Andrew Murphy

Upper Pleistocene sediment sequences of the Western Cordilleran contain a distinct record of pedostratigraphic units that developed in consistent, repeating stratigraphic succession, across depositional environments (Geosols). Three Geosols that span the western states and Canada are presented, with details of their timing, physical characteristics and applied examples of their importance in regional chronostratigraphies. The earliest soil, here termed the Almira Geosol, formed at the last glacial maximum (20-24 ka). This was followed by the Bishop Geosol ( 13.5-15 ka) and the Badger Mountain Geosol ( 9.5-7.7 ka). Timing and characteristics of these regional soils are presented from analysis of several hundred stratigraphic sections located in British Columbia, Alaska, Washington, Oregon, Idaho, California and Utah. Based on the recurrent stratigraphic positions and consistent age associations of the Geosols, we consider them to be significant new contributions to the already rich upper Pleistocene chronostratigraphic record of the Western Cordilleran.