A method of dating based on measuring the rate of radioactive decay of uranium isotopes in bone and other organic remains to the stable isotope of lead. It has proved particularly useful for the period before 50,000 years ago, which lies outside the time range of radiocarbon dating. Each of the isotopes decays through a series of radioactive daughter isotopes until a stable isotope of lead is reached. Three daughter isotopes are created and decay with half-lives useful for dating: ionium, proactinium, and radium. Several uranium dating methods exist and material datable by these methods includes: aragonitic coral, speleothem, travertine, mollusk shell, marl, bone, teeth, caliche, calcretes, peat, wood, and detrital sediment.