Line graphs and radiometric dating
Use this graph (you can download a larger version as a PDF to print) to answer the questions below.
A related article on the age of the earth and geologic ages presented the current best known values for these dates: Ages.
This section may be omitted if readers do not wish to follow the math (although the math used here is nothing beyond what is typically taught in a good high-school math analysis class).
Use this plot to answer the questions below about reading points from a line.
Uranium-thorium dating, for instance, can be used to date specimens up to about 500,000 years old (since the half-life of the U-Th decay is 75,000 years), but Rubidium-Strontium dating can be used to date specimens billions of years old (since the half-life of the Rb-Sr decay is 48.8 billion years).
The following is a brief technical description of how scientists determine dates with radiometric schemes.
Also, such a calculation does not provide us with any statistical error margin to double-check the result.
Fortunately, scientists have developed several methods that not only circumvent the difficulty of not knowing the original amounts, but also provide a very reliable means of statistical validity checking.