http://www.sahara.it/bm/saharaThree/viaggi/resoconti/algeria-tassili-najjer.shtml
Among the images the authors are showing of the travel there is the picture of a Neolithic mound, a "key-hole" tomb. Here a partial reproduction of their image
Algeria was populated since 10,000 BCE, as shown by several archaeological sites located in the Tassili National Park. Very important are there the engravings and cave paintings, dated between 8000 and 4000 BCE, where people of Neolithic age depicted animals such as elephants and hippopotami, showing that once the climate was rather different and far wetter than it is today.
The Tassili n'Ajjer is a vast plateau in south-east of Algeria. In Berber its name means the Plateau of the Rivers. This plateau is composed mainly of sandstone. Because of the water-holding properties of the sandstone, the vegetation here is somewhat richer than in the surrounding desert. In fact, the name "Plateau of the rivers" seems to echo that period of time, known as the Neolithic Subpluvial or Holocene Wet Phase, when the climate of Maghreb was wet. It was a period preceded and followed by drier periods, the most recent of some wet climatic conditions of the Sahara, named "Green Sahara", during which the region supported a rich vegetation, animals and humans.
The Tassili n'Ajjer is a vast plateau in south-east of Algeria. In Berber its name means the Plateau of the Rivers. This plateau is composed mainly of sandstone. Because of the water-holding properties of the sandstone, the vegetation here is somewhat richer than in the surrounding desert. In fact, the name "Plateau of the rivers" seems to echo that period of time, known as the Neolithic Subpluvial or Holocene Wet Phase, when the climate of Maghreb was wet. It was a period preceded and followed by drier periods, the most recent of some wet climatic conditions of the Sahara, named "Green Sahara", during which the region supported a rich vegetation, animals and humans.
Some Neolithic mounds, built by the ancient populations that lived in what once was a "Green Sahara", are visible in the satellite images of Google Maps. In particular, due to a high enough resolution, we can see some of the mounds of the regions of Tassili and Amguid in Algeria.
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