Radiometric Dating

Radiometric Dating In 1896, French physicist, Henry Becquerel discovered the natural radioactive decay of uranium, opening new vistas in science (Time pp). Roughly a decade later, in 1905, British physicist Lord Rutherford, "after defining the structure of the atom," first suggested the use of radioactivity as a tool for measuring geologic time (Time pp). Then, in 1907, radiochemist B.B.

Boltwood, a professor at Yale University, published a list of geologic ages based on radioactivity, and although his "ages" have since been revised, they do show correctly that the duration of geologic time "would be measured in terms of hundreds-to-thousands of millions of years" (Time pp).

The next forty years saw a great deal of research concerning the nature and behavior of atoms, thus, leading to the development of nuclear fission and fusion as energy sources, however, a byproduct of this research has been the development and the on-going refinement of the various methods and techniques used to determine the age of Earth materials, and by 1950, precise dating had been accomplished (Time pp). The invention of the Mass Spectrometer after World War I, post-1918, led to the discovery of more than two hundred isotopes (Dating pp).

A chemical element consists of atoms with a specific number of protons in their nuclei but different atomic weights owing to variations in the number of neutrons" (Time pp). Isotopes are atoms of the same element with differing atomic weights (Time pp). "Radioactive decay is a spontaneous process in which an isotope, the parent, loses particles from its nucleus to form an isotope of a new element, the daughter" (Time pp).

The rate of decay is expressed in terms of an isotope's half-life, or rather the time for one-half of a particular radioactive isotope in a sample to decay (Time pp). Although most radioactive isotopes lose their radioactivity within a few days or years, some, however, are slow to age, and several of these are used as geologic clocks (Time pp). Dating rocks by these radioactive clocks is rather simple in theory, however, the laboratory procedures are complex (Time pp).

The numbers of parent and daughter isotopes within each specimen are determined by a variety of analytical methods, and the difficulty lies in the precision of measuring very small amounts of isotopes (Time pp). All carbon in living organisms has a constant proportion of radiocarbon to non-radioactive carbon, and after the organism's death, the amount of radiocarbon gradually decreases as it reverts to.