The researchers took an unusual approach to find the mineral needed to construct the timeline for the start of the main Deccan Traps eruption. They compared the existing ratio of uranium to lead in petrified lava flows known as basalts given the known rate at which uranium decays over time. To have enough uranium, however, the researchers needed the mineral zircon, which is scarce in basalts that cooled quickly. Turning to new sources, the researchers found zircon in soil deposits known as red boles (right) that formed in between eruptions and contain volcanic ash (left) that had been trapped between lava flows. They also located zircon within thick basalt flows where lava would have cooled more slowly.