No one ever says of the Sahara that a river runs through it. But somewhere between 11,700 and 5,000 years ago, one did. In full flow, it would rank 11th among the largest rivers on the earth today.* Paleoclimatologist and geochemist Charlotte Skonieczny of the French Research Institute for Exploration of the Sea and her colleagues report the evidence for the ancient channel in a recent issue of Nature Communications. The team discovered the so-called Tamanrasett River when examining microwave data collected by a Japanese satellite that had been mapping geologic features in the area. The hidden bedrock valley winds for more than 500 kilometers from the Atlas Mountains in northern Africa to the Atlantic Ocean.

*CHARLOTTE SKONIECZNY AND HER COLLEAGUES HAD PLACED THE RIVER AS THE 12TH LARGEST, PER DIFFERENT ESTIMATES OF RIVER AREA SIZES; SOURCES: “AFRICAN HUMID PERIODS TRIGGERED THE REACTIVATION OF A LARGE RIVER SYSTEM IN WESTERN SAHARA,” BY C. SKONIECZNY ET AL., IN NATURE COMMUNICATIONS, VOL. 6, ARTICLE NO. 8751; NOVEMBER 10, 2015 (illustration of Tamanrasett); “GEOMORPHOMETRIC ATTRIBUTES OF THE GLOBAL SYSTEM OF RIVERS AT 30-MINUTE SPATIAL RESOLUTION,” BY C. J. VÖRÖSMARTY ET AL., IN JOURNAL OF HYDROLOGY, VOL. 237, NOS. 1–2; OCTOBER 25, 2000 (area and length of Tamanrasett); ENCYCLOPÆDIA BRITANNICA www.britannica.com (area and length of all other rivers)

Illustration by Amanda Montañez