How do scientists use the knowledge of radioactive dating
Love-hungry teenagers and archaeologists agree: dating is hard.But while the difficulties of single life may be intractable, the challenge of determining the age of prehistoric artifacts and fossils is greatly aided by measuring certain radioactive isotopes.
Radiocarbon dating involves determining the age of an ancient fossil or specimen by measuring its carbon-14 content.For example, a method based on a parent isotope with a very long half-life, such as C method can only be used to determine the ages of certain types of young organic material and is useless on old granites.Some methods work only on closed systems, whereas others work on open systems.The discovery of radioactivity in 1896 by Henri Becquerel, the isolation of radium by Marie Curie shortly thereafter, the discovery of the radioactive decay laws in 1902 by Ernest Rutherford and Frederick Soddy, the discovery of isotopes in 1910 by Soddy, and the development of the quantitative mass spectrograph in 1914 by J. Thomson all formed the foundation of modern isotopic dating methods.But it was not until the late 1950s that all the pieces were in place; by then the phenomenon of radioactivity was understood, most of the naturally occurring isotopes had been identified and their abundance determined, instrumentation of the necessary sensitivity had been developed, isotopic tracers were available in the required quantities and purity, and the half-lives of the long-lived radioactive isotopes were reasonably well known.There are a number of long-lived radioactive isotopes used in radiometric dating, and a variety of ways they are used to determine the ages of rocks, minerals, and organic materials.
Some of the isotopic parents, end-product daughters, and half-lives involved are listed in Table 1.
The point is that not all methods are applicable to all rocks of all ages.
One of the primary functions of the dating specialist (sometimes called a geochronologist) is to select the applicable method for the particular problem to be solved, and to design the experiment in such a way that there will be checks on the reliability of the results.
Radiometric dating is based on the decay of long-lived radioactive isotopes that occur naturally in rocks and minerals.
These parent isotopes decay to stable daughter isotopes at rates that can be measured experimentally and are effectively constant over time regardless of physical or chemical conditions.
The main point is that the ages of rock formations are rarely based on a single, isolated age measurement.