Radiometric dating. Isotope, Age of the Earth, Stratigraphy, Geologic time scale, Geochronology, Closure temperature, Uranium-lead dating, Potassium-argon dating, Rubidium-strontium dating, Uranium-thorium dating, Radiocarbon dating, Fission track dating, Optical dating, Isochron dating, Isotope geochemistry, Isotopic signature, Radioactive decay, Radiohalo, Sensitive high resolution ion microprobe.