It is one of the deepest and largest depressions in the Sahara of North Africa.
The depression is bounded by cliffs along its northern and western borders. Coincidence of such borders with deep seated major structural elements may suggest tectonic control on its origin.
It is commonly believed that the origin of the depression is due to mass wasting, “aeolian erosion”.
The present author believes that the origin is due to accelerated by thermal contraction during the Cenozoic. The depression was the center of depocenter of several ancient deltas; e.g. the mid Jurassic Khatatba, early Cretaceous Kharita and mid Cretaceous deltas.
The above mentioned concept is important for the petroleum geologists in their construction of the burial history of the sediments. They have to differentiate between the present day geothermal gradients and the past heat flow history.
The depression is covering an area of about 19,500 square kilometers. Its maximum length and width are 300 and 145 km respectively. Its lowest point is 134 m below the sea level near its western end.
Marshes are a common coverage for the floor of the depression creating difficulties in mobilization of heavy equibments.
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