In the past several years, improved dating technology has allowed geologists to identify three distinct phases of Deccan volcanism. The first and weakest began roughly 67.5 million years ago. The second and largest phase accounted for 80 percent of the total volcanism and produced the largest lava flows in Earth's history (represented by vertical black bars). Princeton researchers found that this activity wiped out nearly 100 percent of planktonic foraminifera and ultimately initiated the Cretaceous-Tertiary mass-extinction event. They further reported that a less severe third eruption phase occurred roughly 300,000 years after the mass extinction and kept the Earth nearly uninhabitable for another half-million years. Credit: Image courtesy of Gerta Keller