National Geographic News, Reporting Your World Daily

Thursday, October 28, 2010

Photo: Once Lush Sahara Dried Up Over Millennia, Study Says


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Fed by prehistoric groundwater, Lake Yoa (above) in remote northern Chad, has persisted despite thousands of years of constant drought and searing heat.

A new analysis of the lake's bottom deposits suggests that the Sahara turned from green savanna to arid desert more slowly than previously thought.

Photograph courtesy S. Kröpelin/University of Cologne