Collaborative research between Boise State University Geoscientists and the National Park Service aims to better constrain the timing of the fossil bearing rocks at the John Day Fossil Beds National Monument. BSU PhD candidates Mike Mohr and Thomas Farrell received a NPS research permit and recently collected ash beds within and around the National Monument. The volcanic ash layers within the fossiliferous strata represent volcanic eruptions that occurred between 39-18 million years ago, a time when the Earth was experiencing dramatic climate change and mammalian evolution. The ash beds collected will be dated by U-Pb geochronology in the Boise State University Isotope Geology Laboratory as part of Mike’s dissertation and an ongoing cooperative research effort between the IGL and John Day Fossil Beds paleontologists.