When a volcano erupts, it doesn't just make the news. It leaves a mark on the entire planet. Huge clouds of ash and gas go up into the sky and eventually settle back down. Some of that ash ends up at the bottom of lakes or oceans, buried under layers of silt. For a long time, these tiny bits of ash were almost impossible to find unless the eruption was huge. But thanks to a new way of looking at sediment, we can now find the