Radioactive Dating Methods.  Carbon-14 method is the most common method and is used for dating the age of once living material less than about 60,000 years old.  Carbon -14 (C14) is a radioisotope found in all living material.  It has a half life of 5,750 years, which means that after 5,750 years it has half of the C14 that it originally had.  (The original amount of C14 in a living item at death is about 1 for every 1 trillion normal carbon atoms, C12.)  After about 60,000 years there is so little Carbon 14 left in the tissue that it cannot be accurately measured.  Articles dating back between 40,000 and 60,000 years ago have so little of their original radio-carbon in them (maybe 0.1%) that it is nearly impossible to accurately distinguish from background levels.   However for time periods less than 50,000 years, C14 dating is a viable option.  Again, it is for once living material.  It does not work for rocks and minerals.

Other methods of Radioactive Dating can be used for non-living material and for longer periods.  For example Uranium-235 has a half life of 700 million years and Uranium-238 has a half life of 4,400 million years!  These methods are used in dating non-living material such as rocks and minerals.  The dating gives the time since the rock/mineral was formed.       Return