This award supports acquisition by the Berkeley Geochronology Center (BGC) of a Thermal Ionization Mass Spectrometer (TIMS). The instrument will be used to determine the ages of rocks and minerals, and in turn, to date key events and first-order processes that have shaped today's Earth. Uranium-lead and uranium-series dating, both based on the decay of naturally occurring uranium in diverse geological materials, will be the main techniques used. Together, they can provide ages for rocks and minerals formed as recently as the last few years or as old as the Earth and our solar system. When understood in their geologic context, such radioisotopic ages allow scientists to build a timeline for Earth's past including, for example, the volcanic and tectonic activity that formed the continents and oceans, and the history of life on Earth. Such knowledge is fundamental to basic Earth science research, guides exploration for natural resources, and provides the means to assess hazards posed by earthquakes and active volcanoes. Research at BGC involves collaborators from across the United States and provides hands-on training for undergraduate and graduate students and other early career researchers. Their expertise in analyzing minute quantities of uranium and related elements using the new mass spectrometer will enhance the national capacity and capability not only in Earth sciences but also nuclear energy and forensics. The new TIMS supported by this award will replace an existi