Did You Know?

The Sahara desert in North Africa has a number of distinct physical features, including ergs, regs, hamadas and oases. Ergs, which cover 20% of the Sahara, are sand dunes that stretch for hundreds of kilometres and reach heights of more than 300m. Ergs cover most of Algeria and Libya as well as parts of Mali and Nigeria. Regs, which make up 70% of the Sahara, are plains of sand and gravel. The gravel can be black, red, or white. Regs are the remains of prehistoric seabeds and riverbeds, though they are now nearly waterless. Hamadas are elevated plateaus of rock and stone. They include the Atlas Mountains, which stretch from southwestern Morocco to northeastern Tunisia; the Tibesti Mountains of southern Libya and northern Chad; and the Ahaggar Mountains in southern Algeria. There are over 90 oases throughout the Sahara, and many of them have enough water and other resources to support human life.