Erg Iguidi, Algeria
What look like pale yellow paint streaks slashing through a mosaic of mottled colors are ridges of wind-blown sand that make up Erg Iguidi, an area of ever-shifting sand dunes extending from Algeria into Mauritania in northwestern Africa. Erg Iguidi is one of several Saharan ergs, or sand seas, where individual dunes often surpass 500 meters — nearly one-third of a mile — in both width and height.
Image taken by Landsat 5 on Apr. 8, 1985