Stratigraphy has undergone dramatic changes. From a simple timescale resting on paleontology and relatively few and less precise radiometric dates, it has become an integrated, sophisticated discipline built around a timescale that is increasingly complex and supported by new and equally complex methods. Creationists must understand and address these changes, especially those changes in the methods. This series will focus on one of the newer methods: cyclostratigraphy and its associated astrochronology. Cyclostratigraphy links various properties of sedimentary rocks to an astronomical "clock" based on the extrapolation of orbital mechanics into the past. This clock sends a signal of varying sunlight to Earth, manifested as "Milankovitch cycles," that are thought to force climate change sufficient to be recorded in sedimentary rocks.