SHARING THE FIELD: THE PIERCE LEGACY IN THE CENTENNIAL VALLEY, MONTANA

Dr. Ken Pierce is best known for his work within Yellowstone and Grand Teton National Parks, but 40 miles from the west entrance to Yellowstone, still within the Greater Yellowstone Ecosystem (GYE) sits the Centennial Valley, Montana, an east-west trending basin home to the largest wetland complex in the GYE. Some of Ken’s later years were spent working on a surficial map of the Centennial Valley. I assisted Ken in doing some basic field work on the map, collecting samples, looking at fluvial stratigraphy, mapping and measuring fault scarps because I was already in the valley working on tying in the effects of beaver and climate into the story of the valley. Lidar data from my project also assisted in identifying paleolake shorelines. Those days with Ken are some of the most precious and awesome field days of my career, a chance to watch a field-hardened expert practice his craft.

My work with Dr. Grant Meyer, another beneficiary of Ken’s mentorship, builds on Ken’s understanding of water dynamics in the valley during the Quaternary. On low-gradient Pleistocene-age fans that were deposited in a landslide-dammed lake, beaver evidence is part of the stratigraphy. 40 sites on streams in the valley were examined. 26 of the sites contained beaver-chewed willow stems. Detailed fluvial-stratigraphic work and 64 radiocarbon ages add to our understanding of the fluvial dynamics that have contributed to valley floor development. It appears that In response to appropriate hydrologic conditions, beaver cause dynamic perturbations affecting point bar development and overbank sediment storage, but it is the large scale processes, described by Ken, that control river valley form.

Ken’s map has been valuable in my own research, but it continues to be utilized by the agencies charged with managing the working and wild landscapes of the Centennial Valley as well as by students in the University of Montana Western Surficial Geology Course, a fully field based course centered in the Centennial Valley, where students attempt to taste what it is to know a landscape, to walk in Ken’s footsteps, with his map an integral part of the course. Ken Pierce continues to train a new generation of field geologists and we all have benefitted from a day in the field with Ken.