An event was recorded in some detail by Gregory of Tours in his History of the Franks. He wrote: "A great prodigy appeared in Gaul at the fortress of Tauredunum, which was situated on high ground above the River Rhône. Here a curious bellowing sound was heard for more than sixty days: then the whole hillside was split open and separated from the mountain nearest to it, and it fell into the river, carrying with it men, churches, property and houses. The banks of the river were blocked and the water flowed backwards. This place was shut in by mountains on both sides, for the stream flows there through narrow defiles. The water then flooded the higher reaches and submerged and carried everything which was on its banks. A second time the inhabitants were taken unawares, and as the accumulated water forced its way through again it drowned those who lived there, just as it had done higher up, destroying their houses, killing their cattle, and carrying away and overwhelming with its violent and unexpected inundation everything which stood on its banks as far as the city of Geneva. It is told by many that the mass of water was so great that it went over the walls into the city mentioned. And there is no doubt of this tale because as we have said the Rhone flows in that region between mountains that hem it in closely, and being so closely shut in, it has no place to turn aside. It carried away the fragments of the mountain that had fallen and thus caused it to disappear wholly." Source: https://en.m.wikipedia.org/wiki/Tauredunum_event