Thousands of comparisons between absolute ages and relative time relationships have proven that radiometric age dating works.
Absolute age dating for rocks are calculated by
Once these quantities have been measured, the half-life of the radioactive isotope is used to calculate absolute age of the granite.
How to find absolute dating
Geology, an absolute age is a quantitative measurement of how old something is, or how long ago it occurred, usually expressed in terms of years.
How to calculate absolute age dating
Age dates have confirmed the basic principles of relative timefor example, a uraniumlead date from a dike that intrudes into an older rock always yields an absolute age date that is younger than the absolute age date of the enclosing rock.
Have calculated the beginning and ending dates for the eons, eras, periods, and epochs of the geologic time scale, and major geologic events.
Other decay reactions that are used to calculate absolute age are carbon14 to nitrogen14, potassium40 to argon40, rubidium87 to strontium87, thorium232 to lead208, and uranium235 to lead207.
Accuracy of isotopic dating is affected by:1) the limits of our abilities to determine decay constants.