Sand used to be a stone
History of the Sahara When the desert was full of water
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Today the Sahara is a sea of sand and stone. It is scorching hot during the day and bitterly cold at night. But a few thousand years ago, where there is now desert, there was an abundance of water and greenery.
The Ennedi massif is a mountain range in the east of the Sahara. There is a ravine called the Guelta d'Archei. In this is a small lake that is fed by groundwater. The water comes from a time when rain still fell in the desert. That was thousands of years ago, but a few Sahara crocodiles still live in the lake. They are reminiscent of a time when hippos and elephants still lived in this area, as well as giraffes, gazelles and antelopes. Because the Sahara was not always a desert of stone and sand.
Camels in the Guelta d'Archei
Scientists used to assume that more rain fell in the Sahara during the last ice age than it does today. That turned out to be a mistake: During the last glacial period, the Sahara was even drier in places, and it extended several hundred kilometers further south.
A superlative tropic desert: at nine million square kilometers, the Sahara is by far the largest dry zone on earth. It measures 6,000 kilometers from the Atlantic to the Red Sea. Eleven countries have a share in the Sahara, including Morocco (as shown here in the picture a sand dune near Agadir).
Huge lakes in the desert
A remnant of the once huge lakes: Lake Mandara in Libya
When the most recent ice age came to an end around 12,000 years ago, vast areas of the desert turned into savannah. This is shown by the remains of thousands upon thousands of lakes. Most of them only filled individual depressions or valleys, but some of these bodies of water were huge. The West Nubian Paleo Lake, for example, had an area of over 5,000 square kilometers. It was around ten times larger than Lake Constance. Mega Chad is said to have covered almost two million square kilometers. Today only a few small lakes and oases are left of it.
In northern Africa in particular, the climatic phases changed: it was at times rather green and at times desert-like, like today. Whether it rains there or not depends on the monsoon. It is controlled by cyclical changes in the earth's orbit around the sun, which last about 20,000 years. This is also shown by the analyzes of dust and pollen in drill cores that researchers pulled from the ocean floor off the coast of Africa. After that, the Sahara turned green not only at the beginning of the warm period in which we are currently living, but also during the period before that, which ruled 130,000 to 115,000 years ago.
Lake Yoa in Chad
Remnants from the last green period in the Sahara can also be found in Ounianga in northeastern Chad. There are almost 20 lakes in the middle of the desert. One of the largest and deepest of these lakes is Lake Yoa. Under its bottom it hides a true climate archive: over 10,000 annual layers of fine sand and dust, diatoms and pollen. Analysis of drill cores showed that it had only taken about 500 years for much of the Sahara to become grasslands. Only about 500 to 1,000 years later, people followed this rainfall and the green pastures and hunting areas and settled there for millennia.
3,500 years in the green Sahara
Around 8,500 BC, the Sahara was populated everywhere. But around 5,000 BC the monsoons began to subside. It will then take around 3,000 years for the Sahara to turn back into a hostile and largely uninhabited desert as we know it today.
- Green Sahara. IQ - Science and Research, March 2nd, 2020 at 6:05 p.m., Bavaria 2
- Adventure Sahara. Michael Martin - Planet Desert, December 28th, 2018 at 12:30 p.m., ARD-alpha
- Unknown Africa - Sahara. natur exclusiv, 04/22/2018 at 2:20 p.m., BR television
- The history of the Sahara lakes in the sand: on November 10, 2016 at 3:05 p.m. in "radioWissen am Afternoon", Bavaria 2
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