Dating by thermoluminescence
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.
A consequence of this approach to the Phanerozoic periods is that the ages of their beginnings and ends can change from time to time as the absolute age of the chosen rock sequences, which define them, is more precisely determined.
The set of rocks (sedimentary, igneous or metamorphic) that formed during a geologic period is known as a system, so for example the 'Jurassic System' of rocks was formed during the 'Jurassic Period' (between 201 and 145 million years ago).
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.
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.
These periods form elements of a hierarchy of divisions into which geologists have split the Earth's history.
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.
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.
This method includes carbon dating and thermoluminescence.
The absolute dating method first appeared in 1907 with Lord Rutherford and Professor Boltwood at Yale University, but wasn’t accepted until the 1950s.