Columbia University geophysicist Robin Bell studies the planet's most enigmatic range: the Gamburtsev Mountains, buried beneath two miles of ice in East Antarctica. They were discovered in the 1950s during a Soviet seismic survey, but little research was done there until Bell and her colleagues arrived in 2008. Over two months, often working in -30 degree C temperatures, Bell's team crisscrossed over the invisible mountains in a plane equipped with ice-penetrating radar. The radar waves bounced off the rock beneath the ice; returning echoes yielded this contour map of peaks and valleys as well as hundreds of miles of interconnected subglacial lake systems. Colors indicate elevation, with white the highest.

After studying the map, Bell was stunned by what it revealed: The range of 9,000-foot-tall mountains, mighty as the Pyrenees, seemed to have sprung up out of nowhere. "Normally mountains arise where you've smashed continents together, or from volcanoes or subduction zones," she says. "But none of those exciting things seemed to have happened under Antarctica for hundreds of millions of years. That was the mystery." Now, using gravitometers and magnetometers, which measure fluctuations in gravity and magnetic fields, as well as deep-earth measurements from seismometers embedded in the ice, Bell is closing in on answers. "These images are revealing that there were perhaps some faults and other interesting things happening in places that are now covered with ice," she says.