Nailing Pompeii

Roman hihstorian Pliny the Younger noted that Mount Vesuvius blew its top and destroyed Pompeii in the early afternoon of August 24, 1,918 years ago. Now, a team of scientists, tempted by the certainty of that record, has confirmed the eruption to within 7 years. The team developed and used an improved radioactive argon‐argon dating technique, which they say can reliably establish the age of rocks as old as the solar system or as recent as 1,000 years old. “We nailed the date to 5% on our first attempt, so we could probably get the error down to 1% or less,” says Paul Renne, adjunct associate professor of geology and geophysics at the University of California at Berkeley and director of the private Berkeley Geochronology Center. “Dating things that are really young has always been the Holy Grail of potassium‐argon [an earlier method] and argonargon dating.”