Sahara: A Natural History.

MARQ DE VlLLIERS AND SHEILA HIRTLE

The Sahara Desert is an immense landscape. If you traveled across the United States from Boston to San Diego, you still wouldn't have crossed the distance of the Sahara. Wells with potable water can be 400 miles apart--the distance between LOS Angeles and San Francisco. However, while most people perceive it to be a barren wasteland that sears under the hot sun, the Sahara is rife with life and includes massive dunes and four mountain ranges. Sahara is part history and part glittering travel guide to a place that influences weather patterns for the whole planet. De Villiers and Hirtle begin this journey by defining the desert's geological features and revealing some surprising information. For instance, only about 15 percent of the Sahara is sand--the rest consists of rock-strewn mountains and massive plains of stone and gravel. The desert is also a rich source of manganese, iron, cobalt, and salt. About 2 million people live there, many being nomads with no political allegiance. The authors round out their story by recounting the history of the people who have claimed this land, including the Chaamba, the Moors, the Tubu, and the Tuareg. Walker, 2002, 326 p., b&w photos/illus., hardcover, $27.00.