Based on a discipline of geology called stratigraphy, rock layers are used to decipher the sequence of historical geological events.
Relative techniques can determine the sequence of events but not the precise date of an event, making these methods unreliable.
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.
Today, many different radioactive elements have been used, but the most famous absolute dating method is radiocarbon dating, which uses the isotope C.
This isotope, which can be found in organic materials and can be used only to date organic materials, has been incorrectly used by many to make dating assumptions for non-organic material such as stone buildings.
This method is based on the fact that when a material is heated or exposed to sunlight, electrons are released and some of them are trapped inside the item.
Once you heat this item again using high temperatures, the trapped electrons become excited and recombine with the item’s material.This process frees energy in the form of light, which can be measured.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.Another absolute dating method is thermoluminescence, which dates the last time an item was heated.It is the only method that can be used to date rocks, pottery and minerals for dates that are approximately between 300 to 10,000 years old.