Chile's Atacama Desert, which gets less than 5 millimeters (0.2 inches) of rainfall each year, started to form more than 40 million years ago ‪—‬ 20 million years before the Andes.

China is building a dam system that will generate more hydroelectric power than the U.S. generates yearly. But the project comes with huge risks for people downstream.

Antarctica was long thought to be seismically calm, but new technology makes it possible to detect unexpected types of earthquakes beneath the ice.