How importent are dating methods
Several dating methods exist, depending on different criteria and techniques, and some very well known examples of disciplines using such techniques are, for example, history, archaeology, geology, paleontology, astronomy and even forensic science, since in the latter it is sometimes necessary to investigate the moment in the past in which the death of a cadaver occurred.Relative dating methods are unable to determine the absolute age of an object or event, but can determine the impossibility of a particular event happening before or after another event of which the absolute date is well known.
On the other level, the exact years may not be known, but it is known that one feature is earlier or later in relation to another; this is typically the case on an excavation, where the different archaeological strata allow objects found to be placed in a relative historical framework.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.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.If we knew the precise length of reign for every Egyptian king, chronology would be no problem.
However, we do not even know the number of kings for all periods, and there is also the possibility that reigns overlapped by coregency or in times of political disunity.
In the archaeology of part-literate societies, dating may be said to operate on two levels: the absolute exactness found in political history or 'history event-by-event', and the less precise or relative chronology, as found in social and economic history, where life can be seen to change with less precision over time.
The contrast might also be drawn between two 'dimensions', the historical, and the archaeological, corresponding roughly to the short-term and long-term history envisaged by Fernand Braudel.
The most common relative dating method is stratigraphy.
Other methods include fluorine dating, nitrogen dating, association with bones of extinct fauna, association with certain pollen profiles, association with geological features such as beaches, terraces and river meanders, and the establishment of cultural seriations.
Cultural seriations are based on typologies, in which artifacts that are numerous across a wide variety of sites and over time, like pottery or stone tools.