The Geologic Time Scale was originally laid out using relative dating principles. Numerical ages have been added to the Geologic Time Scale since the advent of radioactive age-dating techniques. Many minerals contain radioactive isotopes. It illustrates how the amount of a radioactive parent isotope decreases with time. This amount is a percentage of the original parent amount.
Time is expressed in half-lives.
Experiment by dragging on the graph. Note that this half-life can be obtained from the graph at the point where the decay and growth curves cross. Determine the half-lives for the other three isotopes and enter your estimate into the text fields below each graph. Note the differences in scale between the various graphs Radiocarbon Dating The radiocarbon dating method was developed in the 1940's by Willard F. Libby and a team of scientists at the University of Chicago. It subsequently evolved into the most powerful method of dating late Pleistocene and Holocene artifacts and geologic events up to about 50,000 years in age.