The aim of my project is to contribute to a better understanding of currently poorly constrained chemical and chronological data for a section of rocks that will lead to a more complete profile of the evolution of continental crust in North America, specifically in the Wyoming Province (Montana and Wyoming). At present, it has been proposed that the first continental crust was the result of melting in a mantle plume that ultimately produced zircon-bearing rocks. Based on zircons, from these rocks and found in later sedimentary rocks, this activity lasted from 3.5-4.0 Ga (billion years) ago. The next well constrained zircons in this region are from a granite that was the result of subduction, and are dated at 2.8 Ga. There is, then, a conspicuous ~0.7 Ga gap between the older mantle plume zircons, and the younger subduction zircons. To fill in this gap I will be using our department’s laser ablation, multi-collector ICP mass spectrometer to measure uranium and lead isotopes of individual zircons to obtain radiometric ages from them. Then, using the same system, I will measure the abundance of Rare Earth Elements in the zircons to obtain a chemical history of their source. By matching dates to the chemically deduced history of these rocks, I will hopefully be able to track their evolution, and as a result fill in the current gap in the crustal evolution history of North America. The understanding of early crustal development is vital to answering larger questions about how and why the Earth looks and works as it does today. Knowing how our current crustal systems began and evolved will provide insight into the history of the Earth, and help predict the future workings of the planet.