Sahara

""If you traveled across the United States from Boston to San Diego, you still wouldn't have crossed the Sahara," write de Villiers and Hirtle, painting a vivid picture of this most extraordinary place. They chart the genesis and course of Atlantic hurricanes, many of which are born in the Tibesti mountains of northern Chad, showing that the Sahara, which has a strong influence on weather patterns the world over, is much closer than it seems.

They offer a description of the physics of windblown sand and the formation of dunes and describe in detail the massive aquifers that lie beneath the desert, some filled with water that predates the appearance of humankind on Earth. They marvel at the jagged mountains and at ancient cave paintings deep in the desert that reveal the Sahara was a verdant grassland 10,000 years ago; what's more, this cycle has been repeated several times, and may well repeat again."--BOOK JACKET.