Floods are one of the most powerful and destructive forces on the planet; every year they claim the lives of thousands of people across the world. But as destructive as these modern-day events are, scientists are finding evidence that floods raged across the Earth on a far more catastrophic scale thousands of years ago. Geologists and scientists use the latest forensic techniques to investigate bizarre landscapes in the United States, Iceland and even on the floor of the English Channel. Stunning aerial footage gives the impression that these landscapes have been created over millions of years by gradual erosion, just like the Grand Canyon.