Vast, windswept plains of sand dunes (ergs), occasionally interrupted by rocky outcrops, stretch across much of Algeria in a giant C-shape. Except for exceedingly rare oases, these seas of sand are usually empty of life, including human civilization.
This natural-color image from the Landsat 7 satellite shows the emptiness of the Erg Iabès in western Algeria’s Adrar province. This rather small erg (compared to the country’s Grand Ergs) occupies the wide gap between the El Eglab Massif to the west and the Tademaït Plateau to the northeast.
Long, linear dunes such as the ones pictured here align in the direction of the prevailing winds, and they usually form under the influence of strong winds. However, linear dunes are not the only types of dunes that are found in ergs. For example, weaker winds blowing over a linear dune in the non-prevailing wind direction may create star dunes. Barchan dunes are shaped like a crescent, with a more gradual slope on the windward side, and a steeper slope on the downwind side.
NASA Earth Observatory image by Robert Simmon, based on 2005 Global Land Survey data. Caption by Rebecca Lindsey.
This natural-color image from the Enhanced Thematic Mapper Plus sensor on the Landsat 7 satellite shows the emptiness of the Erg Iabès in western Algeria’s Adrar province.
he Issaouane Erg (sand sea) is located in eastern Algeria between the Tinrhert Plateau to the north and the Fadnoun Plateau to the south. Considered to be part of the Sahara Desert, the Issaouane Erg covers an area of approximately 38,000 km2. These complex dunes form the active southwestern border of the sand sea.