The Grand Erg Occidental ( ar, العرق الغربي الكبير, al-ʿIrq al-Gharbī al-Kabīr), (also known as the Western Sand Sea) is the second largest
erg
The erg is a unit of energy equal to 10−7joules (100 nJ). It originated in the Centimetre–gram–second system of units (CGS). It has the symbol ''erg''. The erg is not an SI unit. Its name is derived from (), a Greek word meaning 'work' o ...
in northern
Algeria
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, capital = Algiers
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after the
Grand Erg Oriental
The Grand Erg Oriental (English: 'Great Eastern Sand Sea') is a large ''erg'' or "field of sand dunes" in the Sahara Desert. Situated for the most part in Saharan lowlands of northeast Algeria, the Grand Erg Oriental covers an area some 600 k ...
. It covers an area of approximately .
The sand
dunes in the erg are formed by the wind, and can be up to high.
Certain crescent-shaped dunes, known as
barchan
A barchan or barkhan dune (from Kazakh бархан ) is a crescent-shaped dune. The term was introduced in 1881 by Russian naturalist Alexander von Middendorf, based on their occurrence in Turkestan and other inland desert regions. Barchans ...
s, are actually mobile; the wind can push these dunes as much as 20 to 30 m (65–100 ft) in one year.
Geography
It is a
desert natural region
A natural region (landscape unit) is a basic geographic unit. Usually, it is a region which is distinguished by its common natural features of geography, geology, and climate.
From the ecological point of view, the naturally occurring flora and ...
that receives less than 50 mm (1,96 in) of rainfall per year. The mean elevation of the Grand Erg Occidental is about 500 m, on average higher than the elevation of the Grand Erg Oriental, but not as high as the neighboring
Tademaït
Tademaït is a natural region in the Sahara Desert right in the centre of Algeria. It is located north of In Salah and south of the Grand Erg Occidental in the Adrar District of Adrar Province, El Ménia District of Ghardaïa Province and the nor ...
to the southwest. This desolate region is a practically uninhabited area; there are no permanent villages and there are no roads crossing it.
Features
Image:GrandErgOccidental STS059-238-88.jpg, Grand Erg Occidental (centre), as seen from space
File:Ksar aghlad timimoune.jpg, Ksar of Aghlad; a Ksar -which means castle- was a structure where a tribe used to live
See also
*
Grand Erg Oriental
The Grand Erg Oriental (English: 'Great Eastern Sand Sea') is a large ''erg'' or "field of sand dunes" in the Sahara Desert. Situated for the most part in Saharan lowlands of northeast Algeria, the Grand Erg Oriental covers an area some 600 k ...
*
Geography of Algeria
Algeria comprises square kilometers of land, more than 80% of which is desert, in North Africa, between Morocco and Tunisia. It is the largest country in Africa. Its Arabic name, Al Jazair (the islands), is believed to derive from the rocky ...
*
List of ergs
In geomorphology, an erg is a large desert region of sand dunes with little or no vegetation,it is divided into 3 parts back erg ,central erg,fore erg, especially in the Sahara.
This is a list of ergs around the world.
Africa
;Algeria
* Grand ...
References
Landforms of Algeria
Ergs of Africa
Deserts of Algeria
Natural regions of Africa
Geography of Adrar Province
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