UNDER PRESSURE THE BEAUTY SECRETS OF SANDSTONE

摘要

As the story goes, the iconic spires in Utah's Bryce Canyon National Park once were human-animal "legend people," until an angry coyote god turned them into rock. This is probably not how it actually happened, but scientists haven't been able to add much more than to say "it's a weathering thing." So geoscientist Jiri Bruthans and his colleagues at Charles University in Prague tried mimicking the process in miniature: They took 4- by 12-inch blocks of "locked sand"-a material that's between loose sand and sandstone-and crammed decades of erosion into weeks or months by simulating rain and intensive salt weathering. What Bruthans discovered is a sort of geological beauty trick in which thekey factoris weight. The massive load of rock, whichhe approximates by squeezing his blocks with clamps, actually stabilizes the structures: The stress locks the grains of sand into place. It's an elegant explanation and one that befits the sculptural formations. If Bruthans ever gets tired of geoscience, he can always sell his experiments as modern art.