Nature Middle East | House of Wisdom

A vast ancient river is buried beneath the Sahara

Beneath the shifting sands of the Sahara lies a dried-up ancient river network, approximately 520 km in length, bearing witness to a time when the arid land was wetter, greener and flowing with life.

The river network, whose sediments and worn path lies beneath Mauritania, probably slithered for hundreds of kilometers across the Sahara roughly 5,000 to 11,700 years ago. The ancient river was reportedly sourced from the Hoggar Highlands and the southern Atlas mountains in Algeria. If it had managed to endure to this era, its river valley would’ve ranked twelfth among the top 50 largest drainage basins worldwide.

The new study, published this week in Nature Communications by Charlotte Skonieczny of University of Lille, France and her team, may change our understanding of the African continent under past and future climates.

No major rivers exist in the Western Sahara at present, but the recent findings provide the first direct evidence of the presence of a vast waterway and possibly lush vegetation in the currently inhospitable stretch of land.

There were already indications to point to the past existence of a major West African river system: the discovery of fine-grained, river-borne material in the deep ocean, and an extensive submarine channel – the Cap Timiris Canyon – carved into the continental shelf off the Western Sahara coast. The canyon was said to be possibly connected to this river.

Now the use of orbital radar satellite imagery, using an advanced Japanese remote-sensing instrument that has the ability to probe beneath sand dunes, have successfully geologically mapped what lies beneath, revealing a river that, according to the study, aligns perfectly with the submarine canyon previously observed.

The branch of the network identified in this study represents a fifth of the total length of the fossil river.

 

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