Disadvantages of relative dating
Absolute dating, on the other hand is capable of telling the exact age of an item using carbon dating and many other techniques that were not there in earlier times.Relative dating makes use of the common sense principle that in a deposition of layers. Both 10Be and 36Cl are formed as charged ions in the ionosphere. Thus each annual layer starts 10Be and 36Cl poor, becomes 10Be and 36Cl rich, and then becomes poor again. Although what is said above is true, this is an exceedingly minor effect. This depletion is a temperature dependent process so in winter the precipitation is more enriched in H2(16O) than is the case in the summer. As the water vapor travels towards the poles it becomes increasingly poorer in H2(18O) since the heavier molecules tend to precipitate out first. This process also depends on the relative temperatures of different years, which allows comparison with paleoclimatic data. Thus, each annual layer starts 18O rich, becomes 18O poor, and ends up 18O rich.
For similar reasons the ratio of deuterium to hydrogen acts the same way.The most popular method of radio dating is radio carbon dating which is possible because of the presence of C-14, an unstable isotope of carbon.C-14 has a half life of 5730 years which means that only half of the original amount is left in the fossil after 5730 years while half of the remaining amount is left after another 5730 years.It is clear then that absolute dating is based upon physical and chemical properties of artifacts that provide a clue regarding the true age.This is possible because properties of rock formations are closely associated with the age of the artifacts found trapped within them.