Research: Massive river once made the Sahara bloom

Sunday, November 15, 2015, 12:37 PM - When you think of Africa's rivers, it's usually the Nile, the Congo and possibly the Niger rivers that first spring to mind.

Google "Tamanrasett" and you're more likely to turn up an oasis city deep in the Sahara in southern Algeria, not a mighty river capable of sustaining life, but new research says that area was one of the sources of just such a river.

It was enormous, it ran right to the sea at the coast of Mauritania and its banks would have teemed with flora, fauna and humanity as recently as 5,000 years ago, according to a study published in Nature Communications this month.

"This so-called Tamanrasett River valley has been described as a possible vast ancient hydrographic system that would rank twelfth at present among the top 50 largest drainage basins worldwide," the researchers write.

Image: Nature Communications

The authors of the French-led study say the waterway may have begun to form during a series of humid periods around 245,000 years ago.

"At that time, equatorial lakes reached their highest level and the present-day Saharan desert was the location of extensive vegetation, animal life and human settlements," the researchers told the Christian Science Monitor.

Researchers have suspected the existence of of a prehistoric river in the area due to the discovery of rocks and sediments typically found in riverbeds near the coast of Mauretania, as well as a long undersea canyon that stretches out into the ocean from the shore.

However, it wasn't until recently that the discovery was all but confirmed, thanks to orbital radar satellite images that confirmed river-like features beneath the sands of the Sahara.

It's not just a pointer to the past. The researchers told the Monitor the findings could help find sources of water in the present day.

"This large paleo-river system is likely to be related to large amount of fossil water resources in shallow aquifers located where the channels were mapped," the authors told the Monitor. "This gives then some interesting geographical information on where to drill for finding some new water resources in desert regions."

SOURCES: Nature Communications | Christian Science Monitor | The Guardian