Expedition into the lonely Tibesti Mountains

Peaking at 3,445 meters (11,302 feet), the Tibesti is the Sahara's highest mountain range. For four weeks, a team of six researchers of the German University of Cologne traveled through this remote region, one of the least explored places on Earth. Their central aim was to find out how modern human beings reached Europe 100,000 years ago and what role the climate played in this migration.

The leader of the expedition, geologist Stefan Kröpelin, says political unrest in Chad made research impossible until the end of the 1990s. He waited eagerly for this chance for decades: "We can land a probe on a comet 500 million kms (310 million miles) away, to see what it is made of, but we have never before examined the stones on the highest mountain of the biggest desert on Earth."

The main goal of the expedition was to reach Emi Kussi, the highest peak of the region. But at the end of February 2015 the team of researchers first traveled to Bardai in the northwest of Chad. The capital of Tibesti, a region created in 2008, has 1.500 inhabitants. From there the team later reached the uninhabited mountain range.

The team was accompanied by a local guide, four drivers and a cook. "At first we felt people here were very guarded", says Adam Polczyk, the expedition’s press officer and photographer. "But the ice was quickly broken, because we Europeans did not travel by ourselves, but chose to have locals on the expedition too."

The greater part of the trip was made by jeep. The drivers always kept a lookout for appropriate resting places, to escape the searing midday heat. Acacia trees provided the only shadow in the expanse of sand and sun.

To take their first samples, the team had to leave the jeep behind. Donkeys carried the equipment down an 800 meter (2,625 feet) deep crater of volcanic origin. It took the researchers a day and a half to reach the 'trou au natron.' The 'natron hole' owes its name to the crusts of white and shiny sodium that cover parts of the crater.

Stefan Kröpelin found so-called diatomite at the 'trou au natron.' Diatomaceous earth consists of fossilized remains, proving that there must have been a sea here at some point in the past. Hard to believe, but true: 5,000 to 10,000 years ago, the Sahara was a thriving savanna.

This is also proved by the prehistoric rock carvings the researchers discovered on their trip. Once rhinoceroses, elephants, crocodiles and hippopotami roamed what today is the most extensive arid region on Earth.

The second part of the expedition took the researchers to the east of the country. It took the team five days to cross the desert, before they reached Emi Kussim, their main goal. "The Sahara must always have been the principal corridor to Europe for every migration of prehistoric man," says geologist Stefan Kröpelin. "And they must have crossed the Emi Kussi too."

But first they had to take another arduous trip: this time with camels instead of donkeys. "It was astonishing to watch the pack animals climb the very rocky and steep mountain," says photographer Polczyk. "They reached the limit of their capacity, same as we did."

Once he reached the peak, Stefan Kröpelin took several samples. Back in Germany, he now has to be patient, because the analysis in the lab takes a lot of time. But Kröpelin feels the expedition is already a big success and an unforgettable experience: "The landscape is so spectacular that I suggested Tibesi be turned into the next World Heritage site."

Chad already has a UNESCO World Heritage site: the Lakes of Ounianga. The Ennedi Plateau is also under consideration for this honor. Kröpelin says Tibesti should be part of it too: "Calling international attention to places like these improves living conditions for the population, and that is something I am very keen on." This way he hopes to be able to repay the locals for their hospitality.