The dating for Waitt's proposed separation of layers into sequential floods has been supported by subsequent paleomagnetism studies, which supports a 30-40 year interval between depositions of Mount St. Helens' ash, and hence flood events, but do not preclude an up to 60 year interval. Offshore deposits on the bed of the Pacific at the mouth of the Columbia River include 120 meters of material deposited over a several thousand-year period that corresponds to the period of multiple scabland floods seen in the Touchet Beds. Based on Waitt's identification of 40 floods, this would give an average separation between floods of 50 years.