How does radiometric dating work

So in order to date most older fossils, scientists look for layers of igneous rock or volcanic ash above and below the fossil.Scientists date igneous rock using elements that are slow to decay, such as uranium and potassium.those that form during chemical reactions without breaking down).

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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.

From the mapped field relationships, it is a simple matter to work out a geological cross-section and the relative timing of the geologic events.

His geological cross-section may look something like Figure 2.

It takes another 4,460,000,000 years for half of the remaining sample to decay into Pb206 and then another 4,460,000,000 years for half of what’s then left to decay, and so on.

The time it takes for half of a sample to decay is called a “half-life.” By measuring radioactive half-lives, by measuring how much parent and daughter are present in any given specimen, and by making certain key assumptions, scientists believe they are able to accurately determine the age of a specimen. The question is what are the underlying key assumptions and how reliable are they?

The three key underlying assumptions are 1) the rate of decay of parent into daughter has remained constant throughout the unobservable past; 2) the specimen which we are examining hasn’t been contaminated in any way (that is, no parent or daughter has been added or taken away at any point during the unobservable past), and 3) we can determine how much parent and daughter were present at the beginning of the decay process – not all of the Pb206 present today necessarily came from decaying U238; Pb206 may have been part of the original constitution of the specimen.

If any of these assumptions are wrong, the method cannot accurately determine the age of a specimen.

This decay process leads to a more balanced nucleus and when the number of protons and neutrons balance, the atom becomes stable.

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