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THE SAHARA

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Bianca
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« Reply #30 on: May 17, 2009, 09:05:49 am »










Like the alluvial fans and lake bottoms, the Bou Dheir cave bottom doesn’t yield a good, datable sample either. But on the way back to Rabuni, Mather spots something on the roadside she hadn’t expected: a tufa, or carbonate, outcropping.

That usually indicates the remains of a freshwater lake.

She motions to driver Sidi Ahmed to stop, bounds out of the Toyota with her geologist’s hammer and pecks away at the chalk-like protrusion. She points to one good sign. “It’s quite filamentous,” she says, “so it’s likely not just formed by groundwater.” She takes a sample for dating, probably by way
of the uranium-thorium method—similar in principle to carbon-14 dating.

 
The valley of Lajuad has been dry year-round since desertification began. How did the people who

once made their livelihoods here respond when the rains no longer came?


Samples packed away, we bounce back across the arid result of Earth’s last great climate change.

What might happen this time around? The 130-country Intergovernmental Panel on Climate Change—co-winner of the Nobel Peace Prize—has mentioned that future responses to global warming could include the “migration of hundreds of millions of people from equatorial regions.”

Brooks isn’t surprised.

Our desert trip done, freshly shaved and sipping a café au lait in a splash of morning sun on the hotel patio in Algiers, he voices his hope that the latest climate change might be the dawn of a new, more responsible model of civilization.

Speaking of the old model, he says, “We’ve done our early development period, and our period of adolescent rebellion and irresponsibility. We’re now into post-adolescence.”




 Free-lance writer Graham Chandler (www.grahamchandler.ca)

received his doctorate in archeology from the University of London,
and he lives in Calgary, Alberta.
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Your mind understands what you have been taught; your heart what is true.
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