Distributed volcanic fields (DVFs) have many volcanic vents distributed over broad regions that are often close to population centers and important infrastructure. The chance of a volcanic eruption in a DVF in the western U.S. is about 1 in 1,000 per year, which is at least as likely as any individual volcanoes in the Cascade Range. Since these eruptions are hazardous, it is important to learn about how long they last (years? decades?) and how much area is affected by them. To answer these questions, the project team will examine exposed intrusions of the San Rafael Volcanic Field (SRVF, Utah). This 4-million-year-old DVF is eroded to about 1 km depth and now exposed at the Earth’s surface. Precise dates from these magmatic intrusions will help constrain how often underground magma bodies form and change. In doing so, this work informs models for how volcanic systems develop and cause eruptions. This work will also help clarify the link between movement of magma in the subsurface and volcanic structures and hazards at the surface. New ages, paleomagnetic data, and conceptual models will expand knowledge about the evolution of DVFs in the western United States. This project will also provide training for undergraduate and graduate students. Rock samples from this project will be used in courses for hands-on activities. Methods, models and data, will be shared with the community through portals, public databases, and publications. Images from thin sections of rocks will be adde