Elements of radioactive dating
Do some reading on "radioactive dating" or "radiometric dating" for more details - for example, in the Wikipedia.
Radioactive elements tend to degrade or give off radiation at a constant rate.
Radioactive elements decay according to a known pattern.
Scientists can use the elements of that pattern to determine when the rock with the original radioactive element was formed.
"Radiometric dating - the process of determining the age of rocks from the decay of their radioactive elements" Wiens, RC 2002, Radiometric Dating A Christian Perspective, 'Science in Christian Perspective', The American Science Affiliation, viewed 8 September 2009, The evidence is mainly from radioactive decay - measuring the ratio of different elements and isotopes.Radiometric dating--the process of determining the age of rocks from the decay of their radioactive elements--has been in widespread use for over half a century.Relative dating is used to determine the relative ages of geologic strata, artifacts, historical events, etc.Play a game that tests your ability to match the percentage of the dating element that remains to the age of the object.Radioactive elements are used to date the age of rocks.