CHANNELED SCABLAND MEGA-FLOODING: PAST, PRESENT, AND FUTURE

Geology arguably emerged as a science because of humankind’s sense of awe about mega-flooding. Ancient human experience with mega-floods is evident in the close association of flood myths with nearly all cultures on Earth. Nevertheless, in the early nineteenth century a logically false notion of uniformitarianism produced a setback for progress in the scientific study of mega-floods. A century later University of Chicago Professor J (No Period Please!) Harlen Bretz single-handedly resurrected the science of mega-flooding. Though he presented an erroneous explanation in his first published paper on the topic in 1919 (he once told me that he wished that paper to be forever erased from the scientific literature), Bretz was subsequently inspired in the early 1920s by the wonders of the Channeled Scabland to formulate his “Spokane Flood” hypothesis. More importantly for the progress of mega-flood science (and in contrast to unfortunate trends of our own time), Bretz was able to communicate his proposed origin for the Channeled Scabland through the prominent scientific literature and thereby to get his “outrageous hypothesis” taken seriously, at least to the extent that great efforts were made to disprove it. In the ensuing debates of the 1920s and 1930s, Bretz would argue that the late Pleistocene mega-flooding of the Channeled Scabland was a unique event in Earth’s history, and thus that it posed no threat to the widely held (and now known to be false) presumption that uniformitarianism is needed to provide a conceptual warrant for geological explanation. Over the last 50 years, however, numerous examples of ancient, large-scale mega-flooding have been documented for both Earth and Mars. Moreover, these cataclysmic processes are now known to play important roles in the geological evolution of Earth-like planets, a discovery that will become increasingly relevant as more of the latter are discovered around distant stars in the universe.