PROBING THE STORIES THAT BOULDERS CAN TELL, AS SEEN THROUGH THE EYES OF DR. ED EVENSON

Dr Ed Evenson focused his thoughts upon the mechanics of till genesis and deposition throughout his career. His keen eye noticed the geomorphic evolution of moraines as they aged. Happenstance in witnessing range fires around Pinedale and Bull Lake moraines propelled his investigation of spallation as a mechanism to account for destruction of boulders over time, particularly any sized smaller than a school van. His work in mapping surficial deposits in Tierra del Fuego, in concert with the efforts of numerous students, then poised him well for the advances that developed with modern terrestrial cosmogenic nuclide dating of exposed rock surfaces, for when the tools were developed, he knew where provocative boulders were located. For example, boulder swarms in Bahia San Sebastian had been described by Charles Darwin during his voyage on the Beagle in 1833. More recent mapping also noted a boulder similar swarm at Bahia Inutil on the west coast of Grande Isle. In collaboration with other investigators, he contributed to a new interpretation of the geologic history of those groups of boulders. The story of those boulders has been told around the world and will be recounted here to convey the good professor’s perspective upon the historical progression of this rewarding line of inquiry.