Interpreting Earth History involves relatively few principles, but many ramifications of them. Sedimentary rocks have ages and environments, represented within sequences; these ages are relative, based on superposition of sedimentary deposits and fossil faunas. Igneous or metamorphic rocks reveal absolute ages by analysis of radioactive isotopes.The class will emphasize the use of these and other principles within the context of geological time and over broad areas of the earth's crust. An understanding of plate tectonics, the evolution of ocean basins and continents, and the formation of mountain belts are central to constructing ancient geographies and recognizing their succession throughout earth history. The selection and evaluation of modern analogues of ancient environments and the collection of chemical, physical and biological data from them allow understanding the evolution of earth's atmosphere, hydrosphere, lithosphere, and biosphere to reconstruct earth history. Final class meetings will summarize the 4.6 billion years of earth history. Lecture (plus questions).