An erg is a broad, flat area of desert covered with wind-swept sand with little or no vegetative cover. The term takes its name from the Arabic word ʿarq” meaning "dune field".
Ergs are concentrated in two broad belts between 20° to 40°N and 20° to 40°S latitudes, which include regions crossed by the dry, subsiding air of subtropical high presuure. Active ergs are limited to regions that receive, on the average, no more than 150 mm of annual precipitation.
As the wind transports sand from the windward slope (the erosional side) to the crest, sand is piled up and a threshold condition is reached, whereby further accumulation sends the sand avalanching down the slipface (the depositional side) as the angle of repose for dry sand is exceeded. This pattern is repeated and causes the dune to migrate downwind, maintaining its aerodynamic shape. Typical dune heights range from 3 to 100 meters, although dunes of greater height are known.
The largest hot desert in the world, the Sahara, covers 9 million square kilometres and contains several ergs, such as the Chech Erg, the Issaouane Erg in Algeria and erg Chebbi in Morrocco (from Cooke, R., A. Warren, and A. Goudie. 1993. Desert Geomorphology. London: University College London Press)
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lousat (96732) 2014-03-28 4:18
Hi Ecmel,i been there me too 3 years ago and this is a great memory to me,it's nice too see again this magnificent place,fascinating dunes,bright colors and fine details in a beautiful perspective,i like it!! Have a nice weekend and thanks,LUCIANO
Subhogen (4067) 2014-03-28 11:23
Glad to meet you here on TE. This is a such a simple yet so beautiful composition. I love the light and shadow division over the sharp edge of the dune. Good detailing on the texture of the sand. Excellent contrast with the clear blue sky. Good one, thanks for sharing with an elaborate note.
P.S. Surfing through your gallery I see some delightful shots from many countries. Excellent work!
siudzi (34141) 2014-03-28 14:53
A wonderful landscape post due to the brilliant color and textures management. They created a fantastic visual effect in the composition. Well done!
chawax (20760) 2014-03-29 7:43
These dunes at sunset are inredibly beautiful, with fantastic golden colours and beautiful shadows because of the low light that add relief to the landscape. Very good sharpness. Anyway I think you centered too much the horizon line, it would have been better to choose a lower POV to have the sky on third of the picture and give more place to the beautiful sand.
Romano46 (18472) 2014-03-29 10:44
un'altra dlele tue belle foto molto curata nel dettaglio e con una luce favolosa che scolpisce le forme creando una composizione suggestiva.
Splendidi i colori.
Ciao e buon fine settimana
chrislo (4097) 2014-03-30 13:22
This image is as beautiful as it is simple. There is nothing to disturb it, only pure sand and the sky. I like the great feeling of silence you managed to bring in. The shapes and angles are so simple and beautiful, and the way you've captured the texture and colour of the sand make this a most interesting image filled with intense beauty.
mkamionka (39803) 2014-04-28 6:02
I love deserts. This is so beautiful here with the subtle texture of the sand well emphasized. Nice sharp dune well placed in the frame.