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The African humid period ended 6,000–5,000 years ago during the Piora Oscillation cold period. While some evidence points to an end 5,500 years ago, in the Sahel, Arabia and East Africa, the end of the period appears to have taken place in several steps, such as the 4.2-kiloyear event.
These layers occur on a 23,000-year cycle that lags the maximum in precession insolation by roughly 5000 to 6000 years. [5] [14] To explain these cyclic freshwater diatom deposits we have to look inland at the Sahara region of Africa. Around the time of the insolation maximum in the precession cycle the North African Monsoon is at its strongest ...
The Sahara is presently as dry as it was about 13,000 years ago. [2] These conditions are responsible for what has been called the Sahara pump theory. During periods of a wet or "Green Sahara", the Sahara becomes a savanna grassland and various flora and fauna become more common.
Analysis of pollen found at the base levels of the site dating to between 7500 and 5000 BC indicates a wet savannah. [4] Extensive samples from a number of sites indicate that tropical humid plants began to expand northward around 12,000 years ago after a lengthy dry period, eventually reaching deep into what is today the Sahara Desert. [5]
The time from roughly 15,000 to 5,000 BCE was a time of transition, and swift and extensive environmental change, as the planet was moving from an Ice age, towards an interstadial (warm period). Sea levels rose dramatically (and are continuing to do so ), land that was depressed by glaciers began lifting up again , forests and deserts expanded ...
The Sahara is now as dry as it was about 13,000 years ago. [30] Lake Chad is the remnant of a former inland sea, paleolake Mega-Chad, which existed during the African humid period. At its largest extent, sometime before 5000 BCE, Lake Mega-Chad was the largest of four Saharan paleolakes, and is estimated to have covered an area of 350,000 km 2 ...
By 4 million years ago, ... For several hundred thousand years the Sahara has alternated between desert and savanna grassland in a 41,000 year ... By 5000 BC, Africa ...
The Sahara was one of the first regions of Africa to be farmed. Some 5,000 years ago, the area was not so arid and the vegetation might have been closer to a savanna. Previous fauna may be recognised in stone carvings. However, desertification set in around 3000 BC, and the area became much like it is today. The Sahara is largely undisturbed. [1]