The 1345 slide and flood disaster in the Gauldalen valley,Mid-Norway: A new interpretation

The Gauldal disaster of September, 1345, with 500 assumed killed, is the largest recorded in Norway. Contemporaneous written accounts, oral tradition and geological interpretations express divergent opinions about both its location and development. We show that, contrary to tradition, the river Gaula found its present course at Gaulfossen more than 2000 years before the disaster. Lakes in a small, elevated tributary valley, Langdalen, probably represented the 'lost lake' Hagevatnet of oral tradition, and the disaster apparently started with a flood from these lakes. Erosion of an old ice-front delta in the main valley induced a large slide from the eastern side of the valley, which dammed the river Gaula. Failure of the resulting sand and gravel dam would have developed very rapidly, compared to the clay dam postulated by previous workers, and would explain the dramatic results of the downstream deluge. Our data and interpretion fit oral tradition, accounts in the contemporaneous Icelandic Skålholt Annals, and the geological constraints better than previous models.