What Wiped Out the American West? Investigating a Triassic Extinction

Strewn across the dusty ground is the wreckage of a wetland forest that suddenly wilted and died 215 million years ago. Paul Olsen gestures at the broken lumps of white, red, and black quartz scattered about. “You see how it looks ropey?” he asks. He holds up a piece. “It looks like someone took little pieces of rope, snipped them up, and laid them down.” Olsen believes that these scattered rocks mark the moment of a mass extinction that wiped out many species across North America. He would like to identify the calamity that triggered this extinction. But as I stand beside him in the midday sun, I’m unable to see the subtle clues that his trained eye perceives so easily. As I look at the rocks all about, I simply don’t see the ropey, cylindrical shapes that he’s talking about. Olsen is a white-haired paleontologist with the Lamont-Doherty Earth ...