Absolute chronometric dating

Geologists use radiocarbon to date such materials as wood and pollen trapped in sediment, which indicates the date of the sediment itself.The table below shows characteristics of some common radiometric dating methods.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.They use absolute dating methods, sometimes called numerical dating, to give rocks an actual date, or date range, in number of years.This is different to relative dating, which only puts geological events in time Most absolute dates for rocks are obtained with radiometric methods.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.

All radiometric dating methods measure isotopes in some way.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.Because of their unique decay rates, different elements are used for dating different age ranges.For example, the decay of potassium-40 to argon-40 is used to date rocks older than 20,000 years, and the decay of uranium-238 to lead-206 is used for rocks older than 1 million years.