In the ravine they discovered traces of an earthquake in prehistory which had caused a huge landslip at a place where the river makes a sharp turn as it winds through the gorges. Here, with still-surviving banks of sediment deposited on the sides of the gorge, scientists were able to map the landslide deposits and to identify an enormous and still visible landslide scar. Blocked to a height of maybe 240 metres, the water built up over six to nine months before it broke through in what they called ‘one of the largest freshwater floods of the Holocene’.
