A cloud of dust escapes from an excavation site in the sand of Chad's arid north, where scientists are looking for signs of human habitation in an area once humid and called the "Green Sahara".

Kneeling, armed with a brush and trowel inside the largest rock shelter at the Gaora Hallagana site in the Ennedi West province, Djimet Guemona, 35, meticulously removed every layer of sand.

"It's as if we are turning the pages of a historic book to travel back in time," said Guemona, an archaeologist at the National Centre for Research and Development.

His face lit up at the discovery of each fragment of pottery or scrap of charcoal.

The scientific mission, conducted over five days in late July some 30 kilometres (nearly 19 miles) from Fada, the main town in Ennedi West, brought together Chadian archaeologists and geologists from universities in N'Djamena and Abeche.

It aimed to lay "the first cornerstone" of the chronological framework for ancient settlements in Ennedi, Guemona said.

The Natural and Cultural Reserve of Ennedi (RNCE) was created in 2018 in the Chadian province, which stands at the crossroads with Libya and Sudan and is home to a rich archaeological heritage.

Tens of thousands of engravings and paintings........

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