It had been thought that the deserts in northern China are one million years old, but a new study of the Hunshandake Sandy Lands of Inner Mongolia suggests that its desert is only 4,000 years old. Xiaoping Yang of the Chinese Academy of Sciences, Louis Scuderi of the University of New Mexico, and their colleagues examined the patterns of dunes and depressions in the region and lake sediments, and they dated quartz from the region with a technique known as optically stimulated luminescence. They found that Hunshandake had deep lakes and rivers beginning some 12,000 years ago. "We're amazed by...