Explore the compositional evolution of the upper continental crust through ancient glacial diamictites in this 20-minute conference talk from the 2014 AGU Fall Meeting. Delve into the research conducted by a team of international geologists who utilize these unique sedimentary deposits to track changes in Earth's crustal composition over time. Learn about the objectives, approach, and advantages of using glacial diamictites as a proxy for upper crustal composition. Examine the methods employed, including the analysis of matrix material and various geochemical indicators such as nickel, aluminum, thorium, scandium, uranium, and molybdenum. Investigate the role of oxygen isotopes and sedimentary recycling in understanding Earth's infrastructure. Gain insights into how this research contributes to our understanding of the Earth's geological history and the processes that have shaped its crust over billions of years.