Relative dating in archaeology presumes the age of an artefact in relation and by comparison, to other objects found in its vicinity.Limits to relative dating are that it cannot provide an accurate year or a specific date of use.The Wheeler Formation has been previously dated to approximately 507 million year old, so we know the trilobite is also about 507 million years old.But, how can we determine how old a rock formation is, if it hasn’t previously been dated?One argument in favor of the absolute dating methods presented in the preceding articles is that they should work in principle.If they don't, then it's not just a question of geologists being wrong about geology, but of physicists being wrong about physics and chemists being wrong about chemistry; if the geologists are wrong, entire laws of nature will have to be rewritten.
Isotopes are important to geologists because each radioactive element decays at a constant rate, which is unique to that element.
Science, since it concerns just one universe with one set of laws, constitutes a seamless whole; we cannot unpick the single thread of absolute dating without the whole thing beginning to unravel.
Still, it has happened in the past that scientists have thought they'd got hold of a law of nature and then found out it was false.
Each original isotope, called the parent, gradually decays to form a new isotope, called the daughter.
Each isotope is identified with what is called a ‘mass number’.