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Through an analysis of marine sediments, researchers at the University of Arizona have determined rainfall patterns in the Sahara over a period of 6,000 years obtaining fascinating results. The UA-led team has identified the climate pattern that generated a “Green Sahara” from 5,000 to 11,000 years ago. The region had 10 times the rainfall it does today.
As it turns out, what is now the Sahara Desert was the home of hunter-gatherers who lived off the animals and plants present in the savannas of the region and off the wooded prairies sometime between 5,000 and 11,000 years ago. “It was 10 times as wet as today,” said lead author Jessica Tierney of the University of Arizona. Annual rainfall in the Sahara now ranges from about 4 inches to less than 1 inch (100 to 35 mm). Although other research has already identified the existence of a “Green Sahara” period, Tierney and colleagues managed to compile a continuous record of rainfall in the region that existed 25,000 years ago.
Interestingly, archaeological evidence shows that humans occupied much of the Sahara during the wet period, but gradually withdrew some 8,000 years ago.
Other researchers have suggested that the Sahara became drier by the time people left, but the evidence was inconclusive, says Tierney, an assistant professor of geosciences at U of A, whose work was published in Science Advances.
Also, based on erosion marks, several researchers and geologists have suggested that the Great Sphinx was built thousands of years earlier than the official story suggests.