Constant Change Today the Sahara is extremely hot and dry, but its climate was not always this way. Some 10,000 years ago, parts of the Saharan region were covered with grass and other vegetation. Plants, animals, and even people thrived there. T e Sahara began to go through the process of desertifi cation—or drying up—about 4,000 years ago. Why the change? Scientists think the


Sahara dried up due to a change in Earth’s orbit around the sun. T is caused major changes to the


weather and climate of the region. Changes in Earth’s tilt caused less sunlight and rainfall in North Africa. When that happened, plants died, and


rivers dried up. Scientists think that this change happened slowly in some parts of the Sahara. Other parts may have dried up faster to become a desert.


Pools of Life Not all parts of the Sahara are dry, however. Water can be found at an oasis. An oasis is a lush, green area surrounded by desert. Most are formed by underground water sources. Rock layers below the surface trap water in pockets. Water can then bubble to the surface naturally. Or it can be brought up by man-made wells. In the middle of a hot desert, the sight


of an oasis can be welcoming. Timia Oasis, in northern Niger, is tended by the Tuareg people. A pool of water surrounded by palm trees opens up to lush gardens. Oranges and pomegranates hang from branches. Date palms and fruit trees provide a cool canopy for herbs and vegetables. Oases provide habitats for animals and


people. But only two percent of the Sahara is covered by oases.


An oasis formed in this extinct volcanic crater deep in the Sahara.


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