Scientific dating of artifacts
The absolute dating method first appeared in 1907 with Lord Rutherford and Professor Boltwood at Yale University, but wasn’t accepted until the 1950s.The first method was based on radioactive elements whose property of decay occurs at a constant rate, known as the half-life of the isotope.The half-life of C is approximately 5730 years, which is too short for this method to be used to date material millions of years old.The isotope of Potassium-40, which has a half-life of 1.25 Billion years, can be used for such long measurements.
Methods fall into one of two categories: relative or absolute.
Before more precise absolute dating tools were possible, researchers used a variety of comparative approaches called relative dating.
These methods — some of which are still used today — provide only an approximate spot within a previously established sequence: Think of it as ordering rather than dating.
The style of the artefact and its archaeology location stratigraphically are required to arrive at a relative date.
For example, if an artefact, say an oil lamp, is found co-located on the same floor of a governor's dwelling, and that floor can be dated in archaeology terms by reason of the patterns employed in the mosaic, then it is assumed that in relation to the floor that the lamp is of the same age.