At least 1.5 billion years after it last saw the surface, flowing liquid may host life.

DENVER — “I’m a little tired of the cold,” Geoff Hargreaves says with a sigh. No surprise there: Hargreaves works in a deep freeze — 38 degrees Celsius below zero (−36° F). As curator of the National Ice Core Laboratory, his job is to keep ice cores from Antarctica and Greenland frozen. These cylinders — which would stretch more than 17,000 meters if laid end-to-end — are precious. They contain records of past climate and atmospheric chemistry, trapped in tiny bubbles that formed thousands of years ago and froze in chronological layers like tree rings. Melting is the enemy, ... (p. 32)

What do five Porsches, several Kentucky thoroughbreds and a three-story building in Guatemala City have in common? They’ve all been swallowed by sinkholes. Sadly, the sudden cave-ins sometimes claim people’s lives as well. On February 28 the earth opened up underneath the Seffner, Fla., bedroom of Jeff Bush, entombing him. The freak accident highlighted Florida’s vulnerability to sinkholes, and the seemingly sheer randomness of death by earth. But geologists are fighting back. The battle isn’t just one man versus the ground; it’s science versus society’s tendency to put structur...