Geological time age chron eon epoch era period Geochronology Geological history of Earth. Other parts of the uranium decay series are used in dating in the Quaternary. Fossil faunal and floral assemblagesboth marine and terrestrial, make for distinctive marker horizons. Each series is characterized by a parent first member that has a long half-life and a series of daughter nuclides that ultimately lead to a stable end-product—that is, a nuclide on the band of stability Figure 5. What fraction of the present today will be present in y?
For example, cobalt, an isotope that emits gamma rays used to treat cancer, has a half-life of 5.
Solution a The value of the rate constant is given by:. The proportions of two of the isotopes of strontium, 86 Sr and 87 Sr, are measured and the ratio of 86 Sr to 87 Sr will depend on two factors. The textbook is not necessarily set up in the same structure as the Reading Guides. Calculate the age of the rock. If the proportions of parent and daughter isotopes of these decay series can be measured, periods of geological time in millions to thousands of millions of years can be calculated. Because each nuclide has a specific number of nucleons, a particular balance of repulsion and attraction, and its own degree of stability, the half-lives of radioactive nuclides vary widely. The half-life of this decay is