The disappearing forest.

• Position: Environment - Brief Article

Visitors to the Petrified Forest National Perk in Arizona often come away with a sense of wonder at the 250-million-year-old fallen trees that, thanks to ancient volcanic activity, have turned to stone. But more and more often, they are leaving with something else, too--stolen chunks of the petrified wood. "The softball-sized ones get collected up pretty quick in sites where there's a lot of visitors," says park ranger Chuck Dorn. More ambitious visitors hack off larger pieces. Up to...