Radioactive isotopes used in dating fossils

Scientists can use certain types of fossils referred to as index fossils to assist in relative dating via correlation.

Index fossils are fossils that are known to only occur within a very specific age range.

Absolute dating is used to determine a precise age of a fossil by using radiometric dating to measure the decay of isotopes, either within the fossil or more often the rocks associated with it.

radioactive isotopes used in dating fossils-42

We define the rate of this radioactive decay in half-lives.

If a radioactive isotope is said to have a half-life of 5,000 years that means after 5,000 years exactly half of it will have decayed from the parent isotope into the daughter isotopes.

Studying the layers of rock or strata can also be useful. If a layer of rock containing the fossil is higher up in the sequence that another layer, you know that layer must be younger in age. This can often be complicated by the fact that geological forces can cause faulting and tilting of rocks.

Absolute dating is used to determine a precise age of a rock or fossil through radiometric dating methods.

All ordinary matter is made up of combinations of chemical elements, each with its own atomic number, indicating the number of protons in the atomic nucleus.

Additionally, elements may exist in different isotopes, with each isotope of an element differing in the number of neutrons in the nucleus.These isotopes break down at a constant rate over time through radioactive decay.By measuring the ratio of the amount of the original (parent) isotope to the amount of the (daughter) isotopes that it breaks down into an age can be determined.Carbon-14, the radioactive isotope of carbon used in carbon dating has a half-life of 5730 years, so it decays too fast.It can only be used to date fossils younger than about 75,000 years.Among the best-known techniques are radiocarbon dating, potassium-argon dating and uranium-lead dating.

Tags: , ,