How did all that sand wind up in the Sahara? Anybody really know the answer seriously?
The climate of the Sahara has undergone enormous variation between wet and dry over the last few hundred thousand years.[16] During the last ice age, the Sahara was bigger than it is today, extending south beyond its current boundaries.[17] The end of the ice age brought better times to the Sahara, from about 8000 BC to 6000 BC, perhaps due to low pressure areas over the collapsing ice sheets to the north.[18] Once the ice sheets were gone, the northern part of the Sahara dried out. However, not long after the end of the ice sheets, the monsoon, which currently brings rain only as far as the Sahel, came further north and counteracted the drying trend in the southern Sahara. The monsoon in Africa (and elsewhere) is due to heating during the summer. Air over land becomes warmer and rises, pulling in cool wet air from the ocean, which causes rain. Paradoxically, the Sahara was wetter when it received more solar insolation in the summer. Changes in solar insolation are caused by changes in
