Bretz's view of a catastrophic flood finally prevailed. Waitt extended Bretz's argument, arguing for a sequence of multiple Missoula Floods -- 40 or more. Waitt's proposal was based mainly on analysis from glacial lake bottom deposits in Ninemile Creek and the Touchet Formation deposits in Burlingame Canyon. This represented a move away from a single catastrophic flood toward a series of catastrophic floods, but with the flood source still ascribed to Glacial Lake Missoula.

The controversy whether the Channeled Scabland landforms were