Our September speaker will be Dr. Victor R. Baker, Departments of Hydrology and Atmospheric Sciences, Geosciences, and Planetary Sciences, The University of Arizona.
History and Philosophy of an Outrageous Geological Hypothesis: J Harlen Bretz and the Spokane Flood Controversy.
In 1923, J Harlen Bretz, a recently tenured University of Chicago professor, newly appointed to the Journal of Geology editorial board, shocked the geological community with his paper in that journal proposing that an immense late Pleistocene flood had emanated from the margins of the nearby Cordilleran Ice Sheet. Cataclysmic flooding, which Bretz named the “Spokane Flood,” neatly accounted for numerous interrelated aspects of the Channeled Scabland landscape of eastern Washington, as well as features in nearby regions, including the Columbia Gorge, the Portland Basin, and the Willamette Valley.
Nevertheless, in spite of Bretz’s enthusiastic and eloquent defence of this explanatory hypothesis, the geological community largely resisted it for decades. Resolution of the controversy came gradually, initially through the revelation by J. T. Pardee of a plausible source for the flooding: the ice-dammed Pleistocene glacial Lake Missoula in northern Idaho and western Montana. Eventually, by the late 1960s, the documentation of field evidence for cataclysmic flooding became overwhelming, and advances in understanding of the physical processes of megaflooding showed those to be completely consistent with that field evidence.
Today it is widely recognized that megaflooding occurred globally as a fundamental process associated with Earth’s late Pleistocene ice sheets. Moreover, the Spokane Flood controversy is of considerable philosophical interest because of its illustration of attitudes taken by scientists toward hypotheses that seem outrageous relative to prevailing theories, but which, nevertheless, are found to explain striking anomalies showing Nature’s inconsistency with those theories.
Mentioned during the presentation: Vic’s comments on Grau Galofre et al. (2020) article concerning ancient enviromental conditions on Mars.