Their method, a type of radiometric dating called uranium-lead (U-Pb) dating, relies on the fact that uranium isotopes radioactively decay to form lead isotopes.

By comparing the amount of each isotope in a sample, the age of the sample can be calculated.

Learn about important events in the history of living organism on Earth, up to and including the appearance of humans.

In many cases it is quite difficult to prove whether one method is superior to another: and in this regard, the only way of doing so is to closely examine how each method works and try to find fault with it.

In regard to the radiometric dating of rocks, it is known that various different radiometric methods often yield quite discordant dates for the same rock, thus proving that they cannot all be correct.

The methods work because radioactive elements are unstable, and they are always trying to move to a more stable state. This process by which an unstable atomic nucleus loses energy by releasing radiation is called radioactive decay.

The thing that makes this decay process so valuable for determining the age of an object is that each radioactive isotope decays at its own fixed rate, which is expressed in terms of its half-life.

So, if you know the radioactive isotope found in a substance and the isotope's half-life, you can calculate the age of the substance. Well, a simple explanation is that it is the time required for a quantity to fall to half of its starting value.

So, you might say that the 'full-life' of a radioactive isotope ends when it has given off all of its radiation and reaches a point of being non-radioactive.The textbooks speak of the radiometric dating techniques, and the dates themselves, as factual information.Far from being data, these dates are actually interpretations of the data.There are at least 67 different uniformitarian (the present is the key to the past) methods of dating the earth other than long-age radiometric dating: each of which yield ages of less than 500 million years.Yet all these other science-based methods that point to a much younger age than 4.5 billion years for earth's age are ignored or rejected by evolution-believing people with degrees from college who apparently think that nobody (of importance) made them. Yet when asked why they reject all but the oldest science-based dating methods, the answer often given is that (they think) long-age radiometric dating is more reliable and that science settled the matter of the earth's age many years ago.This tutorial covers some of the primary techniques of "dating" (in the geological, not the romantic, sense!