Erg Iguidi#
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Image Courtesy of USGS, under PD
Erg Iguidi is one of several Saharan ergs, or sand seas, where individual dunes often surpass 500 m - nearly a third of a mile - in both width and height. The center and upper right of the enhanced satellite image is black sandstone rock.
The light blue and white areas are chalky deposits and salt crusts left behind after water in the area evaporated.