Geophysics: Percolators in the Earth

While chasing a grizzly bear one day in 1847, Explorer-Surveyor William Bell Elliott blundered into a canyon that looked to him like "the gates of Hell." Huge, spiraling columns of steam hissed out of the ground; the earth trembled beneath his feet. "The Geysers," as he named the hill-rimmed valley 85 miles north of San Francisco, is as awesome as ever. But its frightening bursts of steam are now being harnessed. The canyon is the site of the first commercial geothermal-power plant in the U.S., and the installation has paid off so...