A desert is defined as any place that receives less than 10 inches of rain per year. Some deserts receive no rain at all; their moisture comes from condensed fog. Deserts are found on every continent, but only about 10 percent of them are covered by sand dunes. More than a billion people make their homes in deserts, as does a wide variety of plant and animal life.
The Kalahari Desert, the southernmost one in Africa, covers nearly 560,000 square miles across Botswana, South Africa and Namibia. Light rains in the spring season help to alleviate the heat and cause plant life to bloom. The San Bushmen of the Kalahari carry on Africa's oldest surviving culture, which has changed little since the Stone Age; they still hunt using ancient methods like the bow and arrow.
The Namib Desert, the world's oldest, is located in southwestern Africa and is part of Namibia and southern Botswana, with the Atlantic Ocean on its western side. It gets most of its moisture from the fog that rolls inland from the ocean, which amounts to about 1.6 inches annually. The Namib Desert contains the world's largest deposit of gem diamonds. Part of its coastline has been nicknamed "Skeleton Coast" because the treacherous waters would often wreck many ships there.
The Karoo Desert stretches for about 250,000 square miles on the western side of the nation of South Africa The Great Karoo region contains South Africa's largest deposit of coal, making coal mining an important pillar of the nation's economy. The Little Karoo is home to Oudtshoorn, a town known as "the ostrich feather capital of the world" in Victorian times. Many ostriches still live there.
