Radioactive dating is a method of dating rocks and minerals using radioactive isotopes.
This method is useful for igneous and metamorphic rocks, which cannot be dated by the stratigraphic correlation method used for sedimentary rocks. Some do not change with time and form stable isotopes (i.e.
If a geologist claims to be 45 years old, that is an absolute age.
Superposition: The most basic concept used in relative dating is the law of superposition.
Development of the geologic time scale and dating of formations and rocks relies upon two fundamentally different ways of telling time: relative and absolute.
Relative dating places events or rocks in their chronologic sequence or order of occurrence.
We could be sure that a mineral containing parentium originally had no daughterium.
For geological purposes, this is taken as one year.In other words there was originally 4 parts per million Parentium-123 and 0 parts per million Daughterium-123.Since there is now only 1/4 of the original amount of Parentium-123, we know that two half-lives of Parentium-123 have elapsed.In a way this field, called geochronology, is some of the purest detective work earth scientists do.There are two basic approaches: relative age dating, and absolute age dating.those that form during chemical reactions without breaking down).The unstable or more commonly known radioactive isotopes break down by radioactive decay into other isotopes.Geologists generally know the age of a rock by determining the age of the group of rocks, or formation, that it is found in.The age of formations is marked on a geologic calendar known as the geologic time scale.Imagine we have an undiscovered element, Parentium, that has a radioactive isotope, Parentium-123, which decays to stable Daughterium-123.This is the only way Parentium-123 decays, and there is no other source of Daughterium-123.