Examines how the earth system and its geochemical cycling operate on both global and micro scales. Emphasis is on natural cycles, starting with big themes such as crust-hydrosphere-biosphere interaction and its effects on the long term C cycle, including regulation of carbon dioxide. Elements, isotopes, organic molecules (and their isotopic compositions) are used as tracers of processes and events in earth history. Organic matter, its chemistry and its relationship to both the C and S cycles is explored. Dating of geological materials with radiometric methods is introduced. The course explores themes in both deep time (millions of years) and more recent glacial-interglacial cycles (thousands to hundreds of thousands of years).