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The Sahara is the world's largest desert. It stretches across most of northern Africa. This huge desert is nearly equal in area to the United States and covers about 3.5 million square miles (9 million square kilometers) in all. That is about 30 percent of Africa's total land area. The Sahara is divided among several countries. They are Morocco, Algeria, Tunisia, Mauritania, Mali, Niger, Chad, Senegal, Libya, Egypt, and Sudan, and the territory of Western Sahara.
The name "Sahara" comes from an Arabic word meaning "desert" or "steppe." Parts of the Sahara are known by other names. These areas include the Libyan, Arabian, and Nubian deserts. From west to east, the Sahara stretches from the Atlantic Ocean to the Red Sea. In the north, it meets the Atlas Mountains and the Mediterranean Sea. It reaches south to the Niger River and Lake Chad. There the desert blends into a region of sparse grassland. This grassland area is called the Sahel.
Land and Climate
Many people picture the Sahara as a vast sea of sand. But sand covers only about 10 percent of the land. There are high sand dunes in some areas. The dunes are called ergs. In other places are flat gravel plains. These are called regs. And there are dry, rocky uplands, called hammadas. In places, the dry beds of ancient rivers and lakes can be seen. They show that the area was not always a desert. But by about 2500 B.C., it was as dry as it is today.
The Sahara is very dry. Rainfall is less than 10 inches (250 millimeters) a year. Parts of the desert receive less than 1 inch (25 millimeters) of rain a year. The desert is also very hot, with daytime temperatures of over 100°F (38°C) in summer. The world's highest temperature -136°F (57.8°C)- was recorded in the Sahara in Libya. Nights are much cooler. At times, temperatures dip below freezing at night.
Vegetation and Wildlife
Here and there green oases dot the Sahara. In these places, small streams, springs, or wells provide water, and palm trees and other plants can grow. Elsewhere in the desert, plants are few and far between. Only a few kinds of animals can take the daytime heat. Among them are lizards and snakes. Mammals include gazelles, foxes, jerboas, rabbits, and hedgehogs. There are scorpions, spiders, and insects, too. Rodents and other small mammals take shelter during the day. They come out at night, when the air is cooler. Small desert antelopes live in some parts of the Sahara. Many migrating birds pass through.
People
Few people live in the Sahara. Large areas of the desert are empty. But some people make their homes at the oases. Most of them are Arabs and Berbers. Berbers have lived in the region for as long as records show. Arabs first arrived in the A.D. 600s.
Most of the desert people follow the Muslim religion. Some are nomads. They travel from one oasis to the next with their camels and goats. The best known of the nomads are the Tuareg, a Berber people.
People can live year-round at some of the oases. They grow grains, fruits, and vegetables where there is enough water. But dates from date palms are the chief crop. Camel caravans carry the dates across the desert to cities for sale. The caravans also bring goods and news to the oases.
Desertification
The Sahara has been expanding southward for centuries in a process call desertification. Desertification is a gradual transformation of land into desert. The result is a loss of land on which people are able to earn a living.
Of all the regions of the world, Africa is most affected by desertification. This is because over two-thirds of its land is either desert or drylands. Desertification occurs naturally. It is also the result of over-cropping, overgrazing, and the cutting down of forests. Desertification and severe droughts contribute to large-scale famines in Africa. In response, people move toward more favorable lands. This puts further strain on the environment.
History and Resources
From the 900s to the close of the 1800s, trans-Saharan camel caravans crossed the desert to trade. Camels are still widely used for local trade and travel. But trucks and airplanes are used for longer distances.
The Sahara has vast mineral resources. Huge oil, natural-gas, and coal reserves were first discovered in the mid-1950s. Copper, lead, zinc, salt, and phosphates are also found. These resources are rapidly being developed.
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