Two broad categories of classification methods are relative dating and absolute dating.Though using similar methods, these two techniques differ in certain ways that will be discussed in this article.
When ‘parent’ uranium-238 decays, for example, it produces subatomic particles, energy and ‘daughter’ lead-206.
Isotopes are important to geologists because each radioactive element decays at a constant rate, which is unique to that element.
There are many methods employed by these scientists, interested in the old, to get to know the age of items.
It is possible to tell the number of years ago a particular rock or archeological site had been formed.
The atoms of some chemical elements have different forms, called isotopes.
These break down over time in a process scientists call radioactive decay.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’.In micro paleontological analysis, you may not need the general view if all you are trying to establish is which of two foraminifera is the older.However, if you are mapping an area, if you want to fit your local intuition into the regional picture, you could not do without absolute dating.You will find the essential part of the answer to your question in this "Socratic" link: What remains to be seen is: when should you use the one rather than the other.