauritania
Credit: NASA
Ridges of wind-blown sand flow across Erg Iguidi, a Saharan sand sea. Erg Iguidi is one of several Saharan ergs and extends from Algeria into Mauritania in northwestern Africa. The dunes (in yellow) are about 250 meters wide, rising high above the sand sea. Winds blow from the northwest to the southeast, often under the influence of oceanic monsoons. In this 1985 Landsat 5 image, dunes in the center and upper left lie atop black sandstone rock while the light blue and white areas are edges of the chalk plateaus in the region.
Other Slideshows
Photos | From goofy to geeky, Comic Con fans dress to impress
Cities that lost pro teams and got them back
Photos | Pics of the Week (05/23/13)
Photos | Saying farewell to Dixie's Tavern
Photos | Amazon bio-dome plans for downtown Seattle
Photos | Forbes' list of world's most powerful women